ENGR00273073-1 arm: add cpu idle notification callback

Some modules may need to know cpu idle status and take
actions before and after cpu idle, so we can add
notification callback when enter/exit cpu idle, then
modules only need to register this notification callback,
everytime cpu enter/exit idle, the callback chain will be
executed.

Currently only cpufreq interactive governor use this
notification, as it wants to save power, the timers of
interactive governor are only enabled when cpu is not in idle.

Signed-off-by: Anson Huang <b20788@freescale.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index ac4c2e5e17e4..e59e24ae8f7b 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -170,8 +170,10 @@ void arch_cpu_idle_dead(void)
  */
 void arch_cpu_idle(void)
 {
+        idle_notifier_call_chain(IDLE_START);
         if (cpuidle_idle_call())
                 default_idle();
+        idle_notifier_call_chain(IDLE_END);
 }
 
 static char reboot_mode = 'h';