[V3,6/7] PM / Domains: Allow domain performance states to be read from DT

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 202effbebfd1..a7449c492990 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -2251,6 +2251,107 @@  int of_genpd_parse_idle_states(struct device_node *dn,
 }
 EXPORT_SYMBOL_GPL(of_genpd_parse_idle_states);
 
+/* Power domain performance state management helpers */
+static const struct of_device_id performance_state_match[] = {
+	{ .compatible = "domain-performance-state", },
+	{ }
+};
+
+static int genpd_parse_performance_state(struct genpd_performance_state *state,
+					 struct device_node *np)
+{
+	int ret;
+
+	ret = of_property_read_u32(np, "reg", &state->performance_state);
+	if (ret) {
+		pr_err(" * %s missing reg property\n", np->full_name);
+		return ret;
+	}
+
+	ret = of_property_read_variable_u32_array(np, "domain-microvolt",
+						  &state->u_volt, 1, 3);
+	if (ret >= 0)
+		return 0;
+
+	/* Property not found */
+	if (ret == -EINVAL)
+		return 0;
+
+	pr_err(" * %s Invalid domain-microvolt property\n", np->full_name);
+	return ret;
+}
+
+/**
+ * of_genpd_parse_performance_states: Return array of performance states for the
+ *				      genpd.
+ *
+ * @dn: The genpd device node
+ * @states: The pointer to which the state array will be saved.
+ * @n: The count of elements in the array returned from this function.
+ *
+ * Returns the device performance states parsed from the OF node. The memory for
+ * the states is allocated by this function and is the responsibility of the
+ * caller to free the memory after use.
+ */
+int of_genpd_parse_performance_states(struct device_node *dn,
+				struct genpd_performance_state **states, int *n)
+{
+	struct genpd_performance_state *st;
+	struct device_node *perf_np, *np;
+	int i = 0, ret, count;
+
+	perf_np = of_get_child_by_name(dn, "performance-states");
+	if (!perf_np) {
+		pr_err("performance-states node not found in %s node\n",
+		       dn->full_name);
+		return -ENODEV;
+	}
+
+	if (!of_match_node(performance_state_match, perf_np)) {
+		pr_err("performance-states node found in %s node isn't compatible\n",
+		       dn->full_name);
+		ret = -EINVAL;
+		goto put_node;
+	}
+
+	count = of_get_child_count(perf_np);
+	if (count <= 0) {
+		pr_err("performance-states node found in %s node doesn't have any child nodes\n",
+		       dn->full_name);
+		ret = -EINVAL;
+		goto put_node;
+	}
+
+	st = kcalloc(count, sizeof(*st), GFP_KERNEL);
+	if (!st) {
+		ret = -ENOMEM;
+		goto put_node;
+	}
+
+	for_each_available_child_of_node(perf_np, np) {
+		ret = genpd_parse_performance_state(&st[i++], np);
+		if (ret) {
+			pr_err("Parsing of performance state node %s failed with err %d\n",
+			       np->full_name, ret);
+			goto free_st;
+		}
+	}
+
+	of_node_put(perf_np);
+	*n = count;
+	*states = st;
+
+	return 0;
+
+free_st:
+	kfree(st);
+put_node:
+	of_node_put(perf_np);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(of_genpd_parse_performance_states);
+
 #endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
 
 
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 83795935709e..7659ce3968c7 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -44,6 +44,13 @@  struct genpd_power_state {
 	struct fwnode_handle *fwnode;
 };
 
+struct genpd_performance_state {
+	unsigned int performance_state;
+	unsigned int u_volt;
+	unsigned int u_volt_min;
+	unsigned int u_volt_max;
+};
+
 struct genpd_lock_ops;
 
 struct generic_pm_domain {
@@ -226,6 +233,8 @@  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 int of_genpd_parse_performance_states(struct device_node *dn,
+			struct genpd_performance_state **states, int *n);
 
 int genpd_dev_pm_attach(struct device *dev);
 #else /* !CONFIG_PM_GENERIC_DOMAINS_OF */
@@ -261,6 +270,12 @@  static inline int of_genpd_parse_idle_states(struct device_node *dn,
 	return -ENODEV;
 }
 
+static inline int of_genpd_parse_performance_states(struct device_node *dn,
+			struct genpd_performance_state **states, int *n)
+{
+	return -ENODEV;
+}
+
 static inline int genpd_dev_pm_attach(struct device *dev)
 {
 	return -ENODEV;