[PATCH] staging: comedi: drivers: use comedi_fc.h cmdtest helpers

[H Hartley Sweeten]

Use the cfc_check_trigger_src() helper for Step 1 in all the
driver cmdtest functions.

Use the cfc_check_trigger_is_unique() helper for Step 2 in all
the driver cmdtest functions. Note that single source triggers
do not need to be checked, they are already unique if they pass
Step 1.

The Step 2 checks should also not modify the trigger sources.
Remove the couple cases that are.

For aesthetic reasons, change the comments in the cmdtest
functions for steps 1 and 2 so that they are all the same.

Signed-off-by: H Hartley Sweeten <hsweeten at visionengravers.com>
Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
Cc: Ian Abbott <abbotti at mev.co.uk>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---

This patch is quite large. If needed I can try splitting it up.

 drivers/staging/comedi/drivers/8255.c              |  37 ++---
 .../comedi/drivers/addi-data/hwdrv_apci3120.c      |  55 ++------
 .../comedi/drivers/addi-data/hwdrv_apci3200.c      |  67 +++------
 drivers/staging/comedi/drivers/adl_pci9111.c       |   2 +-
 drivers/staging/comedi/drivers/adl_pci9118.c       |  73 +++-------
 drivers/staging/comedi/drivers/adv_pci1710.c       |   2 +-
 drivers/staging/comedi/drivers/amplc_dio200.c      |  51 ++-----
 drivers/staging/comedi/drivers/amplc_pc236.c       |  36 ++---
 drivers/staging/comedi/drivers/amplc_pci224.c      |  60 +++-----
 drivers/staging/comedi/drivers/amplc_pci230.c      | 146 ++++++--------------
 drivers/staging/comedi/drivers/cb_das16_cs.c       |  50 ++-----
 drivers/staging/comedi/drivers/cb_pcidas.c         | 102 ++++----------
 drivers/staging/comedi/drivers/cb_pcidas64.c       | 106 ++++-----------
 drivers/staging/comedi/drivers/cb_pcidda.c         |  59 ++------
 drivers/staging/comedi/drivers/comedi_parport.c    |  37 ++---
 drivers/staging/comedi/drivers/comedi_test.c       |  43 ++----
 drivers/staging/comedi/drivers/das16.c             |  52 +++----
 drivers/staging/comedi/drivers/das16m1.c           |  44 ++----
 drivers/staging/comedi/drivers/das1800.c           |  58 +++-----
 drivers/staging/comedi/drivers/das800.c            |  44 ++----
 drivers/staging/comedi/drivers/dmm32at.c           |  51 +++----
 drivers/staging/comedi/drivers/dt2814.c            |  42 ++----
 drivers/staging/comedi/drivers/dt282x.c            |  89 +++---------
 drivers/staging/comedi/drivers/dt3000.c            |  36 ++---
 drivers/staging/comedi/drivers/gsc_hpdi.c          |  41 ++----
 drivers/staging/comedi/drivers/me4000.c            | 117 ++++------------
 drivers/staging/comedi/drivers/ni_6527.c           |  37 ++---
 drivers/staging/comedi/drivers/ni_65xx.c           |  37 ++---
 drivers/staging/comedi/drivers/ni_at_a2150.c       |  44 ++----
 drivers/staging/comedi/drivers/ni_atmio16d.c       |  48 ++-----
 drivers/staging/comedi/drivers/ni_labpc.c          |  52 ++-----
 drivers/staging/comedi/drivers/ni_mio_common.c     | 151 ++++++---------------
 drivers/staging/comedi/drivers/ni_pcidio.c         |  47 ++-----
 drivers/staging/comedi/drivers/ni_tiocmd.c         |  61 +++------
 drivers/staging/comedi/drivers/pcl711.c            |  43 ++----
 drivers/staging/comedi/drivers/pcl812.c            |  45 ++----
 drivers/staging/comedi/drivers/pcl816.c            |  46 ++-----
 drivers/staging/comedi/drivers/pcl818.c            |  41 ++----
 drivers/staging/comedi/drivers/pcm_common.c        |  56 ++------
 drivers/staging/comedi/drivers/quatech_daqp_cs.c   |  55 +++-----
 drivers/staging/comedi/drivers/rtd520.c            |  55 ++------
 drivers/staging/comedi/drivers/s626.c              |  60 +++-----
 drivers/staging/comedi/drivers/skel.c              |  68 ++++------
 drivers/staging/comedi/drivers/usbdux.c            | 130 ++++++------------
 drivers/staging/comedi/drivers/usbduxfast.c        |  62 +++------
 drivers/staging/comedi/drivers/usbduxsigma.c       | 125 +++++------------
 46 files changed, 766 insertions(+), 1997 deletions(-)

diff --git a/drivers/staging/comedi/drivers/8255.c b/drivers/staging/comedi/drivers/8255.c
index e2506dd..a256622 100644
--- a/drivers/staging/comedi/drivers/8255.c
+++ b/drivers/staging/comedi/drivers/8255.c
@@ -82,6 +82,8 @@ I/O port base address can be found in the output of 'lspci -v'.
 
 #include <linux/ioport.h>
 #include <linux/slab.h>
+
+#include "comedi_fc.h"
 #include "8255.h"
 
 #define _8255_SIZE	4
@@ -229,39 +231,20 @@ static int subdev_8255_cmdtest(struct comedi_device *dev,
 			       struct comedi_cmd *cmd)
 {
 	int err = 0;
-	unsigned int tmp;
-
-	/* step 1 */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
 
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_FOLLOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2 */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c
index d61fce0..f406dfb 100644
--- a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c
+++ b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c
@@ -479,57 +479,26 @@ int i_APCI3120_CommandTestAnalogInput(struct comedi_device *dev, struct comedi_s
 	struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;		/*  divisor1,divisor2; */
 
-	/*  step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-		cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-
-	if (cmd->convert_src != TRIG_TIMER)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
 
-	if (cmd->scan_end_src != TRIG_COUNT) {
-		cmd->scan_end_src = TRIG_COUNT;
-		err++;
-	}
-
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c
index f6f5092..9110fc9 100644
--- a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c
+++ b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c
@@ -2560,7 +2560,6 @@ int i_APCI3200_CommandTestAnalogInput(struct comedi_device *dev, struct comedi_s
 {
 
 	int err = 0;
-	int tmp;		/*  divisor1,divisor2; */
 	unsigned int ui_ConvertTime = 0;
 	unsigned int ui_ConvertTimeBase = 0;
 	unsigned int ui_DelayTime = 0;
@@ -2571,41 +2570,32 @@ int i_APCI3200_CommandTestAnalogInput(struct comedi_device *dev, struct comedi_s
 	int i_Cpt = 0;
 	double d_ConversionTimeForAllChannels = 0.0;
 	double d_SCANTimeNewUnit = 0.0;
-	/*  step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
-	/* if(i_InterruptFlag==0) */
-	if (s_BoardInfos[dev->minor].i_InterruptFlag == 0) {
-		err++;
-		/*           printk("\nThe interrupt should be enabled\n"); */
-	}
+
+	/* Step 1 : check if triggers are trivially valid */
+
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
+
+	if (s_BoardInfos[dev->minor].i_InterruptFlag == 0)
+		err |= -ENIVAL;
+
 	if (err) {
 		i_APCI3200_Reset(dev);
 		return 1;
 	}
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT) {
-		err++;
-	}
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(&cmd->start_src);
+	err |= cfc_check_trigger_is_unique(&cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(&cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
+
 	if (cmd->start_src == TRIG_EXT) {
 		i_TriggerEdge = cmd->start_arg & 0xFFFF;
 		i_Triggermode = cmd->start_arg >> 16;
@@ -2619,21 +2609,6 @@ int i_APCI3200_CommandTestAnalogInput(struct comedi_device *dev, struct comedi_s
 		}
 	}
 
