clockevents: Manage device's state separately for the core

'enum clock_event_mode' is used for two purposes today:

 - to pass mode to the driver of clockevent device::set_mode().

 - for managing state of the device for clockevents core.

For supporting new modes/states we have moved away from the
legacy set_mode() callback to new per-mode/state callbacks. New
modes/states shouldn't be exposed to the legacy (now OBSOLOTE)
callbacks and so we shouldn't add new states to 'enum
clock_event_mode'.

Lets have separate enums for the two use cases mentioned above.
Keep using the earlier enum for legacy set_mode() callback and
mark it OBSOLETE. And add another enum to clearly specify the
possible states of a clockevent device.

This also renames the newly added per-mode callbacks to reflect
state changes.

We haven't got rid of 'mode' member of 'struct
clock_event_device' as it is used by some of the clockevent
drivers and it would automatically die down once we migrate
those drivers to the new interface. It ('mode') is only updated
now for the drivers using the legacy interface.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: linaro-networking@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/b6b0143a8a57bd58352ad35e08c25424c879c0cb.1425037853.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 53 insertions, 46 deletions

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 1b0ea63de69c..6e53e9a0c2e8 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -94,44 +94,49 @@ u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
 }
 EXPORT_SYMBOL_GPL(clockevent_delta2ns);
 
-static int __clockevents_set_mode(struct clock_event_device *dev,
-				  enum clock_event_mode mode)
+static int __clockevents_set_state(struct clock_event_device *dev,
+				   enum clock_event_state state)
 {
 	/* Transition with legacy set_mode() callback */
 	if (dev->set_mode) {
 		/* Legacy callback doesn't support new modes */
-		if (mode > CLOCK_EVT_MODE_ONESHOT)
+		if (state > CLOCK_EVT_STATE_ONESHOT)
 			return -ENOSYS;
-		dev->set_mode(mode, dev);
+		/*
+		 * 'clock_event_state' and 'clock_event_mode' have 1-to-1
+		 * mapping until *_ONESHOT, and so a simple cast will work.
+		 */
+		dev->set_mode((enum clock_event_mode)state, dev);
+		dev->mode = (enum clock_event_mode)state;
 		return 0;
 	}
 
 	if (dev->features & CLOCK_EVT_FEAT_DUMMY)
 		return 0;
 
-	/* Transition with new mode-specific callbacks */
-	switch (mode) {
-	case CLOCK_EVT_MODE_UNUSED:
+	/* Transition with new state-specific callbacks */
+	switch (state) {
+	case CLOCK_EVT_STATE_DETACHED:
 		/*
 		 * This is an internal state, which is guaranteed to go from
-		 * SHUTDOWN to UNUSED. No driver interaction required.
+		 * SHUTDOWN to DETACHED. No driver interaction required.
 		 */
 		return 0;
 
-	case CLOCK_EVT_MODE_SHUTDOWN:
-		return dev->set_mode_shutdown(dev);
+	case CLOCK_EVT_STATE_SHUTDOWN:
+		return dev->set_state_shutdown(dev);
 
-	case CLOCK_EVT_MODE_PERIODIC:
+	case CLOCK_EVT_STATE_PERIODIC:
 		/* Core internal bug */
 		if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC))
 			return -ENOSYS;
-		return dev->set_mode_periodic(dev);
+		return dev->set_state_periodic(dev);
 
-	case CLOCK_EVT_MODE_ONESHOT:
+	case CLOCK_EVT_STATE_ONESHOT:
 		/* Core internal bug */
 		if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
 			return -ENOSYS;
-		return dev->set_mode_oneshot(dev);
+		return dev->set_state_oneshot(dev);
 
 	default:
 		return -ENOSYS;
@@ -139,26 +144,26 @@ static int __clockevents_set_mode(struct clock_event_device *dev,
 }
 
 /**
- * clockevents_set_mode - set the operating mode of a clock event device
+ * clockevents_set_state - set the operating state of a clock event device
  * @dev:	device to modify
- * @mode:	new mode
+ * @state:	new state
  *
  * Must be called with interrupts disabled !
  */
-void clockevents_set_mode(struct clock_event_device *dev,
-				 enum clock_event_mode mode)
+void clockevents_set_state(struct clock_event_device *dev,
+			   enum clock_event_state state)
 {
-	if (dev->mode != mode) {
-		if (__clockevents_set_mode(dev, mode))
+	if (dev->state != state) {
+		if (__clockevents_set_state(dev, state))
 			return;
 
-		dev->mode = mode;
+		dev->state = state;
 
 		/*
 		 * A nsec2cyc multiplicator of 0 is invalid and we'd crash
 		 * on it, so fix it up and emit a warning:
 		 */
-		if (mode == CLOCK_EVT_MODE_ONESHOT) {
+		if (state == CLOCK_EVT_STATE_ONESHOT) {
 			if (unlikely(!dev->mult)) {
 				dev->mult = 1;
 				WARN_ON(1);
@@ -173,7 +178,7 @@ void clockevents_set_mode(struct clock_event_device *dev,
  */
 void clockevents_shutdown(struct clock_event_device *dev)
 {
-	clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
+	clockevents_set_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
 	dev->next_event.tv64 = KTIME_MAX;
 }
 
@@ -185,13 +190,12 @@ int clockevents_tick_resume(struct clock_event_device *dev)
 {
 	int ret = 0;
 
