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authorThomas Gleixner <tglx@linutronix.de>2011-05-19 01:33:42 +0400
committerThomas Gleixner <tglx@linutronix.de>2011-05-19 16:24:16 +0400
commit80b816b736cfa5b9582279127099b20a479ab7d9 (patch)
tree94a2963c05e8e24d6153a0a2fae2f43fe05605bc /kernel/time/clockevents.c
parent57f0fcbe1dea8a36c9d1673086326059991c5f81 (diff)
downloadlinux-80b816b736cfa5b9582279127099b20a479ab7d9.tar.xz
clockevents: Provide interface to reconfigure an active clock event device
Some ARM SoCs have clock event devices which have their frequency modified due to frequency scaling. Provide an interface which allows to reconfigure an active device. After reconfiguration reprogram the current pending event. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: LAK <linux-arm-kernel@lists.infradead.org> Cc: John Stultz <john.stultz@linaro.org> Acked-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Ingo Molnar <mingo@elte.hu> Link: http://lkml.kernel.org/r/%3C20110518210136.437459958%40linutronix.de%3E
Diffstat (limited to 'kernel/time/clockevents.c')
-rw-r--r--kernel/time/clockevents.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index c69e88c94446..22a9da9a9c96 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -238,6 +238,26 @@ void clockevents_config_and_register(struct clock_event_device *dev,
clockevents_register_device(dev);
}
+/**
+ * clockevents_update_freq - Update frequency and reprogram a clock event device.
+ * @dev: device to modify
+ * @freq: new device frequency
+ *
+ * Reconfigure and reprogram a clock event device in oneshot
+ * mode. Must be called on the cpu for which the device delivers per
+ * cpu timer events with interrupts disabled! Returns 0 on success,
+ * -ETIME when the event is in the past.
+ */
+int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
+{
+ clockevents_config(dev, freq);
+
+ if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
+ return 0;
+
+ return clockevents_program_event(dev, dev->next_event, ktime_get());
+}
+
/*
* Noop handler when we shut down an event device
*/