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-		cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-
-	if (cmd->convert_src != TRIG_TIMER)
-		err++;
-
-	if (cmd->scan_end_src != TRIG_COUNT) {
-		cmd->scan_end_src = TRIG_COUNT;
-		err++;
-	}
-
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
-
 	if (err) {
 		i_APCI3200_Reset(dev);
 		return 2;
diff --git a/drivers/staging/comedi/drivers/adl_pci9111.c b/drivers/staging/comedi/drivers/adl_pci9111.c
index 91efaa4..a87192a 100644
--- a/drivers/staging/comedi/drivers/adl_pci9111.c
+++ b/drivers/staging/comedi/drivers/adl_pci9111.c
@@ -332,7 +332,7 @@ static int pci9111_ai_do_cmd_test(struct comedi_device *dev,
 	int range, reference;
 	int i;
 
-	/* Step 1 : check if trigger are trivialy valid */
+	/* Step 1 : check if triggers are trivially valid */
 
 	error |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
 	error |= cfc_check_trigger_src(&cmd->scan_begin_src,
diff --git a/drivers/staging/comedi/drivers/adl_pci9118.c b/drivers/staging/comedi/drivers/adl_pci9118.c
index f7b254d..06ff65c 100644
--- a/drivers/staging/comedi/drivers/adl_pci9118.c
+++ b/drivers/staging/comedi/drivers/adl_pci9118.c
@@ -1102,7 +1102,7 @@ static int pci9118_ai_cmdtest(struct comedi_device *dev,
 	int tmp;
 	unsigned int divisor1 = 0, divisor2 = 0;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
 	err |= cfc_check_trigger_src(&cmd->start_src,
 					TRIG_NOW | TRIG_EXT | TRIG_INT);
@@ -1124,70 +1124,31 @@ static int pci9118_ai_cmdtest(struct comedi_device *dev,
 	if (err)
 		return 1;
 
-	/*
-	 * step 2:
-	 * make sure trigger sources are
-	 * unique and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW &&
-	    cmd->start_src != TRIG_INT && cmd->start_src != TRIG_EXT) {
-		cmd->start_src = TRIG_NOW;
-		err++;
-	}
-
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_INT &&
-	    cmd->scan_begin_src != TRIG_FOLLOW) {
-		cmd->scan_begin_src = TRIG_FOLLOW;
-		err++;
-	}
-
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW) {
-		cmd->convert_src = TRIG_TIMER;
-		err++;
-	}
-
-	if (cmd->scan_end_src != TRIG_COUNT) {
-		cmd->scan_end_src = TRIG_COUNT;
-		err++;
-	}
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
 
-	if (cmd->stop_src != TRIG_NONE &&
-	    cmd->stop_src != TRIG_COUNT &&
-	    cmd->stop_src != TRIG_INT && cmd->stop_src != TRIG_EXT) {
-		cmd->stop_src = TRIG_COUNT;
-		err++;
-	}
+	/* Step 2b : and mutually compatible */
 
-	if (cmd->start_src == TRIG_EXT && cmd->scan_begin_src == TRIG_EXT) {
-		cmd->start_src = TRIG_NOW;
-		err++;
-	}
+	if (cmd->start_src == TRIG_EXT && cmd->scan_begin_src == TRIG_EXT)
+		err |= -EINVAL;
 
-	if (cmd->start_src == TRIG_INT && cmd->scan_begin_src == TRIG_INT) {
-		cmd->start_src = TRIG_NOW;
-		err++;
-	}
+	if (cmd->start_src == TRIG_INT && cmd->scan_begin_src == TRIG_INT)
+		err |= -EINVAL;
 
 	if ((cmd->scan_begin_src & (TRIG_TIMER | TRIG_EXT)) &&
-	    (!(cmd->convert_src & (TRIG_TIMER | TRIG_NOW)))) {
-		cmd->convert_src = TRIG_TIMER;
-		err++;
-	}
+	    (!(cmd->convert_src & (TRIG_TIMER | TRIG_NOW))))
+		err |= -EINVAL;
 
 	if ((cmd->scan_begin_src == TRIG_FOLLOW) &&
-	    (!(cmd->convert_src & (TRIG_TIMER | TRIG_EXT)))) {
-		cmd->convert_src = TRIG_TIMER;
-		err++;
-	}
+	    (!(cmd->convert_src & (TRIG_TIMER | TRIG_EXT))))
+		err |= -EINVAL;
 
-	if (cmd->stop_src == TRIG_EXT && cmd->scan_begin_src == TRIG_EXT) {
-		cmd->stop_src = TRIG_COUNT;
-		err++;
-	}
+	if (cmd->stop_src == TRIG_EXT && cmd->scan_begin_src == TRIG_EXT)
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/adv_pci1710.c b/drivers/staging/comedi/drivers/adv_pci1710.c
index 0fd021062..def37bc 100644
--- a/drivers/staging/comedi/drivers/adv_pci1710.c
+++ b/drivers/staging/comedi/drivers/adv_pci1710.c
@@ -1046,7 +1046,7 @@ static int pci171x_ai_cmdtest(struct comedi_device *dev,
 	int tmp;
 	unsigned int divisor1 = 0, divisor2 = 0;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
 	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
 	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
diff --git a/drivers/staging/comedi/drivers/amplc_dio200.c b/drivers/staging/comedi/drivers/amplc_dio200.c
index b7cfc13a..08f3052 100644
--- a/drivers/staging/comedi/drivers/amplc_dio200.c
+++ b/drivers/staging/comedi/drivers/amplc_dio200.c
@@ -210,6 +210,7 @@ order they appear in the channel list.
 
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "8255.h"
 #include "8253.h"
 
@@ -771,52 +772,24 @@ dio200_subdev_intr_cmdtest(struct comedi_device *dev,
 			   struct comedi_subdevice *s, struct comedi_cmd *cmd)
 {
 	int err = 0;
-	unsigned int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= (TRIG_NOW | TRIG_INT);
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= (TRIG_COUNT | TRIG_NONE);
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-		   compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* these tests are true if more than one _src bit is set */
-	if ((cmd->start_src & (cmd->start_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
-		err++;
-	if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
-		err++;
-	if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/amplc_pc236.c b/drivers/staging/comedi/drivers/amplc_pc236.c
index a957cd8..eacb5e4 100644
--- a/drivers/staging/comedi/drivers/amplc_pc236.c
+++ b/drivers/staging/comedi/drivers/amplc_pc236.c
@@ -56,6 +56,7 @@ unused.
 
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "8255.h"
 #include "plx9052.h"
 
@@ -313,39 +314,20 @@ static int pc236_intr_cmdtest(struct comedi_device *dev,
 			      struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 
-	/* step 1 */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_FOLLOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: ignored */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/amplc_pci224.c b/drivers/staging/comedi/drivers/amplc_pci224.c
index 365f911..1f65ec4 100644
--- a/drivers/staging/comedi/drivers/amplc_pci224.c
+++ b/drivers/staging/comedi/drivers/amplc_pci224.c
@@ -720,53 +720,31 @@ pci224_ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 	int err = 0;
 	unsigned int tmp;
 
-	/* Step 1: make sure trigger sources are trivially valid. */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT | TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_EXT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_EXT | TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src,
+					TRIG_COUNT | TRIG_EXT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* Step 2: make sure trigger sources are unique and mutually
-	 * compatible. */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* these tests are true if more than one _src bit is set */
-	if ((cmd->start_src & (cmd->start_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
-		err++;
-	if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
-		err++;
-	if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
 
