drivers/gpu/drm/panel/panel-widechips-ws2401.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Panel driver for the WideChips WS2401 480x800 DPI RGB panel, used in
  * the Samsung Mobile Display (SMD) LMS380KF01.
  * Found in the Samsung Galaxy Ace 2 GT-I8160 mobile phone.
  * Linus Walleij <linus.walleij@linaro.org>
  * Inspired by code and know-how in the vendor driver by Gareth Phillips.
  */
 #include <drm/drm_mipi_dbi.h>
 #include <drm/drm_modes.h>
 #include <drm/drm_panel.h>

 #include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/media-bus-format.h>
 #include <linux/module.h>
 #include <linux/regulator/consumer.h>
 #include <linux/spi/spi.h>

 #include <video/mipi_display.h>

 #define WS2401_RESCTL			0xb8 /* Resolution select control */
 #define WS2401_PSMPS			0xbd /* SMPS positive control */
 #define WS2401_NSMPS			0xbe /* SMPS negative control */
 #define WS2401_SMPS			0xbf
 #define WS2401_BCMODE			0xc1 /* Backlight control mode */
 #define WS2401_WRBLCTL			0xc3 /* Backlight control */
 #define WS2401_WRDISBV			0xc4 /* Write manual brightness */
 #define WS2401_WRCTRLD			0xc6 /* Write BL control */
 #define WS2401_WRMIE			0xc7 /* Write MIE mode */
 #define WS2401_READ_ID1			0xda /* Read panel ID 1 */
 #define WS2401_READ_ID2			0xdb /* Read panel ID 2 */
 #define WS2401_READ_ID3			0xdc /* Read panel ID 3 */
 #define WS2401_GAMMA_R1			0xe7 /* Gamma red 1 */
 #define WS2401_GAMMA_G1			0xe8 /* Gamma green 1 */
 #define WS2401_GAMMA_B1			0xe9 /* Gamma blue 1 */
 #define WS2401_GAMMA_R2			0xea /* Gamma red 2 */
 #define WS2401_GAMMA_G2			0xeb /* Gamma green 2 */
 #define WS2401_GAMMA_B2			0xec /* Gamma blue 2 */
 #define WS2401_PASSWD1			0xf0 /* Password command for level 2 */
 #define WS2401_DISCTL			0xf2 /* Display control */
 #define WS2401_PWRCTL			0xf3 /* Power control */
 #define WS2401_VCOMCTL			0xf4 /* VCOM control */
 #define WS2401_SRCCTL			0xf5 /* Source control */
 #define WS2401_PANELCTL			0xf6 /* Panel control */

 static const u8 ws2401_dbi_read_commands[] = {
 	WS2401_READ_ID1,
 	WS2401_READ_ID2,
 	WS2401_READ_ID3,
 	0, /* sentinel */
 };

 /**
  * struct ws2401 - state container for a panel controlled by the WS2401
  * controller
  */
 struct ws2401 {
 	/** @dev: the container device */
 	struct device *dev;
 	/** @dbi: the DBI bus abstraction handle */
 	struct mipi_dbi dbi;
 	/** @panel: the DRM panel instance for this device */
 	struct drm_panel panel;
 	/** @width: the width of this panel in mm */
 	u32 width;
 	/** @height: the height of this panel in mm */
 	u32 height;
 	/** @reset: reset GPIO line */
 	struct gpio_desc *reset;
 	/** @regulators: VCCIO and VIO supply regulators */
 	struct regulator_bulk_data regulators[2];
 	/** @internal_bl: If using internal backlight */
 	bool internal_bl;
 };

 static const struct drm_display_mode lms380kf01_480_800_mode = {
 	/*
 	 * The vendor driver states that the "SMD panel" has a clock
 	 * frequency of 49920000 Hz / 2 = 24960000 Hz.
 	 */
 	.clock = 24960,
 	.hdisplay = 480,
 	.hsync_start = 480 + 8,
 	.hsync_end = 480 + 8 + 10,
 	.htotal = 480 + 8 + 10 + 8,
 	.vdisplay = 800,
 	.vsync_start = 800 + 8,
 	.vsync_end = 800 + 8 + 2,
 	.vtotal = 800 + 8 + 2 + 18,
 	.width_mm = 50,
 	.height_mm = 84,
 	.flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
 };

 static inline struct ws2401 *to_ws2401(struct drm_panel *panel)
 {
 	return container_of(panel, struct ws2401, panel);
 }

 static void ws2401_read_mtp_id(struct ws2401 *ws)
 {
 	struct mipi_dbi *dbi = &ws->dbi;
 	u8 id1, id2, id3;
 	int ret;

