[PATCH] ARM: mach-shmobile: Runtime PM prototype

[PATCH] ARM: mach-shmobile: Runtime PM prototype

[Magnus Damm]

From: Magnus Damm <damm@opensource.se>

This is a simple prototype that enables Runtime PM
on SH-Mobile ARM processors. Only clocks are managed
at this point. Needs more work, especially WRT the
shared ARM bits.

Signed-off-by: Magnus Damm <damm@opensource.se>
---

 arch/arm/include/asm/device.h         |    3 
 arch/arm/mach-shmobile/Kconfig        |    2 
 arch/arm/mach-shmobile/Makefile       |    2 
 arch/arm/mach-shmobile/clock-sh7372.c |    2 
 arch/arm/mach-shmobile/pm_runtime.c   |  109 +++++++++++++++++++++++++++++++++
 5 files changed, 116 insertions(+), 2 deletions(-)

--- 0001/arch/arm/include/asm/device.h
+++ work/arch/arm/include/asm/device.h	2010-07-05 15:36:34.000000000 +0900
@@ -13,6 +13,9 @@ struct dev_archdata {
 };
 
 struct pdev_archdata {
+#ifdef CONFIG_ARCH_SHMOBILE
+	struct clk *clk;
+#endif
 };
 
 #endif
--- 0001/arch/arm/mach-shmobile/Kconfig
+++ work/arch/arm/mach-shmobile/Kconfig	2010-07-05 15:36:34.000000000 +0900
@@ -25,6 +25,8 @@ config ARCH_SH7372
 	select COMMON_CLKDEV
 	select SH_CLK_CPG
 	select GENERIC_CLOCKEVENTS
+	select PM
+	select PM_RUNTIME
 
 comment "SH-Mobile Board Type"
 
--- 0001/arch/arm/mach-shmobile/Makefile
+++ work/arch/arm/mach-shmobile/Makefile	2010-07-05 15:36:55.000000000 +0900
@@ -3,7 +3,7 @@
 #
 
 # Common objects
-obj-y				:= timer.o console.o clock.o
+obj-y				:= timer.o console.o clock.o pm_runtime.o
 
 # CPU objects
 obj-$(CONFIG_ARCH_SH7367)	+= setup-sh7367.o clock-sh7367.o intc-sh7367.o
--- 0001/arch/arm/mach-shmobile/clock-sh7372.c
+++ work/arch/arm/mach-shmobile/clock-sh7372.c	2010-07-05 15:37:50.000000000 +0900
@@ -274,7 +274,7 @@ static struct clk mstp_clks[MSTP_NR] = {
 	[MSTP201] = MSTP(&div6_clks[DIV6_SUB], SMSTPCR2, 1, 0), /* SCIFA3 */
 	[MSTP200] = MSTP(&div6_clks[DIV6_SUB], SMSTPCR2, 0, 0), /* SCIFA4 */
 	[MSTP329] = MSTP(&r_clk, SMSTPCR3, 29, 0), /* CMT10 */
-	[MSTP328] = MSTP(&div6_clks[DIV6_SPU], SMSTPCR3, 28, CLK_ENABLE_ON_INIT), /* FSIA */
+	[MSTP328] = MSTP(&div6_clks[DIV6_SPU], SMSTPCR3, 28, 0), /* FSIA */
 	[MSTP323] = MSTP(&div6_clks[DIV6_SUB], SMSTPCR3, 23, 0), /* IIC1 */
 	[MSTP322] = MSTP(&div6_clks[DIV6_SUB], SMSTPCR3, 22, 0), /* USB0 */
 	[MSTP314] = MSTP(&div4_clks[DIV4_HP], SMSTPCR3, 14, 0), /* SDHI0 */
--- /dev/null
+++ work/arch/arm/mach-shmobile/pm_runtime.c	2010-07-05 16:21:52.000000000 +0900
@@ -0,0 +1,109 @@
+/*
+ * arch/arm/mach-shmobile/pm_runtime.c
+ *
+ * Runtime PM support code for SuperH Mobile ARM
+ *
+ *  Copyright (C) 2009-2010 Magnus Damm
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+//#define DEBUG
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/pm_runtime.h>
+#include <linux/platform_device.h>
+#include <linux/mutex.h>
+#include <linux/clk.h>
+#include <linux/sh_clk.h>
+
+static struct clk uninitialized_clock;
+
+static void platform_pm_init_once(struct platform_device *pdev)
+{
+	if (pdev->archdata.clk = &uninitialized_clock) {
+		pdev->archdata.clk = clk_get(&pdev->dev, NULL);
+		dev_info(&pdev->dev, "clocks managed by runtime pm\n");
+	}
+}
+
+static void platform_pm_init_bug(struct platform_device *pdev)
+{
+	if (pdev->archdata.clk = &uninitialized_clock) {
+		pdev->archdata.clk = NULL;
+		dev_info(&pdev->dev, "incorrect runtime pm usage\n");
+	}
+}
+
+int platform_pm_runtime_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+
+	dev_dbg(dev, "platform_pm_runtime_suspend()\n");
+
+	platform_pm_init_bug(pdev);
+
+	if (pdev->archdata.clk)
+		clk_disable(pdev->archdata.clk);
+
+	return 0;
+}
+
+int platform_pm_runtime_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+
+	dev_dbg(dev, "platform_pm_runtime_resume()\n");
+
+	platform_pm_init_once(pdev);
+
+	if (pdev->archdata.clk)
+		clk_enable(pdev->archdata.clk);
+
+	return 0;
+}
+
+int platform_pm_runtime_idle(struct device *dev)
+{
+	/* suspend synchronously to disable clocks immediately */
+	return pm_runtime_suspend(dev);
+}
+
+static int platform_bus_notify(struct notifier_block *nb,
+			       unsigned long action, void *data)
+{
+	struct device *dev = data;
+	struct platform_device *pdev = to_platform_device(dev);
+
+	dev_dbg(dev, "platform_bus_notify() %ld !\n", action);
+
+	switch (action) {
+	case BUS_NOTIFY_ADD_DEVICE:
+		pdev->archdata.clk = &uninitialized_clock;
+
+		break;
+	case BUS_NOTIFY_DEL_DEVICE:
+		if (pdev->archdata.clk &&
+		    pdev->archdata.clk != &uninitialized_clock)
+			clk_put(pdev->archdata.clk);
+
+		pdev->archdata.clk = NULL;
+		break;
+	}
+
+
+	return 0;
+}
+
+static struct notifier_block platform_bus_notifier = {
+	.notifier_call = platform_bus_notify
+};
+
+static int __init sh_pm_runtime_init(void)
+{
+	bus_register_notifier(&platform_bus_type, &platform_bus_notifier);
+	return 0;
+}
+core_initcall(sh_pm_runtime_init);

