[PATCH 8/8] staging: comedi: skel: do auto-attachment of PCI devices
Ian Abbott
abbotti at mev.co.uk
Thu Nov 1 14:02:20 UTC 2012
This driver is an example of how to write a Comedi driver and includes
some code for handling PCI devices, but not very much. It calls
`comedi_pci_auto_config()` at PCI probe time. That normally expects to
call the comedi driver's `auto_attach()` hook (or the deprecated
`attach_pci()` hook), but will fall back to using the `attach()` hook
that should only be used for attaching devices "manually" via the
`COMEDI_DEVCONFIG` ioctl.
Add an `auto_attach()` hook (`skel_auto_attach()`) to handle
auto-attachment of supported PCI devices. Add comments to the
`attach()` hook (`skel_attach()`) to indicate that it shouldn't
generally allow PCI devices to be attached that way (and probably isn't
needed at all for PCI-only Comedi drivers). Add code to the `detach()`
hook (`skel_detach()`) to disable PCI devices enabled by the
`auto_attach()` hook.
`skel_auto_attach()` calls new function `skel_find_pci_board()` to find
a matching element in `skel_boards[]`. PCI device ID information has
been added to `skel_boards[]` to give the function something to look
for.
Remove the `pci_dev` member of `struct skel_private` as drivers now use
the `hw_dev` member of `struct comedi_device` to get at the PCI device.
Signed-off-by: Ian Abbott <abbotti at mev.co.uk>
---
drivers/staging/comedi/drivers/skel.c | 222 +++++++++++++++++++++++++++++-----
1 file changed, 195 insertions(+), 27 deletions(-)
diff --git a/drivers/staging/comedi/drivers/skel.c b/drivers/staging/comedi/drivers/skel.c
index ccc1e9b..162bf26 100644
--- a/drivers/staging/comedi/drivers/skel.c
+++ b/drivers/staging/comedi/drivers/skel.c
@@ -92,6 +92,7 @@ Configuration Options:
*/
struct skel_board {
const char *name;
+ unsigned int devid;
int ai_chans;
int ai_bits;
int have_dio;
@@ -100,12 +101,14 @@ struct skel_board {
static const struct skel_board skel_boards[] = {
{
.name = "skel-100",
+ .devid = 0x100,
.ai_chans = 16,
.ai_bits = 12,
.have_dio = 1,
},
{
.name = "skel-200",
+ .devid = 0x200,
.ai_chans = 8,
.ai_bits = 16,
.have_dio = 0,
@@ -120,9 +123,6 @@ struct skel_private {
int data;
- /* would be useful for a PCI device */
- struct pci_dev *pci_dev;
-
/* Used for AO readback */
unsigned int ao_readback[2];
};
@@ -421,37 +421,30 @@ static int skel_dio_insn_config(struct comedi_device *dev,
return insn->n;
}
-/*
- * Attach is called by the Comedi core to configure the driver
- * for a particular board. If you specified a board_name array
- * in the driver structure, dev->board_ptr contains that
- * address.
- */
-static int skel_attach(struct comedi_device *dev, struct comedi_devconfig *it)
+static const struct skel_board *skel_find_pci_board(struct pci_dev *pcidev)
{
- const struct skel_board *thisboard;
- struct skel_private *devpriv;
- struct comedi_subdevice *s;
- int ret;
+ unsigned int i;
/*
- * If you can probe the device to determine what device in a series
- * it is, this is the place to do it. Otherwise, dev->board_ptr
- * should already be initialized.
+ * This example code assumes all the entries in skel_boards[] are PCI boards
+ * and all use the same PCI vendor ID. If skel_boards[] contains a mixture
+ * of PCI and non-PCI boards, this loop should skip over the non-PCI boards.