-	/* There's only one external trigger signal (which makes these
-	 * tests easier).  Only one thing can use it. */
+	/* Step 2b : and mutually compatible */
+
+	/*
+	 * There's only one external trigger signal (which makes these
+	 * tests easier).  Only one thing can use it.
+	 */
 	tmp = 0;
 	if (cmd->start_src & TRIG_EXT)
 		tmp++;
@@ -775,7 +753,7 @@ pci224_ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 	if (cmd->stop_src & TRIG_EXT)
 		tmp++;
 	if (tmp > 1)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/amplc_pci230.c b/drivers/staging/comedi/drivers/amplc_pci230.c
index 4c9f131..bd8fb87 100644
--- a/drivers/staging/comedi/drivers/amplc_pci230.c
+++ b/drivers/staging/comedi/drivers/amplc_pci230.c
@@ -193,6 +193,7 @@ for (or detection of) various hardware problems added by Ian Abbott.
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 #include "8255.h"
 
@@ -958,23 +959,11 @@ static int pci230_ao_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	unsigned int tmp;
 
-	/* cmdtest tests a particular command to see if it is valid.
-	 * Using the cmdtest ioctl, a user can create a valid cmd
-	 * and then have it executes by the cmd ioctl.
-	 *
-	 * cmdtest returns 1,2,3,4 or 0, depending on which tests
-	 * the command passes. */
+	/* Step 1 : check if triggers are trivially valid */
 
-	/* Step 1: make sure trigger sources are trivially valid.
-	 * "invalid source" returned by comedilib to user mode process
-	 * if this fails. */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT);
 
-	tmp = cmd->scan_begin_src;
+	tmp = TRIG_TIMER | TRIG_INT;
 	if ((thisboard->min_hwver > 0) && (devpriv->hwver >= 2)) {
 		/*
 		 * For PCI230+ hardware version 2 onwards, allow external
@@ -990,46 +979,23 @@ static int pci230_ao_cmdtest(struct comedi_device *dev,
 		 * scan_begin_src==TRIG_EXT support to be a bonus rather than a
 		 * guarantee!
 		 */
-		cmd->scan_begin_src &= TRIG_TIMER | TRIG_INT | TRIG_EXT;
-	} else {
-		cmd->scan_begin_src &= TRIG_TIMER | TRIG_INT;
+		tmp |= TRIG_EXT;
 	}
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, tmp);
 
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* Step 2: make sure trigger sources are unique and mutually compatible
-	 * "source conflict" returned by comedilib to user mode process
-	 * if this fails. */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* these tests are true if more than one _src bit is set */
-	if ((cmd->start_src & (cmd->start_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
-		err++;
-	if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
-		err++;
-	if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -1610,75 +1576,45 @@ static int pci230_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	unsigned int tmp;
 
-	/* cmdtest tests a particular command to see if it is valid.
-	 * Using the cmdtest ioctl, a user can create a valid cmd
-	 * and then have it executes by the cmd ioctl.
-	 *
-	 * cmdtest returns 1,2,3,4,5 or 0, depending on which tests
-	 * the command passes. */
+	/* Step 1 : check if triggers are trivially valid */
 
-	/* Step 1: make sure trigger sources are trivially valid.
-	 * "invalid source" returned by comedilib to user mode process
-	 * if this fails. */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
 
-	tmp = cmd->scan_begin_src;
-	/* Unfortunately, we cannot trigger a scan off an external source
-	 * on the PCI260 board, since it uses the PPIC0 (DIO) input, which
-	 * isn't present on the PCI260.  For PCI260+ we can use the
-	 * EXTTRIG/EXTCONVCLK input on pin 17 instead. */
+	tmp = TRIG_FOLLOW | TRIG_TIMER | TRIG_INT;
 	if ((thisboard->have_dio) || (thisboard->min_hwver > 0)) {
-		cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER | TRIG_INT
-		    | TRIG_EXT;
-	} else {
-		cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER | TRIG_INT;
+		/*
+		 * Unfortunately, we cannot trigger a scan off an external
+		 * source on the PCI260 board, since it uses the PPIC0 (DIO)
+		 * input, which isn't present on the PCI260.  For PCI260+
+		 * we can use the EXTTRIG/EXTCONVCLK input on pin 17 instead.
+		 */
+		tmp |= TRIG_EXT;
 	}
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_INT | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, tmp);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* Step 2: make sure trigger sources are unique and mutually compatible
-	 * "source conflict" returned by comedilib to user mode process
-	 * if this fails. */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* these tests are true if more than one _src bit is set */
-	if ((cmd->start_src & (cmd->start_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
-		err++;
-	if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
-		err++;
-	if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
-	/* If scan_begin_src is not TRIG_FOLLOW, then a monostable will be
-	 * set up to generate a fixed number of timed conversion pulses. */
+	/*
+	 * If scan_begin_src is not TRIG_FOLLOW, then a monostable will be
+	 * set up to generate a fixed number of timed conversion pulses.
+	 */
 	if ((cmd->scan_begin_src != TRIG_FOLLOW)
 	    && (cmd->convert_src != TRIG_TIMER))
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/cb_das16_cs.c b/drivers/staging/comedi/drivers/cb_das16_cs.c
index a3d53ba..6d81d8b 100644
--- a/drivers/staging/comedi/drivers/cb_das16_cs.c
+++ b/drivers/staging/comedi/drivers/cb_das16_cs.c
@@ -46,6 +46,7 @@ Status: experimental
 #include <pcmcia/cistpl.h>
 #include <pcmcia/ds.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 #define DAS16CS_SIZE			18
@@ -169,47 +170,26 @@ static int das16cs_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and
-	 * mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/cb_pcidas.c b/drivers/staging/comedi/drivers/cb_pcidas.c
index 4dd87c2..de21a26 100644
--- a/drivers/staging/comedi/drivers/cb_pcidas.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas.c
@@ -803,58 +803,35 @@ static int cb_pcidas_ai_cmdtest(struct comedi_device *dev,
 	int tmp;
 	int i, gain, start_chan;
 
-	/* step 1: trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_NOW | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
-	/*  make sure trigger sources are compatible with each other */
 	if (cmd->scan_begin_src == TRIG_FOLLOW && cmd->convert_src == TRIG_NOW)
-		err++;
+		err |= -EINVAL;
 	if (cmd->scan_begin_src != TRIG_FOLLOW && cmd->convert_src != TRIG_NOW)
-		err++;
+		err |= -EINVAL;
 	if (cmd->start_src == TRIG_EXT &&
 	    (cmd->convert_src == TRIG_EXT || cmd->scan_begin_src == TRIG_EXT))
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
@@ -1079,43 +1056,24 @@ static int cb_pcidas_ao_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/cb_pcidas64.c b/drivers/staging/comedi/drivers/cb_pcidas64.c
index 7168883..0472a90 100644
--- a/drivers/staging/comedi/drivers/cb_pcidas64.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas64.c
@@ -2108,74 +2108,50 @@ static int ai_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 		      struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 	unsigned int tmp_arg, tmp_arg2;
 	int i;
 	int aref;
 	unsigned int triggers;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
 
-	tmp = cmd->scan_begin_src;
 	triggers = TRIG_TIMER;
 	if (board(dev)->layout == LAYOUT_4020)
 		triggers |= TRIG_OTHER;
 	else
 		triggers |= TRIG_FOLLOW;
-	cmd->scan_begin_src &= triggers;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, triggers);
 
