From 53b8aaf03b57d96ecb53c27e29916a528cff5514 Mon Sep 17 00:00:00 2001
From: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Date: Fri, 21 Dec 2018 13:26:55 +0100
Subject: drm: panel: Add DTS configurable panel driver.

This driver is derived from the panel-simple driver, but instead of
hard-coded profiles in the source code, it works based on information
found in the DTB.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
---
 drivers/gpu/drm/panel/Kconfig        |  11 +
 drivers/gpu/drm/panel/Makefile       |   1 +
 drivers/gpu/drm/panel/simple-panel.c | 970 +++++++++++++++++++++++++++++++++++
 3 files changed, 982 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/simple-panel.c

diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 6020c30a33b3..d6e2f54799fb 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -38,6 +38,17 @@ config DRM_PANEL_SIMPLE
 	  that it can be automatically turned off when the panel goes into a
 	  low power state.
 
+config DRM_SIMPLE_PANEL
+	tristate "support for simple panels configured via DTS"
+	depends on OF
+	depends on BACKLIGHT_CLASS_DEVICE
+	select VIDEOMODE_HELPERS
+	help
+	  DRM panel driver for dumb panels that need at most a regulator and
+	  a GPIO to be powered up. Optionally a backlight can be attached so
+	  that it can be automatically turned off when the panel goes into a
+	  low power state. Panel configuration can be achieved by DTS nodes.
+
 config DRM_PANEL_ILITEK_IL9322
 	tristate "Ilitek ILI9322 320x240 QVGA panels"
 	depends on OF && SPI
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index 5ccaaa9d13af..1ce143e8ccd9 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -2,6 +2,7 @@
 obj-$(CONFIG_DRM_PANEL_ARM_VERSATILE) += panel-arm-versatile.o
 obj-$(CONFIG_DRM_PANEL_LVDS) += panel-lvds.o
 obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o
+obj-$(CONFIG_DRM_SIMPLE_PANEL) += simple-panel.o
 obj-$(CONFIG_DRM_PANEL_ILITEK_IL9322) += panel-ilitek-ili9322.o
 obj-$(CONFIG_DRM_PANEL_ILITEK_ILI9881C) += panel-ilitek-ili9881c.o
 obj-$(CONFIG_DRM_PANEL_INNOLUX_P079ZCA) += panel-innolux-p079zca.o
diff --git a/drivers/gpu/drm/panel/simple-panel.c b/drivers/gpu/drm/panel/simple-panel.c
new file mode 100644
index 000000000000..0f1eb6df487e
--- /dev/null
+++ b/drivers/gpu/drm/panel/simple-panel.c
@@ -0,0 +1,970 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018 Theobroma Systems Design und Consulting GmbH
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sub license,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <linux/backlight.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+#include <drm/drmP.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_panel.h>
+
+#include <video/display_timing.h>
+#include <video/mipi_display.h>
+#include <linux/of_device.h>
+#include <video/of_display_timing.h>
+#include <video/videomode.h>
+
+struct cmd_ctrl_hdr {
+	u8 dtype;	/* data type */
+	u8 wait;	/* ms */
+	u8 dlen;	/* payload len */
+} __packed;
+
+struct cmd_desc {
+	struct cmd_ctrl_hdr dchdr;
+	u8 *payload;
+};
+
+struct panel_cmds {
+	u8 *buf;
+	int blen;
+	struct cmd_desc *cmds;
