cpufreq: Introduce policy->boost_supported flag

It is possible to have a scenario where not all cpufreq policies support
boost frequencies. And letting sysfs (or other parts of the kernel)
enable boost feature for that policy isn't correct.

Add a new flag, boost_supported, which will be set to true by the
cpufreq core only if the freq table contains valid boost frequencies.

Some cpufreq drivers though don't have boost frequencies in the
freq-table, they can set this flag from their ->init() callbacks.

Once all the drivers are updated to set the flag correctly, we can check
it before enabling boost feature for a policy.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Author: vireshk

drivers/cpufreq/freq_table.c

@@ -359,6 +359,10 @@ int cpufreq_table_validate_and_sort(struct cpufreq_policy *policy)
 	if (ret)
 		return ret;
 
+	/* Driver's may have set this field already */
+	if (policy_has_boost_freq(policy))
+		policy->boost_supported = true;
+
 	return set_freq_table_sorted(policy);
 }
 

include/linux/cpufreq.h

@@ -144,6 +144,9 @@ struct cpufreq_policy {
 	/* Per policy boost enabled flag. */
 	bool			boost_enabled;
 
+	/* Per policy boost supported flag. */
+	bool			boost_supported;
+
 	 /* Cached frequency lookup from cpufreq_driver_resolve_freq. */
 	unsigned int cached_target_freq;
 	unsigned int cached_resolved_idx;