1 files changed, 54 insertions, 0 deletions

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index ebd8ad274d76..8e03567c9583 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -25,6 +25,7 @@
 #include <linux/percpu.h>
 #include <linux/clockchips.h>
 #include <linux/completion.h>
+#include <linux/cpufreq.h>
 
 #include <linux/atomic.h>
 #include <asm/cacheflush.h>
@@ -584,3 +585,56 @@ int setup_profiling_timer(unsigned int multiplier)
 {
         return -EINVAL;
 }
+
+#ifdef CONFIG_CPU_FREQ
+
+static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
+static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
+static unsigned long global_l_p_j_ref;
+static unsigned long global_l_p_j_ref_freq;
+
+static int cpufreq_callback(struct notifier_block *nb,
+                                        unsigned long val, void *data)
+{
+        struct cpufreq_freqs *freq = data;
+        int cpu = freq->cpu;
+
+        if (freq->flags & CPUFREQ_CONST_LOOPS)
+                return NOTIFY_OK;
+
+        if (!per_cpu(l_p_j_ref, cpu)) {
+                per_cpu(l_p_j_ref, cpu) =
+                        per_cpu(cpu_data, cpu).loops_per_jiffy;
+                per_cpu(l_p_j_ref_freq, cpu) = freq->old;
+                if (!global_l_p_j_ref) {
+                        global_l_p_j_ref = loops_per_jiffy;
+                        global_l_p_j_ref_freq = freq->old;
+                }
+        }
+
+        if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
+            (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
+            (val == CPUFREQ_RESUMECHANGE || val == CPUFREQ_SUSPENDCHANGE)) {
+                loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
+                                                global_l_p_j_ref_freq,
+                                                freq->new);
+                per_cpu(cpu_data, cpu).loops_per_jiffy =
+                        cpufreq_scale(per_cpu(l_p_j_ref, cpu),
+                                        per_cpu(l_p_j_ref_freq, cpu),
+                                        freq->new);
+        }
+        return NOTIFY_OK;
+}
+
+static struct notifier_block cpufreq_notifier = {
+        .notifier_call  = cpufreq_callback,
+};
+
+static int __init register_cpufreq_notifier(void)
+{
+        return cpufreq_register_notifier(&cpufreq_notifier,
+                                                CPUFREQ_TRANSITION_NOTIFIER);
+}
+core_initcall(register_cpufreq_notifier);
+
+#endif