Provide an arch specific hook for cpufreq based scaling of cpu_power.

[ dino: backport to 31-rt ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Dinakar Guniguntala <dino@in.ibm.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Darren Hart <dvhltc@us.ibm.com>
Cc: John Kacur <jkacur@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/sched.c

@@ -3793,7 +3793,18 @@ static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
 }
 #endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
 
-unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
+
+unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
+{
+	return SCHED_LOAD_SCALE;
+}
+
+unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
+{
+	return default_scale_freq_power(sd, cpu);
+}
+
+unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
 {
 	unsigned long weight = cpumask_weight(sched_domain_span(sd));
 	unsigned long smt_gain = sd->smt_gain;
@@ -3803,6 +3814,11 @@ unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
 	return smt_gain;
 }
 
+unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
+{
+	return default_scale_smt_power(sd, cpu);
+}
+
 unsigned long scale_rt_power(int cpu)
 {
 	struct rq *rq = cpu_rq(cpu);
@@ -3827,7 +3843,8 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
 	unsigned long power = SCHED_LOAD_SCALE;
 	struct sched_group *sdg = sd->groups;
 
-	/* here we could scale based on cpufreq */
+	power *= arch_scale_freq_power(sd, cpu);
+	power >> SCHED_LOAD_SHIFT;
 
 	if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
 		power *= arch_scale_smt_power(sd, cpu);