linux-kernel - [tip:timers/core] clockevents: Add generic timer broadcast function

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Message-ID: <tip-12ad10004645d38356b14d1fbba379c523a61916@git.kernel.org>
Date:	Mon, 4 Feb 2013 02:31:38 -0800
From:	tip-bot for Mark Rutland <mark.rutland@....com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	santosh.shilimkar@...com, mark.rutland@....com, tglx@...utronix.de,
	sboyd@...eaurora.org
Subject: [tip:timers/core] clockevents:
  Add generic timer broadcast function

Commit-ID:  12ad10004645d38356b14d1fbba379c523a61916
Gitweb:     http://git.kernel.org/tip/12ad10004645d38356b14d1fbba379c523a61916
Author:     Mark Rutland <mark.rutland@....com>
AuthorDate: Mon, 14 Jan 2013 17:05:22 +0000
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 31 Jan 2013 22:15:36 +0100

clockevents: Add generic timer broadcast function

Currently, the timer broadcast mechanism is defined by a function
pointer on struct clock_event_device. As the fundamental mechanism for
broadcast is architecture-specific, this means that clock_event_device
drivers cannot be shared across multiple architectures.

This patch adds an (optional) architecture-specific function for timer
tick broadcast, allowing drivers which may require broadcast
functionality to be shared across multiple architectures.

Signed-off-by: Mark Rutland <mark.rutland@....com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@...com>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: nico@...aro.org
Cc: Will.Deacon@....com
Cc: Marc.Zyngier@....com
Cc: john.stultz@...aro.org
Link: http://lkml.kernel.org/r/1358183124-28461-3-git-send-email-mark.rutland@arm.com
Tested-by: Santosh Shilimkar <santosh.shilimkar@...com>
Reviewed-by: Stephen Boyd <sboyd@...eaurora.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 include/linux/clockchips.h   |  5 +++++
 kernel/time/Kconfig          |  4 ++++
 kernel/time/tick-broadcast.c | 13 +++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index e1089aa..6634652 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -162,6 +162,11 @@ extern void clockevents_suspend(void);
 extern void clockevents_resume(void);
 
 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+#ifdef CONFIG_ARCH_HAS_TICK_BROADCAST
+extern void tick_broadcast(const struct cpumask *mask);
+#else
+#define tick_broadcast	NULL
+#endif
 extern int tick_receive_broadcast(void);
 #endif
 
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 8601f0d..b696922 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -38,6 +38,10 @@ config GENERIC_CLOCKEVENTS_BUILD
 	default y
 	depends on GENERIC_CLOCKEVENTS
 
+# Architecture can handle broadcast in a driver-agnostic way
+config ARCH_HAS_TICK_BROADCAST
+	bool
+
 # Clockevents broadcasting infrastructure
 config GENERIC_CLOCKEVENTS_BROADCAST
 	bool
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 7cc81c5..f726537 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -18,6 +18,7 @@
 #include <linux/percpu.h>
 #include <linux/profile.h>
 #include <linux/sched.h>
+#include <linux/smp.h>
 
 #include "tick-internal.h"
 
@@ -86,6 +87,11 @@ int tick_is_broadcast_device(struct clock_event_device *dev)
 	return (dev && tick_broadcast_device.evtdev == dev);
 }
 
+static void err_broadcast(const struct cpumask *mask)
+{
+	pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
+}
+
 /*
  * Check, if the device is disfunctional and a place holder, which
  * needs to be handled by the broadcast device.
@@ -105,6 +111,13 @@ int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
 	 */
 	if (!tick_device_is_functional(dev)) {
 		dev->event_handler = tick_handle_periodic;
+		if (!dev->broadcast)
+			dev->broadcast = tick_broadcast;
+		if (!dev->broadcast) {
+			pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
+				     dev->name);
+			dev->broadcast = err_broadcast;
+		}
 		cpumask_set_cpu(cpu, tick_get_broadcast_mask());
 		tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
 		ret = 1;
--
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