Re: [Update][PATCH 8/8] ARM / shmobile: Support for I/O power domains for SH7372 (v6)

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Monday, June 20, 2011, Paul Mundt wrote:
> On Mon, Jun 20, 2011 at 12:07:47AM +0200, Rafael J. Wysocki wrote:
> > +static int pd_power_down(struct generic_pm_domain *genpd)
> > +{
> > +	struct sh7372_pm_domain *sh7372_pd = to_sh7372_pd(genpd);
> > +	unsigned int mask = 1 << sh7372_pd->bit_shift;
> > +
> > +	if (__raw_readl(PSTR) & mask) {
> > +		__raw_writel(mask, SPDCR);
> > +
> > +		while (__raw_readl(SPDCR) & mask)
> > +			cpu_relax();
> > +
> > +		pr_debug("sh7372 power domain down 0x%08x -> PSTR = 0x%08x\n",
> > +			 mask, __raw_readl(PSTR));
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int pd_power_up(struct generic_pm_domain *genpd)
> > +{
> > +	struct sh7372_pm_domain *sh7372_pd = to_sh7372_pd(genpd);
> > +	unsigned int mask = 1 << sh7372_pd->bit_shift;
> > +
> > +	if (!(__raw_readl(PSTR) & mask)) {
> > +		__raw_writel(mask, SWUCR);
> > +
> > +		while (__raw_readl(SWUCR) & mask)
> > +			cpu_relax();
> > +
> > +		pr_debug("sh7372 power domain up 0x%08x -> PSTR = 0x%08x\n",
> > +			 mask, __raw_readl(PSTR));
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> Given that these functions can return errors, it's probably more prudent
> to implement some timeout logic on top of the busy loop. Hardware does
> get stuck, after all.

Yes, it does, but we don't really know what timeout value to use in there.

In fact, failures of pd_power_down() don't really matter (at worst the power
domain won't be powered off really) and pd_power_up() should only return error
code if the error is known to be unrecoverable.

So, what about this: repeat certain number of times (I verified that it took
several iterations of the loop until the new value settled on my hardware)
and then return from pd_power_down() or go to sleep for a short time and repeat
in pd_power_up()?

Rafael

---
From: Rafael J. Wysocki <rjw@sisk.pl>
Subject: ARM / shmobile: Support for I/O power domains for SH7372 (v7)

Use the generic power domains support introduced by the previous
patch to implement support for power domains on SH7372.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 arch/arm/Kconfig                             |    1 
 arch/arm/mach-shmobile/Makefile              |    4 +
 arch/arm/mach-shmobile/board-mackerel.c      |    4 +
 arch/arm/mach-shmobile/include/mach/sh7372.h |   28 +++++++++
 arch/arm/mach-shmobile/pm-sh7372.c           |   84 +++++++++++++++++++++++++++
 5 files changed, 121 insertions(+)

Index: linux-2.6/arch/arm/mach-shmobile/board-mackerel.c
===================================================================
--- linux-2.6.orig/arch/arm/mach-shmobile/board-mackerel.c
+++ linux-2.6/arch/arm/mach-shmobile/board-mackerel.c
@@ -1582,6 +1582,10 @@ static void __init mackerel_init(void)
 
 	platform_add_devices(mackerel_devices, ARRAY_SIZE(mackerel_devices));
 
+	sh7372_init_pm_domain(&sh7372_a4lc_domain);
+	sh7372_add_device_to_domain(SH7372_A4LC, &lcdc_device);
+	sh7372_add_device_to_domain(SH7372_A4LC, &hdmi_lcdc_device);
+
 	hdmi_init_pm_clock();
 	sh7372_pm_init();
 }
Index: linux-2.6/arch/arm/mach-shmobile/include/mach/sh7372.h
===================================================================
--- linux-2.6.orig/arch/arm/mach-shmobile/include/mach/sh7372.h
+++ linux-2.6/arch/arm/mach-shmobile/include/mach/sh7372.h
@@ -12,6 +12,7 @@
 #define __ASM_SH7372_H__
 
 #include <linux/sh_clk.h>
+#include <linux/pm_domain.h>
 
 /*
  * Pin Function Controller:
@@ -470,4 +471,31 @@ extern struct clk sh7372_fsibck_clk;
 extern struct clk sh7372_fsidiva_clk;
 extern struct clk sh7372_fsidivb_clk;
 
+struct platform_device;
+
+struct sh7372_pm_domain {
+	struct generic_pm_domain genpd;
+	unsigned int bit_shift;
+};
+
+static inline struct sh7372_pm_domain *to_sh7372_pd(struct generic_pm_domain *d)
+{
+	return container_of(d, struct sh7372_pm_domain, genpd);
+}
+
+#ifdef CONFIG_PM
+extern struct sh7372_pm_domain sh7372_a4lc_domain;
+#define SH7372_A4LC	(&sh7372_a4lc_domain)
+
+extern void sh7372_init_pm_domain(struct sh7372_pm_domain *sh7372_pd);
+extern void sh7372_add_device_to_domain(struct sh7372_pm_domain *sh7372_pd,
+					struct platform_device *pdev);
+#else
+#define SH7372_A4LC	NULL
+
+static inline void sh7372_init_pm_domain(struct sh7372_pm_domain *sh7372_pd) {}
+static inline void sh7372_add_device_to_domain(struct sh7372_pm_domain *pd,
+					       struct platform_device *pdev) {}
+#endif /* CONFIG_PM */
+
 #endif /* __ASM_SH7372_H__ */
Index: linux-2.6/arch/arm/mach-shmobile/Makefile
===================================================================
--- linux-2.6.orig/arch/arm/mach-shmobile/Makefile
+++ linux-2.6/arch/arm/mach-shmobile/Makefile
@@ -42,6 +42,10 @@ obj-$(CONFIG_MACH_AP4EVB)	+= board-ap4ev
 obj-$(CONFIG_MACH_AG5EVM)	+= board-ag5evm.o
 obj-$(CONFIG_MACH_MACKEREL)	+= board-mackerel.o
 
