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[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>
This commit is contained in:
Hans-Christian Egtvedt 2007-02-26 13:50:43 +01:00 committed by Haavard Skinnemoen
parent 7760989e5e
commit 19b7ce8bad
3 changed files with 42 additions and 7 deletions
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42
arch/avr32/kernel/entry-avr32b.S
View File

@ -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

5
arch/avr32/kernel/process.c
View File

@ -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();

2
include/asm-avr32/thread_info.h
View File

@ -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 */