+	int cmd_cnt;
+};
+
+struct panel_desc {
+	const struct drm_display_mode *modes;
+	unsigned int num_modes;
+	const struct display_timing *timings;
+	unsigned int num_timings;
+
+	unsigned int bpc;
+
+	/**
+	 * @width: width (in millimeters) of the panel's active display area
+	 * @height: height (in millimeters) of the panel's active display area
+	 */
+	struct {
+		unsigned int width;
+		unsigned int height;
+	} size;
+
+	/**
+	 * @reset: the time (in milliseconds) indicates the delay time
+	 *         after the panel to operate reset gpio
+	 * @init: the time (in milliseconds) that it takes for the panel to
+	 *           power on and dsi host can send command to panel
+	 * @prepare: the time (in milliseconds) that it takes for the panel to
+	 *           become ready and start receiving video data
+	 * @enable: the time (in milliseconds) that it takes for the panel to
+	 *          display the first valid frame after starting to receive
+	 *          video data
+	 * @disable: the time (in milliseconds) that it takes for the panel to
+	 *           turn the display off (no content is visible)
+	 * @unprepare: the time (in milliseconds) that it takes for the panel
+	 *             to power itself down completely
+	 */
+	struct {
+		unsigned int reset;
+		unsigned int init;
+		unsigned int prepare;
+		unsigned int enable;
+		unsigned int disable;
+		unsigned int unprepare;
+	} delay;
+
+	u32 bus_format;
+	u32 bus_flags;
+};
+
+struct panel_simple {
+	struct drm_panel base;
+	struct mipi_dsi_device *dsi;
+	bool prepared;
+	bool enabled;
+	bool power_invert;
+
+	struct device *dev;
+	const struct panel_desc *desc;
+
+	struct backlight_device *backlight;
+	struct regulator *supply;
+	struct i2c_adapter *ddc;
+
+	struct gpio_desc *enable_gpio;
+	struct gpio_desc *reset_gpio;
+	int cmd_type;
+
+	struct gpio_desc *spi_sdi_gpio;
+	struct gpio_desc *spi_scl_gpio;
+	struct gpio_desc *spi_cs_gpio;
+
+	struct panel_cmds *on_cmds;
+	struct panel_cmds *off_cmds;
+};
+
+enum rockchip_cmd_type {
+	CMD_TYPE_DEFAULT,
+	CMD_TYPE_SPI,
+	CMD_TYPE_MCU
+};
+
+static inline int get_panel_cmd_type(const char *s)
+{
+	if (!s)
+		return -EINVAL;
+
+	if (strncmp(s, "spi", 3) == 0)
+		return CMD_TYPE_SPI;
+	else if (strncmp(s, "mcu", 3) == 0)
+		return CMD_TYPE_MCU;
+
+	return CMD_TYPE_DEFAULT;
+}
+
+static inline struct panel_simple *to_panel_simple(struct drm_panel *panel)
+{
+	return container_of(panel, struct panel_simple, base);
+}
+
+static void panel_simple_cmds_cleanup(struct panel_simple *p)
+{
+	if (p->on_cmds) {
+		kfree(p->on_cmds->buf);
+		kfree(p->on_cmds->cmds);
+	}
+
+	if (p->off_cmds) {
+		kfree(p->off_cmds->buf);
+		kfree(p->off_cmds->cmds);
+	}
+}
+
+static int panel_simple_parse_cmds(struct device *dev,
+				   const u8 *data, int blen,
+				   struct panel_cmds *pcmds)
+{
+	int len;
+	char *buf, *bp;
+	struct cmd_ctrl_hdr *dchdr;
+	int i, cnt;
+
+	if (!pcmds)
+		return -EINVAL;
+
+	buf = kmemdup(data, blen, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/* scan init commands */
+	bp = buf;
+	len = blen;
+	cnt = 0;
+	while (len > sizeof(*dchdr)) {
