[RFC PATCH v4 1/4] cpuidle: Add time keeping and irq enabling

[rob.lee@linaro.org (Robert Lee)]

Make necessary changes to add implement time keepign and irq enabling
in the core cpuidle code.  This will allow the remove of these
functionalities from the platform cpuidle implementations.

Signed-off-by: Robert Lee <rob.lee@linaro.org>
---
 drivers/cpuidle/cpuidle.c |   75 +++++++++++++++++++++++++++++++++++---------
 include/linux/cpuidle.h   |   26 ++++++++++-----
 2 files changed, 76 insertions(+), 25 deletions(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 59f4261..8ea0fc3 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -57,14 +57,18 @@ static int __cpuidle_register_device(struct cpuidle_device *dev);
  * cpuidle_idle_call - the main idle loop
  *
  * NOTE: no locks or semaphores should be used here
+ * NOTE: Should only be called from a local irq disabled context
  * return non-zero on failure
+ *
  */
 int cpuidle_idle_call(void)
 {
 	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
 	struct cpuidle_driver *drv = cpuidle_get_driver();
 	struct cpuidle_state *target_state;
-	int next_state, entered_state;
+	int idx, ret = 0;
+	ktime_t	t1, t2;
+	s64 diff;
 
 	if (off)
 		return -ENODEV;
@@ -86,37 +90,76 @@ int cpuidle_idle_call(void)
 #endif
 
 	/* ask the governor for the next state */
-	next_state = cpuidle_curr_governor->select(drv, dev);
+	idx = cpuidle_curr_governor->select(drv, dev);
+
+	target_state = &drv->states[idx];
+
+	/*
+	 * Check with the device to see if it can enter this state or if another
+	 * state should be used.
+	 */
+	if (target_state->pre_enter) {
+		idx = target_state->
+			pre_enter(dev, drv, idx);
+	}
+
+	if (idx < 0) {
+		local_irq_enable();
+		return idx;
+	}
+
 	if (need_resched()) {
 		local_irq_enable();
-		return 0;
+		return -EBUSY;
 	}
 
-	target_state = &drv->states[next_state];
+	target_state = &drv->states[idx];
 
-	trace_power_start(POWER_CSTATE, next_state, dev->cpu);
-	trace_cpu_idle(next_state, dev->cpu);
+	if ((target_state->flags & CPUIDLE_FLAG_TIME_VALID))
+		t1 = ktime_get();
 
-	entered_state = target_state->enter(dev, drv, next_state);
+	trace_power_start(POWER_CSTATE, idx, dev->cpu);
+	trace_cpu_idle(idx, dev->cpu);
+
+	idx = target_state->enter(dev, drv, idx);
 
 	trace_power_end(dev->cpu);
 	trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
 
-	if (entered_state >= 0) {
-		/* Update cpuidle counters */
-		/* This can be moved to within driver enter routine
-		 * but that results in multiple copies of same code.
-		 */
-		dev->states_usage[entered_state].time +=
+	if (idx < 0) {
+		local_irq_enable();
+		return idx;
+	}
+
+	if (likely(target_state->flags & drv->states[idx].flags &
+		CPUIDLE_FLAG_TIME_VALID))
+		t2 = ktime_get();
+
+	local_irq_enable();
+
+	if (target_state->post_enter)
+		target_state->post_enter(dev, drv, idx);
+
+	if (likely(target_state->flags & drv->states[idx].flags &
+		CPUIDLE_FLAG_TIME_VALID)) {
+
+		diff = ktime_to_us(ktime_sub(t2, t1));
+		if (diff > INT_MAX)
+			diff = INT_MAX;
+
+		dev->last_residency = (int) diff;
+
+		dev->states_usage[idx].time +=
 				(unsigned long long)dev->last_residency;
-		dev->states_usage[entered_state].usage++;
 	}
 
+	dev->states_usage[idx].usage++;
+
 	/* give the governor an opportunity to reflect on the outcome */
 	if (cpuidle_curr_governor->reflect)
-		cpuidle_curr_governor->reflect(dev, entered_state);
+		cpuidle_curr_governor->reflect(dev, idx);
 
-	return 0;
+	return ret;
 }
 
 /**
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 712abcc..8154f60 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -38,17 +38,25 @@ struct cpuidle_state_usage {
 };
 
 struct cpuidle_state {
-	char		name[CPUIDLE_NAME_LEN];
-	char		desc[CPUIDLE_DESC_LEN];
+	char			name[CPUIDLE_NAME_LEN];
+	char			desc[CPUIDLE_DESC_LEN];
+
+	unsigned int		flags;
+	unsigned int		exit_latency; /* in US */
+	unsigned int		power_usage; /* in mW */
+	unsigned int		target_residency; /* in US */
+
+	int (*pre_enter)	(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv,
+				int index);
 
-	unsigned int	flags;
-	unsigned int	exit_latency; /* in US */
-	unsigned int	power_usage; /* in mW */
-	unsigned int	target_residency; /* in US */
+	int (*enter)		(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv,
+				int index);
 
-	int (*enter)	(struct cpuidle_device *dev,
-			struct cpuidle_driver *drv,
-			int index);
+	int (*post_enter)	(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv,
+				int index);
 };
 
 /* Idle State Flags */
-- 
1.7.1