drm/bridge: lt8912b: Add power supplies

Add supplies to the driver that can be used to turn the Lontium lt8912b
on and off. It can have up to 7 independent supplies, we add them all
and enable/disable them with bulk_enable/disable.
Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231115121338.22959-4-francesco@dolcini.it

drivers/gpu/drm/bridge/lontium-lt8912b.c

@@ -43,6 +43,8 @@ struct lt8912 {
 
 	struct videomode mode;
 
+	struct regulator_bulk_data supplies[7];
+
 	u8 data_lanes;
 	bool is_power_on;
 };
@@ -257,6 +259,12 @@ static int lt8912_free_i2c(struct lt8912 *lt)
 
 static int lt8912_hard_power_on(struct lt8912 *lt)
 {
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(lt->supplies), lt->supplies);
+	if (ret)
+		return ret;
+
 	gpiod_set_value_cansleep(lt->gp_reset, 0);
 	msleep(20);
 
@@ -267,6 +275,9 @@ static void lt8912_hard_power_off(struct lt8912 *lt)
 {
 	gpiod_set_value_cansleep(lt->gp_reset, 1);
 	msleep(20);
+
+	regulator_bulk_disable(ARRAY_SIZE(lt->supplies), lt->supplies);
+
 	lt->is_power_on = false;
 }
 
@@ -661,6 +672,21 @@ static int lt8912_bridge_suspend(struct device *dev)
 
 static DEFINE_SIMPLE_DEV_PM_OPS(lt8912_bridge_pm_ops, lt8912_bridge_suspend, lt8912_bridge_resume);
 
+static int lt8912_get_regulators(struct lt8912 *lt)
+{
+	unsigned int i;
+	const char * const supply_names[] = {
+		"vdd", "vccmipirx", "vccsysclk", "vcclvdstx",
+		"vcchdmitx", "vcclvdspll", "vcchdmipll"
+	};
+
+	for (i = 0; i < ARRAY_SIZE(lt->supplies); i++)
+		lt->supplies[i].supply = supply_names[i];
+
+	return devm_regulator_bulk_get(lt->dev, ARRAY_SIZE(lt->supplies),
+				       lt->supplies);
+}
+
 static int lt8912_parse_dt(struct lt8912 *lt)
 {
 	struct gpio_desc *gp_reset;
@@ -712,6 +738,10 @@ static int lt8912_parse_dt(struct lt8912 *lt)
 		goto err_free_host_node;
 	}
 
+	ret = lt8912_get_regulators(lt);
+	if (ret)
+		goto err_free_host_node;
+
 	of_node_put(port_node);
 	return 0;