 	ret = mipi_dbi_command_read(dbi, WS2401_READ_ID1, &id1);
 	if (ret) {
 		dev_err(ws->dev, "unable to read MTP ID 1\n");
 		return;
 	}
 	ret = mipi_dbi_command_read(dbi, WS2401_READ_ID2, &id2);
 	if (ret) {
 		dev_err(ws->dev, "unable to read MTP ID 2\n");
 		return;
 	}
 	ret = mipi_dbi_command_read(dbi, WS2401_READ_ID3, &id3);
 	if (ret) {
 		dev_err(ws->dev, "unable to read MTP ID 3\n");
 		return;
 	}
 	dev_info(ws->dev, "MTP ID: %02x %02x %02x\n", id1, id2, id3);
 }

 static int ws2401_power_on(struct ws2401 *ws)
 {
 	struct mipi_dbi *dbi = &ws->dbi;
 	int ret;

 	/* Power up */
 	ret = regulator_bulk_enable(ARRAY_SIZE(ws->regulators),
 				    ws->regulators);
 	if (ret) {
 		dev_err(ws->dev, "failed to enable regulators: %d\n", ret);
 		return ret;
 	}
 	msleep(10);

 	/* Assert reset >=1 ms */
 	gpiod_set_value_cansleep(ws->reset, 1);
 	usleep_range(1000, 5000);
 	/* De-assert reset */
 	gpiod_set_value_cansleep(ws->reset, 0);
 	/* Wait >= 10 ms */
 	msleep(10);
 	dev_dbg(ws->dev, "de-asserted RESET\n");

 	/*
 	 * Exit sleep mode and initialize display - some hammering is
 	 * necessary.
 	 */
 	mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
 	mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
 	msleep(50);

 	/* Magic to unlock level 2 control of the display */
 	mipi_dbi_command(dbi, WS2401_PASSWD1, 0x5a, 0x5a);
 	/* Configure resolution to 480RGBx800 */
 	mipi_dbi_command(dbi, WS2401_RESCTL, 0x12);
 	/* Set addressing mode Flip V(d0), Flip H(d1) RGB/BGR(d3) */
 	mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, 0x01);
 	/* Set pixel format: 24 bpp */
 	mipi_dbi_command(dbi, MIPI_DCS_SET_PIXEL_FORMAT, 0x70);
 	mipi_dbi_command(dbi, WS2401_SMPS, 0x00, 0x0f);
 	mipi_dbi_command(dbi, WS2401_PSMPS, 0x06, 0x03, /* DDVDH: 4.6v */
 			 0x7e, 0x03, 0x12, 0x37);
 	mipi_dbi_command(dbi, WS2401_NSMPS, 0x06, 0x03, /* DDVDH: -4.6v */
 			 0x7e, 0x02, 0x15, 0x37);
 	mipi_dbi_command(dbi, WS2401_SMPS, 0x02, 0x0f);
 	mipi_dbi_command(dbi, WS2401_PWRCTL, 0x10, 0xA9, 0x00, 0x01, 0x44,
 			 0xb4,	/* VGH:16.1v, VGL:-13.8v */
 			 0x50,	/* GREFP:4.2v (default) */
 			 0x50,	/* GREFN:-4.2v (default) */
 			 0x00,
 			 0x44);	/* VOUTL:-10v (default) */
 	mipi_dbi_command(dbi, WS2401_DISCTL, 0x01, 0x00, 0x00, 0x00, 0x14,
 			 0x16);
 	mipi_dbi_command(dbi, WS2401_VCOMCTL, 0x30, 0x53, 0x53);
 	mipi_dbi_command(dbi, WS2401_SRCCTL, 0x03, 0x0C, 0x00, 0x00, 0x00,
 			 0x01,	/* 2 dot inversion */
 			 0x01, 0x06, 0x03);
 	mipi_dbi_command(dbi, WS2401_PANELCTL, 0x14, 0x00, 0x80, 0x00);
 	mipi_dbi_command(dbi, WS2401_WRMIE, 0x01);