-	tmp = cmd->convert_src;
 	triggers = TRIG_TIMER;
 	if (board(dev)->layout == LAYOUT_4020)
 		triggers |= TRIG_NOW;
 	else
 		triggers |= TRIG_EXT;
-	cmd->convert_src &= triggers;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, triggers);
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_EXT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src,
+					TRIG_COUNT | TRIG_EXT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/*  uniqueness check */
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_OTHER &&
-	    cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT &&
-	    cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
-	/*  compatibility check */
 	if (cmd->convert_src == TRIG_EXT && cmd->scan_begin_src == TRIG_TIMER)
-		err++;
+		err |= -EINVAL;
 	if (cmd->stop_src != TRIG_COUNT &&
 	    cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_EXT)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
@@ -3466,55 +3442,33 @@ static int ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 		      struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 	unsigned int tmp_arg;
 	int i;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/*  uniqueness check */
-	if (cmd->start_src != TRIG_INT && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+
+	/* Step 2b : and mutually compatible */
 
-	/*  compatibility check */
 	if (cmd->convert_src == TRIG_EXT && cmd->scan_begin_src == TRIG_TIMER)
-		err++;
+		err |= -EINVAL;
 	if (cmd->stop_src != TRIG_COUNT &&
 	    cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_EXT)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/cb_pcidda.c b/drivers/staging/comedi/drivers/cb_pcidda.c
index ad9f3a3..aef946d 100644
--- a/drivers/staging/comedi/drivers/cb_pcidda.c
+++ b/drivers/staging/comedi/drivers/cb_pcidda.c
@@ -48,6 +48,7 @@ Please report success/failure with other different cards to
 
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "8255.h"
 
 /* PCI vendor number of ComputerBoards */
@@ -247,56 +248,26 @@ static int cb_pcidda_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* cmdtest tests a particular command to see if it is valid.
-	 * Using the cmdtest ioctl, a user can create a valid cmd
-	 * and then have it executes by the cmd ioctl.
-	 *
-	 * cmdtest returns 1,2,3,4 or 0, depending on which tests
-	 * the command passes. */
+	/* Step 1 : check if triggers are trivially valid */
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually
-	 * compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER
-	    && cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_TIMER && cmd->stop_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/comedi_parport.c b/drivers/staging/comedi/drivers/comedi_parport.c
index c9e40a9..22ef942 100644
--- a/drivers/staging/comedi/drivers/comedi_parport.c
+++ b/drivers/staging/comedi/drivers/comedi_parport.c
@@ -85,6 +85,8 @@ pin, which can be used to wake up tasks.
 #include <linux/interrupt.h>
 #include <linux/ioport.h>
 
+#include "comedi_fc.h"
+
 #define PARPORT_SIZE 3
 
 #define PARPORT_A 0
@@ -176,39 +178,20 @@ static int parport_intr_cmdtest(struct comedi_device *dev,
 				struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
-
-	/* step 1 */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
 
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_FOLLOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: ignored */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c
index b0f0ec5..7817def 100644
--- a/drivers/staging/comedi/drivers/comedi_test.c
+++ b/drivers/staging/comedi/drivers/comedi_test.c
@@ -231,44 +231,23 @@ static int waveform_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW | TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW | TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->convert_src != TRIG_NOW && cmd->convert_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/das16.c b/drivers/staging/comedi/drivers/das16.c
index 744376a..fcb8a32 100644
--- a/drivers/staging/comedi/drivers/das16.c
+++ b/drivers/staging/comedi/drivers/das16.c
@@ -402,62 +402,42 @@ static int das16_cmd_test(struct comedi_device *dev, struct comedi_subdevice *s,
 	int gain, start_chan, i;
 	int mask;
 
-	/* make sure triggers are valid */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
+
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
 
-	tmp = cmd->scan_begin_src;
 	mask = TRIG_FOLLOW;
 	/*  if board supports burst mode */
 	if (board->size > 0x400)
 		mask |= TRIG_TIMER | TRIG_EXT;
-	cmd->scan_begin_src &= mask;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, mask);
 
 	tmp = cmd->convert_src;
 	mask = TRIG_TIMER | TRIG_EXT;
 	/*  if board supports burst mode */
 	if (board->size > 0x400)
 		mask |= TRIG_NOW;
-	cmd->convert_src &= mask;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, mask);
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/**
-	 * step 2: make sure trigger sources are unique and
-	 * mutually compatible
-	 */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	/*  make sure scan_begin_src and convert_src dont conflict */
 	if (cmd->scan_begin_src == TRIG_FOLLOW && cmd->convert_src == TRIG_NOW)
-		err++;
+		err |= -EINVAL;
 	if (cmd->scan_begin_src != TRIG_FOLLOW && cmd->convert_src != TRIG_NOW)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/das16m1.c b/drivers/staging/comedi/drivers/das16m1.c
index 7f0668f..3f87d75 100644
--- a/drivers/staging/comedi/drivers/das16m1.c
+++ b/drivers/staging/comedi/drivers/das16m1.c
@@ -170,42 +170,24 @@ static int das16m1_cmd_test(struct comedi_device *dev,
 	const struct das16m1_board *board = comedi_board(dev);
 	unsigned int err = 0, tmp, i;
 
-	/* make sure triggers are valid */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/das1800.c b/drivers/staging/comedi/drivers/das1800.c
index 711d4e2..2555f32 100644
--- a/drivers/staging/comedi/drivers/das1800.c
+++ b/drivers/staging/comedi/drivers/das1800.c
@@ -784,59 +784,35 @@ static int das1800_ai_do_cmdtest(struct comedi_device *dev,
 				 struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 	unsigned int tmp_arg;
 	int i;
 	int unipolar;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_EXT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src,
+					TRIG_COUNT | TRIG_EXT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
-	/*  uniqueness check */
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT &&
-	    cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_EXT)
-		err++;
-	/* compatibility check */
 	if (cmd->scan_begin_src != TRIG_FOLLOW &&
 	    cmd->convert_src != TRIG_TIMER)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/das800.c b/drivers/staging/comedi/drivers/das800.c
index 8e89101..215deac 100644
--- a/drivers/staging/comedi/drivers/das800.c
+++ b/drivers/staging/comedi/drivers/das800.c
@@ -609,44 +609,24 @@ static int das800_ai_do_cmdtest(struct comedi_device *dev,
 	int gain, startChan;
 	int i;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/dmm32at.c b/drivers/staging/comedi/drivers/dmm32at.c
index 0703ca5..4d5c33c 100644
--- a/drivers/staging/comedi/drivers/dmm32at.c
+++ b/drivers/staging/comedi/drivers/dmm32at.c
@@ -41,6 +41,8 @@ Configuration Options:
 #include "../comedidev.h"
 #include <linux/ioport.h>
 
+#include "comedi_fc.h"
+
 /* Board register addresses */
 
 #define DMM32AT_MEMSIZE 0x10
@@ -258,47 +260,26 @@ static int dmm32at_ai_cmdtest(struct comedi_device *dev,
 	int tmp;
 	int start_chan, gain, i;
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER /*| TRIG_EXT */ ;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER /*| TRIG_EXT */ ;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER /*| TRIG_EXT */);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER /*| TRIG_EXT */);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-	 * compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/dt2814.c b/drivers/staging/comedi/drivers/dt2814.c
index ce5d837..064a8f2 100644
--- a/drivers/staging/comedi/drivers/dt2814.c
+++ b/drivers/staging/comedi/drivers/dt2814.c
@@ -45,6 +45,8 @@ addition, the clock does not seem to be very accurate.
 #include <linux/ioport.h>
 #include <linux/delay.h>
 
+#include "comedi_fc.h"
+
 #define DT2814_SIZE 2
 
 #define DT2814_CSR 0
@@ -129,42 +131,22 @@ static int dt2814_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are
-	 * unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->stop_src != TRIG_TIMER && cmd->stop_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c
index b7c43c8..78d3407 100644
--- a/drivers/staging/comedi/drivers/dt282x.c
+++ b/drivers/staging/comedi/drivers/dt282x.c
@@ -582,47 +582,24 @@ static int dt282x_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique
-	 * and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -862,44 +839,22 @@ static int dt282x_ao_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique
-	 * and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/dt3000.c b/drivers/staging/comedi/drivers/dt3000.c
index 3a940a2..43d05ef 100644
--- a/drivers/staging/comedi/drivers/dt3000.c
+++ b/drivers/staging/comedi/drivers/dt3000.c
@@ -63,6 +63,8 @@ AO commands are not supported.
 #include "../comedidev.h"
 #include <linux/delay.h>
 
