drm: panel: add support for Synaptics TDDI series DSI panels

Synaptics TDDI (Touch/Display Integration) panels utilize a single chip
for display and touch controllers. Implement a simple device driver for
such panels, along with its built-in LED backlight controller, and add
support for TD4101 and TD4300 panels in the driver.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20251009-panel-synaptics-tddi-v5-2-59390997644e@disroot.org

drivers/gpu/drm/panel/Kconfig

@@ -1073,6 +1073,17 @@ config DRM_PANEL_SYNAPTICS_R63353
 	  Say Y if you want to enable support for panels based on the
 	  Synaptics R63353 controller.
 
+config DRM_PANEL_SYNAPTICS_TDDI
+	tristate "Synaptics TDDI display panels"
+	depends on OF
+	depends on DRM_MIPI_DSI
+	depends on BACKLIGHT_CLASS_DEVICE
+	help
+	  Say Y if you want to enable support for the Synaptics TDDI display
+	  panels. There are multiple MIPI DSI panels manufactured under the TDDI
+	  namesake, with varying resolutions and data lanes. They also have a
+	  built-in LED backlight and a touch controller.
+
 config DRM_PANEL_TDO_TL070WSH30
 	tristate "TDO TL070WSH30 DSI panel"
 	depends on OF

drivers/gpu/drm/panel/Makefile

@@ -102,6 +102,7 @@ obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7703) += panel-sitronix-st7703.o
 obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7789V) += panel-sitronix-st7789v.o
 obj-$(CONFIG_DRM_PANEL_SUMMIT) += panel-summit.o
 obj-$(CONFIG_DRM_PANEL_SYNAPTICS_R63353) += panel-synaptics-r63353.o
+obj-$(CONFIG_DRM_PANEL_SYNAPTICS_TDDI) += panel-synaptics-tddi.o
 obj-$(CONFIG_DRM_PANEL_SONY_ACX565AKM) += panel-sony-acx565akm.o
 obj-$(CONFIG_DRM_PANEL_SONY_TD4353_JDI) += panel-sony-td4353-jdi.o
 obj-$(CONFIG_DRM_PANEL_SONY_TULIP_TRULY_NT35521) += panel-sony-tulip-truly-nt35521.o

