AT91: pm: use plain cpu_do_idle() for "wait for interrupt"
Nicolas Ferre [Fri, 22 Oct 2010 15:53:39 +0000 (17:53 +0200)]
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
arch/arm/mach-at91/pm.h

index 6156689..87a31ba 100644 (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:
index 8c87d0c..2c4424b 100644 (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