On Thu, 24 Sep 2015, Thierry Reding thierry.reding@gmail.com wrote:
From: Thierry Reding treding@nvidia.com
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.
Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Thierry Reding treding@nvidia.com
Documentation/driver-model/platform.txt | 11 ++++++ drivers/base/platform.c | 60 +++++++++++++++++++++++++++++++++ include/linux/platform_device.h | 5 +++ 3 files changed, 76 insertions(+)
diff --git a/Documentation/driver-model/platform.txt b/Documentation/driver-model/platform.txt index 07795ec51cde..e80468738ba9 100644 --- a/Documentation/driver-model/platform.txt +++ b/Documentation/driver-model/platform.txt @@ -63,6 +63,17 @@ 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);- 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.
Device Enumeration
diff --git a/drivers/base/platform.c b/drivers/base/platform.c index f80aaaf9f610..b7d7987fda97 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -711,6 +711,66 @@ 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 + * + * 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) +{ + 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]); + 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]); + }
This will call platform_driver_unregister() on the driver that failed, but not the first driver.
You should probably make i an int, and use while (--i >= 0).
BR, Jani.
- 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"diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h index bba08f44cc97..0c9f16bfdd99 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -270,6 +270,11 @@ 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);+void platform_unregister_drivers(struct platform_driver * const *drivers,
unsigned int count);/* early platform driver interface */ struct early_platform_driver { const char *class_str; -- 2.5.0
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