 	/* Set up gamma, probably these are P-gamma and N-gamma for each color */
 	mipi_dbi_command(dbi, WS2401_GAMMA_R1, 0x00,
 			 0x5b, 0x42, 0x41, 0x3f, 0x42, 0x3d, 0x38, 0x2e,
 			 0x2b, 0x2a, 0x27, 0x22, 0x27, 0x0f, 0x00, 0x00);
 	mipi_dbi_command(dbi, WS2401_GAMMA_R2, 0x00,
 			 0x5b, 0x42, 0x41, 0x3f, 0x42, 0x3d, 0x38, 0x2e,
 			 0x2b, 0x2a, 0x27, 0x22, 0x27, 0x0f, 0x00, 0x00);
 	mipi_dbi_command(dbi, WS2401_GAMMA_G1, 0x00,
 			 0x59, 0x40, 0x3f, 0x3e, 0x41, 0x3d, 0x39, 0x2f,
 			 0x2c, 0x2b, 0x29, 0x25, 0x29, 0x19, 0x08, 0x00);
 	mipi_dbi_command(dbi, WS2401_GAMMA_G2, 0x00,
 			 0x59, 0x40, 0x3f, 0x3e, 0x41, 0x3d, 0x39, 0x2f,
 			 0x2c, 0x2b, 0x29, 0x25, 0x29, 0x19, 0x08, 0x00);
 	mipi_dbi_command(dbi, WS2401_GAMMA_B1, 0x00,
 			 0x57, 0x3b, 0x3a, 0x3b, 0x3f, 0x3b, 0x38, 0x27,
 			 0x38, 0x2a, 0x26, 0x22, 0x34, 0x0c, 0x09, 0x00);
 	mipi_dbi_command(dbi, WS2401_GAMMA_B2, 0x00,
 			 0x57, 0x3b, 0x3a, 0x3b, 0x3f, 0x3b, 0x38, 0x27,
 			 0x38, 0x2a, 0x26, 0x22, 0x34, 0x0c, 0x09, 0x00);

 	if (ws->internal_bl) {
 		mipi_dbi_command(dbi, WS2401_WRCTRLD, 0x2c);
 	} else {
 		mipi_dbi_command(dbi, WS2401_WRCTRLD, 0x00);
 		/*
 		 * When not using internal backlight we do not need any further
 		 * L2 accesses to the panel so we close the door on our way out.
 		 * Otherwise we need to leave the L2 door open.
 		 */
 		mipi_dbi_command(dbi, WS2401_PASSWD1, 0xa5, 0xa5);
 	}

 	return 0;
 }

 static int ws2401_power_off(struct ws2401 *ws)
 {
 	/* Go into RESET and disable regulators */
 	gpiod_set_value_cansleep(ws->reset, 1);
 	return regulator_bulk_disable(ARRAY_SIZE(ws->regulators),
 				      ws->regulators);
 }

 static int ws2401_unprepare(struct drm_panel *panel)
 {
 	struct ws2401 *ws = to_ws2401(panel);
 	struct mipi_dbi *dbi = &ws->dbi;

 	/* Make sure we disable backlight, if any */
 	if (ws->internal_bl)
 		mipi_dbi_command(dbi, WS2401_WRCTRLD, 0x00);
 	mipi_dbi_command(dbi, MIPI_DCS_ENTER_SLEEP_MODE);
 	msleep(120);
 	return ws2401_power_off(to_ws2401(panel));
 }

 static int ws2401_disable(struct drm_panel *panel)
 {
 	struct ws2401 *ws = to_ws2401(panel);
 	struct mipi_dbi *dbi = &ws->dbi;

 	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_OFF);
 	msleep(25);

 	return 0;
 }

 static int ws2401_prepare(struct drm_panel *panel)
 {
 	return ws2401_power_on(to_ws2401(panel));
 }

 static int ws2401_enable(struct drm_panel *panel)
 {
 	struct ws2401 *ws = to_ws2401(panel);
 	struct mipi_dbi *dbi = &ws->dbi;

 	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);

 	return 0;
 }

 /**
  * ws2401_get_modes() - return the mode
  * @panel: the panel to get the mode for
  * @connector: reference to the central DRM connector control structure
  */
 static int ws2401_get_modes(struct drm_panel *panel,
 			    struct drm_connector *connector)
 {
 	struct ws2401 *ws = to_ws2401(panel);
 	struct drm_display_mode *mode;
 	static const u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;

 	/*
 	 * We just support the LMS380KF01 so far, if we implement more panels
 	 * this mode, the following connector display_info settings and
 	 * probably the custom DCS sequences needs to selected based on what
 	 * the target panel needs.
 	 */
 	mode = drm_mode_duplicate(connector->dev, &lms380kf01_480_800_mode);
 	if (!mode) {
 		dev_err(ws->dev, "failed to add mode\n");
 		return -ENOMEM;
 	}

 	connector->display_info.bpc = 8;
 	connector->display_info.width_mm = mode->width_mm;
 	connector->display_info.height_mm = mode->height_mm;
 	connector->display_info.bus_flags =
 		DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE;
 	drm_display_info_set_bus_formats(&connector->display_info,
 					 &bus_format, 1);

