staging: comedi: comedi_pci.c: improve function documentation

Expand the descriptions of the functions and document the return values.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/comedi_pci.c

@@ -22,8 +22,14 @@
 #include "comedi_pci.h"
 
 /**
- * comedi_to_pci_dev() - comedi_device pointer to pci_dev pointer.
- * @dev: comedi_device struct
+ * comedi_to_pci_dev() - Return PCI device attached to COMEDI device
+ * @dev: COMEDI device.
+ *
+ * Assuming @dev->hw_dev is non-%NULL, it is assumed to be pointing to a
+ * a &struct device embedded in a &struct pci_dev.
+ *
+ * Returns: Attached PCI device if @dev->hw_dev is non-%NULL.
+ * Returns %NULL if @dev->hw_dev is %NULL.
  */
 struct pci_dev *comedi_to_pci_dev(struct comedi_device *dev)
 {
@@ -32,8 +38,22 @@ struct pci_dev *comedi_to_pci_dev(struct comedi_device *dev)
 EXPORT_SYMBOL_GPL(comedi_to_pci_dev);
 
 /**
- * comedi_pci_enable() - Enable the PCI device and request the regions.
- * @dev: comedi_device struct
+ * comedi_pci_enable() - Enable the PCI device and request the regions
+ * @dev: COMEDI device.
+ *
+ * Assuming @dev->hw_dev is non-%NULL, it is assumed to be pointing to a
+ * a &struct device embedded in a &struct pci_dev.  Enable the PCI device
+ * and request its regions.  Set @dev->ioenabled to %true if successful,
+ * otherwise undo what was done.
+ *
+ * Calls to comedi_pci_enable() and comedi_pci_disable() cannot be nested.
+ *
+ * Returns:
+ *	0 on success,
+ *	-%ENODEV if @dev->hw_dev is %NULL,
+ *	-%EBUSY if regions busy,
+ *	or some negative error number if failed to enable PCI device.
+ *
  */
 int comedi_pci_enable(struct comedi_device *dev)
 {
@@ -58,8 +78,13 @@ int comedi_pci_enable(struct comedi_device *dev)
 EXPORT_SYMBOL_GPL(comedi_pci_enable);
 
 /**
- * comedi_pci_disable() - Release the regions and disable the PCI device.
- * @dev: comedi_device struct
+ * comedi_pci_disable() - Release the regions and disable the PCI device
+ * @dev: COMEDI device.
+ *
+ * Assuming @dev->hw_dev is non-%NULL, it is assumed to be pointing to a
+ * a &struct device embedded in a &struct pci_dev.  If the earlier call
+ * to comedi_pci_enable() was successful, release the PCI device's regions
+ * and disable it.  Reset @dev->ioenabled back to %false.
  */
 void comedi_pci_disable(struct comedi_device *dev)
 {
@@ -74,8 +99,18 @@ void comedi_pci_disable(struct comedi_device *dev)
 EXPORT_SYMBOL_GPL(comedi_pci_disable);
 
 /**
- * comedi_pci_detach() - A generic (*detach) function for PCI drivers.
- * @dev: comedi_device struct
+ * comedi_pci_detach() - A generic "detach" handler for PCI COMEDI drivers
+ * @dev: COMEDI device.
+ *
+ * COMEDI drivers for PCI devices that need no special clean-up of private data
+ * and have no ioremapped regions other than that pointed to by @dev->mmio may
+ * use this function as its "detach" handler called by the COMEDI core when a
+ * COMEDI device is being detached from the low-level driver.  It may be also
+ * called from a more specific "detach" handler that does additional clean-up.
+ *
+ * Free the IRQ if @dev->irq is non-zero, iounmap @dev->mmio if it is
+ * non-%NULL, and call comedi_pci_disable() to release the PCI device's regions
+ * and disable it.
  */
 void comedi_pci_detach(struct comedi_device *dev)
 {
@@ -97,12 +132,19 @@ void comedi_pci_detach(struct comedi_device *dev)
 EXPORT_SYMBOL_GPL(comedi_pci_detach);
 
