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: Thierry Reding <treding@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thierry Reding 2015-09-25 17:29:04 +02:00 committed by Greg Kroah-Hartman
parent 7568fb63f5
commit dbe2256ddd
3 changed files with 83 additions and 0 deletions

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@ -63,6 +63,20 @@ runtime memory footprint:
int platform_driver_probe(struct platform_driver *drv,
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
~~~~~~~~~~~~~~~~~~

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@ -710,6 +710,67 @@ err_out:
}
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:
* (a) environment variable lets new-style hotplug events work once system is
* fully running: "modprobe $MODALIAS"

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@ -270,6 +270,14 @@ extern struct platform_device *__platform_create_bundle(
struct resource *res, unsigned int n_res,
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 */
struct early_platform_driver {
const char *class_str;