+		dchdr = (struct cmd_ctrl_hdr *)bp;
+
+		if (dchdr->dlen > len) {
+			dev_err(dev, "%s: error, len=%d", __func__,
+				dchdr->dlen);
+			return -EINVAL;
+		}
+
+		bp += sizeof(*dchdr);
+		len -= sizeof(*dchdr);
+		bp += dchdr->dlen;
+		len -= dchdr->dlen;
+		cnt++;
+	}
+
+	if (len != 0) {
+		dev_err(dev, "%s: dcs_cmd=%x len=%d error!",
+			__func__, buf[0], blen);
+		kfree(buf);
+		return -EINVAL;
+	}
+
+	pcmds->cmds = kcalloc(cnt, sizeof(struct cmd_desc), GFP_KERNEL);
+	if (!pcmds->cmds) {
+		kfree(buf);
+		return -ENOMEM;
+	}
+
+	pcmds->cmd_cnt = cnt;
+	pcmds->buf = buf;
+	pcmds->blen = blen;
+
+	bp = buf;
+	len = blen;
+	for (i = 0; i < cnt; i++) {
+		dchdr = (struct cmd_ctrl_hdr *)bp;
+		len -= sizeof(*dchdr);
+		bp += sizeof(*dchdr);
+		pcmds->cmds[i].dchdr = *dchdr;
+		pcmds->cmds[i].payload = bp;
+		bp += dchdr->dlen;
+		len -= dchdr->dlen;
+	}
+
+	return 0;
+}
+
+static void panel_simple_spi_write_cmd(struct panel_simple *panel,
+				       u8 type, int value)
+{
+	int i;
+
+	gpiod_direction_output(panel->spi_cs_gpio, 0);
+
+	if (type == 0)
+		value &= (~(1 << 8));
+	else
+		value |= (1 << 8);
+
+	for (i = 0; i < 9; i++) {
+		if (value & 0x100)
+			gpiod_direction_output(panel->spi_sdi_gpio, 1);
+		else
+			gpiod_direction_output(panel->spi_sdi_gpio, 0);
+
+		gpiod_direction_output(panel->spi_scl_gpio, 0);
+		udelay(10);
+		gpiod_direction_output(panel->spi_scl_gpio, 1);
+		value <<= 1;
+		udelay(10);
+	}
+
+	gpiod_direction_output(panel->spi_cs_gpio, 1);
+}
+
+static int panel_simple_spi_send_cmds(struct panel_simple *panel,
+				      struct panel_cmds *cmds)
+{
+	int i;
+
+	if (!cmds)
+		return -EINVAL;
+
+	for (i = 0; i < cmds->cmd_cnt; i++) {
+		struct cmd_desc *cmd = &cmds->cmds[i];
+		int value = 0;
+
+		if (cmd->dchdr.dlen == 2)
+			value = (cmd->payload[0] << 8) | cmd->payload[1];
+		else
+			value = cmd->payload[0];
+		panel_simple_spi_write_cmd(panel, cmd->dchdr.dtype, value);
+
+		if (cmd->dchdr.wait)
+			msleep(cmd->dchdr.wait);
+	}
+
+	return 0;
+}
+
+#if IS_ENABLED(CONFIG_DRM_MIPI_DSI)
+static int panel_simple_dsi_send_cmds(struct panel_simple *panel,
+				      struct panel_cmds *cmds)
+{
+	struct mipi_dsi_device *dsi = panel->dsi;
+	int i, err;
+
+	if (!cmds)
+		return -EINVAL;
+
+	for (i = 0; i < cmds->cmd_cnt; i++) {
+		struct cmd_desc *cmd = &cmds->cmds[i];
+
+		switch (cmd->dchdr.dtype) {
+		case MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM:
+		case MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM:
+		case MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM:
+		case MIPI_DSI_GENERIC_LONG_WRITE:
+			err = mipi_dsi_generic_write(dsi, cmd->payload,
+						     cmd->dchdr.dlen);
+			break;
+		case MIPI_DSI_DCS_SHORT_WRITE:
+		case MIPI_DSI_DCS_SHORT_WRITE_PARAM:
+		case MIPI_DSI_DCS_LONG_WRITE:
+			err = mipi_dsi_dcs_write_buffer(dsi, cmd->payload,
+							cmd->dchdr.dlen);
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		if (err < 0)
+			dev_err(panel->dev, "failed to write dcs cmd: %d\n",
+				err);
+
+		if (cmd->dchdr.wait)
+			msleep(cmd->dchdr.wait);
+	}
+
+	return 0;
+}
+#else
