drivers/gpu/drm/panel/panel-ld9040.c - arm/linux-arm64-legacy - Git at Google

 /*
  * ld9040 AMOLED LCD drm_panel driver.
  *
  * Copyright (c) 2014 Samsung Electronics Co., Ltd
  * Derived from drivers/video/backlight/ld9040.c
  *
  * Andrzej Hajda <a.hajda@samsung.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
 */

 #include <drm/drmP.h>
 #include <drm/drm_panel.h>

 #include <linux/gpio/consumer.h>
 #include <linux/regulator/consumer.h>
 #include <linux/spi/spi.h>

 #include <video/mipi_display.h>
 #include <video/of_videomode.h>
 #include <video/videomode.h>

 /* Manufacturer Command Set */
 #define MCS_MANPWR		0xb0
 #define MCS_ELVSS_ON		0xb1
 #define MCS_USER_SETTING	0xf0
 #define MCS_DISPCTL		0xf2
 #define MCS_GTCON		0xf7
 #define MCS_PANEL_CONDITION	0xf8
 #define MCS_GAMMA_SET1		0xf9
 #define MCS_GAMMA_CTRL		0xfb

 /* array of gamma tables for gamma value 2.2 */
 static u8 const ld9040_gammas[25][22] = {
 	{ 0xf9, 0x00, 0x13, 0xb2, 0xba, 0xd2, 0x00, 0x30, 0x00, 0xaf, 0xc0,
 	  0xb8, 0xcd, 0x00, 0x3d, 0x00, 0xa8, 0xb8, 0xb7, 0xcd, 0x00, 0x44 },
 	{ 0xf9, 0x00, 0x13, 0xb9, 0xb9, 0xd0, 0x00, 0x3c, 0x00, 0xaf, 0xbf,
 	  0xb6, 0xcb, 0x00, 0x4b, 0x00, 0xa8, 0xb9, 0xb5, 0xcc, 0x00, 0x52 },
 	{ 0xf9, 0x00, 0x13, 0xba, 0xb9, 0xcd, 0x00, 0x41, 0x00, 0xb0, 0xbe,
 	  0xb5, 0xc9, 0x00, 0x51, 0x00, 0xa9, 0xb9, 0xb5, 0xca, 0x00, 0x57 },
 	{ 0xf9, 0x00, 0x13, 0xb9, 0xb8, 0xcd, 0x00, 0x46, 0x00, 0xb1, 0xbc,
 	  0xb5, 0xc8, 0x00, 0x56, 0x00, 0xaa, 0xb8, 0xb4, 0xc9, 0x00, 0x5d },
 	{ 0xf9, 0x00, 0x13, 0xba, 0xb8, 0xcb, 0x00, 0x4b, 0x00, 0xb3, 0xbc,
 	  0xb4, 0xc7, 0x00, 0x5c, 0x00, 0xac, 0xb8, 0xb4, 0xc8, 0x00, 0x62 },
 	{ 0xf9, 0x00, 0x13, 0xbb, 0xb7, 0xca, 0x00, 0x4f, 0x00, 0xb4, 0xbb,
 	  0xb3, 0xc7, 0x00, 0x60, 0x00, 0xad, 0xb8, 0xb4, 0xc7, 0x00, 0x67 },
 	{ 0xf9, 0x00, 0x47, 0xba, 0xb6, 0xca, 0x00, 0x53, 0x00, 0xb5, 0xbb,
 	  0xb3, 0xc6, 0x00, 0x65, 0x00, 0xae, 0xb8, 0xb3, 0xc7, 0x00, 0x6c },
 	{ 0xf9, 0x00, 0x71, 0xbb, 0xb5, 0xc8, 0x00, 0x57, 0x00, 0xb5, 0xbb,
 	  0xb0, 0xc5, 0x00, 0x6a, 0x00, 0xae, 0xb9, 0xb1, 0xc6, 0x00, 0x70 },
 	{ 0xf9, 0x00, 0x7b, 0xbb, 0xb4, 0xc8, 0x00, 0x5b, 0x00, 0xb5, 0xba,
 	  0xb1, 0xc4, 0x00, 0x6e, 0x00, 0xae, 0xb9, 0xb0, 0xc5, 0x00, 0x75 },
