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Date: Wed, 25 Aug 2010 12:50:00 -0700
From: Kevin Hilman <khilman@...prootsystems.com>
To: Grant Likely <grant.likely@...retlab.ca>
Cc: linux-kernel@...r.kernel.org, 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>,
Eric Miao <eric.y.miao@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH v2] driver core: platform_bus: allow runtime override of dev_pm_ops
Grant Likely <grant.likely@...retlab.ca> writes:
> On Mon, Aug 23, 2010 at 11:18 AM, Kevin Hilman
> <khilman@...prootsystems.com> wrote:
>> 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>
>
> Looks good to me. A handful of nitpicks below, I don't know if Greg
> will want you to respin for these or not. Feel free to add my
> acked-by line though:
>
> Acked-by: Grant Likely <grant.likely@...retlab.ca>
Thanks, here's a re-spin with your signoff and fixing the issues you
raised.
Applies to v2.6.36-rc1.
Kevin
>From 728f0ae551e805a10c9a45bcfb29f81ad45842da Mon Sep 17 00:00:00 2001
From: Kevin Hilman <khilman@...com>
Date: Fri, 20 Aug 2010 10:46:53 -0700
Subject: [PATCH] driver core: platform_bus: allow runtime override of dev_pm_ops
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 <magnus.damm@...il.com>
Acked-by: Grant Likely <grant.likely@...retlab.ca>
Signed-off-by: Kevin Hilman <khilman@...prootsystems.com>
---
drivers/base/platform.c | 35 +++++++++++++++++++++++++++++++++++
include/linux/platform_device.h | 3 +++
2 files changed, 38 insertions(+), 0 deletions(-)
diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index c6c933f..468bbfd 100644
--- 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;
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index d7ecad0..2e700ec 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 * 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;
--
1.7.2.1
--
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