clockevents: Split out selection logic

Split out the clockevent device selection logic. Preparatory patch to
allow unbinding active clockevent devices.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.431796247@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 56 insertions, 38 deletions

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 0e374cd2e0ef..d067c01586f5 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -65,19 +65,34 @@ static void tick_broadcast_start_periodic(struct clock_event_device *bc)
 /*
  * Check, if the device can be utilized as broadcast device:
  */
+static bool tick_check_broadcast_device(struct clock_event_device *curdev,
+                                        struct clock_event_device *newdev)
+{
+        if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
+            (newdev->features & CLOCK_EVT_FEAT_C3STOP))
+                return false;
+
+        if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
+            !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
+                return false;
+
+        return !curdev || newdev->rating > curdev->rating;
+}
+
+/*
+ * Conditionally install/replace broadcast device
+ */
 void tick_install_broadcast_device(struct clock_event_device *dev)
 {
         struct clock_event_device *cur = tick_broadcast_device.evtdev;
 
-        if ((dev->features & CLOCK_EVT_FEAT_DUMMY) ||
-            (tick_broadcast_device.evtdev &&
-             tick_broadcast_device.evtdev->rating >= dev->rating) ||
-             (dev->features & CLOCK_EVT_FEAT_C3STOP))
+        if (!tick_check_broadcast_device(cur, dev))
                 return;
+
         if (!try_module_get(dev->owner))
                 return;
 
-        clockevents_exchange_device(tick_broadcast_device.evtdev, dev);
+        clockevents_exchange_device(cur, dev);
         if (cur)
                 cur->event_handler = clockevents_handle_noop;
         tick_broadcast_device.evtdev = dev;
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 433a1e11d13b..c34021650348 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -205,6 +205,37 @@ static void tick_setup_device(struct tick_device *td,
                 tick_setup_oneshot(newdev, handler, next_event);
 }
 
+static bool tick_check_percpu(struct clock_event_device *curdev,
+                              struct clock_event_device *newdev, int cpu)
+{
+        if (!cpumask_test_cpu(cpu, newdev->cpumask))
+                return false;
+        if (cpumask_equal(newdev->cpumask, cpumask_of(cpu)))
+                return true;
+        /* Check if irq affinity can be set */
+        if (newdev->irq >= 0 && !irq_can_set_affinity(newdev->irq))
+                return false;
+        /* Prefer an existing cpu local device */
+        if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu)))
+                return false;
+        return true;
+}
+
+static bool tick_check_preferred(struct clock_event_device *curdev,
+                                 struct clock_event_device *newdev)
+{
+        /* Prefer oneshot capable device */
+        if (!(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) {
+                if (curdev && (curdev->features & CLOCK_EVT_FEAT_ONESHOT))
+                        return false;
+                if (tick_oneshot_mode_active())
+                        return false;
+        }
+
+        /* Use the higher rated one */
+        return !curdev || newdev->rating > curdev->rating;
+}
+
 /*
  * Check, if the new registered device should be used. Called with
  * clockevents_lock held and interrupts disabled.
@@ -223,40 +254,12 @@ void tick_check_new_device(struct clock_event_device *newdev)
         curdev = td->evtdev;
 
         /* cpu local device ? */
-        if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu))) {
-
-                /*
-                 * If the cpu affinity of the device interrupt can not
-                 * be set, ignore it.
-                 */
-                if (!irq_can_set_affinity(newdev->irq))
-                        goto out_bc;
-
-                /*
-                 * If we have a cpu local device already, do not replace it
-                 * by a non cpu local device
-                 */
-                if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu)))
-                        goto out_bc;
-        }
+        if (!tick_check_percpu(curdev, newdev, cpu))
+                goto out_bc;
 
-        /*
-         * If we have an active device, then check the rating and the oneshot
-         * feature.
-         */
-        if (curdev) {
-                /*
-                 * Prefer one shot capable devices !
-                 */
-                if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) &&
-                    !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
-                        goto out_bc;
-                /*
-                 * Check the rating
-                 */
-                if (curdev->rating >= newdev->rating)
-                        goto out_bc;
-        }
+        /* Preference decision */
+        if (!tick_check_preferred(curdev, newdev))
+                goto out_bc;
 
         if (!try_module_get(newdev->owner))
                 return;