drm/bridge: tc358762: Add reset GPIO support

Add reset GPIO support. The reset GPIO is cleared after supply regulator
was enabled, and set before supply regulator is disabled.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230530192805.648646-2-marex@denx.de

drivers/gpu/drm/bridge/tc358762.c

@@ -11,6 +11,7 @@
  */
 
 #include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/of_graph.h>
@@ -63,6 +64,7 @@ struct tc358762 {
 	struct drm_bridge bridge;
 	struct regulator *regulator;
 	struct drm_bridge *panel_bridge;
+	struct gpio_desc *reset_gpio;
 	bool pre_enabled;
 	int error;
 };
@@ -138,6 +140,9 @@ static void tc358762_post_disable(struct drm_bridge *bridge)
 
 	ctx->pre_enabled = false;
 
+	if (ctx->reset_gpio)
+		gpiod_set_value_cansleep(ctx->reset_gpio, 0);
+
 	ret = regulator_disable(ctx->regulator);
 	if (ret < 0)
 		dev_err(ctx->dev, "error disabling regulators (%d)\n", ret);
@@ -152,6 +157,11 @@ static void tc358762_pre_enable(struct drm_bridge *bridge)
 	if (ret < 0)
 		dev_err(ctx->dev, "error enabling regulators (%d)\n", ret);
 
+	if (ctx->reset_gpio) {
+		gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+		usleep_range(5000, 10000);
+	}
+
 	ret = tc358762_init(ctx);
 	if (ret < 0)
 		dev_err(ctx->dev, "error initializing bridge (%d)\n", ret);
@@ -185,6 +195,11 @@ static int tc358762_parse_dt(struct tc358762 *ctx)
 
 	ctx->panel_bridge = panel_bridge;
 
+	/* Reset GPIO is optional */
+	ctx->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(ctx->reset_gpio))
+		return PTR_ERR(ctx->reset_gpio);
+
 	return 0;
 }