 	drm_mode_set_name(mode);
 	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;

 	drm_mode_probed_add(connector, mode);

 	return 1;
 }

 static const struct drm_panel_funcs ws2401_drm_funcs = {
 	.disable = ws2401_disable,
 	.unprepare = ws2401_unprepare,
 	.prepare = ws2401_prepare,
 	.enable = ws2401_enable,
 	.get_modes = ws2401_get_modes,
 };

 static int ws2401_set_brightness(struct backlight_device *bl)
 {
 	struct ws2401 *ws = bl_get_data(bl);
 	struct mipi_dbi *dbi = &ws->dbi;
 	u8 brightness = backlight_get_brightness(bl);

 	if (backlight_is_blank(bl)) {
 		mipi_dbi_command(dbi, WS2401_WRCTRLD, 0x00);
 	} else {
 		mipi_dbi_command(dbi, WS2401_WRCTRLD, 0x2c);
 		mipi_dbi_command(dbi, WS2401_WRDISBV, brightness);
 	}

 	return 0;
 }

 static const struct backlight_ops ws2401_bl_ops = {
 	.update_status = ws2401_set_brightness,
 };

 static const struct backlight_properties ws2401_bl_props = {
 	.type = BACKLIGHT_PLATFORM,
 	.brightness = 120,
 	.max_brightness = U8_MAX,
 };

 static int ws2401_probe(struct spi_device *spi)
 {
 	struct device *dev = &spi->dev;
 	struct ws2401 *ws;
 	int ret;

 	ws = devm_kzalloc(dev, sizeof(*ws), GFP_KERNEL);
 	if (!ws)
 		return -ENOMEM;
 	ws->dev = dev;

 	/*
 	 * VCI   is the analog voltage supply
 	 * VCCIO is the digital I/O voltage supply
 	 */
 	ws->regulators[0].supply = "vci";
 	ws->regulators[1].supply = "vccio";
 	ret = devm_regulator_bulk_get(dev,
 				      ARRAY_SIZE(ws->regulators),
 				      ws->regulators);
 	if (ret)
 		return dev_err_probe(dev, ret, "failed to get regulators\n");

 	ws->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
 	if (IS_ERR(ws->reset)) {
 		ret = PTR_ERR(ws->reset);
 		return dev_err_probe(dev, ret, "no RESET GPIO\n");
 	}

 	ret = mipi_dbi_spi_init(spi, &ws->dbi, NULL);
 	if (ret)
 		return dev_err_probe(dev, ret, "MIPI DBI init failed\n");
 	ws->dbi.read_commands = ws2401_dbi_read_commands;

 	ws2401_power_on(ws);
 	ws2401_read_mtp_id(ws);
 	ws2401_power_off(ws);

 	drm_panel_init(&ws->panel, dev, &ws2401_drm_funcs,
 		       DRM_MODE_CONNECTOR_DPI);

 	ret = drm_panel_of_backlight(&ws->panel);
 	if (ret)
 		return dev_err_probe(dev, ret,
 				"failed to get external backlight device\n");

 	if (!ws->panel.backlight) {
 		dev_dbg(dev, "no external backlight, using internal backlight\n");
 		ws->panel.backlight =
 			devm_backlight_device_register(dev, "ws2401", dev, ws,
 				&ws2401_bl_ops, &ws2401_bl_props);
 		if (IS_ERR(ws->panel.backlight))
 			return dev_err_probe(dev, PTR_ERR(ws->panel.backlight),
 				"failed to register backlight device\n");
 	} else {
 		dev_dbg(dev, "using external backlight\n");
 	}

 	spi_set_drvdata(spi, ws);

 	drm_panel_add(&ws->panel);
 	dev_dbg(dev, "added panel\n");

 	return 0;
 }

 static void ws2401_remove(struct spi_device *spi)
 {
 	struct ws2401 *ws = spi_get_drvdata(spi);

 	drm_panel_remove(&ws->panel);
 }

 /*
  * Samsung LMS380KF01 is the one instance of this display controller that we
  * know about, but if more are found, the controller can be parameterized
  * here and used for other configurations.
  */
 static const struct of_device_id ws2401_match[] = {
 	{ .compatible = "samsung,lms380kf01", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, ws2401_match);

 static const struct spi_device_id ws2401_ids[] = {
 	{ "lms380kf01" },
 	{ },
 };
 MODULE_DEVICE_TABLE(spi, ws2401_ids);

 static struct spi_driver ws2401_driver = {
 	.probe		= ws2401_probe,
 	.remove		= ws2401_remove,
 	.id_table	= ws2401_ids,
 	.driver		= {
 		.name	= "ws2401-panel",
 		.of_match_table = ws2401_match,
 	},
 };
 module_spi_driver(ws2401_driver);

 MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
 MODULE_DESCRIPTION("Samsung WS2401 panel driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Panel driver for the WideChips WS2401 480x800 DPI RGB panel, used in
	* the Samsung Mobile Display (SMD) LMS380KF01.
	* Found in the Samsung Galaxy Ace 2 GT-I8160 mobile phone.
	* Linus Walleij <linus.walleij@linaro.org>
	* Inspired by code and know-how in the vendor driver by Gareth Phillips.
	*/
	#include <drm/drm_mipi_dbi.h>
	#include <drm/drm_modes.h>
	#include <drm/drm_panel.h>

	#include <linux/backlight.h>
	#include <linux/delay.h>
	#include <linux/gpio/consumer.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/media-bus-format.h>
	#include <linux/module.h>
	#include <linux/regulator/consumer.h>
	#include <linux/spi/spi.h>

	#include <video/mipi_display.h>

	#define WS2401_RESCTL 0xb8 /* Resolution select control */
	#define WS2401_PSMPS 0xbd /* SMPS positive control */
	#define WS2401_NSMPS 0xbe /* SMPS negative control */
	#define WS2401_SMPS 0xbf
	#define WS2401_BCMODE 0xc1 /* Backlight control mode */
	#define WS2401_WRBLCTL 0xc3 /* Backlight control */
	#define WS2401_WRDISBV 0xc4 /* Write manual brightness */
	#define WS2401_WRCTRLD 0xc6 /* Write BL control */
	#define WS2401_WRMIE 0xc7 /* Write MIE mode */
	#define WS2401_READ_ID1 0xda /* Read panel ID 1 */
	#define WS2401_READ_ID2 0xdb /* Read panel ID 2 */
	#define WS2401_READ_ID3 0xdc /* Read panel ID 3 */
	#define WS2401_GAMMA_R1 0xe7 /* Gamma red 1 */
	#define WS2401_GAMMA_G1 0xe8 /* Gamma green 1 */
	#define WS2401_GAMMA_B1 0xe9 /* Gamma blue 1 */
	#define WS2401_GAMMA_R2 0xea /* Gamma red 2 */
	#define WS2401_GAMMA_G2 0xeb /* Gamma green 2 */
	#define WS2401_GAMMA_B2 0xec /* Gamma blue 2 */
	#define WS2401_PASSWD1 0xf0 /* Password command for level 2 */
	#define WS2401_DISCTL 0xf2 /* Display control */
	#define WS2401_PWRCTL 0xf3 /* Power control */
	#define WS2401_VCOMCTL 0xf4 /* VCOM control */
	#define WS2401_SRCCTL 0xf5 /* Source control */
	#define WS2401_PANELCTL 0xf6 /* Panel control */

	static const u8 ws2401_dbi_read_commands[] = {
	WS2401_READ_ID1,
	WS2401_READ_ID2,
	WS2401_READ_ID3,
	0, /* sentinel */
	};

	/**
	* struct ws2401 - state container for a panel controlled by the WS2401
	* controller
	*/
	struct ws2401 {
	/** @dev: the container device */
	struct device *dev;
	/** @dbi: the DBI bus abstraction handle */
	struct mipi_dbi dbi;
	/** @panel: the DRM panel instance for this device */
	struct drm_panel panel;
	/** @width: the width of this panel in mm */
	u32 width;
	/** @height: the height of this panel in mm */
	u32 height;
	/** @reset: reset GPIO line */
	struct gpio_desc *reset;
	/** @regulators: VCCIO and VIO supply regulators */
	struct regulator_bulk_data regulators[2];
	/** @internal_bl: If using internal backlight */
	bool internal_bl;
	};

	static const struct drm_display_mode lms380kf01_480_800_mode = {
	/*
	* The vendor driver states that the "SMD panel" has a clock
	* frequency of 49920000 Hz / 2 = 24960000 Hz.
	*/
	.clock = 24960,
	.hdisplay = 480,
	.hsync_start = 480 + 8,
	.hsync_end = 480 + 8 + 10,
	.htotal = 480 + 8 + 10 + 8,
	.vdisplay = 800,
	.vsync_start = 800 + 8,
	.vsync_end = 800 + 8 + 2,
	.vtotal = 800 + 8 + 2 + 18,
	.width_mm = 50,
	.height_mm = 84,
	.flags = DRM_MODE_FLAG_NVSYNC \| DRM_MODE_FLAG_NHSYNC,
	};

