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Commit dbe2256d authored by Thierry Reding's avatar Thierry Reding Committed by Greg Kroah-Hartman
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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
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+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
~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~
+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"
+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;