 	{ 0xf9, 0x00, 0x82, 0xba, 0xb4, 0xc7, 0x00, 0x5f, 0x00, 0xb5, 0xba,
 	  0xb0, 0xc3, 0x00, 0x72, 0x00, 0xae, 0xb8, 0xb0, 0xc3, 0x00, 0x7a },
 	{ 0xf9, 0x00, 0x89, 0xba, 0xb3, 0xc8, 0x00, 0x62, 0x00, 0xb6, 0xba,
 	  0xaf, 0xc3, 0x00, 0x76, 0x00, 0xaf, 0xb7, 0xae, 0xc4, 0x00, 0x7e },
 	{ 0xf9, 0x00, 0x8b, 0xb9, 0xb3, 0xc7, 0x00, 0x65, 0x00, 0xb7, 0xb8,
 	  0xaf, 0xc3, 0x00, 0x7a, 0x00, 0x80, 0xb6, 0xae, 0xc4, 0x00, 0x81 },
 	{ 0xf9, 0x00, 0x93, 0xba, 0xb3, 0xc5, 0x00, 0x69, 0x00, 0xb8, 0xb9,
 	  0xae, 0xc1, 0x00, 0x7f, 0x00, 0xb0, 0xb6, 0xae, 0xc3, 0x00, 0x85 },
 	{ 0xf9, 0x00, 0x97, 0xba, 0xb2, 0xc5, 0x00, 0x6c, 0x00, 0xb8, 0xb8,
 	  0xae, 0xc1, 0x00, 0x82, 0x00, 0xb0, 0xb6, 0xae, 0xc2, 0x00, 0x89 },
 	{ 0xf9, 0x00, 0x9a, 0xba, 0xb1, 0xc4, 0x00, 0x6f, 0x00, 0xb8, 0xb8,
 	  0xad, 0xc0, 0x00, 0x86, 0x00, 0xb0, 0xb7, 0xad, 0xc0, 0x00, 0x8d },
 	{ 0xf9, 0x00, 0x9c, 0xb9, 0xb0, 0xc4, 0x00, 0x72, 0x00, 0xb8, 0xb8,
 	  0xac, 0xbf, 0x00, 0x8a, 0x00, 0xb0, 0xb6, 0xac, 0xc0, 0x00, 0x91 },
 	{ 0xf9, 0x00, 0x9e, 0xba, 0xb0, 0xc2, 0x00, 0x75, 0x00, 0xb9, 0xb8,
 	  0xab, 0xbe, 0x00, 0x8e, 0x00, 0xb0, 0xb6, 0xac, 0xbf, 0x00, 0x94 },
 	{ 0xf9, 0x00, 0xa0, 0xb9, 0xaf, 0xc3, 0x00, 0x77, 0x00, 0xb9, 0xb7,
 	  0xab, 0xbe, 0x00, 0x90, 0x00, 0xb0, 0xb6, 0xab, 0xbf, 0x00, 0x97 },
 	{ 0xf9, 0x00, 0xa2, 0xb9, 0xaf, 0xc2, 0x00, 0x7a, 0x00, 0xb9, 0xb7,
 	  0xaa, 0xbd, 0x00, 0x94, 0x00, 0xb0, 0xb5, 0xab, 0xbf, 0x00, 0x9a },
 	{ 0xf9, 0x00, 0xa4, 0xb9, 0xaf, 0xc1, 0x00, 0x7d, 0x00, 0xb9, 0xb6,
 	  0xaa, 0xbb, 0x00, 0x97, 0x00, 0xb1, 0xb5, 0xaa, 0xbf, 0x00, 0x9d },
 	{ 0xf9, 0x00, 0xa4, 0xb8, 0xb0, 0xbf, 0x00, 0x80, 0x00, 0xb8, 0xb6,
 	  0xaa, 0xbc, 0x00, 0x9a, 0x00, 0xb0, 0xb5, 0xab, 0xbd, 0x00, 0xa0 },
 	{ 0xf9, 0x00, 0xa8, 0xb8, 0xae, 0xbe, 0x00, 0x84, 0x00, 0xb9, 0xb7,
 	  0xa8, 0xbc, 0x00, 0x9d, 0x00, 0xb2, 0xb5, 0xaa, 0xbc, 0x00, 0xa4 },
 	{ 0xf9, 0x00, 0xa9, 0xb6, 0xad, 0xbf, 0x00, 0x86, 0x00, 0xb8, 0xb5,
 	  0xa8, 0xbc, 0x00, 0xa0, 0x00, 0xb3, 0xb3, 0xa9, 0xbc, 0x00, 0xa7 },
 	{ 0xf9, 0x00, 0xa9, 0xb7, 0xae, 0xbd, 0x00, 0x89, 0x00, 0xb7, 0xb6,
 	  0xa8, 0xba, 0x00, 0xa4, 0x00, 0xb1, 0xb4, 0xaa, 0xbb, 0x00, 0xaa },
 	{ 0xf9, 0x00, 0xa7, 0xb4, 0xae, 0xbf, 0x00, 0x91, 0x00, 0xb2, 0xb4,
 	  0xaa, 0xbb, 0x00, 0xac, 0x00, 0xb3, 0xb1, 0xaa, 0xbc, 0x00, 0xb3 },
 };

