[PATCH v6 5/7] cpufreq: add function to get the hardware max frequency

[Ionela Voinescu <ionela.voinescu@xxxxxxx>]

Add weak function to return the hardware maximum frequency of a CPU,
with the default implementation returning cpuinfo.max_freq, which is
the best information we can generically get from the cpufreq framework.

The default can be overwritten by a strong function in platforms
that want to provide an alternative implementation, with more accurate
information, obtained either from hardware or firmware.

Signed-off-by: Ionela Voinescu <ionela.voinescu@xxxxxxx>
Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Reviewed-by: Valentin Schneider <valentin.schneider@xxxxxxx>
Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
 drivers/cpufreq/cpufreq.c | 20 ++++++++++++++++++++
 include/linux/cpufreq.h   |  5 +++++
 2 files changed, 25 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index cbe6c94bf158..985228aee46f 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1725,6 +1725,26 @@ unsigned int cpufreq_quick_get_max(unsigned int cpu)
 }
 EXPORT_SYMBOL(cpufreq_quick_get_max);
 
+/**
+ * cpufreq_get_hw_max_freq - get the max hardware frequency of the CPU
+ * @cpu: CPU number
+ *
+ * The default return value is the max_freq field of cpuinfo.
+ */
+__weak unsigned int cpufreq_get_hw_max_freq(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+	unsigned int ret_freq = 0;
+
+	if (policy) {
+		ret_freq = policy->cpuinfo.max_freq;
+		cpufreq_cpu_put(policy);
+	}
+
+	return ret_freq;
+}
+EXPORT_SYMBOL(cpufreq_get_hw_max_freq);
+
 static unsigned int __cpufreq_get(struct cpufreq_policy *policy)
 {
 	if (unlikely(policy_is_inactive(policy)))
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 0fb561d1b524..f7240251a949 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -205,6 +205,7 @@ static inline bool policy_is_shared(struct cpufreq_policy *policy)
 unsigned int cpufreq_get(unsigned int cpu);
 unsigned int cpufreq_quick_get(unsigned int cpu);
 unsigned int cpufreq_quick_get_max(unsigned int cpu);
+unsigned int cpufreq_get_hw_max_freq(unsigned int cpu);
 void disable_cpufreq(void);
 
 u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy);
@@ -232,6 +233,10 @@ static inline unsigned int cpufreq_quick_get_max(unsigned int cpu)
 {
 	return 0;
 }
+static inline unsigned int cpufreq_get_hw_max_freq(unsigned int cpu)
+{
+	return 0;
+}
 static inline void disable_cpufreq(void) { }
 #endif
 
-- 
2.17.1