+static inline int panel_simple_dsi_send_cmds(struct panel_simple *panel,
+					     struct panel_cmds *cmds)
+{
+	return -EINVAL;
+}
+#endif
+
+static int panel_simple_get_cmds(struct panel_simple *panel)
+{
+	const void *data;
+	int len;
+	int err;
+
+	data = of_get_property(panel->dev->of_node, "panel-init-sequence",
+			       &len);
+	if (data) {
+		panel->on_cmds = devm_kzalloc(panel->dev,
+					      sizeof(*panel->on_cmds),
+					      GFP_KERNEL);
+		if (!panel->on_cmds)
+			return -ENOMEM;
+
+		err = panel_simple_parse_cmds(panel->dev, data, len,
+					      panel->on_cmds);
+		if (err) {
+			dev_err(panel->dev, "failed to parse panel init sequence\n");
+			return err;
+		}
+	}
+
+	data = of_get_property(panel->dev->of_node, "panel-exit-sequence",
+			       &len);
+	if (data) {
+		panel->off_cmds = devm_kzalloc(panel->dev,
+					       sizeof(*panel->off_cmds),
+					       GFP_KERNEL);
+		if (!panel->off_cmds)
+			return -ENOMEM;
+
+		err = panel_simple_parse_cmds(panel->dev, data, len,
+					      panel->off_cmds);
+		if (err) {
+			dev_err(panel->dev, "failed to parse panel exit sequence\n");
+			return err;
+		}
+	}
+	return 0;
+}
+
+static int panel_simple_get_fixed_modes(struct panel_simple *panel)
+{
+	struct drm_connector *connector = panel->base.connector;
+	struct drm_device *drm = panel->base.drm;
+	struct drm_display_mode *mode;
+	unsigned int i, num = 0;
+
+	if (!panel->desc)
+		return 0;
+
+	for (i = 0; i < panel->desc->num_timings; i++) {
+		const struct display_timing *dt = &panel->desc->timings[i];
+		struct videomode vm;
+
+		videomode_from_timing(dt, &vm);
+		mode = drm_mode_create(drm);
+		if (!mode) {
+			dev_err(drm->dev, "failed to add mode %ux%u\n",
+				dt->hactive.typ, dt->vactive.typ);
+			continue;
+		}
+
+		drm_display_mode_from_videomode(&vm, mode);
+		drm_mode_set_name(mode);
+
+		drm_mode_probed_add(connector, mode);
+		num++;
+	}
+
+	for (i = 0; i < panel->desc->num_modes; i++) {
+		const struct drm_display_mode *m = &panel->desc->modes[i];
+
+		mode = drm_mode_duplicate(drm, m);
+		if (!mode) {
+			dev_err(drm->dev, "failed to add mode %ux%u@%u\n",
+				m->hdisplay, m->vdisplay, m->vrefresh);
+			continue;
+		}
+
+		drm_mode_set_name(mode);
+
+		drm_mode_probed_add(connector, mode);
+		num++;
+	}
+
+	connector->display_info.bpc = panel->desc->bpc;
+	connector->display_info.width_mm = panel->desc->size.width;
+	connector->display_info.height_mm = panel->desc->size.height;
+	if (panel->desc->bus_format)
+		drm_display_info_set_bus_formats(&connector->display_info,
+						 &panel->desc->bus_format, 1);
+
+	return num;
+}
+
+static int panel_simple_of_get_native_mode(struct panel_simple *panel)
+{
+	struct drm_connector *connector = panel->base.connector;
+	struct drm_device *drm = panel->base.drm;
+	struct drm_display_mode *mode;
+	struct device_node *timings_np;
+	int ret;
+
+	timings_np = of_get_child_by_name(panel->dev->of_node,
+					  "display-timings");
+	if (!timings_np) {
+		dev_dbg(panel->dev, "failed to find display-timings node\n");
+		return 0;
+	}
+
+	of_node_put(timings_np);
+	mode = drm_mode_create(drm);
