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AT91: pm: use plain cpu_do_idle() for "wait for interrupt"

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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>
This commit is contained in:
Nicolas Ferre 2010-10-22 17:53:39 +02:00
parent bb413db591
commit 8aeeda822f
2 changed files with 8 additions and 2 deletions
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6
arch/arm/mach-at91/pm.c
View file

@ -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:

4
arch/arm/mach-at91/pm.h
View file

@ -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