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Commit dbe2256d authored by Thierry Reding's avatar Thierry Reding Committed by Greg Kroah-Hartman
Browse files

driver-core: platform: Provide helpers for multi-driver modules 



Some modules register several sub-drivers. Provide a helper that makes
it easy to register and unregister a list of sub-drivers, as well as
unwind properly on error.

Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7568fb63

Documentation/driver-model/platform.txt

+14 −0
Original line number Original line Diff line number Diff line
@@ -63,6 +63,20 @@ runtime memory footprint: 
	int platform_driver_probe(struct platform_driver *drv,

	int platform_driver_probe(struct platform_driver *drv,

			  int (*probe)(struct platform_device *))

			  int (*probe)(struct platform_device *))





Kernel modules can be composed of several platform drivers. The platform core

provides helpers to register and unregister an array of drivers:



	int __platform_register_drivers(struct platform_driver * const *drivers,

				      unsigned int count, struct module *owner);

	void platform_unregister_drivers(struct platform_driver * const *drivers,

					 unsigned int count);



If one of the drivers fails to register, all drivers registered up to that

point will be unregistered in reverse order. Note that there is a convenience

macro that passes THIS_MODULE as owner parameter:



	#define platform_register_driver(drivers, count)







Device Enumeration

Device Enumeration

~~~~~~~~~~~~~~~~~~

~~~~~~~~~~~~~~~~~~

drivers/base/platform.c

+61 −0
Original line number Original line Diff line number Diff line
@@ -710,6 +710,67 @@ struct platform_device * __init_or_module __platform_create_bundle( 
}

}

EXPORT_SYMBOL_GPL(__platform_create_bundle);

EXPORT_SYMBOL_GPL(__platform_create_bundle);





/**

 * __platform_register_drivers - register an array of platform drivers

 * @drivers: an array of drivers to register

 * @count: the number of drivers to register

 * @owner: module owning the drivers

 *

 * Registers platform drivers specified by an array. On failure to register a

 * driver, all previously registered drivers will be unregistered. Callers of

 * this API should use platform_unregister_drivers() to unregister drivers in

 * the reverse order.

 *

 * Returns: 0 on success or a negative error code on failure.

 */

int __platform_register_drivers(struct platform_driver * const *drivers,

				unsigned int count, struct module *owner)

{

	unsigned int i;

	int err;



	for (i = 0; i < count; i++) {

		pr_debug("registering platform driver %ps\n", drivers[i]);



		err = __platform_driver_register(drivers[i], owner);

		if (err < 0) {

			pr_err("failed to register platform driver %ps: %d\n",

			       drivers[i], err);

			goto error;

		}

	}



	return 0;



error:

	while (i--) {

		pr_debug("unregistering platform driver %ps\n", drivers[i]);

		platform_driver_unregister(drivers[i]);

	}



	return err;

}

EXPORT_SYMBOL_GPL(__platform_register_drivers);



/**

 * platform_unregister_drivers - unregister an array of platform drivers

 * @drivers: an array of drivers to unregister

 * @count: the number of drivers to unregister

 *

 * Unegisters platform drivers specified by an array. This is typically used

 * to complement an earlier call to platform_register_drivers(). Drivers are

 * unregistered in the reverse order in which they were registered.

 */

void platform_unregister_drivers(struct platform_driver * const *drivers,

				 unsigned int count)

{

	while (count--) {

		pr_debug("unregistering platform driver %ps\n", drivers[count]);

		platform_driver_unregister(drivers[count]);

	}

}

EXPORT_SYMBOL_GPL(platform_unregister_drivers);



/* modalias support enables more hands-off userspace setup:

/* modalias support enables more hands-off userspace setup:

 * (a) environment variable lets new-style hotplug events work once system is

 * (a) environment variable lets new-style hotplug events work once system is

 *     fully running:  "modprobe $MODALIAS"

 *     fully running:  "modprobe $MODALIAS"

include/linux/platform_device.h

+8 −0
Original line number Original line Diff line number Diff line
@@ -270,6 +270,14 @@ extern struct platform_device *__platform_create_bundle( 
	struct resource *res, unsigned int n_res,

	struct resource *res, unsigned int n_res,

	const void *data, size_t size, struct module *module);

	const void *data, size_t size, struct module *module);





int __platform_register_drivers(struct platform_driver * const *drivers,

				unsigned int count, struct module *owner);

void platform_unregister_drivers(struct platform_driver * const *drivers,

				 unsigned int count);



#define platform_register_drivers(drivers, count) \

	__platform_register_drivers(drivers, count, THIS_MODULE)



/* early platform driver interface */

/* early platform driver interface */

struct early_platform_driver {

struct early_platform_driver {

	const char *class_str;

	const char *class_str;