staging: comedi: comedi_pcmcia.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_pcmcia.c

@@ -22,8 +22,14 @@
 #include "comedi_pcmcia.h"
 
 /**
- * comedi_to_pcmcia_dev() - comedi_device pointer to pcmcia_device pointer.
- * @dev: comedi_device struct
+ * comedi_to_pcmcia_dev() - Return PCMCIA 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 pcmcia_device.
+ *
+ * Return: Attached PCMCIA device if @dev->hw_dev is non-%NULL.
+ * Return %NULL if @dev->hw_dev is %NULL.
  */
 struct pcmcia_device *comedi_to_pcmcia_dev(struct comedi_device *dev)
 {
@@ -41,13 +47,35 @@ static int comedi_pcmcia_conf_check(struct pcmcia_device *link,
 }
 
 /**
- * comedi_pcmcia_enable() - Request the regions and enable the PCMCIA device.
- * @dev: comedi_device struct
- * @conf_check: optional callback to check the pcmcia_device configuration
+ * comedi_pcmcia_enable() - Request the regions and enable the PCMCIA device
+ * @dev: COMEDI device.
+ * @conf_check: Optional callback to check each configuration option of the
+ *	PCMCIA device and request I/O regions.
+ *
+ * Assuming @dev->hw_dev is non-%NULL, it is assumed to be pointing to a a
+ * &struct device embedded in a &struct pcmcia_device.  The comedi PCMCIA
+ * driver needs to set the 'config_flags' member in the &struct pcmcia_device,
+ * as appropriate for that driver, before calling this function in order to
+ * allow pcmcia_loop_config() to do its internal autoconfiguration.
+ *
+ * If @conf_check is %NULL it is set to a default function.  If is
+ * passed to pcmcia_loop_config() and should return %0 if the configuration
+ * is valid and I/O regions requested successfully, otherwise it should return
+ * a negative error value.  The default function returns -%EINVAL if the
+ * 'config_index' member is %0, otherwise it calls pcmcia_request_io() and
+ * returns the result.
+ *
+ * If the above configuration check passes, pcmcia_enable_device() is called
+ * to set up and activate the PCMCIA device.
  *
- * The comedi PCMCIA driver needs to set the link->config_flags, as
- * appropriate for that driver, before calling this function in order
- * to allow pcmcia_loop_config() to do its internal autoconfiguration.
+ * If this function returns an error, comedi_pcmcia_disable() should be called
+ * to release requested resources.
+ *
+ * Return:
+ *	0 on success,
+ *	-%ENODEV id @dev->hw_dev is %NULL,
+ *	a negative error number from pcmcia_loop_config() if it fails,
+ *	or a negative error number from pcmcia_enable_device() if it fails.
  */
 int comedi_pcmcia_enable(struct comedi_device *dev,
 			 int (*conf_check)(struct pcmcia_device *, void *))
@@ -70,8 +98,12 @@ int comedi_pcmcia_enable(struct comedi_device *dev,
 EXPORT_SYMBOL_GPL(comedi_pcmcia_enable);
 
 /**
- * comedi_pcmcia_disable() - Disable the PCMCIA device and release the regions.
- * @dev: comedi_device struct
+ * comedi_pcmcia_disable() - Disable the PCMCIA device and release 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 pcmcia_device.  Call
+ * pcmcia_disable_device() to disable and clean up the PCMCIA device.
  */
 void comedi_pcmcia_disable(struct comedi_device *dev)
 {
@@ -83,11 +115,17 @@ void comedi_pcmcia_disable(struct comedi_device *dev)
 EXPORT_SYMBOL_GPL(comedi_pcmcia_disable);
 
