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 --- Changes in v2: - properly pass around the owner module
Documentation/driver-model/platform.txt | 14 ++++++++ drivers/base/platform.c | 61 +++++++++++++++++++++++++++++++++ include/linux/platform_device.h | 8 +++++ 3 files changed, 83 insertions(+)
diff --git a/Documentation/driver-model/platform.txt b/Documentation/driver-model/platform.txt index 07795ec51cde..e456696cfef2 100644 --- a/Documentation/driver-model/platform.txt +++ b/Documentation/driver-model/platform.txt @@ -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 ~~~~~~~~~~~~~~~~~~ diff --git a/drivers/base/platform.c b/drivers/base/platform.c index f80aaaf9f610..68c58c43e45a 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -711,6 +711,67 @@ 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" diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h index bba08f44cc97..dc777be5f2e1 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -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;