+# PM objects
+pm-$(CONFIG_ARCH_SH7372)	+= pm-sh7372.o
+
 # Framework support
 obj-$(CONFIG_SMP)		+= $(smp-y)
 obj-$(CONFIG_GENERIC_GPIO)	+= $(pfc-y)
+obj-$(CONFIG_PM)		+= $(pm-y)
Index: linux-2.6/arch/arm/mach-shmobile/pm-sh7372.c
===================================================================
--- linux-2.6.orig/arch/arm/mach-shmobile/pm-sh7372.c
+++ linux-2.6/arch/arm/mach-shmobile/pm-sh7372.c
@@ -15,16 +15,100 @@
 #include <linux/list.h>
 #include <linux/err.h>
 #include <linux/slab.h>
+#include <linux/pm_runtime.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
 #include <asm/system.h>
 #include <asm/io.h>
 #include <asm/tlbflush.h>
 #include <mach/common.h>
+#include <mach/sh7372.h>
 
 #define SMFRAM 0xe6a70000
 #define SYSTBCR 0xe6150024
 #define SBAR 0xe6180020
 #define APARMBAREA 0xe6f10020
 
+#define SPDCR 0xe6180008
+#define SWUCR 0xe6180014
+#define PSTR 0xe6180080
+
+#define PSTR_RETRIES 100
+#define PSTR_DELAY_MS 10
+
+static int pd_power_down(struct generic_pm_domain *genpd)
+{
+	struct sh7372_pm_domain *sh7372_pd = to_sh7372_pd(genpd);
+	unsigned int mask = 1 << sh7372_pd->bit_shift;
+
+	if (__raw_readl(PSTR) & mask) {
+		unsigned int retry_count = PSTR_RETRIES;
+
+		__raw_writel(mask, SPDCR);
+		while ((__raw_readl(SPDCR) & mask) && retry_count--)
+			cpu_relax();
+	}
+
+	pr_debug("sh7372 power domain down 0x%08x -> PSTR = 0x%08x\n",
+		 mask, __raw_readl(PSTR));
+
+	return 0;
+}
+
+static int pd_power_up(struct generic_pm_domain *genpd)
+{
+	struct sh7372_pm_domain *sh7372_pd = to_sh7372_pd(genpd);
+	unsigned int mask = 1 << sh7372_pd->bit_shift;
+
+	if (!(__raw_readl(PSTR) & mask)) {
+		do {
+			unsigned int retry_count = PSTR_RETRIES;
+
+			__raw_writel(mask, SWUCR);
+			while ((__raw_readl(SWUCR) & mask) && retry_count--)
+				cpu_relax();
+
+			if (!(__raw_readl(SWUCR) & mask))
+				break;
+
+			msleep(PSTR_DELAY_MS);
+		} while (true);
+	}
+
+	pr_debug("sh7372 power domain up 0x%08x -> PSTR = 0x%08x\n",
+		 mask, __raw_readl(PSTR));
+
+	return 0;
+}
+
+void sh7372_init_pm_domain(struct sh7372_pm_domain *sh7372_pd)
+{
+	struct generic_pm_domain *genpd = &sh7372_pd->genpd;
+
+	pm_genpd_init(genpd, NULL, false);
+	genpd->stop_device = pm_runtime_clk_suspend;
+	genpd->start_device = pm_runtime_clk_resume;
+	genpd->power_off = pd_power_down;
+	genpd->power_on = pd_power_up;
+	pd_power_up(&sh7372_pd->genpd);
+}
+
+void sh7372_add_device_to_domain(struct sh7372_pm_domain *sh7372_pd,
+				 struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+
+	if (!dev->power.subsys_data) {
+		pm_runtime_clk_init(dev);
+		pm_runtime_clk_add(dev, NULL);
+	}
+	pm_genpd_add_device(&sh7372_pd->genpd, dev);
+}
+
+struct sh7372_pm_domain sh7372_a4lc_domain = {
+	.bit_shift = 1,
+};
+
 static void sh7372_enter_core_standby(void)
 {
 	void __iomem *smfram = (void __iomem *)SMFRAM;
Index: linux-2.6/arch/arm/Kconfig
===================================================================
--- linux-2.6.orig/arch/arm/Kconfig
+++ linux-2.6/arch/arm/Kconfig
@@ -642,6 +642,7 @@ config ARCH_SHMOBILE
 	select NO_IOPORT
 	select SPARSE_IRQ
 	select MULTI_IRQ_HANDLER
+	select PM_GENERIC_DOMAINS
 	help
 	  Support for Renesas's SH-Mobile and R-Mobile ARM platforms.