*/
- /* dev->board_ptr = skel_probe(dev, it); */
+ for (i = 0; i < ARRAY_SIZE(skel_boards); i++)
+ if (/* skel_boards[i].bustype == pci_bustype && */
+ pcidev->device == skel_boards[i].devid)
+ return &skel_boards[i];
+ return NULL;
+}
- thisboard = comedi_board(dev);
/*
- * Initialize dev->board_name.
+ * Handle common part of skel_attach() and skel_auto_attach().
*/
- dev->board_name = thisboard->name;
-
- /* Allocate the private data */
- devpriv = kzalloc(sizeof(*devpriv), GFP_KERNEL);
- if (!devpriv)
- return -ENOMEM;
- dev->private = devpriv;
+static int skel_common_attach(struct comedi_device *dev)
+{
+ const struct skel_board *thisboard = comedi_board(dev);
+ struct comedi_subdevice *s;
+ int ret;
ret = comedi_alloc_subdevices(dev, 3);
if (ret)
@@ -505,6 +498,146 @@ static int skel_attach(struct comedi_device *dev, struct comedi_devconfig *it)
}
/*
+ * _attach is called by the Comedi core to configure the driver
+ * for a particular board in response to the COMEDI_DEVCONFIG ioctl for
+ * a matching board or driver name. If you specified a board_name array
+ * in the driver structure, dev->board_ptr contains that address.
+ *
+ * Drivers that handle only PCI or USB devices do not usually support
+ * manual attachment of those devices via the COMEDI_DEVCONFIG ioctl, so
+ * those drivers do not have an _attach function; they just have an
+ * _auto_attach function instead. (See skel_auto_attach() for an example
+ * of such a function.)
+ */
+static int skel_attach(struct comedi_device *dev, struct comedi_devconfig *it)
+{
+ const struct skel_board *thisboard;
+ struct skel_private *devpriv;
+
+/*
+ * If you can probe the device to determine what device in a series
+ * it is, this is the place to do it. Otherwise, dev->board_ptr
+ * should already be initialized.
+ */
+ /* dev->board_ptr = skel_probe(dev, it); */
+
+ thisboard = comedi_board(dev);
+
+/*
+ * Initialize dev->board_name.
+ */
+ dev->board_name = thisboard->name;
+
+ /* Allocate the private data */
+ devpriv = kzalloc(sizeof(*devpriv), GFP_KERNEL);
+ if (!devpriv)
+ return -ENOMEM;
+ dev->private = devpriv;
+
+/*
+ * Supported boards are usually either auto-attached via the
+ * Comedi driver's _auto_attach routine, or manually attached via the
+ * Comedi driver's _attach routine. In most cases, attempts to
+ * manual attach boards that are usually auto-attached should be
+ * rejected by this function.
+ */
+/*
+ * if (thisboard->bustype == pci_bustype) {
+ * dev_err(dev->class_dev,
+ * "Manual attachment of PCI board '%s' not supported\n",
+ * thisboard->name);
+ * }
+ */
+
+/*
+ * For ISA boards, get the i/o base address from it->options[],
+ * request the i/o region and set dev->iobase * from it->options[].
+ * If using interrupts, get the IRQ number from it->options[].
+ */
+
+ /*
+ * Call a common function to handle the remaining things to do for
+ * attaching ISA or PCI boards. (Extra parameters could be added
+ * to pass additional information such as IRQ number.)
+ */
+ return skel_common_attach(dev);
+}
+
+/*
+ * _auto_attach is called via comedi_pci_auto_config() (or
+ * comedi_usb_auto_config(), etc.) to handle devices that can be attached
+ * to the Comedi core automatically without the COMEDI_DEVCONFIG ioctl.
+ *
+ * For PCI devices, comedi_pci_auto_config() is usually called directly from
+ * the struct pci_driver probe() function, so this _auto_attach() function
+ * can be tagged __devinit.
+ *
+ * The context parameter is usually unused, but if the driver called
+ * comedi_auto_config() directly instead of the comedi_pci_auto_config()
+ * wrapper function, this will be a copy of the context passed to
+ * comedi_auto_config().