+	if (!mode)
+		return 0;
+
+	ret = of_get_drm_display_mode(panel->dev->of_node, mode,
+				      NULL, OF_USE_NATIVE_MODE);
+	if (ret) {
+		dev_dbg(panel->dev, "failed to find dts display timings\n");
+		drm_mode_destroy(drm, mode);
+		return 0;
+	}
+
+	drm_mode_set_name(mode);
+	mode->type |= DRM_MODE_TYPE_PREFERRED;
+	drm_mode_probed_add(connector, mode);
+
+	return 1;
+}
+
+static int panel_simple_regulator_enable(struct drm_panel *panel)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+	int err = 0;
+
+	if (p->power_invert) {
+		if (regulator_is_enabled(p->supply) > 0)
+			regulator_disable(p->supply);
+	} else {
+		err = regulator_enable(p->supply);
+		if (err < 0) {
+			dev_err(panel->dev, "failed to enable supply: %d\n",
+				err);
+			return err;
+		}
+	}
+
+	return err;
+}
+
+static int panel_simple_regulator_disable(struct drm_panel *panel)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+	int err = 0;
+
+	if (p->power_invert) {
+		if (!regulator_is_enabled(p->supply)) {
+			err = regulator_enable(p->supply);
+			if (err < 0) {
+				dev_err(panel->dev, "failed to enable supply: %d\n",
+					err);
+				return err;
+			}
+		}
+	} else {
+		regulator_disable(p->supply);
+	}
+
+	return err;
+}
+
+static int panel_simple_disable(struct drm_panel *panel)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+
+	if (!p->enabled)
+		return 0;
+
+	if (p->backlight) {
+		p->backlight->props.power = FB_BLANK_POWERDOWN;
+		backlight_update_status(p->backlight);
+	}
+
+	if (p->desc && p->desc->delay.disable)
+		msleep(p->desc->delay.disable);
+
+	p->enabled = false;
+
+	return 0;
+}
+
+static int panel_simple_unprepare(struct drm_panel *panel)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+	int err = 0;
+
+	if (!p->prepared)
+		return 0;
+
+	if (p->off_cmds) {
+		if (p->dsi)
+			err = panel_simple_dsi_send_cmds(p, p->off_cmds);
+		else if (p->cmd_type == CMD_TYPE_SPI)
+			err = panel_simple_spi_send_cmds(p, p->off_cmds);
+		if (err)
+			dev_err(p->dev, "failed to send off cmds\n");
+	}
+
+	if (p->reset_gpio)
+		gpiod_direction_output(p->reset_gpio, 1);
+
+	if (p->enable_gpio)
+		gpiod_direction_output(p->enable_gpio, 0);
+
+	panel_simple_regulator_disable(panel);
+
+	if (p->desc && p->desc->delay.unprepare)
+		msleep(p->desc->delay.unprepare);
+
+	p->prepared = false;
+
+	return 0;
+}
+
+static int panel_simple_prepare(struct drm_panel *panel)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+	int err;
+
+	if (p->prepared)
+		return 0;
+
+	err = panel_simple_regulator_enable(panel);
+	if (err < 0) {
+		dev_err(panel->dev, "failed to enable supply: %d\n", err);
+		return err;
+	}
+
+	if (p->enable_gpio)
+		gpiod_direction_output(p->enable_gpio, 1);
+
+	if (p->desc && p->desc->delay.prepare)
+		msleep(p->desc->delay.prepare);
+
+	if (p->reset_gpio)
+		gpiod_direction_output(p->reset_gpio, 1);
+
+	if (p->desc && p->desc->delay.reset)
+		msleep(p->desc->delay.reset);
+
+	if (p->reset_gpio)
+		gpiod_direction_output(p->reset_gpio, 0);
+
+	if (p->desc && p->desc->delay.init)
+		msleep(p->desc->delay.init);
+
+	if (p->on_cmds) {