+#include "comedi_fc.h"
+
 #define PCI_VENDOR_ID_DT	0x1116
 
 static const struct comedi_lrange range_dt3000_ai = { 4, {
@@ -408,37 +410,19 @@ static int dt3k_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/gsc_hpdi.c b/drivers/staging/comedi/drivers/gsc_hpdi.c
index 5d3fa71..abff660 100644
--- a/drivers/staging/comedi/drivers/gsc_hpdi.c
+++ b/drivers/staging/comedi/drivers/gsc_hpdi.c
@@ -723,45 +723,24 @@ static int di_cmd_test(struct comedi_device *dev, struct comedi_subdevice *s,
 		       struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 	int i;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-	 * compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/*  uniqueness check */
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/me4000.c b/drivers/staging/comedi/drivers/me4000.c
index d7c5146..22db35d 100644
--- a/drivers/staging/comedi/drivers/me4000.c
+++ b/drivers/staging/comedi/drivers/me4000.c
@@ -52,6 +52,7 @@ broken.
 #include <linux/list.h>
 #include <linux/spinlock.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 #if 0
@@ -895,18 +896,6 @@ static int me4000_ai_do_cmd(struct comedi_device *dev,
 	return 0;
 }
 
-/*
- * me4000_ai_do_cmd_test():
- *
- * The demo cmd.c in ./comedilib/demo specifies 6 return values:
- * - success
- * - invalid source
- * - source conflict
- * - invalid argument
- * - argument conflict
- * - invalid chanlist
- * So I tried to adopt this scheme.
- */
 static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 				 struct comedi_subdevice *s,
 				 struct comedi_cmd *cmd)
@@ -923,81 +912,29 @@ static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 	/* Round the timer arguments */
 	ai_round_cmd_args(dev, s, cmd, &init_ticks, &scan_ticks, &chan_ticks);
 
-	/*
-	 * Stage 1. Check if the trigger sources are generally valid.
-	 */
-	switch (cmd->start_src) {
-	case TRIG_NOW:
-	case TRIG_EXT:
-		break;
-	case TRIG_ANY:
-		cmd->start_src &= TRIG_NOW | TRIG_EXT;
-		err++;
-		break;
-	default:
-		dev_err(dev->class_dev, "Invalid start source\n");
-		cmd->start_src = TRIG_NOW;
-		err++;
-	}
-	switch (cmd->scan_begin_src) {
-	case TRIG_FOLLOW:
-	case TRIG_TIMER:
-	case TRIG_EXT:
-		break;
-	case TRIG_ANY:
-		cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT;
-		err++;
-		break;
-	default:
-		dev_err(dev->class_dev, "Invalid scan begin source\n");
-		cmd->scan_begin_src = TRIG_FOLLOW;
-		err++;
-	}
-	switch (cmd->convert_src) {
-	case TRIG_TIMER:
-	case TRIG_EXT:
-		break;
-	case TRIG_ANY:
-		cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-		err++;
-		break;
-	default:
-		dev_err(dev->class_dev, "Invalid convert source\n");
-		cmd->convert_src = TRIG_TIMER;
-		err++;
-	}
-	switch (cmd->scan_end_src) {
-	case TRIG_NONE:
-	case TRIG_COUNT:
-		break;
-	case TRIG_ANY:
-		cmd->scan_end_src &= TRIG_NONE | TRIG_COUNT;
-		err++;
-		break;
-	default:
-		dev_err(dev->class_dev, "Invalid scan end source\n");
-		cmd->scan_end_src = TRIG_NONE;
-		err++;
-	}
-	switch (cmd->stop_src) {
-	case TRIG_NONE:
-	case TRIG_COUNT:
-		break;
-	case TRIG_ANY:
-		cmd->stop_src &= TRIG_NONE | TRIG_COUNT;
-		err++;
-		break;
-	default:
-		dev_err(dev->class_dev, "Invalid stop source\n");
-		cmd->stop_src = TRIG_NONE;
-		err++;
-	}
+	/* Step 1 : check if triggers are trivially valid */
+
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src,
+					TRIG_NONE | TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE | TRIG_COUNT);
+
 	if (err)
 		return 1;
 
-	/*
-	 * Stage 2. Check for trigger source conflicts.
-	 */
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_end_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
+
 	if (cmd->start_src == TRIG_NOW &&
 	    cmd->scan_begin_src == TRIG_TIMER &&
 	    cmd->convert_src == TRIG_TIMER) {
@@ -1017,11 +954,7 @@ static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 		   cmd->scan_begin_src == TRIG_EXT &&
 		   cmd->convert_src == TRIG_EXT) {
 	} else {
-		dev_err(dev->class_dev, "Invalid start trigger combination\n");
-		cmd->start_src = TRIG_NOW;
-		cmd->scan_begin_src = TRIG_FOLLOW;
-		cmd->convert_src = TRIG_TIMER;
-		err++;
+		err |= -EINVAL;
 	}
 
 	if (cmd->stop_src == TRIG_NONE && cmd->scan_end_src == TRIG_NONE) {
@@ -1032,11 +965,9 @@ static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 	} else if (cmd->stop_src == TRIG_COUNT &&
 		   cmd->scan_end_src == TRIG_COUNT) {
 	} else {
-		dev_err(dev->class_dev, "Invalid stop trigger combination\n");
-		cmd->stop_src = TRIG_NONE;
-		cmd->scan_end_src = TRIG_NONE;
-		err++;
+		err |= -EINVAL;
 	}
+
 	if (err)
 		return 2;
 
diff --git a/drivers/staging/comedi/drivers/ni_6527.c b/drivers/staging/comedi/drivers/ni_6527.c
index 8125d50..51295f3 100644
--- a/drivers/staging/comedi/drivers/ni_6527.c
+++ b/drivers/staging/comedi/drivers/ni_6527.c
@@ -44,6 +44,7 @@ Updated: Sat, 25 Jan 2003 13:24:40 -0800
 #include <linux/interrupt.h>
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "mite.h"
 
 #define DRIVER_NAME "ni_6527"
@@ -224,40 +225,20 @@ static int ni6527_intr_cmdtest(struct comedi_device *dev,
 			       struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_OTHER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_FOLLOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_OTHER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and */
-	/*         are mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_65xx.c b/drivers/staging/comedi/drivers/ni_65xx.c
index aab2b06..2a73ff5 100644
--- a/drivers/staging/comedi/drivers/ni_65xx.c
+++ b/drivers/staging/comedi/drivers/ni_65xx.c
@@ -55,6 +55,7 @@ except maybe the 6514.
 #include <linux/slab.h>
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "mite.h"
 
 #define NI6514_DIO_SIZE 4096
@@ -486,40 +487,20 @@ static int ni_65xx_intr_cmdtest(struct comedi_device *dev,
 				struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_OTHER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_FOLLOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_OTHER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-	compatible */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_at_a2150.c b/drivers/staging/comedi/drivers/ni_at_a2150.c
index 5895d4d..8395080 100644
--- a/drivers/staging/comedi/drivers/ni_at_a2150.c
+++ b/drivers/staging/comedi/drivers/ni_at_a2150.c
@@ -321,45 +321,23 @@ static int a2150_ai_cmdtest(struct comedi_device *dev,
 	int startChan;
 	int i;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually
-	 * compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_atmio16d.c b/drivers/staging/comedi/drivers/ni_atmio16d.c
index 4108cbf..e91a620 100644
--- a/drivers/staging/comedi/drivers/ni_atmio16d.c
+++ b/drivers/staging/comedi/drivers/ni_atmio16d.c
@@ -40,6 +40,7 @@ Devices: [National Instruments] AT-MIO-16 (atmio16), AT-MIO-16D (atmio16d)
 
