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

From: Rafael J. Wysocki
Date: Mon Jun 20 2011 - 18:29:29 EST

Next message: Greg KH: "Re: [Stable-review] [00/91] 2.6.32.42-longterm review"
Previous message: Tony Luck: "Re: [PATCH 2/3] pstore: Add extra context for writes and erases"
In reply to: Paul Mundt: "Re: [Update][PATCH 8/8] ARM / shmobile: Support for I/O power domains for SH7372 (v6)"
Next in thread: Rafael J. Wysocki: "Re: [Update][PATCH 8/8] ARM / shmobile: Support for I/O power domains for SH7372 (v6)"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

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@xxxxxxx>
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@xxxxxxx>
---
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.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: Greg KH: "Re: [Stable-review] [00/91] 2.6.32.42-longterm review"
Previous message: Tony Luck: "Re: [PATCH 2/3] pstore: Add extra context for writes and erases"
In reply to: Paul Mundt: "Re: [Update][PATCH 8/8] ARM / shmobile: Support for I/O power domains for SH7372 (v6)"
Next in thread: Rafael J. Wysocki: "Re: [Update][PATCH 8/8] ARM / shmobile: Support for I/O power domains for SH7372 (v6)"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]