-	if (dev->set_mode)
+	if (dev->set_mode) {
 		dev->set_mode(CLOCK_EVT_MODE_RESUME, dev);
-	else if (dev->tick_resume)
-		ret = dev->tick_resume(dev);
-
-	if (likely(!ret))
 		dev->mode = CLOCK_EVT_MODE_RESUME;
+	} else if (dev->tick_resume) {
+		ret = dev->tick_resume(dev);
+	}
 
 	return ret;
 }
@@ -248,7 +252,7 @@ static int clockevents_program_min_delta(struct clock_event_device *dev)
 		delta = dev->min_delta_ns;
 		dev->next_event = ktime_add_ns(ktime_get(), delta);
 
-		if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
+		if (dev->state == CLOCK_EVT_STATE_SHUTDOWN)
 			return 0;
 
 		dev->retries++;
@@ -285,7 +289,7 @@ static int clockevents_program_min_delta(struct clock_event_device *dev)
 	delta = dev->min_delta_ns;
 	dev->next_event = ktime_add_ns(ktime_get(), delta);
 
-	if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
+	if (dev->state == CLOCK_EVT_STATE_SHUTDOWN)
 		return 0;
 
 	dev->retries++;
@@ -317,7 +321,7 @@ int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
 
 	dev->next_event = expires;
 
-	if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
+	if (dev->state == CLOCK_EVT_STATE_SHUTDOWN)
 		return 0;
 
 	/* Shortcut for clockevent devices that can deal with ktime. */
@@ -362,7 +366,7 @@ static int clockevents_replace(struct clock_event_device *ced)
 	struct clock_event_device *dev, *newdev = NULL;
 
 	list_for_each_entry(dev, &clockevent_devices, list) {
-		if (dev == ced || dev->mode != CLOCK_EVT_MODE_UNUSED)
+		if (dev == ced || dev->state != CLOCK_EVT_STATE_DETACHED)
 			continue;
 
 		if (!tick_check_replacement(newdev, dev))
@@ -388,7 +392,7 @@ static int clockevents_replace(struct clock_event_device *ced)
 static int __clockevents_try_unbind(struct clock_event_device *ced, int cpu)
 {
 	/* Fast track. Device is unused */
-	if (ced->mode == CLOCK_EVT_MODE_UNUSED) {
+	if (ced->state == CLOCK_EVT_STATE_DETACHED) {
 		list_del_init(&ced->list);
 		return 0;
 	}
@@ -438,30 +442,30 @@ int clockevents_unbind_device(struct clock_event_device *ced, int cpu)
 }
 EXPORT_SYMBOL_GPL(clockevents_unbind);
 
-/* Sanity check of mode transition callbacks */
+/* Sanity check of state transition callbacks */
 static int clockevents_sanity_check(struct clock_event_device *dev)
 {
 	/* Legacy set_mode() callback */
 	if (dev->set_mode) {
 		/* We shouldn't be supporting new modes now */
-		WARN_ON(dev->set_mode_periodic || dev->set_mode_oneshot ||
-			dev->set_mode_shutdown || dev->tick_resume);
+		WARN_ON(dev->set_state_periodic || dev->set_state_oneshot ||
+			dev->set_state_shutdown || dev->tick_resume);
 		return 0;
 	}
 
 	if (dev->features & CLOCK_EVT_FEAT_DUMMY)
 		return 0;
 
-	/* New mode-specific callbacks */
-	if (!dev->set_mode_shutdown)
+	/* New state-specific callbacks */
+	if (!dev->set_state_shutdown)
 		return -EINVAL;
 
 	if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
-	    !dev->set_mode_periodic)
+	    !dev->set_state_periodic)
 		return -EINVAL;
 
 	if ((dev->features & CLOCK_EVT_FEAT_ONESHOT) &&
-	    !dev->set_mode_oneshot)
+	    !dev->set_state_oneshot)
 		return -EINVAL;
 
 	return 0;
@@ -478,6 +482,9 @@ void clockevents_register_device(struct clock_event_device *dev)
 	BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
 	BUG_ON(clockevents_sanity_check(dev));
 
+	/* Initialize state to DETACHED */
+	dev->state = CLOCK_EVT_STATE_DETACHED;
+
 	if (!dev->cpumask) {
 		WARN_ON(num_possible_cpus() > 1);
 		dev->cpumask = cpumask_of(smp_processor_id());
@@ -541,11 +548,11 @@ int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
 {
 	clockevents_config(dev, freq);
 
-	if (dev->mode == CLOCK_EVT_MODE_ONESHOT)
+	if (dev->state == CLOCK_EVT_STATE_ONESHOT)
 		return clockevents_program_event(dev, dev->next_event, false);
 
-	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
-		return __clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
+	if (dev->state == CLOCK_EVT_STATE_PERIODIC)
+		return __clockevents_set_state(dev, CLOCK_EVT_STATE_PERIODIC);
 
 	return 0;
 }
@@ -601,13 +608,13 @@ void clockevents_exchange_device(struct clock_event_device *old,
 	 */
 	if (old) {
 		module_put(old->owner);
-		clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
+		clockevents_set_state(old, CLOCK_EVT_STATE_DETACHED);
 		list_del(&old->list);
 		list_add(&old->list, &clockevents_released);
 	}
 
 	if (new) {
-		BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED);
+		BUG_ON(new->state != CLOCK_EVT_STATE_DETACHED);
 		clockevents_shutdown(new);
 	}
 	local_irq_restore(flags);
@@ -693,7 +700,7 @@ int clockevents_notify(unsigned long reason, void *arg)
 			if (cpumask_test_cpu(cpu, dev->cpumask) &&
 			    cpumask_weight(dev->cpumask) == 1 &&
 			    !tick_is_broadcast_device(dev)) {
-				BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
+				BUG_ON(dev->state != CLOCK_EVT_STATE_DETACHED);
 				list_del(&dev->list);
 			}
 		}