 #include <linux/ioport.h>
 
+#include "comedi_fc.h"
 #include "8255.h"
 
 /* Configuration and Status Registers */
@@ -246,45 +247,26 @@ static int atmio16d_ai_cmdtest(struct comedi_device *dev,
 			       struct comedi_subdevice *s,
 			       struct comedi_cmd *cmd)
 {
-	int err = 0, tmp;
+	int err = 0;
 
-	/* make sure triggers are valid */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique & mutually compatible */
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_labpc.c b/drivers/staging/comedi/drivers/ni_labpc.c
index d534e63..28b91a6 100644
--- a/drivers/staging/comedi/drivers/ni_labpc.c
+++ b/drivers/staging/comedi/drivers/ni_labpc.c
@@ -979,55 +979,33 @@ static int labpc_ai_cmdtest(struct comedi_device *dev,
 {
 	int err = 0;
 	int tmp, tmp2;
-	int stop_mask;
+	unsigned int stop_mask;
 	enum scan_mode mode;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_FOLLOW | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_FOLLOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
 
-	tmp = cmd->stop_src;
 	stop_mask = TRIG_COUNT | TRIG_NONE;
 	if (thisboard->register_layout == labpc_1200_layout)
 		stop_mask |= TRIG_EXT;
-	cmd->stop_src &= stop_mask;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->stop_src, stop_mask);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT &&
-	    cmd->stop_src != TRIG_EXT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	/* can't have external stop and start triggers at once */
 	if (cmd->start_src == TRIG_EXT && cmd->stop_src == TRIG_EXT)
diff --git a/drivers/staging/comedi/drivers/ni_mio_common.c b/drivers/staging/comedi/drivers/ni_mio_common.c
index 87995da..e55c3d75 100644
--- a/drivers/staging/comedi/drivers/ni_mio_common.c
+++ b/drivers/staging/comedi/drivers/ni_mio_common.c
@@ -2166,61 +2166,38 @@ static int ni_ai_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 {
 	int err = 0;
 	int tmp;
-	int sources;
+	unsigned int sources;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	if ((cmd->flags & CMDF_WRITE)) {
+	if ((cmd->flags & CMDF_WRITE))
 		cmd->flags &= ~CMDF_WRITE;
-	}
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src,
+					TRIG_NOW | TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
 
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
 	sources = TRIG_TIMER | TRIG_EXT;
-	if ((boardtype.reg_type == ni_reg_611x)
-	    || (boardtype.reg_type == ni_reg_6143))
+	if (boardtype.reg_type == ni_reg_611x ||
+	    boardtype.reg_type == ni_reg_6143)
 		sources |= TRIG_NOW;
-	cmd->convert_src &= sources;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, sources);
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->start_src != TRIG_NOW &&
-	    cmd->start_src != TRIG_INT && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_OTHER)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -3358,44 +3335,28 @@ static int ni_ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	if ((cmd->flags & CMDF_WRITE) == 0) {
+	if ((cmd->flags & CMDF_WRITE) == 0)
 		cmd->flags |= CMDF_WRITE;
-	}
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
 
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -3645,51 +3606,21 @@ static int ni_cdio_cmdtest(struct comedi_device *dev,
 {
 	int err = 0;
 	int tmp;
-	int sources;
 	unsigned i;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	sources = TRIG_INT;
-	cmd->start_src &= sources;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique... */
-
-	if (cmd->start_src != TRIG_INT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_NONE)
-		err++;
-	/* ... and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_pcidio.c b/drivers/staging/comedi/drivers/ni_pcidio.c
index 6a70e26..bc9313e 100644
--- a/drivers/staging/comedi/drivers/ni_pcidio.c
+++ b/drivers/staging/comedi/drivers/ni_pcidio.c
@@ -60,6 +60,7 @@ comedi_nonfree_firmware tarball available from http://www.comedi.org
 #include <linux/firmware.h>
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "mite.h"
 
 #undef DPRINTK
@@ -683,45 +684,25 @@ static int ni_pcidio_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-	compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_INT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_tiocmd.c b/drivers/staging/comedi/drivers/ni_tiocmd.c
index a961158..8ee93d3 100644
--- a/drivers/staging/comedi/drivers/ni_tiocmd.c
+++ b/drivers/staging/comedi/drivers/ni_tiocmd.c
@@ -48,6 +48,7 @@ TODO:
 	Support use of both banks X and Y
 */
 
+#include "comedi_fc.h"
 #include "ni_tio_internal.h"
 #include "mite.h"
 
@@ -237,61 +238,35 @@ EXPORT_SYMBOL_GPL(ni_tio_cmd);
 int ni_tio_cmdtest(struct ni_gpct *counter, struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
-	int sources;
+	unsigned int sources;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
 	sources = TRIG_NOW | TRIG_INT | TRIG_OTHER;
 	if (ni_tio_counting_mode_registers_present(counter->counter_dev))
 		sources |= TRIG_EXT;
-	cmd->start_src &= sources;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_EXT | TRIG_OTHER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	sources = TRIG_NOW | TRIG_EXT | TRIG_OTHER;
-	cmd->convert_src &= sources;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, sources);
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_EXT | TRIG_OTHER);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_NOW | TRIG_EXT | TRIG_OTHER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique... */
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+
+	/* Step 2b : and mutually compatible */
 
-	if (cmd->start_src != TRIG_NOW &&
-	    cmd->start_src != TRIG_INT &&
-	    cmd->start_src != TRIG_EXT && cmd->start_src != TRIG_OTHER)
-		err++;
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_OTHER)
-		err++;
-	if (cmd->convert_src != TRIG_OTHER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_NONE)
-		err++;
-	/* ... and mutually compatible */
 	if (cmd->convert_src != TRIG_NOW && cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/pcl711.c b/drivers/staging/comedi/drivers/pcl711.c
index ef77b15..89305a1 100644
--- a/drivers/staging/comedi/drivers/pcl711.c
+++ b/drivers/staging/comedi/drivers/pcl711.c
@@ -64,6 +64,7 @@ supported.
 #include <linux/ioport.h>
 #include <linux/delay.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 #define PCL711_SIZE 16
@@ -266,42 +267,24 @@ static int pcl711_ai_cmdtest(struct comedi_device *dev,
 	int tmp;
 	int err = 0;
 
-	/* step 1 */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/pcl812.c b/drivers/staging/comedi/drivers/pcl812.c
index d196343..3cf55ff 100644
--- a/drivers/staging/comedi/drivers/pcl812.c
+++ b/drivers/staging/comedi/drivers/pcl812.c
@@ -117,6 +117,7 @@
 #include <linux/io.h>
 #include <asm/dma.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 /* hardware types of the cards */
@@ -533,49 +534,31 @@ static int pcl812_ai_cmdtest(struct comedi_device *dev,
 {
 	const struct pcl812_board *board = comedi_board(dev);
 	int err = 0;
+	unsigned int flags;
 	int tmp, divisor1, divisor2;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
 
