PM / Domain: Implement of_genpd_opp_to_performance_state()

This implements of_genpd_opp_to_performance_state() which can be used
from the device drivers or the OPP core to find the performance state
encoded in the "required-opps" property of a node. Normally this would
be called only once for each OPP of the device for which the OPP table
of the device is getting generated.

Different platforms may encode the performance state differently using
the OPP table (they may simply return value of opp-hz or opp-microvolt,
or apply some algorithm on top of those values) and so a new callback
->opp_to_performance_state() is implemented to allow platform specific
drivers to convert the power domain OPP to a performance state value.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/base/power/domain.c

@@ -2412,6 +2412,54 @@ int of_genpd_parse_idle_states(struct device_node *dn,
 }
 EXPORT_SYMBOL_GPL(of_genpd_parse_idle_states);
 
+/**
+ * of_genpd_opp_to_performance_state- Gets performance state of device's
+ * power domain corresponding to a DT node's "required-opps" property.
+ *
+ * @dev: Device for which the performance-state needs to be found.
+ * @opp_node: DT node where the "required-opps" property is present. This can be
+ *	the device node itself (if it doesn't have an OPP table) or a node
+ *	within the OPP table of a device (if device has an OPP table).
+ * @state: Pointer to return performance state.
+ *
+ * Returns performance state corresponding to the "required-opps" property of
+ * a DT node. This calls platform specific genpd->opp_to_performance_state()
+ * callback to translate power domain OPP to performance state.
+ *
+ * Returns performance state on success and 0 on failure.
+ */
+unsigned int of_genpd_opp_to_performance_state(struct device *dev,
+					       struct device_node *opp_node)
+{
+	struct generic_pm_domain *genpd;
+	struct dev_pm_opp *opp;
+	int state = 0;
+
+	genpd = dev_to_genpd(dev);
+	if (IS_ERR(genpd))
+		return 0;
+
+	if (unlikely(!genpd->set_performance_state))
+		return 0;
+
+	genpd_lock(genpd);
+
+	opp = of_dev_pm_opp_find_required_opp(&genpd->dev, opp_node);
+	if (IS_ERR(opp)) {
+		state = PTR_ERR(opp);
+		goto unlock;
+	}
+
+	state = genpd->opp_to_performance_state(genpd, opp);
+	dev_pm_opp_put(opp);
+
+unlock:
+	genpd_unlock(genpd);
+
+	return state;
+}
+EXPORT_SYMBOL_GPL(of_genpd_opp_to_performance_state);
+
 #endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
 
 

include/linux/pm_domain.h

@@ -47,6 +47,7 @@ struct genpd_power_state {
 };
 
 struct genpd_lock_ops;
+struct dev_pm_opp;
 
 struct generic_pm_domain {
 	struct device dev;
@@ -68,6 +69,8 @@ struct generic_pm_domain {
 	unsigned int performance_state;	/* Aggregated max performance state */
 	int (*power_off)(struct generic_pm_domain *domain);
 	int (*power_on)(struct generic_pm_domain *domain);
+	unsigned int (*opp_to_performance_state)(struct generic_pm_domain *genpd,
+						 struct dev_pm_opp *opp);
 	int (*set_performance_state)(struct generic_pm_domain *genpd,
 				     unsigned int state);
 	struct gpd_dev_ops dev_ops;
@@ -244,6 +247,8 @@ extern int of_genpd_add_subdomain(struct of_phandle_args *parent,
 extern struct generic_pm_domain *of_genpd_remove_last(struct device_node *np);
 extern int of_genpd_parse_idle_states(struct device_node *dn,
 			struct genpd_power_state **states, int *n);
+extern unsigned int of_genpd_opp_to_performance_state(struct device *dev,
+				struct device_node *opp_node);
 
 int genpd_dev_pm_attach(struct device *dev);
 #else /* !CONFIG_PM_GENERIC_DOMAINS_OF */
@@ -279,6 +284,13 @@ static inline int of_genpd_parse_idle_states(struct device_node *dn,
 	return -ENODEV;
 }
 
+static inline unsigned int
+of_genpd_opp_to_performance_state(struct device *dev,
+				  struct device_node *opp_node)
+{
+	return -ENODEV;
+}
+
 static inline int genpd_dev_pm_attach(struct device *dev)
 {
 	return -ENODEV;