[PATCH] driver core: platform_bus: allow runtime override of dev_pm_ops

[PATCH] driver core: platform_bus: allow runtime override of dev_pm_ops

[Kevin Hilman]

From: Kevin Hilman <khilman@ti.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@secretlab.ca>
Cc: Magnus Damm <magnus.damm@gmail.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
---
 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

Re: [PATCH] driver core: platform_bus: allow runtime override of dev_pm_ops

[Grant Likely]

"Kevin Hilman" <khilman@deeprootsystems.com> wrote:

>From: Kevin Hilman <khilman@ti.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@secretlab.ca>
>Cc: Magnus Damm <magnus.damm@gmail.com>
>Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
>---
> 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;
>+}
>+

Looks okay to me,  but these functions should have kerneldoc headers describing what they are, and more importantly, the constraints and what the acceptable use case is.

g.

> 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
>

-- 
Sent from my Android phone with K-9 Mail. Please excuse my brevity.

Re: [PATCH] driver core: platform_bus: allow runtime override of dev_pm_ops

[Grant Likely]

"Grant Likely" <grant.likely@secretlab.ca> wrote:

>
>
>"Kevin Hilman" <khilman@deeprootsystems.com> wrote:
>
>>From: Kevin Hilman <khilman@ti.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@secretlab.ca>
>>Cc: Magnus Damm <magnus.damm@gmail.com>
>>Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
>>---
>> 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;
>>+}
>>+

Another (minor) note, these can be more concise.  The set open function can have a void return, and bus = &platform_bus_type lines are unnecessary.

g.

>-- 
>Sent from my Android phone with K-9 Mail. Please excuse my brevity.

-- 
Sent from my Android phone with K-9 Mail. Please excuse my brevity.

[PATCH] driver core: platform_bus: allow runtime override of dev_pm_ops

[Kevin Hilman]

From: Kevin Hilman <khilman@ti.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@secretlab.ca>
Cc: Magnus Damm <magnus.damm@gmail.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.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