From 8aeeda822fbfe7da2d4ea391a9757e9532796598 Mon Sep 17 00:00:00 2001
From: Nicolas Ferre <nicolas.ferre@atmel.com>
Date: Fri, 22 Oct 2010 17:53:39 +0200
Subject: [PATCH] AT91: pm: use plain cpu_do_idle() for "wait for interrupt"
For power management at91_pm_enter() routine, use the cpu_do_idle() for a
rock solid "wait for interrupt" implementation.
For AT91SAM9 ARM 926 based chips, we can exceed the cache line length as
we can access RAM even while in self-refresh mode.
We keep plain access to CP15 for at91rm9200 as this feature is not
available: instructions have to be in a single cache line.
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
---
arch/arm/mach-at91/pm.c | 6 ++++--
arch/arm/mach-at91/pm.h | 4 ++++
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index 6156689864800..87a31baf1cb3e 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -258,16 +258,18 @@ static int at91_pm_enter(suspend_state_t state)
* NOTE: the Wait-for-Interrupt instruction needs to be
* in icache so no SDRAM accesses are needed until the
* wakeup IRQ occurs and self-refresh is terminated.
+ * For ARM 926 based chips, this requirement is weaker
+ * as at91sam9 can access a RAM in self-refresh mode.
*/
asm("b 1f; .align 5; 1:");
asm("mcr p15, 0, r0, c7, c10, 4"); /* drain write buffer */
saved_lpr = sdram_selfrefresh_enable();
- asm("mcr p15, 0, r0, c7, c0, 4"); /* wait for interrupt */
+ wait_for_interrupt_enable();
sdram_selfrefresh_disable(saved_lpr);
break;
case PM_SUSPEND_ON:
- asm("mcr p15, 0, r0, c7, c0, 4"); /* wait for interrupt */
+ cpu_do_idle();
break;
default:
diff --git a/arch/arm/mach-at91/pm.h b/arch/arm/mach-at91/pm.h
index 8c87d0c1b8f8b..2c4424bfa6c41 100644
--- a/arch/arm/mach-at91/pm.h
+++ b/arch/arm/mach-at91/pm.h
@@ -21,6 +21,7 @@ static inline u32 sdram_selfrefresh_enable(void)
}
#define sdram_selfrefresh_disable(saved_lpr) at91_sys_write(AT91_SDRAMC_LPR, saved_lpr)
+#define wait_for_interrupt_enable() asm("mcr p15, 0, r0, c7, c0, 4")
#elif defined(CONFIG_ARCH_AT91CAP9)
#include <mach/at91cap9_ddrsdr.h>
@@ -38,6 +39,7 @@ static inline u32 sdram_selfrefresh_enable(void)
}
#define sdram_selfrefresh_disable(saved_lpr) at91_ramc_write(0, AT91_DDRSDRC_LPR, saved_lpr)
+#define wait_for_interrupt_enable() cpu_do_idle()
#elif defined(CONFIG_ARCH_AT91SAM9G45)
#include <mach/at91sam9_ddrsdr.h>
@@ -74,6 +76,7 @@ static inline u32 sdram_selfrefresh_enable(void)
at91_ramc_write(0, AT91_DDRSDRC_LPR, saved_lpr0); \
at91_ramc_write(1, AT91_DDRSDRC_LPR, saved_lpr1); \
} while (0)
+#define wait_for_interrupt_enable() cpu_do_idle()
#else
#include <mach/at91sam9_sdramc.h>
@@ -98,5 +101,6 @@ static inline u32 sdram_selfrefresh_enable(void)
}
#define sdram_selfrefresh_disable(saved_lpr) at91_ramc_write(0, AT91_SDRAMC_LPR, saved_lpr)
+#define wait_for_interrupt_enable() cpu_do_idle()
#endif
--
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