cpufreq-dt: add suspend frequency support

Add suspend frequency support and if needed set it to
the frequency obtained from the suspend opp (can be defined
using opp-v2 bindings and is optional).

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq-dt.c

@@ -196,6 +196,7 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 	struct device *cpu_dev;
 	struct regulator *cpu_reg;
 	struct clk *cpu_clk;
+	struct dev_pm_opp *suspend_opp;
 	unsigned long min_uV = ~0, max_uV = 0;
 	unsigned int transition_latency;
 	bool need_update = false;
@@ -333,6 +334,13 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 	policy->driver_data = priv;
 
 	policy->clk = cpu_clk;
+
+	rcu_read_lock();
+	suspend_opp = dev_pm_opp_get_suspend_opp(cpu_dev);
+	if (suspend_opp)
+		policy->suspend_freq = dev_pm_opp_get_freq(suspend_opp) / 1000;
+	rcu_read_unlock();
+
 	ret = cpufreq_table_validate_and_show(policy, freq_table);
 	if (ret) {
 		dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__,
@@ -423,6 +431,7 @@ static struct cpufreq_driver dt_cpufreq_driver = {
 	.ready = cpufreq_ready,
 	.name = "cpufreq-dt",
 	.attr = cpufreq_dt_attr,
+	.suspend = cpufreq_generic_suspend,
 };
 
 static int dt_cpufreq_probe(struct platform_device *pdev)