 struct ld9040 {
 	struct device *dev;
 	struct drm_panel panel;

 	struct regulator_bulk_data supplies[2];
 	struct gpio_desc *reset_gpio;
 	u32 power_on_delay;
 	u32 reset_delay;
 	struct videomode vm;
 	u32 width_mm;
 	u32 height_mm;

 	int brightness;

 	/* This field is tested by functions directly accessing bus before
 	 * transfer, transfer is skipped if it is set. In case of transfer
 	 * failure or unexpected response the field is set to error value.
 	 * Such construct allows to eliminate many checks in higher level
 	 * functions.
 	 */
 	int error;
 };

 #define panel_to_ld9040(p) container_of(p, struct ld9040, panel)

 static int ld9040_clear_error(struct ld9040 *ctx)
 {
 	int ret = ctx->error;

 	ctx->error = 0;
 	return ret;
 }

 static int ld9040_spi_write_word(struct ld9040 *ctx, u16 data)
 {
 	struct spi_device *spi = to_spi_device(ctx->dev);
 	struct spi_transfer xfer = {
 		.len		= 2,
 		.tx_buf		= &data,
 	};
 	struct spi_message msg;

 	spi_message_init(&msg);
 	spi_message_add_tail(&xfer, &msg);

 	return spi_sync(spi, &msg);
 }

 static void ld9040_dcs_write(struct ld9040 *ctx, const u8 *data, size_t len)
 {
 	int ret = 0;

 	if (ctx->error < 0 || len == 0)
 		return;

 	dev_dbg(ctx->dev, "writing dcs seq: %*ph\n", len, data);
 	ret = ld9040_spi_write_word(ctx, *data);

 	while (!ret && --len) {
 		++data;
 		ret = ld9040_spi_write_word(ctx, *data | 0x100);
 	}

 	if (ret) {
 		dev_err(ctx->dev, "error %d writing dcs seq: %*ph\n", ret, len,
 			data);
 		ctx->error = ret;
 	}

 	usleep_range(300, 310);
 }

 #define ld9040_dcs_write_seq_static(ctx, seq...) \
 ({\
 	static const u8 d[] = { seq };\
 	ld9040_dcs_write(ctx, d, ARRAY_SIZE(d));\
 })

 static void ld9040_brightness_set(struct ld9040 *ctx)
 {
 	ld9040_dcs_write(ctx, ld9040_gammas[ctx->brightness],
 			 ARRAY_SIZE(ld9040_gammas[ctx->brightness]));

 	ld9040_dcs_write_seq_static(ctx, MCS_GAMMA_CTRL, 0x02, 0x5a);
 }

 static void ld9040_init(struct ld9040 *ctx)
 {
 	ld9040_dcs_write_seq_static(ctx, MCS_USER_SETTING, 0x5a, 0x5a);
 	ld9040_dcs_write_seq_static(ctx, MCS_PANEL_CONDITION,
 		0x05, 0x65, 0x96, 0x71, 0x7d, 0x19, 0x3b, 0x0d,
 		0x19, 0x7e, 0x0d, 0xe2, 0x00, 0x00, 0x7e, 0x7d,
 		0x07, 0x07, 0x20, 0x20, 0x20, 0x02, 0x02);
 	ld9040_dcs_write_seq_static(ctx, MCS_DISPCTL,
 		0x02, 0x08, 0x08, 0x10, 0x10);
 	ld9040_dcs_write_seq_static(ctx, MCS_MANPWR, 0x04);
 	ld9040_dcs_write_seq_static(ctx, MCS_ELVSS_ON, 0x0d, 0x00, 0x16);
 	ld9040_dcs_write_seq_static(ctx, MCS_GTCON, 0x09, 0x00, 0x00);
 	ld9040_brightness_set(ctx);
 	ld9040_dcs_write_seq_static(ctx, MIPI_DCS_EXIT_SLEEP_MODE);
 	ld9040_dcs_write_seq_static(ctx, MIPI_DCS_SET_DISPLAY_ON);
 }

