[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 eeb6679..5f5f7e4 100644
--- a/arch/avr32/kernel/entry-avr32b.S
+++ b/arch/avr32/kernel/entry-avr32b.S
@@ -630,9 +630,12 @@
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 @@
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 @@
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 0b43259..4f8d2d4 100644
--- 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 @@
{
/* 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 d1f5b35..a2e606d 100644
--- a/include/asm-avr32/thread_info.h
+++ b/include/asm-avr32/thread_info.h
@@ -83,6 +83,7 @@
#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 @@
#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 */