Re: [PATCH] ARM: mach-shmobile: Runtime PM prototype

[Guennadi Liakhovetski]

Hi Magnus

On Mon, 5 Jul 2010, Magnus Damm wrote:

> From: Magnus Damm <damm@opensource.se>
> 
> This is a simple prototype that enables Runtime PM
> on SH-Mobile ARM processors. Only clocks are managed
> at this point. Needs more work, especially WRT the
> shared ARM bits.
> 
> Signed-off-by: Magnus Damm <damm@opensource.se>

I think, something like this is needed on top of your patch:

diff --git a/arch/arm/mach-shmobile/pm_runtime.c b/arch/arm/mach-shmobile/pm_runtime.c
index 93950dc..4036269 100644
--- a/arch/arm/mach-shmobile/pm_runtime.c
+++ b/arch/arm/mach-shmobile/pm_runtime.c
@@ -40,20 +40,27 @@ static void platform_pm_init_bug(struct platform_device *pdev)
 int platform_pm_runtime_suspend(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
+	int ret;
 
 	dev_dbg(dev, "platform_pm_runtime_suspend()\n");
 
 	platform_pm_init_bug(pdev);
 
+	if (dev->driver && dev->driver->pm && dev->driver->pm->runtime_suspend)
+		ret = dev->driver->pm->runtime_suspend(dev);
+	else
+		ret = 0;
+
 	if (pdev->archdata.clk)
 		clk_disable(pdev->archdata.clk);
 
-	return 0;
+	return ret;
 }
 
 int platform_pm_runtime_resume(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
+	int ret;
 
 	dev_dbg(dev, "platform_pm_runtime_resume()\n");
 
@@ -62,7 +69,12 @@ int platform_pm_runtime_resume(struct device *dev)
 	if (pdev->archdata.clk)
 		clk_enable(pdev->archdata.clk);
 
-	return 0;
+	if (dev->driver && dev->driver->pm && dev->driver->pm->runtime_resume)
+		ret = dev->driver->pm->runtime_resume(dev);
+	else
+		ret = 0;
+
+	return ret;
 }
 
 int platform_pm_runtime_idle(struct device *dev)

I.e., you also have to call driver runtime-pm methofs, similarly to how it 
is done on SuperH. Otherwise, e.g., lcdcfb doesn't work.