-	tmp = cmd->convert_src;
 	if (devpriv->use_ext_trg)
-		cmd->convert_src &= TRIG_EXT;
+		flags = TRIG_EXT;
 	else
-		cmd->convert_src &= TRIG_TIMER;
-
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+		flags = TRIG_TIMER;
+	err |= cfc_check_trigger_src(&cmd->convert_src, flags);
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are
-	 * unique and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/pcl816.c b/drivers/staging/comedi/drivers/pcl816.c
index f65fd66..0822de0 100644
--- a/drivers/staging/comedi/drivers/pcl816.c
+++ b/drivers/staging/comedi/drivers/pcl816.c
@@ -41,6 +41,7 @@ Configuration Options:
 #include <linux/io.h>
 #include <asm/dma.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 #define DEBUG(x) x
@@ -458,48 +459,23 @@ static int pcl816_ai_cmdtest(struct comedi_device *dev,
 	      pcl816_cmdtest_out(-1, cmd);
 	     );
 
-	/* step 1: make sure trigger sources are trivially valid */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_EXT | TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_EXT | TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
+	/* Step 2a : make sure trigger sources are unique */
 
-	/*
-	 * step 2: make sure trigger sources
-	 * are unique and mutually compatible
-	 */
-
-	if (cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_TIMER) {
-		cmd->convert_src = TRIG_TIMER;
-		err++;
-	}
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
 
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/pcl818.c b/drivers/staging/comedi/drivers/pcl818.c
index 023a27d..d4b0859 100644
--- a/drivers/staging/comedi/drivers/pcl818.c
+++ b/drivers/staging/comedi/drivers/pcl818.c
@@ -107,6 +107,7 @@ A word or two about DMA. Driver support DMA operations at two ways:
 #include <linux/io.h>
 #include <asm/dma.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 /* #define PCL818_MODE13_AO 1 */
@@ -1261,43 +1262,23 @@ static int ai_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 	int err = 0;
 	int tmp, divisor1 = 0, divisor2 = 0;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
 
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/pcm_common.c b/drivers/staging/comedi/drivers/pcm_common.c
index 474af7b..85ee05e 100644
--- a/drivers/staging/comedi/drivers/pcm_common.c
+++ b/drivers/staging/comedi/drivers/pcm_common.c
@@ -1,60 +1,30 @@
 #include "../comedidev.h"
+
+#include "comedi_fc.h"
 #include "pcm_common.h"
 
-/*
- * 'do_cmdtest' function for an 'INTERRUPT' subdevice.  This is for
- * the PCM drivers.
- */
 int comedi_pcm_cmdtest(struct comedi_device *dev,
 		       struct comedi_subdevice *s, struct comedi_cmd *cmd)
 {
 	int err = 0;
-	unsigned int tmp;
-
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= (TRIG_NOW | TRIG_INT);
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= (TRIG_COUNT | TRIG_NONE);
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and
-	 * mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* these tests are true if more than one _src bit is set */
-	if ((cmd->start_src & (cmd->start_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
-		err++;
-	if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
-		err++;
-	if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/quatech_daqp_cs.c b/drivers/staging/comedi/drivers/quatech_daqp_cs.c
index e95a4eb..3e276f7 100644
--- a/drivers/staging/comedi/drivers/quatech_daqp_cs.c
+++ b/drivers/staging/comedi/drivers/quatech_daqp_cs.c
@@ -56,6 +56,8 @@ Devices: [Quatech] DAQP-208 (daqp), DAQP-308
 
 #include <linux/completion.h>
 
+#include "comedi_fc.h"
+
 /* Maximum number of separate DAQP devices we'll allow */
 #define MAX_DEV         4
 
@@ -456,51 +458,26 @@ static int daqp_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources
-	 * are unique and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-	if (cmd->convert_src != TRIG_NOW && cmd->convert_src != TRIG_TIMER)
-		err++;
-	if (cmd->scan_begin_src == TRIG_FOLLOW && cmd->convert_src == TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/rtd520.c b/drivers/staging/comedi/drivers/rtd520.c
index d0e4844..41d24b0 100644
--- a/drivers/staging/comedi/drivers/rtd520.c
+++ b/drivers/staging/comedi/drivers/rtd520.c
@@ -106,6 +106,8 @@ Configuration options:
 
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
+
 #define DRV_NAME "rtd520"
 
 /*======================================================================
@@ -976,52 +978,25 @@ static int rtd_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique
-	   and mutually compatible */
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT) {
-		err++;
-	}
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/s626.c b/drivers/staging/comedi/drivers/s626.c
index e1d10f3..98099ad 100644
--- a/drivers/staging/comedi/drivers/s626.c
+++ b/drivers/staging/comedi/drivers/s626.c
@@ -1505,56 +1505,28 @@ static int s626_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* cmdtest tests a particular command to see if it is valid.  Using
-	 * the cmdtest ioctl, a user can create a valid cmd and then have it
-	 * executes by the cmd ioctl.
-	 *
-	 * cmdtest returns 1,2,3,4 or 0, depending on which tests the
-	 * command passes. */
-
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT | TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT | TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src,
+					TRIG_NOW | TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT | TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_EXT | TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-	   compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT
-	    && cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/skel.c b/drivers/staging/comedi/drivers/skel.c
index eb70bac..b70cdf3 100644
--- a/drivers/staging/comedi/drivers/skel.c
+++ b/drivers/staging/comedi/drivers/skel.c
@@ -76,6 +76,8 @@ Configuration Options:
 
 #include <linux/pci.h>		/* for PCI devices */
 
+#include "comedi_fc.h"
+
 /* Imaginary registers for the imaginary board */
 
 #define SKEL_SIZE 0
@@ -349,60 +351,40 @@ static int skel_ai_rinsn(struct comedi_device *dev, struct comedi_subdevice *s,
 	return n;
 }
 
+/*
+ * cmdtest tests a particular command to see if it is valid.
+ * Using the cmdtest ioctl, a user can create a valid cmd
+ * and then have it executes by the cmd ioctl.
+ *
+ * cmdtest returns 1,2,3,4 or 0, depending on which tests
+ * the command passes.
+ */
 static int skel_ai_cmdtest(struct comedi_device *dev,
-			   struct comedi_subdevice *s, struct comedi_cmd *cmd)
+			   struct comedi_subdevice *s,
+			   struct comedi_cmd *cmd)
 {
 	int err = 0;
 	int tmp;
 
-	/* cmdtest tests a particular command to see if it is valid.
-	 * Using the cmdtest ioctl, a user can create a valid cmd
-	 * and then have it executes by the cmd ioctl.
-	 *
-	 * cmdtest returns 1,2,3,4 or 0, depending on which tests
-	 * the command passes. */
-
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible
-     */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/usbdux.c b/drivers/staging/comedi/drivers/usbdux.c
index bc5fc5c..b536bba 100644
--- a/drivers/staging/comedi/drivers/usbdux.c
+++ b/drivers/staging/comedi/drivers/usbdux.c
@@ -98,6 +98,8 @@ sampling rate. If you sample two channels you get 4kHz and so on.
 
