opp: core: add regulators enable and disable

Add enable regulators to dev_pm_opp_set_regulators() and disable
regulators to dev_pm_opp_put_regulators(). Even if bootloader
leaves regulators enabled, they should be enabled in kernel in
order to increase the reference count.
Tested-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Acked-by: NClément Péron <peron.clem@gmail.com>
Tested-by: NClément Péron <peron.clem@gmail.com>
Signed-off-by: NKamil Konieczny <k.konieczny@samsung.com>
[ Viresh: Enable the regulator only after it is programmed and add a
	  flag to track its status. ]
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>

drivers/opp/core.c

@@ -664,7 +664,7 @@ static inline int _generic_set_opp_clk_only(struct device *dev, struct clk *clk,
 	return ret;
 }
 
-static int _generic_set_opp_regulator(const struct opp_table *opp_table,
+static int _generic_set_opp_regulator(struct opp_table *opp_table,
 				      struct device *dev,
 				      unsigned long old_freq,
 				      unsigned long freq,
@@ -699,6 +699,18 @@ static int _generic_set_opp_regulator(const struct opp_table *opp_table,
 			goto restore_freq;
 	}
 
+	/*
+	 * Enable the regulator after setting its voltages, otherwise it breaks
+	 * some boot-enabled regulators.
+	 */
+	if (unlikely(!opp_table->regulator_enabled)) {
+		ret = regulator_enable(reg);
+		if (ret < 0)
+			dev_warn(dev, "Failed to enable regulator: %d", ret);
+		else
+			opp_table->regulator_enabled = true;
+	}
+
 	return 0;
 
 restore_freq:
@@ -825,12 +837,17 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 		if (!_get_opp_count(opp_table))
 			return 0;
 
-		if (!opp_table->required_opp_tables) {
+		if (!opp_table->required_opp_tables && !opp_table->regulators) {
 			dev_err(dev, "target frequency can't be 0\n");
 			ret = -EINVAL;
 			goto put_opp_table;
 		}
 
+		if (opp_table->regulator_enabled) {
+			regulator_disable(opp_table->regulators[0]);
+			opp_table->regulator_enabled = false;
+		}
+
 		ret = _set_required_opps(dev, opp_table, NULL);
 		goto put_opp_table;
 	}
@@ -1718,6 +1735,13 @@ void dev_pm_opp_put_regulators(struct opp_table *opp_table)
 	/* Make sure there are no concurrent readers while updating opp_table */
 	WARN_ON(!list_empty(&opp_table->opp_list));
 
+	if (opp_table->regulator_enabled) {
+		for (i = opp_table->regulator_count - 1; i >= 0; i--)
+			regulator_disable(opp_table->regulators[i]);
+
+		opp_table->regulator_enabled = false;
+	}
+
 	for (i = opp_table->regulator_count - 1; i >= 0; i--)
 		regulator_put(opp_table->regulators[i]);
 

drivers/opp/opp.h

@@ -147,6 +147,7 @@ enum opp_table_access {
  * @clk: Device's clock handle
  * @regulators: Supply regulators
  * @regulator_count: Number of power supply regulators. Its value can be -1
+ * @regulator_enabled: Set to true if regulators were previously enabled.
  * (uninitialized), 0 (no opp-microvolt property) or > 0 (has opp-microvolt
  * property).
  * @paths: Interconnect path handles
@@ -194,6 +195,7 @@ struct opp_table {
 	struct clk *clk;
 	struct regulator **regulators;
 	int regulator_count;
+	bool regulator_enabled;
 	struct icc_path **paths;
 	unsigned int path_count;
 	bool genpd_performance_state;