 /**
- * comedi_pci_auto_config() - Configure/probe a comedi PCI driver.
- * @pcidev: pci_dev struct
- * @driver: comedi_driver struct
- * @context: driver specific data, passed to comedi_auto_config()
+ * comedi_pci_auto_config() - Configure/probe a PCI COMEDI device
+ * @pcidev: PCI device.
+ * @driver: Registered COMEDI driver.
+ * @context: Driver specific data, passed to comedi_auto_config().
  *
- * Typically called from the pci_driver (*probe) function.
+ * Typically called from the pci_driver (*probe) function.  Auto-configure
+ * a COMEDI device, using the &struct device embedded in *@pcidev as the
+ * hardware device.  The @context value gets passed through to @driver's
+ * "auto_attach" handler.  The "auto_attach" handler may call
+ * comedi_to_pci_dev() on the passed in COMEDI device to recover @pcidev.
+ *
+ * Returns: The result of calling comedi_auto_config() (0 on success, or
+ * a negative error number on failure).
  */
 int comedi_pci_auto_config(struct pci_dev *pcidev,
 			   struct comedi_driver *driver,
@@ -113,10 +155,18 @@ int comedi_pci_auto_config(struct pci_dev *pcidev,
 EXPORT_SYMBOL_GPL(comedi_pci_auto_config);
 
 /**
- * comedi_pci_auto_unconfig() - Unconfigure/remove a comedi PCI driver.
- * @pcidev: pci_dev struct
+ * comedi_pci_auto_unconfig() - Unconfigure/remove a PCI COMEDI device
+ * @pcidev: PCI device.
+ *
+ * Typically called from the pci_driver (*remove) function.  Auto-unconfigure
+ * a COMEDI device attached to this PCI device, using a pointer to the
+ * &struct device embedded in *@pcidev as the hardware device.  The COMEDI
+ * driver's "detach" handler will be called during unconfiguration of the
+ * COMEDI device.
  *
- * Typically called from the pci_driver (*remove) function.
+ * Note that the COMEDI device may have already been unconfigured using the
+ * %COMEDI_DEVCONFIG ioctl, in which case this attempt to unconfigure it
+ * again should be ignored.
  */
 void comedi_pci_auto_unconfig(struct pci_dev *pcidev)
 {
@@ -125,13 +175,15 @@ void comedi_pci_auto_unconfig(struct pci_dev *pcidev)
 EXPORT_SYMBOL_GPL(comedi_pci_auto_unconfig);
 
 /**
- * comedi_pci_driver_register() - Register a comedi PCI driver.
- * @comedi_driver: comedi_driver struct
- * @pci_driver: pci_driver struct
+ * comedi_pci_driver_register() - Register a PCI COMEDI driver
+ * @comedi_driver: COMEDI driver to be registered.
+ * @pci_driver: PCI driver to be registered.
+ *
+ * This function is called from the module_init() of PCI COMEDI driver modules
+ * to register the COMEDI driver and the PCI driver.  Do not call it directly,
+ * use the module_comedi_pci_driver() helper macro instead.
  *
- * This function is used for the module_init() of comedi PCI drivers.
- * Do not call it directly, use the module_comedi_pci_driver() helper
- * macro instead.
+ * Returns: 0 on success, or a negative error number on failure.
  */
 int comedi_pci_driver_register(struct comedi_driver *comedi_driver,
 			       struct pci_driver *pci_driver)
@@ -153,13 +205,13 @@ int comedi_pci_driver_register(struct comedi_driver *comedi_driver,
 EXPORT_SYMBOL_GPL(comedi_pci_driver_register);
 
 /**
- * comedi_pci_driver_unregister() - Unregister a comedi PCI driver.
- * @comedi_driver: comedi_driver struct
- * @pci_driver: pci_driver struct
+ * comedi_pci_driver_unregister() - Unregister a PCI COMEDI driver
+ * @comedi_driver: COMEDI driver to be unregistered.
+ * @pci_driver: PCI driver to be unregistered.
  *
- * This function is used for the module_exit() of comedi PCI drivers.
- * Do not call it directly, use the module_comedi_pci_driver() helper
- * macro instead.
+ * This function is called from the module_exit() of PCI COMEDI driver modules
+ * to unregister the PCI driver and the COMEDI driver.  Do not call it
+ * directly, use the module_comedi_pci_driver() helper macro instead.
  */
 void comedi_pci_driver_unregister(struct comedi_driver *comedi_driver,
 				  struct pci_driver *pci_driver)