linux-kernel - [PATCH] driver core: platform_bus: allow runtime override of dev_pm

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Message-Id: <1282577310-10430-1-git-send-email-khilman@deeprootsystems.com>
Date:	Mon, 23 Aug 2010 08:28:16 -0700
From:	Kevin Hilman <khilman@...prootsystems.com>
To:	linux-kernel@...r.kernel.org
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	Magnus Damm <magnus.damm@...il.com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>, Paul Mundt <lethal@...ux-sh.org>,
	Magnus Damm <damm@...nsource.se>,
	Kevin Hilman <khilman@...prootsystems.com>,
	Eric Miao <eric.y.miao@...il.com>, netdev@...r.kernel.org
Subject: [PATCH] driver core: platform_bus: allow runtime override of dev_pm_ops

From: Kevin Hilman <khilman@...com>

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: Grant Likely <grant.likely@...retlab.ca>
Cc: Magnus Damm <magnus.damm@...il.com>
Signed-off-by: Kevin Hilman <khilman@...prootsystems.com>
---
Apolgies for duplicate mails.  I fat-fingered the LKML list addr the first try.

 drivers/base/platform.c         |   16 ++++++++++++++++
 include/linux/platform_device.h |    3 +++
 2 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index c6c933f..a7d8a00 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -976,6 +976,22 @@ struct bus_type platform_bus_type = {
 };
 EXPORT_SYMBOL_GPL(platform_bus_type);
 
+const struct dev_pm_ops * __init platform_bus_get_pm_ops(void)
+{
+	struct bus_type *bus = &platform_bus_type;
+
+	return bus->pm;
+}
+
+int __init platform_bus_set_pm_ops(struct dev_pm_ops *pm)
+{
+	struct bus_type *bus = &platform_bus_type;
+
+	bus->pm = pm;
+
+	return 0;
+}
+
 int __init platform_bus_init(void)
 {
 	int error;
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index d7ecad0..4bce2c9 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -138,6 +138,9 @@ extern struct platform_device *platform_create_bundle(struct platform_driver *dr
 					struct resource *res, unsigned int n_res,
 					const void *data, size_t size);
 
+extern const struct dev_pm_ops * __init platform_bus_get_pm_ops(void);
+extern int __init platform_bus_set_pm_ops(struct dev_pm_ops *pm);
+
 /* early platform driver interface */
 struct early_platform_driver {
 	const char *class_str;
-- 
1.7.2.1

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