ARM: OMAP4: cpuidle: Switch to gptimer from twd in deeper C-states.

CPU local timer(TWD) stops when the CPU is transitioning into
deeper C-States. Since these timers are not wakeup capable, we
need the wakeup capable global timer to program the wakeup time
depending on the next timer expiry.

It can be handled by registering a global wakeup capable timer along
with local timers marked with (mis)feature flag CLOCK_EVT_FEAT_C3STOP.
Then notify the clock events layer from idle code using
CLOCK_EVT_NOTIFY_BROADCAST_ENTER/EXIT).

ARM local timers are already marked with C3STOP feature. Add the
notifiers to OMAP4 CPU idle code for the broadcast entry and exit.
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Jean Pihet <j-pihet@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Vishwanath BS <vishwanath.bs@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>

arch/arm/mach-omap2/cpuidle44xx.c

@@ -14,6 +14,7 @@
 #include <linux/cpuidle.h>
 #include <linux/cpu_pm.h>
 #include <linux/export.h>
+#include <linux/clockchips.h>
 
 #include <asm/proc-fns.h>
 
@@ -65,6 +66,7 @@ static int omap4_enter_idle(struct cpuidle_device *dev,
 	u32 cpu1_state;
 	int idle_time;
 	int new_state_idx;
+	int cpu_id = smp_processor_id();
 
 	/* Used to keep track of the total time in idle */
 	getnstimeofday(&ts_preidle);
@@ -86,6 +88,9 @@ static int omap4_enter_idle(struct cpuidle_device *dev,
 		cx = cpuidle_get_statedata(&dev->states_usage[new_state_idx]);
 	}
 
+	if (index > 0)
+		clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu_id);
+
 	/*
 	 * Call idle CPU PM enter notifier chain so that
 	 * VFP and per CPU interrupt context is saved.
@@ -121,6 +126,9 @@ static int omap4_enter_idle(struct cpuidle_device *dev,
 	if (omap4_mpuss_read_prev_context_state())
 		cpu_cluster_pm_exit();
 
+	if (index > 0)
+		clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu_id);
+
 	getnstimeofday(&ts_postidle);
 	ts_idle = timespec_sub(ts_postidle, ts_preidle);