clockevents: Allow set-state callbacks to be optional

Its mandatory for the drivers to provide set_state_{oneshot|periodic}()
(only if related modes are supported) and set_state_shutdown() callbacks
today, if they are implementing the new set-state interface.

But this leads to unnecessary noop callbacks for drivers which don't
want to implement them. Over that, it will lead to a full function call
for nothing really useful.

Lets make all set-state callbacks optional.

Suggested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: http://lkml.kernel.org/r/1436256875-15562-1-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 08ccc3da3ca086366eadaae89f46e0604099d661..50eb107f119877ab0762bb671a69cf9c0cd418bc 100644 (file)
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -120,19 +120,25 @@ static int __clockevents_switch_state(struct clock_event_device *dev,
                /* The clockevent device is getting replaced. Shut it down. */
 
        case CLOCK_EVT_STATE_SHUTDOWN:
-               return dev->set_state_shutdown(dev);
+               if (dev->set_state_shutdown)
+                       return dev->set_state_shutdown(dev);
+               return 0;
 
        case CLOCK_EVT_STATE_PERIODIC:
                /* Core internal bug */
                if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC))
                        return -ENOSYS;
-               return dev->set_state_periodic(dev);
+               if (dev->set_state_periodic)
+                       return dev->set_state_periodic(dev);
+               return 0;
 
        case CLOCK_EVT_STATE_ONESHOT:
                /* Core internal bug */
                if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
                        return -ENOSYS;
-               return dev->set_state_oneshot(dev);
+               if (dev->set_state_oneshot)
+                       return dev->set_state_oneshot(dev);
+               return 0;
 
        case CLOCK_EVT_STATE_ONESHOT_STOPPED:
                /* Core internal bug */
@@ -471,18 +477,6 @@ static int clockevents_sanity_check(struct clock_event_device *dev)
        if (dev->features & CLOCK_EVT_FEAT_DUMMY)
                return 0;
 
-       /* New state-specific callbacks */
-       if (!dev->set_state_shutdown)
-               return -EINVAL;
-
-       if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
-           !dev->set_state_periodic)
-               return -EINVAL;
-
-       if ((dev->features & CLOCK_EVT_FEAT_ONESHOT) &&
-           !dev->set_state_oneshot)
-               return -EINVAL;
-
        return 0;
 }