[DPU PATCH 2/2] drm/panel: add backlight control support for truly panel

[Abhinav Kumar]

Register truly panel as a backlight led device and
provide methods to control its backlight operation.

Signed-off-by: Abhinav Kumar <abhinavk at codeaurora.org>
---
 drivers/gpu/drm/panel/panel-truly-dual-dsi.c | 96 +++++++++++++++++++++++++++-
 1 file changed, 94 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-truly-dual-dsi.c b/drivers/gpu/drm/panel/panel-truly-dual-dsi.c
index 47891ee..5d0ef90 100644
--- a/drivers/gpu/drm/panel/panel-truly-dual-dsi.c
+++ b/drivers/gpu/drm/panel/panel-truly-dual-dsi.c
@@ -14,6 +14,7 @@
 #include <linux/gpio/consumer.h>
 #include <linux/regulator/consumer.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/leds.h>
 
 #include <video/mipi_display.h>
 #include <video/of_videomode.h>
@@ -23,6 +24,9 @@
 #include <drm/drm_panel.h>
 #include <drm/drm_mipi_dsi.h>
 
+#define BL_NODE_NAME_SIZE 32
+#define PRIM_DISPLAY_NODE 0
+
 struct truly_wqxga {
 	struct device *dev;
 	struct drm_panel panel;
@@ -33,6 +37,8 @@ struct truly_wqxga {
 	struct gpio_desc *mode_gpio;
 
 	struct backlight_device *backlight;
+	/* WLED params */
+	struct led_trigger *wled;
 	struct videomode vm;
 
 	struct mipi_dsi_device *dsi[2];
@@ -447,6 +453,83 @@ static void truly_wqxga_panel_del(struct truly_wqxga *ctx)
 		put_device(&ctx->dsi[1]->dev);
 }
 
+static int truly_backlight_device_update_status(struct backlight_device *bd)
+{
+	int brightness;
+	int max_brightness;
+	int rc = 0;
+
+	struct truly_wqxga *ctx = dev_get_drvdata(&bd->dev);
+
+	brightness = bd->props.brightness;
+	max_brightness = bd->props.max_brightness;
+
+	if ((bd->props.power != FB_BLANK_UNBLANK) ||
+		(bd->props.state & BL_CORE_FBBLANK) ||
+		  (bd->props.state & BL_CORE_SUSPENDED))
+		brightness = 0;
+
+	if (brightness > max_brightness)
+		brightness = max_brightness;
+
+	/* Need to check WLED driver capability upstream */
+	if (ctx && ctx->wled)
+		led_trigger_event(ctx->wled, brightness);
+
+	return rc;
+}
+
+static int truly_backlight_device_get_brightness(struct backlight_device *bd)
+{
+	return bd->props.brightness;
+}
+
+static const struct backlight_ops truly_backlight_device_ops = {
+	.update_status = truly_backlight_device_update_status,
+	.get_brightness = truly_backlight_device_get_brightness,
+};
+
+static int truly_backlight_setup(struct truly_wqxga *ctx)
+{
+	struct backlight_properties props;
+	char bl_node_name[BL_NODE_NAME_SIZE];
+
+	if (!ctx) {
+		dev_err(ctx->dev, "invalid context\n");
+		return -EINVAL;
+	}
+
+	if (!ctx->backlight) {
+		memset(&props, 0, sizeof(props));
+		props.type = BACKLIGHT_RAW;
+		props.power = FB_BLANK_UNBLANK;
+		props.max_brightness = 4096;
+
+		snprintf(bl_node_name, BL_NODE_NAME_SIZE, "panel%u-backlight",
+				 PRIM_DISPLAY_NODE);
+
+		ctx->backlight =  backlight_device_register(bl_node_name,
+				ctx->dev, ctx,
+				&truly_backlight_device_ops, &props);
+
+		if (IS_ERR_OR_NULL(ctx->backlight)) {
+			pr_err("Failed to register backlight\n");
+			ctx->backlight = NULL;
+			return -ENODEV;
+		}
+
+		/* Register with the LED driver interface */
+		led_trigger_register_simple("bkl-trigger", &ctx->wled);
+
+		if (!ctx->wled) {
+			pr_err("backlight led registration failed\n");
+			return -ENODEV;
+		}
+	}
+
+	return 0;
+}
+
 static int truly_wqxga_probe(struct mipi_dsi_device *dsi)
 {
 	struct device *dev = &dsi->dev;
@@ -466,10 +549,11 @@ static int truly_wqxga_probe(struct mipi_dsi_device *dsi)
 		secondary = of_find_mipi_dsi_device_by_node(np);
 		of_node_put(np);
 
+		ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
+
 		if (!secondary)
 			return -EPROBE_DEFER;
 
-		ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 		if (!ctx) {
 			put_device(&secondary->dev);
 			return -ENOMEM;
@@ -485,6 +569,12 @@ static int truly_wqxga_probe(struct mipi_dsi_device *dsi)
 			put_device(&secondary->dev);
 			return ret;
 		}
+
+		ret = truly_backlight_setup(ctx);
+		if (ret) {
+			put_device(&secondary->dev);
+			return ret;
+		}
 	}
 
 	ret = mipi_dsi_attach(dsi);
@@ -504,8 +594,10 @@ static int truly_wqxga_remove(struct mipi_dsi_device *dsi)
 	mipi_dsi_detach(dsi);
 
 	/* delete panel only for the DSI1 interface */
-	if (ctx)
+	if (ctx) {
 		truly_wqxga_panel_del(ctx);
+		kfree(ctx);
+	}
 
 	return 0;
 }
-- 
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