From 8097e8eb85bd04983f38cecab00e8a9e90a6189f Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@linaro.org>
Date: Tue, 13 Dec 2011 12:48:18 +0100
Subject: [PATCH] --- yaml --- r: 279798 b: refs/heads/master c:
 4fd7f9b128107034fa925b6877fae3c275f0da86 h: refs/heads/master v: v3

---
 [refs]                          |  2 +-
 trunk/arch/arm/kernel/smp_twd.c | 47 +++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index eee902588ce6..e8f4edb07788 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 5def51b0f827931bb559e6195060d774894fc9f9
+refs/heads/master: 4fd7f9b128107034fa925b6877fae3c275f0da86
diff --git a/trunk/arch/arm/kernel/smp_twd.c b/trunk/arch/arm/kernel/smp_twd.c
index a9783947c086..c8e938553d47 100644
--- a/trunk/arch/arm/kernel/smp_twd.c
+++ b/trunk/arch/arm/kernel/smp_twd.c
@@ -11,6 +11,7 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/clk.h>
+#include <linux/cpufreq.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
@@ -92,6 +93,52 @@ void twd_timer_stop(struct clock_event_device *clk)
 	disable_percpu_irq(clk->irq);
 }
 
+#ifdef CONFIG_CPU_FREQ
+
+/*
+ * Updates clockevent frequency when the cpu frequency changes.
+ * Called on the cpu that is changing frequency with interrupts disabled.
+ */
+static void twd_update_frequency(void *data)
+{
+	twd_timer_rate = clk_get_rate(twd_clk);
+
+	clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
+}
+
+static int twd_cpufreq_transition(struct notifier_block *nb,
+	unsigned long state, void *data)
+{
+	struct cpufreq_freqs *freqs = data;
+
+	/*
+	 * The twd clock events must be reprogrammed to account for the new
+	 * frequency.  The timer is local to a cpu, so cross-call to the
+	 * changing cpu.
+	 */
+	if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
+		smp_call_function_single(freqs->cpu, twd_update_frequency,
+			NULL, 1);
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block twd_cpufreq_nb = {
+	.notifier_call = twd_cpufreq_transition,
+};
+
+static int twd_cpufreq_init(void)
+{
+	if (!IS_ERR(twd_clk))
+		return cpufreq_register_notifier(&twd_cpufreq_nb,
+			CPUFREQ_TRANSITION_NOTIFIER);
+
+	return 0;
+}
+core_initcall(twd_cpufreq_init);
+
+#endif
+
 static void __cpuinit twd_calibrate_rate(void)
 {
 	unsigned long count;