 static int ld9040_power_on(struct ld9040 *ctx)
 {
 	int ret;

 	ret = regulator_bulk_enable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
 	if (ret < 0)
 		return ret;

 	msleep(ctx->power_on_delay);
 	gpiod_set_value(ctx->reset_gpio, 0);
 	msleep(ctx->reset_delay);
 	gpiod_set_value(ctx->reset_gpio, 1);
 	msleep(ctx->reset_delay);

 	return 0;
 }

 static int ld9040_power_off(struct ld9040 *ctx)
 {
 	return regulator_bulk_disable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
 }

 static int ld9040_disable(struct drm_panel *panel)
 {
 	struct ld9040 *ctx = panel_to_ld9040(panel);

 	msleep(120);
 	ld9040_dcs_write_seq_static(ctx, MIPI_DCS_SET_DISPLAY_OFF);
 	ld9040_dcs_write_seq_static(ctx, MIPI_DCS_ENTER_SLEEP_MODE);
 	msleep(40);

 	ld9040_clear_error(ctx);

 	return ld9040_power_off(ctx);
 }

 static int ld9040_enable(struct drm_panel *panel)
 {
 	struct ld9040 *ctx = panel_to_ld9040(panel);
 	int ret;

 	ret = ld9040_power_on(ctx);
 	if (ret < 0)
 		return ret;

 	ld9040_init(ctx);

 	ret = ld9040_clear_error(ctx);

 	if (ret < 0)
 		ld9040_disable(panel);

 	return ret;
 }

 static int ld9040_get_modes(struct drm_panel *panel)
 {
 	struct drm_connector *connector = panel->connector;
 	struct ld9040 *ctx = panel_to_ld9040(panel);
 	struct drm_display_mode *mode;

 	mode = drm_mode_create(connector->dev);
 	if (!mode) {
 		DRM_ERROR("failed to create a new display mode\n");
 		return 0;
 	}

 	drm_display_mode_from_videomode(&ctx->vm, mode);
 	mode->width_mm = ctx->width_mm;
 	mode->height_mm = ctx->height_mm;
 	connector->display_info.width_mm = mode->width_mm;
 	connector->display_info.height_mm = mode->height_mm;

 	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
 	drm_mode_probed_add(connector, mode);

 	return 1;
 }

 static const struct drm_panel_funcs ld9040_drm_funcs = {
 	.disable = ld9040_disable,
 	.enable = ld9040_enable,
 	.get_modes = ld9040_get_modes,
 };

 static int ld9040_parse_dt(struct ld9040 *ctx)
 {
 	struct device *dev = ctx->dev;
 	struct device_node *np = dev->of_node;
 	int ret;

 	ret = of_get_videomode(np, &ctx->vm, 0);
 	if (ret < 0)
 		return ret;

 	of_property_read_u32(np, "power-on-delay", &ctx->power_on_delay);
 	of_property_read_u32(np, "reset-delay", &ctx->reset_delay);
 	of_property_read_u32(np, "panel-width-mm", &ctx->width_mm);
 	of_property_read_u32(np, "panel-height-mm", &ctx->height_mm);

 	return 0;
 }

 static int ld9040_probe(struct spi_device *spi)
 {
 	struct device *dev = &spi->dev;
 	struct ld9040 *ctx;
 	int ret;

 	ctx = devm_kzalloc(dev, sizeof(struct ld9040), GFP_KERNEL);
 	if (!ctx)
 		return -ENOMEM;

 	spi_set_drvdata(spi, ctx);

 	ctx->dev = dev;
 	ctx->brightness = ARRAY_SIZE(ld9040_gammas) - 1;

 	ret = ld9040_parse_dt(ctx);
 	if (ret < 0)
 		return ret;

 	ctx->supplies[0].supply = "vdd3";
 	ctx->supplies[1].supply = "vci";
 	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(ctx->supplies),
 				      ctx->supplies);
 	if (ret < 0)
 		return ret;

