From b8571e232108dfd57e04a3b24536404a34802c73 Mon Sep 17 00:00:00 2001
From: Guochun Huang <hero.huang@rock-chips.com>
Date: Wed, 15 Dec 2021 02:40:54 +0000
Subject: [PATCH] drm/panel: simple: Add support for dcs backlight

Signed-off-by: Guochun Huang <hero.huang@rock-chips.com>
Change-Id: Id9380a16c1db606f30032259a3bbba0884731c97
---
 drivers/gpu/drm/panel/panel-simple.c | 66 ++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 5a87800e1766..d8acc4d660fd 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -728,6 +728,52 @@ static void panel_simple_parse_panel_timing_node(struct device *dev,
 		dev_err(dev, "Reject override mode: No display_timing found\n");
 }
 
+static int dcs_bl_update_status(struct backlight_device *bl)
+{
+	struct panel_simple *p = bl_get_data(bl);
+	struct mipi_dsi_device *dsi = p->dsi;
+	int ret;
+
+	if (!p->prepared)
+		return 0;
+
+	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, bl->props.brightness);
+	if (ret < 0)
+		return ret;
+
+	dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+	return 0;
+}
+
+static int dcs_bl_get_brightness(struct backlight_device *bl)
+{
+	struct panel_simple *p = bl_get_data(bl);
+	struct mipi_dsi_device *dsi = p->dsi;
+	u16 brightness = bl->props.brightness;
+	int ret;
+
+	if (!p->prepared)
+		return 0;
+
+	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness);
+	if (ret < 0)
+		return ret;
+
+	dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+	return brightness & 0xff;
+}
+
+static const struct backlight_ops dcs_bl_ops = {
+	.update_status = dcs_bl_update_status,
+	.get_brightness = dcs_bl_get_brightness,
+};
+
 static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 {
 	struct panel_simple *panel;
@@ -4994,6 +5040,26 @@ static int panel_simple_dsi_probe(struct mipi_dsi_device *dsi)
 	panel = dev_get_drvdata(dev);
 	panel->dsi = dsi;
 
+	if (!panel->base.backlight) {
+		struct backlight_properties props;
+
+		memset(&props, 0, sizeof(props));
+		props.type = BACKLIGHT_RAW;
+		props.brightness = 255;
+		props.max_brightness = 255;
+
+		panel->base.backlight =
+			devm_backlight_device_register(dev, "dcs-backlight",
+						       dev, panel, &dcs_bl_ops,
+						       &props);
+		if (IS_ERR(panel->base.backlight)) {
+			err = PTR_ERR(panel->base.backlight);
+			dev_err(dev, "failed to register dcs backlight: %d\n",
+				err);
+			return err;
+		}
+	}
+
 	dsi->mode_flags = desc->flags;
 	dsi->format = desc->format;
 	dsi->lanes = desc->lanes;