+		if (p->dsi)
+			err = panel_simple_dsi_send_cmds(p, p->on_cmds);
+		else if (p->cmd_type == CMD_TYPE_SPI)
+			err = panel_simple_spi_send_cmds(p, p->on_cmds);
+		if (err)
+			dev_err(p->dev, "failed to send on cmds\n");
+	}
+
+	p->prepared = true;
+
+	return 0;
+}
+
+static int panel_simple_enable(struct drm_panel *panel)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+
+	if (p->enabled)
+		return 0;
+
+	if (p->desc && p->desc->delay.enable)
+		msleep(p->desc->delay.enable);
+
+	if (p->backlight) {
+		p->backlight->props.power = FB_BLANK_UNBLANK;
+		backlight_update_status(p->backlight);
+	}
+
+	p->enabled = true;
+
+	return 0;
+}
+
+static int panel_simple_get_modes(struct drm_panel *panel)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+	int num = 0;
+
+	/* add device node plane modes */
+	num += panel_simple_of_get_native_mode(p);
+
+	/* add hard-coded panel modes */
+	num += panel_simple_get_fixed_modes(p);
+
+	/* probe EDID if a DDC bus is available */
+	if (p->ddc) {
+		struct edid *edid = drm_get_edid(panel->connector, p->ddc);
+		drm_connector_update_edid_property(panel->connector, edid);
+		if (edid) {
+			num += drm_add_edid_modes(panel->connector, edid);
+			kfree(edid);
+		}
+	}
+
+	return num;
+}
+
+static int panel_simple_get_timings(struct drm_panel *panel,
+				    unsigned int num_timings,
+				    struct display_timing *timings)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+	unsigned int i;
+
+	if (!p->desc)
+		return 0;
+
+	if (p->desc->num_timings < num_timings)
+		num_timings = p->desc->num_timings;
+
+	if (timings)
+		for (i = 0; i < num_timings; i++)
+			timings[i] = p->desc->timings[i];
+
+	return p->desc->num_timings;
+}
+
+static const struct drm_panel_funcs panel_simple_funcs = {
+	.disable = panel_simple_disable,
+	.unprepare = panel_simple_unprepare,
+	.prepare = panel_simple_prepare,
+	.enable = panel_simple_enable,
+	.get_modes = panel_simple_get_modes,
+	.get_timings = panel_simple_get_timings,
+};
+
+static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
+{
+	struct device_node *backlight, *ddc;
+	struct panel_simple *panel;
+	struct panel_desc *of_desc;
+	const char *cmd_type;
+	u32 val;
+	int err;
+
+	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
+	if (!panel)
+		return -ENOMEM;
+
+	if (!desc)
+		of_desc = devm_kzalloc(dev, sizeof(*of_desc), GFP_KERNEL);
+	else
+		of_desc = devm_kmemdup(dev, desc, sizeof(*of_desc), GFP_KERNEL);
+
+	if (!of_property_read_u32(dev->of_node, "bus-format", &val))
+		of_desc->bus_format = val;
+	if (!of_property_read_u32(dev->of_node, "prepare-delay-ms", &val))
+		of_desc->delay.prepare = val;
+	if (!of_property_read_u32(dev->of_node, "enable-delay-ms", &val))
+		of_desc->delay.enable = val;
+	if (!of_property_read_u32(dev->of_node, "disable-delay-ms", &val))
+		of_desc->delay.disable = val;
+	if (!of_property_read_u32(dev->of_node, "unprepare-delay-ms", &val))
+		of_desc->delay.unprepare = val;
+	if (!of_property_read_u32(dev->of_node, "reset-delay-ms", &val))
+		of_desc->delay.reset = val;
+	if (!of_property_read_u32(dev->of_node, "init-delay-ms", &val))
