[PATCH 7/9] staging: comedi: mpc624: introduce mpc624_ai_get_sample()
H Hartley Sweeten
hsweeten at visionengravers.com
Tue Oct 6 00:33:32 UTC 2015
Introduce a helper function to read the analog sample from the serially
connected A/D converter and handle the munging of the data.
Signed-off-by: H Hartley Sweeten <hsweeten at visionengravers.com>
Cc: Ian Abbott <abbotti at mev.co.uk>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
drivers/staging/comedi/drivers/mpc624.c | 172 +++++++++++++++-----------------
1 file changed, 83 insertions(+), 89 deletions(-)
diff --git a/drivers/staging/comedi/drivers/mpc624.c b/drivers/staging/comedi/drivers/mpc624.c
index 0e89760..3763dc5 100644
--- a/drivers/staging/comedi/drivers/mpc624.c
+++ b/drivers/staging/comedi/drivers/mpc624.c
@@ -115,6 +115,85 @@ static const struct comedi_lrange range_mpc624_bipolar10 = {
}
};
+static unsigned int mpc624_ai_get_sample(struct comedi_device *dev,
+ struct comedi_subdevice *s)
+{
+ struct mpc624_private *devpriv = dev->private;
+ unsigned int data_out = devpriv->ai_speed;
+ unsigned int data_in = 0;
+ unsigned int bit;
+ int i;
+
+ /* Start reading data */
+ udelay(1);
+ for (i = 0; i < 32; i++) {
+ /* Set the clock low */
+ outb(0, dev->iobase + MPC624_ADC);
+ udelay(1);
+
+ /* Set the ADSDI line for the next bit (send to MPC624) */
+ bit = (data_out & BIT(31)) ? MPC624_ADSDI : 0;
+ outb(bit, dev->iobase + MPC624_ADC);
+ udelay(1);
+
+ /* Set the clock high */
+ outb(MPC624_ADSCK | bit, dev->iobase + MPC624_ADC);
+ udelay(1);
+
+ /* Read ADSDO on high clock (receive from MPC624) */
+ data_in <<= 1;
+ data_in |= (inb(dev->iobase + MPC624_ADC) & MPC624_ADSDO) >> 4;
+ udelay(1);
+
+ data_out <<= 1;
+ }
+
+ /*
+ * Received 32-bit long value consist of:
+ * 31: EOC - (End Of Transmission) bit - should be 0
+ * 30: DMY - (Dummy) bit - should be 0
+ * 29: SIG - (Sign) bit - 1 if positive, 0 if negative
+ * 28: MSB - (Most Significant Bit) - the first bit of the
+ * conversion result
+ * ....
+ * 05: LSB - (Least Significant Bit)- the last bit of the
+ * conversion result
+ * 04-00: sub-LSB - sub-LSBs are basically noise, but when
+ * averaged properly, they can increase
+ * conversion precision up to 29 bits;
+ * they can be discarded without loss of
+ * resolution.