Thanks
Guennadi

> ---
> 
>  arch/arm/include/asm/device.h         |    3 
>  arch/arm/mach-shmobile/Kconfig        |    2 
>  arch/arm/mach-shmobile/Makefile       |    2 
>  arch/arm/mach-shmobile/clock-sh7372.c |    2 
>  arch/arm/mach-shmobile/pm_runtime.c   |  109 +++++++++++++++++++++++++++++++++
>  5 files changed, 116 insertions(+), 2 deletions(-)
> 
> --- 0001/arch/arm/include/asm/device.h
> +++ work/arch/arm/include/asm/device.h	2010-07-05 15:36:34.000000000 +0900
> @@ -13,6 +13,9 @@ struct dev_archdata {
>  };
>  
>  struct pdev_archdata {
> +#ifdef CONFIG_ARCH_SHMOBILE
> +	struct clk *clk;
> +#endif
>  };
>  
>  #endif
> --- 0001/arch/arm/mach-shmobile/Kconfig
> +++ work/arch/arm/mach-shmobile/Kconfig	2010-07-05 15:36:34.000000000 +0900
> @@ -25,6 +25,8 @@ config ARCH_SH7372
>  	select COMMON_CLKDEV
>  	select SH_CLK_CPG
>  	select GENERIC_CLOCKEVENTS
> +	select PM
> +	select PM_RUNTIME
>  
>  comment "SH-Mobile Board Type"
>  
> --- 0001/arch/arm/mach-shmobile/Makefile
> +++ work/arch/arm/mach-shmobile/Makefile	2010-07-05 15:36:55.000000000 +0900
> @@ -3,7 +3,7 @@
>  #
>  
>  # Common objects
> -obj-y				:= timer.o console.o clock.o
> +obj-y				:= timer.o console.o clock.o pm_runtime.o
>  
>  # CPU objects
>  obj-$(CONFIG_ARCH_SH7367)	+= setup-sh7367.o clock-sh7367.o intc-sh7367.o
> --- 0001/arch/arm/mach-shmobile/clock-sh7372.c
> +++ work/arch/arm/mach-shmobile/clock-sh7372.c	2010-07-05 15:37:50.000000000 +0900
> @@ -274,7 +274,7 @@ static struct clk mstp_clks[MSTP_NR] = {
>  	[MSTP201] = MSTP(&div6_clks[DIV6_SUB], SMSTPCR2, 1, 0), /* SCIFA3 */
>  	[MSTP200] = MSTP(&div6_clks[DIV6_SUB], SMSTPCR2, 0, 0), /* SCIFA4 */
>  	[MSTP329] = MSTP(&r_clk, SMSTPCR3, 29, 0), /* CMT10 */
> -	[MSTP328] = MSTP(&div6_clks[DIV6_SPU], SMSTPCR3, 28, CLK_ENABLE_ON_INIT), /* FSIA */
> +	[MSTP328] = MSTP(&div6_clks[DIV6_SPU], SMSTPCR3, 28, 0), /* FSIA */
>  	[MSTP323] = MSTP(&div6_clks[DIV6_SUB], SMSTPCR3, 23, 0), /* IIC1 */
>  	[MSTP322] = MSTP(&div6_clks[DIV6_SUB], SMSTPCR3, 22, 0), /* USB0 */
>  	[MSTP314] = MSTP(&div4_clks[DIV4_HP], SMSTPCR3, 14, 0), /* SDHI0 */
> --- /dev/null
> +++ work/arch/arm/mach-shmobile/pm_runtime.c	2010-07-05 16:21:52.000000000 +0900
> @@ -0,0 +1,109 @@
> +/*
> + * arch/arm/mach-shmobile/pm_runtime.c
> + *
> + * Runtime PM support code for SuperH Mobile ARM
> + *
> + *  Copyright (C) 2009-2010 Magnus Damm
> + *
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License.  See the file "COPYING" in the main directory of this archive
> + * for more details.
> + */
> +//#define DEBUG
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/io.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/platform_device.h>
> +#include <linux/mutex.h>
> +#include <linux/clk.h>
> +#include <linux/sh_clk.h>
> +
> +static struct clk uninitialized_clock;
> +
> +static void platform_pm_init_once(struct platform_device *pdev)
> +{
> +	if (pdev->archdata.clk = &uninitialized_clock) {
> +		pdev->archdata.clk = clk_get(&pdev->dev, NULL);
> +		dev_info(&pdev->dev, "clocks managed by runtime pm\n");
> +	}
> +}
> +
> +static void platform_pm_init_bug(struct platform_device *pdev)
> +{
> +	if (pdev->archdata.clk = &uninitialized_clock) {
> +		pdev->archdata.clk = NULL;
> +		dev_info(&pdev->dev, "incorrect runtime pm usage\n");
> +	}
> +}
> +
> +int platform_pm_runtime_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +
> +	dev_dbg(dev, "platform_pm_runtime_suspend()\n");
> +
> +	platform_pm_init_bug(pdev);
> +
> +	if (pdev->archdata.clk)
> +		clk_disable(pdev->archdata.clk);
> +
> +	return 0;
> +}
> +
> +int platform_pm_runtime_resume(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +
> +	dev_dbg(dev, "platform_pm_runtime_resume()\n");
> +
> +	platform_pm_init_once(pdev);
> +
> +	if (pdev->archdata.clk)
> +		clk_enable(pdev->archdata.clk);
> +
> +	return 0;
> +}
> +
> +int platform_pm_runtime_idle(struct device *dev)
> +{
> +	/* suspend synchronously to disable clocks immediately */
> +	return pm_runtime_suspend(dev);
> +}
> +
> +static int platform_bus_notify(struct notifier_block *nb,
> +			       unsigned long action, void *data)
> +{
> +	struct device *dev = data;
> +	struct platform_device *pdev = to_platform_device(dev);
> +
> +	dev_dbg(dev, "platform_bus_notify() %ld !\n", action);
> +
> +	switch (action) {
> +	case BUS_NOTIFY_ADD_DEVICE:
> +		pdev->archdata.clk = &uninitialized_clock;
> +
> +		break;
> +	case BUS_NOTIFY_DEL_DEVICE:
> +		if (pdev->archdata.clk &&
> +		    pdev->archdata.clk != &uninitialized_clock)
> +			clk_put(pdev->archdata.clk);
> +
> +		pdev->archdata.clk = NULL;
> +		break;
> +	}
> +
> +
> +	return 0;
> +}
> +
> +static struct notifier_block platform_bus_notifier = {
> +	.notifier_call = platform_bus_notify
> +};
> +
> +static int __init sh_pm_runtime_init(void)
> +{
> +	bus_register_notifier(&platform_bus_type, &platform_bus_notifier);
> +	return 0;
> +}
> +core_initcall(sh_pm_runtime_init);
> --
> To unsubscribe from this list: send the line "unsubscribe linux-sh" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/

