ARM: smp_twd: Use cpufreq notifiers to update prescalers

Change-Id: I957d5ca8580d4e7a98fb9fc754ca8f00133940d9
Signed-off-by: Colin Cross <ccross@android.com>

diff --git a/arch/arm/include/asm/smp_twd.h b/arch/arm/include/asm/smp_twd.h
index 79aebe2ad7a8ec6749a4459476fb751cd51ad8bf..ce0a8b95da391b08cfc96c589b06169fd7eb1d55 100644 (file)
--- a/arch/arm/include/asm/smp_twd.h
+++ b/arch/arm/include/asm/smp_twd.h
@@ -37,12 +37,4 @@ void twd_timer_setup(struct clock_event_device *);
 void twd_timer_setup_scalable(struct clock_event_device *,
        unsigned long target_rate, unsigned int periphclk_prescaler);
 
-/*
- * Recalculate the twd prescaler value when the cpu frequency changes. To
- * prevent early timer interrupts, must be called before changing the cpu
- * frequency if the frequency is increasing, or after if the frequency is
- * decreasing.
- */
-void twd_recalc_prescaler(unsigned long new_rate);
-
 #endif

diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index 97f93496785021acbf0728d0963cf8dcf8388e35..3dc62ee456394ba435031b63755b7a9655d7f376 100644 (file)
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -17,6 +17,7 @@
 #include <linux/clockchips.h>
 #include <linux/irq.h>
 #include <linux/io.h>
+#include <linux/cpufreq.h>
 
 #include <asm/smp_twd.h>
 #include <asm/hardware/gic.h>
@@ -88,7 +89,7 @@ int twd_timer_ack(void)
  * frequency if the frequency is increasing, or after if the frequency is
  * decreasing.
  */
-void twd_recalc_prescaler(unsigned long new_rate)
+static void twd_update_prescaler(void *data)
 {
        u32 ctrl;
        int prescaler;
@@ -96,9 +97,7 @@ void twd_recalc_prescaler(unsigned long new_rate)
 
        BUG_ON(twd_periphclk_prescaler == 0 || twd_timer_rate == 0);
 
-       twd_cpu_rate = new_rate;
-
-       periphclk_rate = new_rate / twd_periphclk_prescaler;
+       periphclk_rate = twd_cpu_rate / twd_periphclk_prescaler;
 
        prescaler = DIV_ROUND_UP(periphclk_rate, twd_timer_rate);
        prescaler = clamp(prescaler - 1, 0, 0xFF);
@@ -109,6 +108,36 @@ void twd_recalc_prescaler(unsigned long new_rate)
        __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
 }
 
+static int twd_cpufreq_transition(struct notifier_block *nb,
+       unsigned long state, void *data)
+{
+       struct cpufreq_freqs *freqs = data;
+       if (((freqs->new > freqs->old) && state == CPUFREQ_PRECHANGE) ||
+           ((freqs->old > freqs->new) && state == CPUFREQ_POSTCHANGE)) {
+               /* freqs->new is in kHz, twd_cpu_rate is in Hz */
+               twd_cpu_rate = freqs->new * 1000;
+
+               smp_call_function_single(freqs->cpu, twd_update_prescaler,
+                       NULL, 1);
+       }
+
+       return NOTIFY_OK;
+}
+
+static struct notifier_block twd_cpufreq_nb = {
+       .notifier_call = twd_cpufreq_transition,
+};
+
+static int twd_cpufreq_init(void)
+{
+       if (twd_cpu_rate)
+               return cpufreq_register_notifier(&twd_cpufreq_nb,
+                       CPUFREQ_TRANSITION_NOTIFIER);
+
+       return 0;
+}
+core_initcall(twd_cpufreq_init);
+
 static void __cpuinit twd_calibrate_rate(unsigned long target_rate,
        unsigned int periphclk_prescaler)
 {
@@ -156,7 +185,7 @@ static void __cpuinit twd_calibrate_rate(unsigned long target_rate,
                                (twd_timer_rate / 10000) % 100);
                        twd_cpu_rate = twd_timer_rate * periphclk_prescaler;
                        twd_timer_rate = target_rate;
-                       twd_recalc_prescaler(twd_cpu_rate);
+                       twd_update_prescaler(NULL);
                }
 
                printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
@@ -164,7 +193,7 @@ static void __cpuinit twd_calibrate_rate(unsigned long target_rate,
        } else {
                if (target_rate) {
                        BUG_ON(target_rate != twd_timer_rate);
-                       twd_recalc_prescaler(twd_cpu_rate);
+                       twd_update_prescaler(NULL);
                }
        }