trace: cpufreq: Add tracing for min/max cpufreq

Change-Id: I73f6ec437c1f805437d9376abb6510d1364b07ec
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>

Documentation/trace/events-power.txt

@@ -25,6 +25,7 @@ cpufreq.
 
 cpu_idle		"state=%lu cpu_id=%lu"
 cpu_frequency		"state=%lu cpu_id=%lu"
+cpu_frequency_limits	"min=%lu max=%lu cpu_id=%lu"
 
 A suspend event is used to indicate the system going in and out of the
 suspend mode:

drivers/cpufreq/cpufreq.c

@@ -2128,6 +2128,7 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
 
 	policy->min = new_policy->min;
 	policy->max = new_policy->max;
+	trace_cpu_frequency_limits(policy->max, policy->min, policy->cpu);
 
 	pr_debug("new min and max freqs are %u - %u kHz\n",
 		 policy->min, policy->max);

include/trace/events/power.h

@@ -120,6 +120,31 @@ DEFINE_EVENT(cpu, cpu_frequency,
 	TP_ARGS(frequency, cpu_id)
 );
 
+TRACE_EVENT(cpu_frequency_limits,
+
+	TP_PROTO(unsigned int max_freq, unsigned int min_freq,
+		unsigned int cpu_id),
+
+	TP_ARGS(max_freq, min_freq, cpu_id),
+
+	TP_STRUCT__entry(
+		__field(	u32,		min_freq	)
+		__field(	u32,		max_freq	)
+		__field(	u32,		cpu_id		)
+	),
+
+	TP_fast_assign(
+		__entry->min_freq = min_freq;
+		__entry->max_freq = min_freq;
+		__entry->cpu_id = cpu_id;
+	),
+
+	TP_printk("min=%lu max=%lu cpu_id=%lu",
+		  (unsigned long)__entry->min_freq,
+		  (unsigned long)__entry->max_freq,
+		  (unsigned long)__entry->cpu_id)
+);
+
 TRACE_EVENT(device_pm_callback_start,
 
 	TP_PROTO(struct device *dev, const char *pm_ops, int event),