drm/panel: simple: support positive/negative driven supply

Change-Id: I0f100f4f6fef67996edbcaa5d24d02ba38c38124
Signed-off-by: Wyon Bi <bivvy.bi@rock-chips.com>

Documentation/devicetree/bindings/display/panel/simple-panel.txt

@@ -12,6 +12,8 @@ Required properties:
 - power-supply: See panel-common.txt
 
 Optional properties:
+- vsp-supply: positive voltage supply
+- vsn-supply: negative voltage supply
 - ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing
 - enable-gpios: GPIO pin to enable or disable the panel
 - reset-gpios: GPIO pin to reset the panel

drivers/gpu/drm/panel/panel-simple.c

@@ -116,6 +116,7 @@ struct panel_simple {
 
 	struct backlight_device *backlight;
 	struct regulator *supply;
+	struct regulator_bulk_data supplies[2];
 	struct i2c_adapter *ddc;
 
 	struct gpio_desc *enable_gpio;
@@ -428,6 +429,10 @@ static int panel_simple_regulator_enable(struct panel_simple *p)
 {
 	int err;
 
+	err = regulator_bulk_enable(ARRAY_SIZE(p->supplies), p->supplies);
+	if (err < 0)
+		return err;
+
 	if (p->power_invert) {
 		if (regulator_is_enabled(p->supply) > 0)
 			regulator_disable(p->supply);
@@ -454,6 +459,8 @@ static int panel_simple_regulator_disable(struct panel_simple *p)
 		regulator_disable(p->supply);
 	}
 
+	regulator_bulk_disable(ARRAY_SIZE(p->supplies), p->supplies);
+
 	return 0;
 }
 
@@ -674,6 +681,14 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 	if (IS_ERR(panel->supply))
 		return PTR_ERR(panel->supply);
 
+	panel->supplies[0].supply = "vsp";
+	panel->supplies[1].supply = "vsn";
+
+	err = devm_regulator_bulk_get(dev, ARRAY_SIZE(panel->supplies),
+				      panel->supplies);
+	if (err)
+		return err;
+
 	panel->enable_gpio = devm_gpiod_get_optional(dev, "enable",
 						     GPIOD_ASIS);
 	if (IS_ERR(panel->enable_gpio)) {