	static inline struct ws2401 to_ws2401(struct drm_panel panel)
	{
	return container_of(panel, struct ws2401, panel);
	}

	static void ws2401_read_mtp_id(struct ws2401 *ws)
	{
	struct mipi_dbi *dbi = &ws->dbi;
	u8 id1, id2, id3;
	int ret;

	ret = mipi_dbi_command_read(dbi, WS2401_READ_ID1, &id1);
	if (ret) {
	dev_err(ws->dev, "unable to read MTP ID 1\n");
	return;
	}
	ret = mipi_dbi_command_read(dbi, WS2401_READ_ID2, &id2);
	if (ret) {
	dev_err(ws->dev, "unable to read MTP ID 2\n");
	return;
	}
	ret = mipi_dbi_command_read(dbi, WS2401_READ_ID3, &id3);
	if (ret) {
	dev_err(ws->dev, "unable to read MTP ID 3\n");
	return;
	}
	dev_info(ws->dev, "MTP ID: %02x %02x %02x\n", id1, id2, id3);
	}

	static int ws2401_power_on(struct ws2401 *ws)
	{
	struct mipi_dbi *dbi = &ws->dbi;
	int ret;

	/* Power up */
	ret = regulator_bulk_enable(ARRAY_SIZE(ws->regulators),
	ws->regulators);
	if (ret) {
	dev_err(ws->dev, "failed to enable regulators: %d\n", ret);
	return ret;
	}
	msleep(10);

	/* Assert reset >=1 ms */
	gpiod_set_value_cansleep(ws->reset, 1);
	usleep_range(1000, 5000);
	/* De-assert reset */
	gpiod_set_value_cansleep(ws->reset, 0);
	/* Wait >= 10 ms */
	msleep(10);
	dev_dbg(ws->dev, "de-asserted RESET\n");

	/*
	* Exit sleep mode and initialize display - some hammering is
	* necessary.
	*/
	mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
	mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
	msleep(50);

	/* Magic to unlock level 2 control of the display */
	mipi_dbi_command(dbi, WS2401_PASSWD1, 0x5a, 0x5a);
	/* Configure resolution to 480RGBx800 */
	mipi_dbi_command(dbi, WS2401_RESCTL, 0x12);
	/* Set addressing mode Flip V(d0), Flip H(d1) RGB/BGR(d3) */
	mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, 0x01);
	/* Set pixel format: 24 bpp */
	mipi_dbi_command(dbi, MIPI_DCS_SET_PIXEL_FORMAT, 0x70);
	mipi_dbi_command(dbi, WS2401_SMPS, 0x00, 0x0f);
	mipi_dbi_command(dbi, WS2401_PSMPS, 0x06, 0x03, /* DDVDH: 4.6v */
	0x7e, 0x03, 0x12, 0x37);
	mipi_dbi_command(dbi, WS2401_NSMPS, 0x06, 0x03, /* DDVDH: -4.6v */
	0x7e, 0x02, 0x15, 0x37);
	mipi_dbi_command(dbi, WS2401_SMPS, 0x02, 0x0f);
	mipi_dbi_command(dbi, WS2401_PWRCTL, 0x10, 0xA9, 0x00, 0x01, 0x44,
	0xb4, /* VGH:16.1v, VGL:-13.8v */
	0x50, /* GREFP:4.2v (default) */
	0x50, /* GREFN:-4.2v (default) */
	0x00,
	0x44); /* VOUTL:-10v (default) */
	mipi_dbi_command(dbi, WS2401_DISCTL, 0x01, 0x00, 0x00, 0x00, 0x14,
	0x16);
	mipi_dbi_command(dbi, WS2401_VCOMCTL, 0x30, 0x53, 0x53);
	mipi_dbi_command(dbi, WS2401_SRCCTL, 0x03, 0x0C, 0x00, 0x00, 0x00,
	0x01, /* 2 dot inversion */
	0x01, 0x06, 0x03);
	mipi_dbi_command(dbi, WS2401_PANELCTL, 0x14, 0x00, 0x80, 0x00);
	mipi_dbi_command(dbi, WS2401_WRMIE, 0x01);