+		of_desc->delay.init = val;
+	if (!of_property_read_u32(dev->of_node, "width-mm", &val))
+		of_desc->size.width = val;
+	if (!of_property_read_u32(dev->of_node, "height-mm", &val))
+		of_desc->size.height = val;
+
+	panel->enabled = false;
+	panel->prepared = false;
+	panel->desc = of_desc;
+	panel->dev = dev;
+
+	err = panel_simple_get_cmds(panel);
+	if (err) {
+		dev_err(dev, "failed to get init cmd: %d\n", err);
+		return err;
+	}
+	panel->supply = devm_regulator_get(dev, "power");
+	if (IS_ERR(panel->supply))
+		return PTR_ERR(panel->supply);
+
+	panel->enable_gpio = devm_gpiod_get_optional(dev, "enable", 0);
+	if (IS_ERR(panel->enable_gpio)) {
+		err = PTR_ERR(panel->enable_gpio);
+		dev_err(dev, "failed to request enable GPIO: %d\n", err);
+		return err;
+	}
+
+	panel->reset_gpio = devm_gpiod_get_optional(dev, "reset", 0);
+	if (IS_ERR(panel->reset_gpio)) {
+		err = PTR_ERR(panel->reset_gpio);
+		dev_err(dev, "failed to request reset GPIO: %d\n", err);
+		return err;
+	}
+
+	if (of_property_read_string(dev->of_node, "rockchip,cmd-type",
+				    &cmd_type))
+		panel->cmd_type = CMD_TYPE_DEFAULT;
+	else
+		panel->cmd_type = get_panel_cmd_type(cmd_type);
+
+	if (panel->cmd_type == CMD_TYPE_SPI) {
+		panel->spi_sdi_gpio =
+				devm_gpiod_get_optional(dev, "spi-sdi", 0);
+		if (IS_ERR(panel->spi_sdi_gpio)) {
+			err = PTR_ERR(panel->spi_sdi_gpio);
+			dev_err(dev, "failed to request spi_sdi: %d\n", err);
+			return err;
+		}
+
+		panel->spi_scl_gpio =
+				devm_gpiod_get_optional(dev, "spi-scl", 0);
+		if (IS_ERR(panel->spi_scl_gpio)) {
+			err = PTR_ERR(panel->spi_scl_gpio);
+			dev_err(dev, "failed to request spi_scl: %d\n", err);
+			return err;
+		}
+
+		panel->spi_cs_gpio = devm_gpiod_get_optional(dev, "spi-cs", 0);
+		if (IS_ERR(panel->spi_cs_gpio)) {
+			err = PTR_ERR(panel->spi_cs_gpio);
+			dev_err(dev, "failed to request spi_cs: %d\n", err);
+			return err;
+		}
+		gpiod_direction_output(panel->spi_cs_gpio, 1);
+		gpiod_direction_output(panel->spi_sdi_gpio, 1);
+		gpiod_direction_output(panel->spi_scl_gpio, 1);
+	}
+	panel->power_invert =
+			of_property_read_bool(dev->of_node, "power-invert");
+
+	backlight = of_parse_phandle(dev->of_node, "backlight", 0);
+	if (backlight) {
+		panel->backlight = of_find_backlight_by_node(backlight);
+		of_node_put(backlight);
+
+		if (!panel->backlight) {
+			return -EPROBE_DEFER;
+		}
+	}
+
+	ddc = of_parse_phandle(dev->of_node, "ddc-i2c-bus", 0);
+	if (ddc) {
+		panel->ddc = of_find_i2c_adapter_by_node(ddc);
+		of_node_put(ddc);
+
+		if (!panel->ddc) {
+			err = -EPROBE_DEFER;
+			goto free_backlight;
+		}
+	}
+
+	drm_panel_init(&panel->base);
+	panel->base.dev = dev;
+	panel->base.funcs = &panel_simple_funcs;
+
+	err = drm_panel_add(&panel->base);
+	if (err < 0) {
+		goto free_ddc;
+	}
+
+	dev_set_drvdata(dev, panel);
+
+	return 0;
+
+free_ddc:
+	if (panel->ddc)
+		put_device(&panel->ddc->dev);
+free_backlight:
+	if (panel->backlight)
+		put_device(&panel->backlight->dev);
+
+	return err;
+}
+
+static int panel_simple_remove(struct device *dev)
+{
+	struct panel_simple *panel = dev_get_drvdata(dev);