 /**
- * comedi_pcmcia_auto_config() - Configure/probe a comedi PCMCIA driver.
- * @link: pcmcia_device struct
- * @driver: comedi_driver struct
+ * comedi_pcmcia_auto_config() - Configure/probe a PCMCIA COMEDI device
+ * @link: PCMCIA device.
+ * @driver: Registered COMEDI driver.
+ *
+ * Typically called from the pcmcia_driver (*probe) function.  Auto-configure
+ * a COMEDI device, using a pointer to the &struct device embedded in *@link
+ * as the hardware device.  The @driver's "auto_attach" handler may call
+ * comedi_to_pcmcia_dev() on the passed in COMEDI device to recover @link.
  *
- * Typically called from the pcmcia_driver (*probe) function.
+ * Return: The result of calling comedi_auto_config() (0 on success, or a
+ * negative error number on failure).
  */
 int comedi_pcmcia_auto_config(struct pcmcia_device *link,
 			      struct comedi_driver *driver)
@@ -97,10 +135,18 @@ int comedi_pcmcia_auto_config(struct pcmcia_device *link,
 EXPORT_SYMBOL_GPL(comedi_pcmcia_auto_config);
 
 /**
- * comedi_pcmcia_auto_unconfig() - Unconfigure/remove a comedi PCMCIA driver.
- * @link: pcmcia_device struct
+ * comedi_pcmcia_auto_unconfig() - Unconfigure/remove a PCMCIA COMEDI device
+ * @link: PCMCIA device.
  *
  * Typically called from the pcmcia_driver (*remove) function.
+ * Auto-unconfigure a COMEDI device attached to this PCMCIA device, using a
+ * pointer to the &struct device embedded in *@link as the hardware device.
+ * The COMEDI driver's "detach" handler will be called during unconfiguration
+ * of the COMEDI device.
+ *
+ * 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_pcmcia_auto_unconfig(struct pcmcia_device *link)
 {
@@ -109,13 +155,15 @@ void comedi_pcmcia_auto_unconfig(struct pcmcia_device *link)
 EXPORT_SYMBOL_GPL(comedi_pcmcia_auto_unconfig);
 
 /**
- * comedi_pcmcia_driver_register() - Register a comedi PCMCIA driver.
- * @comedi_driver: comedi_driver struct
- * @pcmcia_driver: pcmcia_driver struct
+ * comedi_pcmcia_driver_register() - Register a PCMCIA COMEDI driver
+ * @comedi_driver: COMEDI driver to be registered.
+ * @pcmcia_driver: PCMCIA driver to be registered.
+ *
+ * This function is used for the module_init() of PCMCIA COMEDI driver modules
+ * to register the COMEDI driver and the PCMCIA driver.  Do not call it
+ * directly, use the module_comedi_pcmcia_driver() helper macro instead.
  *
- * This function is used for the module_init() of comedi USB drivers.
- * Do not call it directly, use the module_comedi_pcmcia_driver() helper
- * macro instead.
+ * Return: 0 on success, or a negative error number on failure.
  */
 int comedi_pcmcia_driver_register(struct comedi_driver *comedi_driver,
 				  struct pcmcia_driver *pcmcia_driver)
@@ -137,13 +185,13 @@ int comedi_pcmcia_driver_register(struct comedi_driver *comedi_driver,
 EXPORT_SYMBOL_GPL(comedi_pcmcia_driver_register);
 
 /**
- * comedi_pcmcia_driver_unregister() - Unregister a comedi PCMCIA driver.
- * @comedi_driver: comedi_driver struct
- * @pcmcia_driver: pcmcia_driver struct
+ * comedi_pcmcia_driver_unregister() - Unregister a PCMCIA COMEDI driver
+ * @comedi_driver: COMEDI driver to be registered.
+ * @pcmcia_driver: PCMCIA driver to be registered.
  *
- * This function is used for the module_exit() of comedi PCMCIA drivers.
- * Do not call it directly, use the module_comedi_pcmcia_driver() helper
- * macro instead.
+ * This function is called from the module_exit() of PCMCIA COMEDI driver
+ * modules to unregister the PCMCIA driver and the COMEDI driver.  Do not call
+ * it directly, use the module_comedi_pcmcia_driver() helper macro instead.
  */
 void comedi_pcmcia_driver_unregister(struct comedi_driver *comedi_driver,
 				     struct pcmcia_driver *pcmcia_driver)