	/* Set up gamma, probably these are P-gamma and N-gamma for each color */
	mipi_dbi_command(dbi, WS2401_GAMMA_R1, 0x00,
	0x5b, 0x42, 0x41, 0x3f, 0x42, 0x3d, 0x38, 0x2e,
	0x2b, 0x2a, 0x27, 0x22, 0x27, 0x0f, 0x00, 0x00);
	mipi_dbi_command(dbi, WS2401_GAMMA_R2, 0x00,
	0x5b, 0x42, 0x41, 0x3f, 0x42, 0x3d, 0x38, 0x2e,
	0x2b, 0x2a, 0x27, 0x22, 0x27, 0x0f, 0x00, 0x00);
	mipi_dbi_command(dbi, WS2401_GAMMA_G1, 0x00,
	0x59, 0x40, 0x3f, 0x3e, 0x41, 0x3d, 0x39, 0x2f,
	0x2c, 0x2b, 0x29, 0x25, 0x29, 0x19, 0x08, 0x00);
	mipi_dbi_command(dbi, WS2401_GAMMA_G2, 0x00,
	0x59, 0x40, 0x3f, 0x3e, 0x41, 0x3d, 0x39, 0x2f,
	0x2c, 0x2b, 0x29, 0x25, 0x29, 0x19, 0x08, 0x00);
	mipi_dbi_command(dbi, WS2401_GAMMA_B1, 0x00,
	0x57, 0x3b, 0x3a, 0x3b, 0x3f, 0x3b, 0x38, 0x27,
	0x38, 0x2a, 0x26, 0x22, 0x34, 0x0c, 0x09, 0x00);
	mipi_dbi_command(dbi, WS2401_GAMMA_B2, 0x00,
	0x57, 0x3b, 0x3a, 0x3b, 0x3f, 0x3b, 0x38, 0x27,
	0x38, 0x2a, 0x26, 0x22, 0x34, 0x0c, 0x09, 0x00);

	if (ws->internal_bl) {
	mipi_dbi_command(dbi, WS2401_WRCTRLD, 0x2c);
	} else {
	mipi_dbi_command(dbi, WS2401_WRCTRLD, 0x00);
	/*
	* When not using internal backlight we do not need any further
	* L2 accesses to the panel so we close the door on our way out.
	* Otherwise we need to leave the L2 door open.
	*/
	mipi_dbi_command(dbi, WS2401_PASSWD1, 0xa5, 0xa5);
	}

	return 0;
	}

	static int ws2401_power_off(struct ws2401 *ws)
	{
	/* Go into RESET and disable regulators */
	gpiod_set_value_cansleep(ws->reset, 1);
	return regulator_bulk_disable(ARRAY_SIZE(ws->regulators),
	ws->regulators);
	}

	static int ws2401_unprepare(struct drm_panel *panel)
	{
	struct ws2401 *ws = to_ws2401(panel);
	struct mipi_dbi *dbi = &ws->dbi;

	/* Make sure we disable backlight, if any */
	if (ws->internal_bl)
	mipi_dbi_command(dbi, WS2401_WRCTRLD, 0x00);
	mipi_dbi_command(dbi, MIPI_DCS_ENTER_SLEEP_MODE);
	msleep(120);
	return ws2401_power_off(to_ws2401(panel));
	}

	static int ws2401_disable(struct drm_panel *panel)
	{
	struct ws2401 *ws = to_ws2401(panel);
	struct mipi_dbi *dbi = &ws->dbi;

	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_OFF);
	msleep(25);

	return 0;
	}

	static int ws2401_prepare(struct drm_panel *panel)
	{
	return ws2401_power_on(to_ws2401(panel));
	}

	static int ws2401_enable(struct drm_panel *panel)
	{
	struct ws2401 *ws = to_ws2401(panel);
	struct mipi_dbi *dbi = &ws->dbi;

	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);

	return 0;
	}

	/**
	* ws2401_get_modes() - return the mode
	* @panel: the panel to get the mode for
	* @connector: reference to the central DRM connector control structure
	*/
	static int ws2401_get_modes(struct drm_panel *panel,
	struct drm_connector *connector)
	{
	struct ws2401 *ws = to_ws2401(panel);
	struct drm_display_mode *mode;
	static const u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;

	/*
	* We just support the LMS380KF01 so far, if we implement more panels
	* this mode, the following connector display_info settings and
	* probably the custom DCS sequences needs to selected based on what
	* the target panel needs.
	*/
	mode = drm_mode_duplicate(connector->dev, &lms380kf01_480_800_mode);
	if (!mode) {
	dev_err(ws->dev, "failed to add mode\n");
	return -ENOMEM;
	}

	connector->display_info.bpc = 8;
	connector->display_info.width_mm = mode->width_mm;
	connector->display_info.height_mm = mode->height_mm;
	connector->display_info.bus_flags =
	DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE;
	drm_display_info_set_bus_formats(&connector->display_info,
	&bus_format, 1);

	drm_mode_set_name(mode);
	mode->type = DRM_MODE_TYPE_DRIVER \| DRM_MODE_TYPE_PREFERRED;

	drm_mode_probed_add(connector, mode);