+
+	drm_panel_detach(&panel->base);
+	drm_panel_remove(&panel->base);
+
+	panel_simple_disable(&panel->base);
+	panel_simple_unprepare(&panel->base);
+
+	if (panel->ddc)
+		put_device(&panel->ddc->dev);
+
+	if (panel->backlight)
+		put_device(&panel->backlight->dev);
+
+	panel_simple_cmds_cleanup(panel);
+
+	return 0;
+}
+
+static void panel_simple_shutdown(struct device *dev)
+{
+	struct panel_simple *panel = dev_get_drvdata(dev);
+
+	panel_simple_disable(&panel->base);
+	panel_simple_unprepare(&panel->base);
+}
+
+struct panel_desc_dsi {
+	struct panel_desc desc;
+
+	unsigned long flags;
+	enum mipi_dsi_pixel_format format;
+	unsigned int lanes;
+};
+
+static const struct of_device_id dsi_of_match[] = {
+	{
+		.compatible = "simple-panel-dt",
+		.data = NULL
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, dsi_of_match);
+
+static int panel_simple_dsi_probe(struct mipi_dsi_device *dsi)
+{
+	struct panel_simple *panel;
+	const struct panel_desc_dsi *desc;
+	const struct of_device_id *id;
+	const struct panel_desc *pdesc;
+	int err;
+	u32 val;
+
+	id = of_match_node(dsi_of_match, dsi->dev.of_node);
+	if (!id) {
+		return -ENODEV;
+	}
+
+	desc = id->data;
+
+	if (desc) {
+		dsi->mode_flags = desc->flags;
+		dsi->format = desc->format;
+		dsi->lanes = desc->lanes;
+		pdesc = &desc->desc;
+	} else {
+		pdesc = NULL;
+	}
+
+	err = panel_simple_probe(&dsi->dev, pdesc);
+	if (err < 0) {
+		return err;
+	}
+
+	panel = dev_get_drvdata(&dsi->dev);
+	panel->dsi = dsi;
+
+	if (!of_property_read_u32(dsi->dev.of_node, "dsi,flags", &val))
+		dsi->mode_flags = val;
+
+	if (!of_property_read_u32(dsi->dev.of_node, "dsi,format", &val))
+		dsi->format = val;
+
+	if (!of_property_read_u32(dsi->dev.of_node, "dsi,lanes", &val))
+		dsi->lanes = val;
+
+	return mipi_dsi_attach(dsi);
+}
+
+static int panel_simple_dsi_remove(struct mipi_dsi_device *dsi)
+{
+	int err;
+
+	err = mipi_dsi_detach(dsi);
+	if (err < 0)
+		dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", err);
+
+	return panel_simple_remove(&dsi->dev);
+}
+
+static void panel_simple_dsi_shutdown(struct mipi_dsi_device *dsi)
+{
+	panel_simple_shutdown(&dsi->dev);
+}
+
+static struct mipi_dsi_driver panel_simple_dsi_driver = {
+	.driver = {
+		.name = "panel-simple-dt",
+		.of_match_table = dsi_of_match,
+	},
+	.probe = panel_simple_dsi_probe,
+	.remove = panel_simple_dsi_remove,
+	.shutdown = panel_simple_dsi_shutdown,
+};
+
+static int __init panel_simple_init(void)
+{
+	int err;
+
+	if (IS_ENABLED(CONFIG_DRM_MIPI_DSI)) {
+		err = mipi_dsi_driver_register(&panel_simple_dsi_driver);
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+module_init(panel_simple_init);
+
+static void __exit panel_simple_exit(void)
+{
+	if (IS_ENABLED(CONFIG_DRM_MIPI_DSI))
+		mipi_dsi_driver_unregister(&panel_simple_dsi_driver);
+}
+module_exit(panel_simple_exit);
+
+MODULE_AUTHOR("Christoph Muellner <christoph.muellner@theobroma-systems.com>");
+MODULE_DESCRIPTION("DRM Driver for Simple Panels with DTS configuration");
+MODULE_LICENSE("GPL and additional rights");
-- 
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