video: bridge: add transparent LVDS de/encoder bridge

Add a simple and transparent LVDS de/encoder driver with a powerdown
gpio and a power supply.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/video/bridge/Kconfig

@@ -59,3 +59,10 @@ config VIDEO_BRIDGE_TOSHIBA_TC358768
 	help
 	  Toshiba TC358768AXBG/TC358778XBG DSI bridge chip driver.
 	  Found in Asus Transformer Infinity TF700T.
+
+config VIDEO_BRIDGE_LVDS_CODEC
+	bool "Transparent LVDS encoders and decoders support"
+	depends on VIDEO_BRIDGE && PANEL && DM_GPIO
+	help
+	  Support for transparent LVDS encoders and decoders that don't
+	  require any configuration.

drivers/video/bridge/Makefile

@@ -10,3 +10,4 @@ obj-$(CONFIG_VIDEO_BRIDGE_NXP_PTN3460) += ptn3460.o
 obj-$(CONFIG_VIDEO_BRIDGE_ANALOGIX_ANX6345) += anx6345.o
 obj-$(CONFIG_VIDEO_BRIDGE_SOLOMON_SSD2825) += ssd2825.o
 obj-$(CONFIG_VIDEO_BRIDGE_TOSHIBA_TC358768) += tc358768.o
+obj-$(CONFIG_VIDEO_BRIDGE_LVDS_CODEC) += lvds-codec.o

drivers/video/bridge/lvds-codec.c

@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2025 Svyatoslav Ryhel <clamor95@gmail.com>
+ * Loosely based on Linux lvds-codec.c driver
+ */
+
+#include <dm.h>
+#include <dm/ofnode_graph.h>
+#include <log.h>
+#include <panel.h>
+#include <video_bridge.h>
+#include <asm/gpio.h>
+#include <power/regulator.h>
+
+struct lvds_codec_priv {
+	struct udevice *panel;
+	struct display_timing timing;
+
+	struct gpio_desc powerdown_gpio;
+	struct udevice *power;
+};
+
+static int lvds_codec_attach(struct udevice *dev)
+{
+	struct lvds_codec_priv *priv = dev_get_priv(dev);
+
+	regulator_set_enable_if_allowed(priv->power, 1);
+	dm_gpio_set_value(&priv->powerdown_gpio, 0);
+
+	return panel_enable_backlight(priv->panel);
+}
+
+static int lvds_codec_set_panel(struct udevice *dev, int percent)
+{
+	struct lvds_codec_priv *priv = dev_get_priv(dev);
+
+	return panel_set_backlight(priv->panel, percent);
+}
+
+static int lvds_codec_panel_timings(struct udevice *dev,
+				    struct display_timing *timing)
+{
+	struct lvds_codec_priv *priv = dev_get_priv(dev);
+
+	memcpy(timing, &priv->timing, sizeof(*timing));
+
+	return 0;
+}
+
+/* Function is purely for sandbox testing */
+static int lvds_codec_read_edid(struct udevice *dev, u8 *buf, int buf_size)
+{
+	return 0;
+}
+
+static int lvds_codec_get_panel(struct udevice *dev)
+{
+	struct lvds_codec_priv *priv = dev_get_priv(dev);
+	int i, ret;
+
+	u32 num = ofnode_graph_get_port_count(dev_ofnode(dev));
+
+	for (i = 0; i < num; i++) {
+		ofnode remote = ofnode_graph_get_remote_node(dev_ofnode(dev), i, -1);
+
+		ret = uclass_get_device_by_of_offset(UCLASS_PANEL,
+						     ofnode_to_offset(remote),
+						     &priv->panel);
+		if (!ret)
+			return 0;
+	}
+
+	/* If this point is reached, no panels were found */
+	return -ENODEV;
+}
+
+static int lvds_codec_probe(struct udevice *dev)
+{
+	struct lvds_codec_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = lvds_codec_get_panel(dev);
+	if (ret) {
+		log_debug("%s: cannot get panel: ret=%d\n", __func__, ret);
+		return log_ret(ret);
+	}
+
+	panel_get_display_timing(priv->panel, &priv->timing);
+
+	ret = gpio_request_by_name(dev, "powerdown-gpios", 0,
+				   &priv->powerdown_gpio, GPIOD_IS_OUT);
+	if (ret) {
+		log_debug("%s: could not get powerdown-gpios (%d)\n", __func__, ret);
+		if (ret != -ENOENT)
+			return log_ret(ret);
+	}
+
+	ret = device_get_supply_regulator(dev, "power-supply", &priv->power);
+	if (ret) {
+		log_debug("%s: power regulator error: %d\n", __func__, ret);
+		if (ret != -ENOENT)
+			return log_ret(ret);
+	}
+
+	return 0;
+}
+
+static const struct video_bridge_ops lvds_codec_ops = {
+	.attach			= lvds_codec_attach,
+	.set_backlight		= lvds_codec_set_panel,
+	.get_display_timing	= lvds_codec_panel_timings,
+	.read_edid		= lvds_codec_read_edid,
+};
+
+static const struct udevice_id lvds_codec_ids[] = {
+	{ .compatible = "lvds-decoder" },
+	{ .compatible = "lvds-encoder" },
+	{ }
+};
+
+U_BOOT_DRIVER(lvds_codec) = {
+	.name		= "lvds_codec",
+	.id		= UCLASS_VIDEO_BRIDGE,
+	.of_match	= lvds_codec_ids,
+	.ops		= &lvds_codec_ops,
+	.probe		= lvds_codec_probe,
+	.priv_auto	= sizeof(struct lvds_codec_priv),
+};