 	ctx->reset_gpio = devm_gpiod_get(dev, "reset");
 	if (IS_ERR(ctx->reset_gpio)) {
 		dev_err(dev, "cannot get reset-gpios %ld\n",
 			PTR_ERR(ctx->reset_gpio));
 		return PTR_ERR(ctx->reset_gpio);
 	}
 	ret = gpiod_direction_output(ctx->reset_gpio, 1);
 	if (ret < 0) {
 		dev_err(dev, "cannot configure reset-gpios %d\n", ret);
 		return ret;
 	}

 	spi->bits_per_word = 9;
 	ret = spi_setup(spi);
 	if (ret < 0) {
 		dev_err(dev, "spi setup failed.\n");
 		return ret;
 	}

 	drm_panel_init(&ctx->panel);
 	ctx->panel.dev = dev;
 	ctx->panel.funcs = &ld9040_drm_funcs;

 	return drm_panel_add(&ctx->panel);
 }

 static int ld9040_remove(struct spi_device *spi)
 {
 	struct ld9040 *ctx = spi_get_drvdata(spi);

 	ld9040_power_off(ctx);
 	drm_panel_remove(&ctx->panel);

 	return 0;
 }

 static struct of_device_id ld9040_of_match[] = {
 	{ .compatible = "samsung,ld9040" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, ld9040_of_match);

 static struct spi_driver ld9040_driver = {
 	.probe		= ld9040_probe,
 	.remove		= ld9040_remove,
 	.driver = {
 		.name	= "ld9040",
 		.owner	= THIS_MODULE,
 		.of_match_table = ld9040_of_match,
 	},
 };
 module_spi_driver(ld9040_driver);

 MODULE_AUTHOR("Andrzej Hajda <a.hajda@samsung.com>");
 MODULE_DESCRIPTION("ld9040 LCD Driver");
 MODULE_LICENSE("GPL v2");
	/*
	* ld9040 AMOLED LCD drm_panel driver.
	*
	* Copyright (c) 2014 Samsung Electronics Co., Ltd
	* Derived from drivers/video/backlight/ld9040.c
	*
	* Andrzej Hajda <a.hajda@samsung.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <drm/drmP.h>
	#include <drm/drm_panel.h>

	#include <linux/gpio/consumer.h>
	#include <linux/regulator/consumer.h>
	#include <linux/spi/spi.h>

	#include <video/mipi_display.h>
	#include <video/of_videomode.h>
	#include <video/videomode.h>

	/* Manufacturer Command Set */
	#define MCS_MANPWR 0xb0
	#define MCS_ELVSS_ON 0xb1
	#define MCS_USER_SETTING 0xf0
	#define MCS_DISPCTL 0xf2
	#define MCS_GTCON 0xf7
	#define MCS_PANEL_CONDITION 0xf8
	#define MCS_GAMMA_SET1 0xf9
	#define MCS_GAMMA_CTRL 0xfb