drivers/gpu/drm/panel/panel-synaptics-tddi.c

@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Synaptics TDDI display panel driver.
+ *
+ * Copyright (C) 2025 Kaustabh Chakraborty <kauschluss@disroot.org>
+ */
+
+#include <linux/backlight.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+#include <video/mipi_display.h>
+
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_panel.h>
+#include <drm/drm_probe_helper.h>
+
+struct tddi_panel_data {
+	u8 lanes;
+	/* wait timings for panel enable */
+	u8 delay_ms_sleep_exit;
+	u8 delay_ms_display_on;
+	/* wait timings for panel disable */
+	u8 delay_ms_display_off;
+	u8 delay_ms_sleep_enter;
+};
+
+struct tddi_ctx {
+	struct drm_panel panel;
+	struct mipi_dsi_device *dsi;
+	struct drm_display_mode mode;
+	struct backlight_device *backlight;
+	const struct tddi_panel_data *data;
+	struct regulator_bulk_data *supplies;
+	struct gpio_desc *reset_gpio;
+	struct gpio_desc *backlight_gpio;
+};
+
+static const struct regulator_bulk_data tddi_supplies[] = {
+	{ .supply = "vio" },
+	{ .supply = "vsn" },
+	{ .supply = "vsp" },
+};
+
+static inline struct tddi_ctx *to_tddi_ctx(struct drm_panel *panel)
+{
+	return container_of(panel, struct tddi_ctx, panel);
+}
+
+static int tddi_update_status(struct backlight_device *backlight)
+{
+	struct tddi_ctx *ctx = bl_get_data(backlight);
+	struct mipi_dsi_multi_context dsi = { .dsi = ctx->dsi };
+	u8 brightness = backlight_get_brightness(backlight);
+
+	if (!ctx->panel.enabled)
+		return 0;
+
+	mipi_dsi_dcs_set_display_brightness_multi(&dsi, brightness);
+
+	return dsi.accum_err;
+}
+
+static int tddi_prepare(struct drm_panel *panel)
+{
+	struct tddi_ctx *ctx = to_tddi_ctx(panel);
+	struct device *dev = &ctx->dsi->dev;
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(tddi_supplies), ctx->supplies);
+	if (ret < 0) {
+		dev_err(dev, "failed to enable regulators: %d\n", ret);
+		return ret;
+	}
+
+	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
+	usleep_range(5000, 6000);
+	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+	usleep_range(5000, 6000);
+	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
+	usleep_range(10000, 11000);
+
+	gpiod_set_value_cansleep(ctx->backlight_gpio, 0);
+	usleep_range(5000, 6000);
+
+	return 0;
+}
+
+static int tddi_unprepare(struct drm_panel *panel)
+{
+	struct tddi_ctx *ctx = to_tddi_ctx(panel);
+
+	gpiod_set_value_cansleep(ctx->backlight_gpio, 1);
+	usleep_range(5000, 6000);
+
+	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+	usleep_range(5000, 6000);
+
+	regulator_bulk_disable(ARRAY_SIZE(tddi_supplies), ctx->supplies);
+
+	return 0;
+}
+
+static int tddi_enable(struct drm_panel *panel)
+{
+	struct tddi_ctx *ctx = to_tddi_ctx(panel);
+	struct mipi_dsi_multi_context dsi = { .dsi = ctx->dsi };
+	u8 brightness = ctx->backlight->props.brightness;
+
+	mipi_dsi_dcs_write_seq_multi(&dsi, MIPI_DCS_WRITE_POWER_SAVE, 0x00);
+	mipi_dsi_dcs_write_seq_multi(&dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY, 0x0c);
+
+	mipi_dsi_dcs_exit_sleep_mode_multi(&dsi);
+	mipi_dsi_msleep(&dsi, ctx->data->delay_ms_sleep_exit);
+
+	/* sync the panel with the backlight's brightness level */
+	mipi_dsi_dcs_set_display_brightness_multi(&dsi, brightness);
+
+	mipi_dsi_dcs_set_display_on_multi(&dsi);
+	mipi_dsi_msleep(&dsi, ctx->data->delay_ms_display_on);
+
+	return dsi.accum_err;
+};
+
+static int tddi_disable(struct drm_panel *panel)
+{
+	struct tddi_ctx *ctx = to_tddi_ctx(panel);
+	struct mipi_dsi_multi_context dsi = { .dsi = ctx->dsi };
+
+	mipi_dsi_dcs_set_display_off_multi(&dsi);
+	mipi_dsi_msleep(&dsi, ctx->data->delay_ms_display_off);
+
+	mipi_dsi_dcs_enter_sleep_mode_multi(&dsi);
+	mipi_dsi_msleep(&dsi, ctx->data->delay_ms_sleep_enter);
+
+	return dsi.accum_err;
+}
+
+static int tddi_get_modes(struct drm_panel *panel,
