From khilman@deeprootsystems.com Wed Sep 1 15:33:18 2010 From: Kevin Hilman To: Grant Likely Cc: linux-kernel@vger.kernel.org, Magnus Damm , Greg Kroah-Hartman , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Paul Mundt , Magnus Damm , Eric Miao , netdev@vger.kernel.org Subject: driver core: platform_bus: allow runtime override of dev_pm_ops Date: Wed, 25 Aug 2010 12:50:00 -0700 Message-ID: <871v9mfp5j.fsf@deeprootsystems.com> From: Kevin Hilman Currently, the platform_bus allows customization of several of the busses dev_pm_ops methods by using weak symbols so that platform code can override them. The weak-symbol approach is not scalable when wanting to support multiple platforms in a single kernel binary. Instead, provide __init methods for platform code to customize the dev_pm_ops methods at runtime. NOTE: after these dynamic methods are merged, the weak symbols should be removed from drivers/base/platform.c. AFAIK, this will only affect SH and sh-mobile which should be converted to use this runtime approach instead of the weak symbols. After SH & sh-mobile are converted, the weak symobols could be removed. Tested on OMAP3. Cc: Magnus Damm Acked-by: Grant Likely Signed-off-by: Kevin Hilman Signed-off-by: Greg Kroah-Hartman --- drivers/base/platform.c | 35 +++++++++++++++++++++++++++++++++++ include/linux/platform_device.h | 3 +++ 2 files changed, 38 insertions(+) --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -976,6 +976,41 @@ struct bus_type platform_bus_type = { }; EXPORT_SYMBOL_GPL(platform_bus_type); +/** + * platform_bus_get_pm_ops() - return pointer to busses dev_pm_ops + * + * This function can be used by platform code to get the current + * set of dev_pm_ops functions used by the platform_bus_type. + */ +const struct dev_pm_ops * __init platform_bus_get_pm_ops(void) +{ + return platform_bus_type.pm; +} + +/** + * platform_bus_set_pm_ops() - update dev_pm_ops for the platform_bus_type + * + * @pm: pointer to new dev_pm_ops struct to be used for platform_bus_type + * + * Platform code can override the dev_pm_ops methods of + * platform_bus_type by using this function. It is expected that + * platform code will first do a platform_bus_get_pm_ops(), then + * kmemdup it, then customize selected methods and pass a pointer to + * the new struct dev_pm_ops to this function. + * + * Since platform-specific code is customizing methods for *all* + * devices (not just platform-specific devices) it is expected that + * any custom overrides of these functions will keep existing behavior + * and simply extend it. For example, any customization of the + * runtime PM methods should continue to call the pm_generic_* + * functions as the default ones do in addition to the + * platform-specific behavior. + */ +void __init platform_bus_set_pm_ops(const struct dev_pm_ops *pm) +{ + platform_bus_type.pm = pm; +} + int __init platform_bus_init(void) { int error; --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -138,6 +138,9 @@ extern struct platform_device *platform_ struct resource *res, unsigned int n_res, const void *data, size_t size); +extern const struct dev_pm_ops * platform_bus_get_pm_ops(void); +extern void platform_bus_set_pm_ops(const struct dev_pm_ops *pm); + /* early platform driver interface */ struct early_platform_driver { const char *class_str;