[AVR32] Put cpu in sleep 0 when idle.

This patch puts the CPU in sleep 0 when doing nothing, idle. This will
turn of the CPU clock and thus save power. The CPU is waken again when
an interrupt occurs.

Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

diff --git a/arch/avr32/kernel/entry-avr32b.S b/arch/avr32/kernel/entry-avr32b.S
index eeb66792bc37887e382640c297a116d8de5d22b4..5f5f7e42f51b3c9d722636e1f90f4bf3802d879f 100644 (file)
--- a/arch/avr32/kernel/entry-avr32b.S
+++ b/arch/avr32/kernel/entry-avr32b.S
@@ -630,9 +630,12 @@ irq_level\level:
        rcall   do_IRQ
 
        lddsp   r4, sp[REG_SR]
-       andh    r4, (MODE_MASK >> 16), COH
+       bfextu  r4, r4, SYSREG_M0_OFFSET, 3
+       cp.w    r4, MODE_SUPERVISOR >> SYSREG_M0_OFFSET
+       breq    2f
+       cp.w    r4, MODE_USER >> SYSREG_M0_OFFSET
 #ifdef CONFIG_PREEMPT
-       brne    2f
+       brne    3f
 #else
        brne    1f
 #endif
@@ -649,9 +652,18 @@ irq_level\level:
        sub     sp, -4          /* ignore r12_orig */
        rete
 
+2:     get_thread_info r0
+       ld.w    r1, r0[TI_flags]
+       bld     r1, TIF_CPU_GOING_TO_SLEEP
 #ifdef CONFIG_PREEMPT
-2:
-       get_thread_info r0
+       brcc    3f
+#else
+       brcc    1b
+#endif
+       sub     r1, pc, . - cpu_idle_skip_sleep
+       stdsp   sp[REG_PC], r1
+#ifdef CONFIG_PREEMPT
+3:     get_thread_info r0
        ld.w    r2, r0[TI_preempt_count]
        cp.w    r2, 0
        brne    1b
@@ -662,12 +674,32 @@ irq_level\level:
        bld     r4, SYSREG_GM_OFFSET
        brcs    1b
        rcall   preempt_schedule_irq
-       rjmp    1b
 #endif
+       rjmp    1b
        .endm
 
        .section .irq.text,"ax",@progbits
 
+.global cpu_idle_sleep
+cpu_idle_sleep:
+       mask_interrupts
+       get_thread_info r8
+       ld.w    r9, r8[TI_flags]
+       bld     r9, TIF_NEED_RESCHED
+       brcs    cpu_idle_enable_int_and_exit
+       sbr     r9, TIF_CPU_GOING_TO_SLEEP
+       st.w    r8[TI_flags], r9
+       unmask_interrupts
+       sleep 0
+cpu_idle_skip_sleep:
+       mask_interrupts
+       ld.w    r9, r8[TI_flags]
+       cbr     r9, TIF_CPU_GOING_TO_SLEEP
+       st.w    r8[TI_flags], r9
+cpu_idle_enable_int_and_exit:
+       unmask_interrupts
+       retal   r12
+
        .global irq_level0
        .global irq_level1
        .global irq_level2

diff --git a/arch/avr32/kernel/process.c b/arch/avr32/kernel/process.c
index 0b4325946a41629cc7a4755a7c679311e85e688f..4f8d2d4747406d0aa4210d50a40424324adcc6d8 100644 (file)
--- a/arch/avr32/kernel/process.c
+++ b/arch/avr32/kernel/process.c
@@ -19,6 +19,8 @@
 void (*pm_power_off)(void) = NULL;
 EXPORT_SYMBOL(pm_power_off);
 
+extern void cpu_idle_sleep(void);
+
 /*
  * This file handles the architecture-dependent parts of process handling..
  */
@@ -27,9 +29,8 @@ void cpu_idle(void)
 {
        /* endless idle loop with no priority at all */
        while (1) {
-               /* TODO: Enter sleep mode */
                while (!need_resched())
-                       cpu_relax();
+                       cpu_idle_sleep();
                preempt_enable_no_resched();
                schedule();
                preempt_disable();

diff --git a/include/asm-avr32/thread_info.h b/include/asm-avr32/thread_info.h
index d1f5b35ebd54212f7cfec40cb2458a648c305dd3..a2e606dd4f4a8bc3ba465fbd205a12cf6475925a 100644 (file)
--- a/include/asm-avr32/thread_info.h
+++ b/include/asm-avr32/thread_info.h
@@ -83,6 +83,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SINGLE_STEP                6       /* single step after next break */
 #define TIF_MEMDIE             7
 #define TIF_RESTORE_SIGMASK    8       /* restore signal mask in do_signal */
+#define TIF_CPU_GOING_TO_SLEEP 9       /* CPU is entering sleep 0 mode */
 #define TIF_USERSPACE          31      /* true if FS sets userspace */
 
 #define _TIF_SYSCALL_TRACE     (1 << TIF_SYSCALL_TRACE)
@@ -94,6 +95,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SINGLE_STEP       (1 << TIF_SINGLE_STEP)
 #define _TIF_MEMDIE            (1 << TIF_MEMDIE)
 #define _TIF_RESTORE_SIGMASK   (1 << TIF_RESTORE_SIGMASK)
+#define _TIF_CPU_GOING_TO_SLEEP (1 << TIF_CPU_GOING_TO_SLEEP)
 
 /* XXX: These two masks must never span more than 16 bits! */
 /* work to do on interrupt/exception return */