opp: Allow _generic_set_opp_regulator() to work for non-freq devices

The _generic_set_opp_regulator() helper will be used for devices which
don't change frequency (like power domains, etc.) later on, prepare for
that by not relying on frequency for making decisions here.

While at it, update its parameters to pass only what is necessary.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Dmitry Osipenko <digetx@gmail.com>

drivers/opp/core.c

@@ -737,12 +737,12 @@ static inline int _generic_set_opp_clk_only(struct device *dev, struct clk *clk,
 
 static int _generic_set_opp_regulator(struct opp_table *opp_table,
 				      struct device *dev,
-				      unsigned long old_freq,
+				      struct dev_pm_opp *opp,
 				      unsigned long freq,
-				      struct dev_pm_opp_supply *old_supply,
-				      struct dev_pm_opp_supply *new_supply)
+				      int scaling_down)
 {
 	struct regulator *reg = opp_table->regulators[0];
+	struct dev_pm_opp *old_opp = opp_table->current_opp;
 	int ret;
 
 	/* This function only supports single regulator per device */
@@ -752,8 +752,8 @@ static int _generic_set_opp_regulator(struct opp_table *opp_table,
 	}
 
 	/* Scaling up? Scale voltage before frequency */
-	if (freq >= old_freq) {
-		ret = _set_opp_voltage(dev, reg, new_supply);
+	if (!scaling_down) {
+		ret = _set_opp_voltage(dev, reg, opp->supplies);
 		if (ret)
 			goto restore_voltage;
 	}
@@ -764,8 +764,8 @@ static int _generic_set_opp_regulator(struct opp_table *opp_table,
 		goto restore_voltage;
 
 	/* Scaling down? Scale voltage after frequency */
-	if (freq < old_freq) {
-		ret = _set_opp_voltage(dev, reg, new_supply);
+	if (scaling_down) {
+		ret = _set_opp_voltage(dev, reg, opp->supplies);
 		if (ret)
 			goto restore_freq;
 	}
@@ -783,12 +783,12 @@ static int _generic_set_opp_regulator(struct opp_table *opp_table,
 	return 0;
 
 restore_freq:
-	if (_generic_set_opp_clk_only(dev, opp_table->clk, old_freq))
+	if (_generic_set_opp_clk_only(dev, opp_table->clk, old_opp->rate))
 		dev_err(dev, "%s: failed to restore old-freq (%lu Hz)\n",
-			__func__, old_freq);
+			__func__, old_opp->rate);
 restore_voltage:
 	/* This shouldn't harm even if the voltages weren't updated earlier */
-	_set_opp_voltage(dev, reg, old_supply);
+	_set_opp_voltage(dev, reg, old_opp->supplies);
 
 	return ret;
 }
@@ -1041,9 +1041,8 @@ static int _set_opp(struct device *dev, struct opp_table *opp_table,
 		ret = _set_opp_custom(opp_table, dev, old_freq, freq,
 				      old_opp->supplies, opp->supplies);
 	} else if (opp_table->regulators) {
-		ret = _generic_set_opp_regulator(opp_table, dev, old_freq, freq,
-						 old_opp->supplies,
-						 opp->supplies);
+		ret = _generic_set_opp_regulator(opp_table, dev, opp, freq,
+						 scaling_down);
 	} else {
 		/* Only frequency scaling */
 		ret = _generic_set_opp_clk_only(dev, opp_table->clk, freq);