+			  struct drm_connector *connector)
+{
+	struct tddi_ctx *ctx = to_tddi_ctx(panel);
+
+	return drm_connector_helper_get_modes_fixed(connector, &ctx->mode);
+}
+
+static const struct backlight_ops tddi_bl_ops = {
+	.update_status = tddi_update_status,
+};
+
+static const struct backlight_properties tddi_bl_props = {
+	.type = BACKLIGHT_PLATFORM,
+	.brightness = 255,
+	.max_brightness = 255,
+};
+
+static const struct drm_panel_funcs tddi_drm_panel_funcs = {
+	.prepare = tddi_prepare,
+	.unprepare = tddi_unprepare,
+	.enable = tddi_enable,
+	.disable = tddi_disable,
+	.get_modes = tddi_get_modes,
+};
+
+static int tddi_probe(struct mipi_dsi_device *dsi)
+{
+	struct device *dev = &dsi->dev;
+	struct tddi_ctx *ctx;
+	int ret;
+
+	ctx = devm_drm_panel_alloc(dev, struct tddi_ctx, panel,
+				   &tddi_drm_panel_funcs, DRM_MODE_CONNECTOR_DSI);
+	if (IS_ERR(ctx))
+		return PTR_ERR(ctx);
+
+	ctx->data = of_device_get_match_data(dev);
+
+	ctx->dsi = dsi;
+	mipi_dsi_set_drvdata(dsi, ctx);
+
+	ret = devm_regulator_bulk_get_const(dev, ARRAY_SIZE(tddi_supplies),
+					    tddi_supplies, &ctx->supplies);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "failed to get regulators\n");
+
+	ctx->backlight_gpio = devm_gpiod_get_optional(dev, "backlight", GPIOD_ASIS);
+	if (IS_ERR(ctx->backlight_gpio))
+		return dev_err_probe(dev, PTR_ERR(ctx->backlight_gpio),
+				     "failed to get backlight-gpios\n");
+
+	ctx->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_ASIS);
+	if (IS_ERR(ctx->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(ctx->reset_gpio),
+				     "failed to get reset-gpios\n");
+
+	ret = of_get_drm_panel_display_mode(dev->of_node, &ctx->mode, NULL);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "failed to get panel timings\n");
+
+	ctx->backlight = devm_backlight_device_register(dev, dev_name(dev), dev,
+							ctx, &tddi_bl_ops,
+							&tddi_bl_props);
+	if (IS_ERR(ctx->backlight))
+		return dev_err_probe(dev, PTR_ERR(ctx->backlight),
+				     "failed to register backlight device");
+
+	dsi->lanes = ctx->data->lanes;
+	dsi->format = MIPI_DSI_FMT_RGB888;
+	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
+			  MIPI_DSI_MODE_VIDEO_NO_HFP;
+
+	ctx->panel.prepare_prev_first = true;
+	drm_panel_add(&ctx->panel);
+
+	ret = devm_mipi_dsi_attach(dev, dsi);
+	if (ret < 0) {
+		drm_panel_remove(&ctx->panel);
+		return dev_err_probe(dev, ret, "failed to attach to DSI host\n");
+	}
+
+	return 0;
+}
+
+static void tddi_remove(struct mipi_dsi_device *dsi)
+{
+	struct tddi_ctx *ctx = mipi_dsi_get_drvdata(dsi);
+
+	drm_panel_remove(&ctx->panel);
+}
+
+static const struct tddi_panel_data td4101_panel_data = {
+	.lanes = 2,
+	/* wait timings for panel enable */
+	.delay_ms_sleep_exit = 100,
+	.delay_ms_display_on = 0,
+	/* wait timings for panel disable */
+	.delay_ms_display_off = 20,
+	.delay_ms_sleep_enter = 90,
+};
+
+static const struct tddi_panel_data td4300_panel_data = {
+	.lanes = 4,
+	/* wait timings for panel enable */
+	.delay_ms_sleep_exit = 100,
+	.delay_ms_display_on = 0,
+	/* wait timings for panel disable */
+	.delay_ms_display_off = 0,
+	.delay_ms_sleep_enter = 0,
+};
+
+static const struct of_device_id tddi_of_device_id[] = {
+	{
+		.compatible = "syna,td4101-panel",
+		.data = &td4101_panel_data,
+	}, {
+		.compatible = "syna,td4300-panel",
+		.data = &td4300_panel_data,
+	}, { }
+};
+MODULE_DEVICE_TABLE(of, tddi_of_device_id);
+
+static struct mipi_dsi_driver tddi_dsi_driver = {
+	.probe = tddi_probe,
+	.remove = tddi_remove,
+	.driver = {
+		.name = "panel-synaptics-tddi",
+		.of_match_table = tddi_of_device_id,
+	},
+};
+module_mipi_dsi_driver(tddi_dsi_driver);
+
+MODULE_AUTHOR("Kaustabh Chakraborty <kauschluss@disroot.org>");
+MODULE_DESCRIPTION("Synaptics TDDI Display Panel Driver");
+MODULE_LICENSE("GPL");