linux-kernel - [RFC PATCH 2/5] clockevents: Add generic timer broadcast receiver

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Message-Id: <1355832418-31692-3-git-send-email-mark.rutland@arm.com>
Date:	Tue, 18 Dec 2012 12:06:55 +0000
From:	Mark Rutland <mark.rutland@....com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-arm-kernel@...ts.infradead.org, linux@....linux.org.uk,
	tglx@...utronix.de, nico@...aro.org, will.deacon@....com,
	marc.zyngier@....com, john.stultz@...aro.org,
	Mark Rutland <mark.rutland@....com>
Subject: [RFC PATCH 2/5] clockevents: Add generic timer broadcast receiver

Currently the broadcast mechanism used for timers is abstracted by a
function pointer on struct clock_event_device. As the fundamental
mechanism for broadcast is architecture-specific, this ties each
clock_event_device driver to a single architecture, even where the
driver is otherwise generic.

This patch adds a standard path for the receipt of timer broadcasts, so
drivers and/or architecture backends need not manage redundant lists of
timers for the purpose of routing broadcast timer ticks.

Signed-off-by: Mark Rutland <mark.rutland@....com>
---
 include/linux/clockchips.h   |    4 ++++
 kernel/time/tick-broadcast.c |   15 +++++++++++++++
 2 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index 8a7096f..e1089aa 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -161,6 +161,10 @@ clockevents_calc_mult_shift(struct clock_event_device *ce, u32 freq, u32 minsec)
 extern void clockevents_suspend(void);
 extern void clockevents_resume(void);
 
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+extern int tick_receive_broadcast(void);
+#endif
+
 #ifdef CONFIG_GENERIC_CLOCKEVENTS
 extern void clockevents_notify(unsigned long reason, void *arg);
 #else
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index f113755..c2dd022 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -125,6 +125,21 @@ int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
 	return ret;
 }
 
+int tick_receive_broadcast(void)
+{
+	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
+	struct clock_event_device *evt = td->evtdev;
+
+	if (!evt)
+		return -ENODEV;
+
+	if (!evt->event_handler)
+		return -EINVAL;
+
+	evt->event_handler(evt);
+	return 0;
+}
+
 /*
  * Broadcast the event to the cpus, which are set in the mask (mangled).
  */
-- 
1.7.0.4


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