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Diffstat (limited to 'arch/arm/kernel/smp_twd.c')
-rw-r--r--arch/arm/kernel/smp_twd.c47
1 files changed, 47 insertions, 0 deletions
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index a9783947c086..c8e938553d47 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/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;