+ */
+static int __devinit skel_auto_attach(struct comedi_device *dev,
+ unsigned long context)
+{
+ struct pci_dev *pcidev = comedi_to_pci_dev(dev);
+ const struct skel_board *thisboard;
+ struct skel_private *devpriv;
+ int ret;
+
+ /* Hack to allow unused code to be optimized out. */
+ if (!IS_ENABLED(CONFIG_COMEDI_PCI_DRIVERS))
+ return -EINVAL;
+
+ /* Find a matching board in skel_boards[]. */
+ thisboard = skel_find_pci_board(pcidev);
+ if (!thisboard) {
+ dev_err(dev->class_dev, "BUG! cannot determine board type!\n");
+ return -EINVAL;
+ }
+
+ /*
+ * Point the struct comedi_device to the matching board info
+ * and set the board name.
+ */
+ dev->board_ptr = thisboard;
+ dev->board_name = thisboard->name;
+
+ /* Allocate the private data */
+ devpriv = kzalloc(sizeof(*devpriv), GFP_KERNEL);
+ if (!devpriv)
+ return -ENOMEM;
+ dev->private = devpriv;
+
+ /* Enable the PCI device. */
+ ret = comedi_pci_enable(pcidev, dev->board_name);
+ if (ret)
+ return ret;
+
+ /*
+ * Record the fact that the PCI device is enabled so that it can
+ * be disabled during _detach().
+ *
+ * For this example driver, we assume PCI BAR 0 is the main I/O
+ * region for the board registers and use dev->iobase to hold the
+ * I/O base address and to indicate that the PCI device has been
+ * enabled.
+ *
+ * (For boards with memory-mapped registers, dev->iobase is not
+ * usually needed for register access, so can just be set to 1
+ * to indicate that the PCI device has been enabled.)
+ */
+ dev->iobase = pci_resource_start(pcidev, 0);
+
+ /*
+ * Call a common function to handle the remaining things to do for
+ * attaching ISA or PCI boards. (Extra parameters could be added
+ * to pass additional information such as IRQ number.)
+ */
+ return skel_common_attach(dev);
+}
+
+/*
* _detach is called to deconfigure a device. It should deallocate
* resources.
* This function is also called when _attach() fails, so it should be
@@ -514,6 +647,40 @@ static int skel_attach(struct comedi_device *dev, struct comedi_devconfig *it)
*/
static void skel_detach(struct comedi_device *dev)
{
+ const struct skel_board *thisboard = comedi_board(dev);
+ struct skel_private *devpriv = dev->private;
+ struct pci_dev *pcidev = comedi_to_pci_dev(dev);
+
+ if (!thisboard || !devpriv)
+ return;
+
+/*
+ * Do common stuff such as freeing IRQ, unmapping remapped memory
+ * regions, etc., being careful to check that the stuff is valid given
+ * that _detach() is called even when _attach() or _auto_attach() return
+ * an error.
+ */
+
+ if (IS_ENABLED(CONFIG_COMEDI_PCI_DRIVERS) /* &&
+ thisboard->bustype == pci_bustype */) {
+ /*
+ * PCI board
+ *
+ * If PCI device enabled by _auto_attach() (or _attach()),
+ * disable it here.
+ */
+ if (pcidev && dev->iobase)
+ comedi_pci_disable(pcidev);
+ } else {
+ /*
+ * ISA board
+ *
+ * If I/O regions successfully requested by _attach(),
+ * release them here.
+ */
+ if (dev->iobase)
+ release_region(dev->iobase, SKEL_SIZE);
+ }
}
/*
@@ -526,6 +693,7 @@ static struct comedi_driver skel_driver = {
.driver_name = "dummy",
.module = THIS_MODULE,
.attach = skel_attach,
+ .auto_attach = skel_auto_attach,
.detach = skel_detach,
/* It is not necessary to implement the following members if you are
* writing a driver for a ISA PnP or PCI card */
--
1.7.12.4
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