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
+
 /* timeout for the USB-transfer in ms*/
 #define BULK_TIMEOUT 1000
 
@@ -929,9 +931,9 @@ static int usbduxsub_submit_OutURBs(struct usbduxsub *usbduxsub)
 static int usbdux_ai_cmdtest(struct comedi_device *dev,
 			     struct comedi_subdevice *s, struct comedi_cmd *cmd)
 {
-	int err = 0, tmp, i;
-	unsigned int tmpTimer;
 	struct usbduxsub *this_usbduxsub = dev->private;
+	int err = 0, i;
+	unsigned int tmpTimer;
 
 	if (!(this_usbduxsub->probed))
 		return -ENODEV;
@@ -939,51 +941,23 @@ static int usbdux_ai_cmdtest(struct comedi_device *dev,
 	dev_dbg(&this_usbduxsub->interface->dev,
 		"comedi%d: usbdux_ai_cmdtest\n", dev->minor);
 
-	/* make sure triggers are valid */
-	/* Only immediate triggers are allowed */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	/* trigger should happen timed */
-	tmp = cmd->scan_begin_src;
-	/* start a new _scan_ with a timer */
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	/* scanning is continuous */
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	/* issue a trigger when scan is finished and start a new scan */
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	/* trigger at the end of count events or not, stop condition or not */
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually compatible
-	 * note that mutual compatibility is not an issue here
-	 */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -1488,8 +1462,9 @@ static int usbdux_ao_inttrig(struct comedi_device *dev,
 static int usbdux_ao_cmdtest(struct comedi_device *dev,
 			     struct comedi_subdevice *s, struct comedi_cmd *cmd)
 {
-	int err = 0, tmp;
 	struct usbduxsub *this_usbduxsub = dev->private;
+	int err = 0;
+	unsigned int flags;
 
 	if (!this_usbduxsub)
 		return -EFAULT;
@@ -1500,69 +1475,46 @@ static int usbdux_ao_cmdtest(struct comedi_device *dev,
 	dev_dbg(&this_usbduxsub->interface->dev,
 		"comedi%d: usbdux_ao_cmdtest\n", dev->minor);
 
-	/* make sure triggers are valid */
-	/* Only immediate triggers are allowed */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
+
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
 
-	/* trigger should happen timed */
-	tmp = cmd->scan_begin_src;
-	/* just now we scan also in the high speed mode every frame */
-	/* this is due to ehci driver limitations */
 	if (0) {		/* (this_usbduxsub->high_speed) */
-		/* start immediately a new scan */
 		/* the sampling rate is set by the coversion rate */
-		cmd->scan_begin_src &= TRIG_FOLLOW;
+		flags = TRIG_FOLLOW;
 	} else {
 		/* start a new scan (output at once) with a timer */
-		cmd->scan_begin_src &= TRIG_TIMER;
+		flags = TRIG_TIMER;
 	}
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, flags);
 
-	/* scanning is continuous */
-	tmp = cmd->convert_src;
-	/* we always output at 1kHz just now all channels at once */
 	if (0) {		/* (this_usbduxsub->high_speed) */
 		/*
-		 * in usb-2.0 only one conversion it transmitted but with 8kHz/n
+		 * in usb-2.0 only one conversion it transmitted
+		 * but with 8kHz/n
 		 */
-		cmd->convert_src &= TRIG_TIMER;
+		flags = TRIG_TIMER;
 	} else {
-		/* all conversion events happen simultaneously with a rate of
-		 * 1kHz/n */
-		cmd->convert_src &= TRIG_NOW;
+		/*
+		 * all conversion events happen simultaneously with
+		 * a rate of 1kHz/n
+		 */
+		flags = TRIG_NOW;
 	}
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	/* issue a trigger when scan is finished and start a new scan */
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, flags);
 
-	/* trigger at the end of count events or not, stop condition or not */
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually compatible
-	 * note that mutual compatibility is not an issue here
-	 */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/usbduxfast.c b/drivers/staging/comedi/drivers/usbduxfast.c
index 0f6c139..1154a7e 100644
--- a/drivers/staging/comedi/drivers/usbduxfast.c
+++ b/drivers/staging/comedi/drivers/usbduxfast.c
@@ -549,10 +549,10 @@ static int usbduxfast_ai_cmdtest(struct comedi_device *dev,
 				 struct comedi_subdevice *s,
 				 struct comedi_cmd *cmd)
 {
-	int err = 0, stop_mask = 0;
+	struct usbduxfastsub_s *udfs = dev->private;
+	int err = 0;
 	long int steps, tmp;
 	int minSamplPer;
-	struct usbduxfastsub_s *udfs = dev->private;
 
 	if (!udfs->probed)
 		return -ENODEV;
@@ -563,57 +563,31 @@ static int usbduxfast_ai_cmdtest(struct comedi_device *dev,
 	       "scan_begin_arg=%u\n",
 	       dev->minor, cmd->convert_arg, cmd->scan_begin_arg);
 #endif
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_FOLLOW | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	stop_mask = TRIG_COUNT | TRIG_NONE;
-	cmd->stop_src &= stop_mask;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src,
+					TRIG_NOW | TRIG_EXT | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_FOLLOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW &&
-	    cmd->start_src != TRIG_EXT && cmd->start_src != TRIG_INT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT &&
-	    cmd->stop_src != TRIG_EXT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	/* can't have external stop and start triggers at once */
 	if (cmd->start_src == TRIG_EXT && cmd->stop_src == TRIG_EXT)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c b/drivers/staging/comedi/drivers/usbduxsigma.c
index b4ab83f..b169412 100644
--- a/drivers/staging/comedi/drivers/usbduxsigma.c
+++ b/drivers/staging/comedi/drivers/usbduxsigma.c
@@ -897,9 +897,9 @@ static int usbdux_ai_cmdtest(struct comedi_device *dev,
 			     struct comedi_subdevice *s,
 			     struct comedi_cmd *cmd)
 {
-	int err = 0, tmp, i;
-	unsigned int tmpTimer;
 	struct usbduxsub *this_usbduxsub = dev->private;
+	int err = 0, i;
+	unsigned int tmpTimer;
 
 	if (!(this_usbduxsub->probed))
 		return -ENODEV;
@@ -907,51 +907,23 @@ static int usbdux_ai_cmdtest(struct comedi_device *dev,
 	dev_dbg(&this_usbduxsub->interface->dev,
 		"comedi%d: usbdux_ai_cmdtest\n", dev->minor);
 
-	/* make sure triggers are valid */
-	/* Only immediate triggers are allowed */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	/* trigger should happen timed */
-	tmp = cmd->scan_begin_src;
-	/* start a new _scan_ with a timer */
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	/* scanning is continuous */
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	/* issue a trigger when scan is finished and start a new scan */
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	/* trigger at the end of count events or not, stop condition or not */
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually compatible
-	 * note that mutual compatibility is not an issue here
-	 */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -1558,8 +1530,9 @@ static int usbdux_ao_cmdtest(struct comedi_device *dev,
 			     struct comedi_subdevice *s,
 			     struct comedi_cmd *cmd)
 {
-	int err = 0, tmp;
 	struct usbduxsub *this_usbduxsub = dev->private;
+	int err = 0;
+	unsigned int flags;
 
 	if (!this_usbduxsub)
 		return -EFAULT;
@@ -1570,63 +1543,35 @@ static int usbdux_ao_cmdtest(struct comedi_device *dev,
 	dev_dbg(&this_usbduxsub->interface->dev,
 		"comedi%d: usbdux_ao_cmdtest\n", dev->minor);
 
-	/* make sure triggers are valid */
-	/* Only immediate triggers are allowed */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
+
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
 
-	/* trigger should happen timed */
-	tmp = cmd->scan_begin_src;
-	/* just now we scan also in the high speed mode every frame */
-	/* this is due to ehci driver limitations */
 	if (0) {		/* (this_usbduxsub->high_speed) */
-		/* start immediately a new scan */
-		/* the sampling rate is set by the coversion rate */
-		cmd->scan_begin_src &= TRIG_FOLLOW;
+		/*
+		 * start immediately a new scan
+		 * the sampling rate is set by the coversion rate
+		 */
+		flags = TRIG_FOLLOW;
 	} else {
 		/* start a new scan (output at once) with a timer */
-		cmd->scan_begin_src &= TRIG_TIMER;
+		flags = TRIG_TIMER;
 	}
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	/* scanning is continuous */
-	tmp = cmd->convert_src;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, flags);
 
-	/* all conversion events happen simultaneously */
-	cmd->convert_src &= TRIG_NOW;
-
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	/* issue a trigger when scan is finished and start a new scan */
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	/* trigger at the end of count events or not, stop condition or not */
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources
-	 * are unique and mutually compatible
-	 * note that mutual compatibility is not an issue here
-	 */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
-- 
1.7.11