Re: [PATCH] ARM: mach-shmobile: Runtime PM prototype

[Magnus Damm]

Hi Guennadi,

On Thu, Jul 8, 2010 at 5:28 AM, Guennadi Liakhovetski
<g.liakhovetski@gmx.de> wrote:
> On Mon, 5 Jul 2010, Magnus Damm wrote:
>
>> From: Magnus Damm <damm@opensource.se>
>>
>> This is a simple prototype that enables Runtime PM
>> on SH-Mobile ARM processors. Only clocks are managed
>> at this point. Needs more work, especially WRT the
>> shared ARM bits.
>>
>> Signed-off-by: Magnus Damm <damm@opensource.se>
>
> I think, something like this is needed on top of your patch:

> +       if (dev->driver && dev->driver->pm && dev->driver->pm->runtime_suspend)
> +               ret = dev->driver->pm->runtime_suspend(dev);
> +       else
> +               ret = 0;

> +       if (dev->driver && dev->driver->pm && dev->driver->pm->runtime_resume)
> +               ret = dev->driver->pm->runtime_resume(dev);
> +       else
> +               ret = 0;

Thanks a lot for your suggestion!

Yes, something like the above is needed. But the code must be extended
to become power domain aware before we start suspending and resuming.
The drivers are supposed to save and restore context using the
runtime_suspend/resume callbacks, and doing that without being able to
power off is just pure overhead. So the drivers will be asked to save
context only when all drivers in the same power domain have been
runtime suspended.

> I.e., you also have to call driver runtime-pm methofs, similarly to how it
> is done on SuperH. Otherwise, e.g., lcdcfb doesn't work.

Drivers should not assume that the runtime_suspend/resume callbacks
will be invoked at a certain point. The power domain partitioning
varies with processor type but drivers are shared across multiple
processors. Drivers are unaware of the power domain partitioning, but
the runtime pm code knows how things fit together. Because of this it
is up to the runtime pm code to decide when to invoke the driver
callbacks.

Please update the LCDC driver to only save and restore context in the
runtime pm callbacks. And remove any code that assumes that the
callbacks will be invoked when the device is suspended.

Cheers,

/ magnus