	return 1;
	}

	static const struct drm_panel_funcs ws2401_drm_funcs = {
	.disable = ws2401_disable,
	.unprepare = ws2401_unprepare,
	.prepare = ws2401_prepare,
	.enable = ws2401_enable,
	.get_modes = ws2401_get_modes,
	};

	static int ws2401_set_brightness(struct backlight_device *bl)
	{
	struct ws2401 *ws = bl_get_data(bl);
	struct mipi_dbi *dbi = &ws->dbi;
	u8 brightness = backlight_get_brightness(bl);

	if (backlight_is_blank(bl)) {
	mipi_dbi_command(dbi, WS2401_WRCTRLD, 0x00);
	} else {
	mipi_dbi_command(dbi, WS2401_WRCTRLD, 0x2c);
	mipi_dbi_command(dbi, WS2401_WRDISBV, brightness);
	}

	return 0;
	}

	static const struct backlight_ops ws2401_bl_ops = {
	.update_status = ws2401_set_brightness,
	};

	static const struct backlight_properties ws2401_bl_props = {
	.type = BACKLIGHT_PLATFORM,
	.brightness = 120,
	.max_brightness = U8_MAX,
	};

	static int ws2401_probe(struct spi_device *spi)
	{
	struct device *dev = &spi->dev;
	struct ws2401 *ws;
	int ret;

	ws = devm_kzalloc(dev, sizeof(*ws), GFP_KERNEL);
	if (!ws)
	return -ENOMEM;
	ws->dev = dev;

	/*
	* VCI is the analog voltage supply
	* VCCIO is the digital I/O voltage supply
	*/
	ws->regulators[0].supply = "vci";
	ws->regulators[1].supply = "vccio";
	ret = devm_regulator_bulk_get(dev,
	ARRAY_SIZE(ws->regulators),
	ws->regulators);
	if (ret)
	return dev_err_probe(dev, ret, "failed to get regulators\n");

	ws->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
	if (IS_ERR(ws->reset)) {
	ret = PTR_ERR(ws->reset);
	return dev_err_probe(dev, ret, "no RESET GPIO\n");
	}

	ret = mipi_dbi_spi_init(spi, &ws->dbi, NULL);
	if (ret)
	return dev_err_probe(dev, ret, "MIPI DBI init failed\n");
	ws->dbi.read_commands = ws2401_dbi_read_commands;

	ws2401_power_on(ws);
	ws2401_read_mtp_id(ws);
	ws2401_power_off(ws);

	drm_panel_init(&ws->panel, dev, &ws2401_drm_funcs,
	DRM_MODE_CONNECTOR_DPI);

	ret = drm_panel_of_backlight(&ws->panel);
	if (ret)
	return dev_err_probe(dev, ret,
	"failed to get external backlight device\n");

	if (!ws->panel.backlight) {
	dev_dbg(dev, "no external backlight, using internal backlight\n");
	ws->panel.backlight =
	devm_backlight_device_register(dev, "ws2401", dev, ws,
	&ws2401_bl_ops, &ws2401_bl_props);
	if (IS_ERR(ws->panel.backlight))
	return dev_err_probe(dev, PTR_ERR(ws->panel.backlight),
	"failed to register backlight device\n");
	} else {
	dev_dbg(dev, "using external backlight\n");
	}

	spi_set_drvdata(spi, ws);

	drm_panel_add(&ws->panel);
	dev_dbg(dev, "added panel\n");

	return 0;
	}

	static void ws2401_remove(struct spi_device *spi)
	{
	struct ws2401 *ws = spi_get_drvdata(spi);

	drm_panel_remove(&ws->panel);
	}

	/*
	* Samsung LMS380KF01 is the one instance of this display controller that we
	* know about, but if more are found, the controller can be parameterized
	* here and used for other configurations.
	*/
	static const struct of_device_id ws2401_match[] = {
	{ .compatible = "samsung,lms380kf01", },
	{},
	};
	MODULE_DEVICE_TABLE(of, ws2401_match);

	static const struct spi_device_id ws2401_ids[] = {
	{ "lms380kf01" },
	{ },
	};
	MODULE_DEVICE_TABLE(spi, ws2401_ids);

	static struct spi_driver ws2401_driver = {
	.probe = ws2401_probe,
	.remove = ws2401_remove,
	.id_table = ws2401_ids,
	.driver = {
	.name = "ws2401-panel",
	.of_match_table = ws2401_match,
	},
	};
	module_spi_driver(ws2401_driver);

	MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
	MODULE_DESCRIPTION("Samsung WS2401 panel driver");
	MODULE_LICENSE("GPL v2");