+ */
+ if (data_in & MPC624_EOC_BIT)
+ dev_dbg(dev->class_dev, "EOC bit is set!");
+ if (data_in & MPC624_DMY_BIT)
+ dev_dbg(dev->class_dev, "DMY bit is set!");
+
+ if (data_in & MPC624_SGN_BIT) {
+ /*
+ * Voltage is positive
+ *
+ * comedi operates on unsigned numbers, so mask off EOC
+ * and DMY and don't clear the SGN bit
+ */
+ data_in &= 0x3fffffff;
+ } else {
+ /*
+ * The voltage is negative
+ *
+ * data_in contains a number in 30-bit two's complement
+ * code and we must deal with it
+ */
+ data_in |= MPC624_SGN_BIT;
+ data_in = ~data_in;
+ data_in += 1;
+ /* clear EOC and DMY bits */
+ data_in &= ~(MPC624_EOC_BIT | MPC624_DMY_BIT);
+ data_in = 0x20000000 - data_in;
+ }
+ return data_in;
+}
+
static int mpc624_ai_eoc(struct comedi_device *dev,
struct comedi_subdevice *s,
struct comedi_insn *insn,
@@ -133,10 +212,8 @@ static int mpc624_ai_insn_read(struct comedi_device *dev,
struct comedi_insn *insn,
unsigned int *data)
{
- struct mpc624_private *devpriv = dev->private;
- int n, i;
- unsigned long int data_in, data_out;
int ret;
+ int i;
/*
* WARNING:
@@ -144,7 +221,7 @@ static int mpc624_ai_insn_read(struct comedi_device *dev,
*/
outb(insn->chanspec, dev->iobase + MPC624_GNMUXCH);
- for (n = 0; n < insn->n; n++) {
+ for (i = 0; i < insn->n; i++) {
/* Trigger the conversion */
outb(MPC624_ADSCK, dev->iobase + MPC624_ADC);
udelay(1);
@@ -158,93 +235,10 @@ static int mpc624_ai_insn_read(struct comedi_device *dev,
if (ret)
return ret;
- /* Start reading data */
- data_in = 0;
- data_out = devpriv->ai_speed;
- udelay(1);
- for (i = 0; i < 32; i++) {
- /* Set the clock low */
- outb(0, dev->iobase + MPC624_ADC);
- udelay(1);
-
- if (data_out & BIT(31)) { /* the next bit is a 1 */
- /* Set the ADSDI line (send to MPC624) */
- outb(MPC624_ADSDI, dev->iobase + MPC624_ADC);
- udelay(1);
- /* Set the clock high */
- outb(MPC624_ADSCK | MPC624_ADSDI,
- dev->iobase + MPC624_ADC);
- } else { /* the next bit is a 0 */
-
- /* Set the ADSDI line (send to MPC624) */
- outb(0, dev->iobase + MPC624_ADC);
- udelay(1);
- /* Set the clock high */
- outb(MPC624_ADSCK, dev->iobase + MPC624_ADC);
- }
- /* Read ADSDO on high clock (receive from MPC624) */
- udelay(1);
- data_in <<= 1;
- data_in |=
- (inb(dev->iobase + MPC624_ADC) & MPC624_ADSDO) >> 4;
- udelay(1);
-
- data_out <<= 1;
- }
-
- /*
- * Received 32-bit long value consist of:
- * 31: EOC -
- * (End Of Transmission) bit - should be 0
- * 30: DMY
- * (Dummy) bit - should be 0
- * 29: SIG
- * (Sign) bit- 1 if the voltage is positive,
- * 0 if negative
- * 28: MSB
- * (Most Significant Bit) - the first bit of
- * the conversion result
- * ....
- * 05: LSB
- * (Least Significant Bit)- the last bit of the
- * conversion result
- * 04-00: sub-LSB
- * - sub-LSBs are basically noise, but when
- * averaged properly, they can increase conversion
- * precision up to 29 bits; they can be discarded
- * without loss of resolution.
- */
-
- if (data_in & MPC624_EOC_BIT)
- dev_dbg(dev->class_dev,
- "EOC bit is set (data_in=%lu)!", data_in);
- if (data_in & MPC624_DMY_BIT)
- dev_dbg(dev->class_dev,
- "DMY bit is set (data_in=%lu)!", data_in);
- if (data_in & MPC624_SGN_BIT) { /* Volatge is positive */
- /*
- * comedi operates on unsigned numbers, so mask off EOC
- * and DMY and don't clear the SGN bit
- */
- data_in &= 0x3FFFFFFF;
- data[n] = data_in;
- } else { /* The voltage is negative */
- /*
- * data_in contains a number in 30-bit two's complement
- * code and we must deal with it
- */
- data_in |= MPC624_SGN_BIT;
- data_in = ~data_in;
- data_in += 1;
- data_in &= ~(MPC624_EOC_BIT | MPC624_DMY_BIT);
- /* clear EOC and DMY bits */
- data_in = 0x20000000 - data_in;
- data[n] = data_in;
- }
+ data[i] = mpc624_ai_get_sample(dev, s);
}
- /* Return the number of samples read/written */
- return n;
+ return insn->n;
}
static int mpc624_attach(struct comedi_device *dev, struct comedi_devconfig *it)
--
2.5.1
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