	/* array of gamma tables for gamma value 2.2 */
	static u8 const ld9040_gammas[25][22] = {
	{ 0xf9, 0x00, 0x13, 0xb2, 0xba, 0xd2, 0x00, 0x30, 0x00, 0xaf, 0xc0,
	0xb8, 0xcd, 0x00, 0x3d, 0x00, 0xa8, 0xb8, 0xb7, 0xcd, 0x00, 0x44 },
	{ 0xf9, 0x00, 0x13, 0xb9, 0xb9, 0xd0, 0x00, 0x3c, 0x00, 0xaf, 0xbf,
	0xb6, 0xcb, 0x00, 0x4b, 0x00, 0xa8, 0xb9, 0xb5, 0xcc, 0x00, 0x52 },
	{ 0xf9, 0x00, 0x13, 0xba, 0xb9, 0xcd, 0x00, 0x41, 0x00, 0xb0, 0xbe,
	0xb5, 0xc9, 0x00, 0x51, 0x00, 0xa9, 0xb9, 0xb5, 0xca, 0x00, 0x57 },
	{ 0xf9, 0x00, 0x13, 0xb9, 0xb8, 0xcd, 0x00, 0x46, 0x00, 0xb1, 0xbc,
	0xb5, 0xc8, 0x00, 0x56, 0x00, 0xaa, 0xb8, 0xb4, 0xc9, 0x00, 0x5d },
	{ 0xf9, 0x00, 0x13, 0xba, 0xb8, 0xcb, 0x00, 0x4b, 0x00, 0xb3, 0xbc,
	0xb4, 0xc7, 0x00, 0x5c, 0x00, 0xac, 0xb8, 0xb4, 0xc8, 0x00, 0x62 },
	{ 0xf9, 0x00, 0x13, 0xbb, 0xb7, 0xca, 0x00, 0x4f, 0x00, 0xb4, 0xbb,
	0xb3, 0xc7, 0x00, 0x60, 0x00, 0xad, 0xb8, 0xb4, 0xc7, 0x00, 0x67 },
	{ 0xf9, 0x00, 0x47, 0xba, 0xb6, 0xca, 0x00, 0x53, 0x00, 0xb5, 0xbb,
	0xb3, 0xc6, 0x00, 0x65, 0x00, 0xae, 0xb8, 0xb3, 0xc7, 0x00, 0x6c },
	{ 0xf9, 0x00, 0x71, 0xbb, 0xb5, 0xc8, 0x00, 0x57, 0x00, 0xb5, 0xbb,
	0xb0, 0xc5, 0x00, 0x6a, 0x00, 0xae, 0xb9, 0xb1, 0xc6, 0x00, 0x70 },
	{ 0xf9, 0x00, 0x7b, 0xbb, 0xb4, 0xc8, 0x00, 0x5b, 0x00, 0xb5, 0xba,
	0xb1, 0xc4, 0x00, 0x6e, 0x00, 0xae, 0xb9, 0xb0, 0xc5, 0x00, 0x75 },
	{ 0xf9, 0x00, 0x82, 0xba, 0xb4, 0xc7, 0x00, 0x5f, 0x00, 0xb5, 0xba,
	0xb0, 0xc3, 0x00, 0x72, 0x00, 0xae, 0xb8, 0xb0, 0xc3, 0x00, 0x7a },
	{ 0xf9, 0x00, 0x89, 0xba, 0xb3, 0xc8, 0x00, 0x62, 0x00, 0xb6, 0xba,
	0xaf, 0xc3, 0x00, 0x76, 0x00, 0xaf, 0xb7, 0xae, 0xc4, 0x00, 0x7e },
	{ 0xf9, 0x00, 0x8b, 0xb9, 0xb3, 0xc7, 0x00, 0x65, 0x00, 0xb7, 0xb8,
	0xaf, 0xc3, 0x00, 0x7a, 0x00, 0x80, 0xb6, 0xae, 0xc4, 0x00, 0x81 },
	{ 0xf9, 0x00, 0x93, 0xba, 0xb3, 0xc5, 0x00, 0x69, 0x00, 0xb8, 0xb9,
	0xae, 0xc1, 0x00, 0x7f, 0x00, 0xb0, 0xb6, 0xae, 0xc3, 0x00, 0x85 },
	{ 0xf9, 0x00, 0x97, 0xba, 0xb2, 0xc5, 0x00, 0x6c, 0x00, 0xb8, 0xb8,
	0xae, 0xc1, 0x00, 0x82, 0x00, 0xb0, 0xb6, 0xae, 0xc2, 0x00, 0x89 },
	{ 0xf9, 0x00, 0x9a, 0xba, 0xb1, 0xc4, 0x00, 0x6f, 0x00, 0xb8, 0xb8,
	0xad, 0xc0, 0x00, 0x86, 0x00, 0xb0, 0xb7, 0xad, 0xc0, 0x00, 0x8d },
	{ 0xf9, 0x00, 0x9c, 0xb9, 0xb0, 0xc4, 0x00, 0x72, 0x00, 0xb8, 0xb8,
	0xac, 0xbf, 0x00, 0x8a, 0x00, 0xb0, 0xb6, 0xac, 0xc0, 0x00, 0x91 },
	{ 0xf9, 0x00, 0x9e, 0xba, 0xb0, 0xc2, 0x00, 0x75, 0x00, 0xb9, 0xb8,
	0xab, 0xbe, 0x00, 0x8e, 0x00, 0xb0, 0xb6, 0xac, 0xbf, 0x00, 0x94 },
	{ 0xf9, 0x00, 0xa0, 0xb9, 0xaf, 0xc3, 0x00, 0x77, 0x00, 0xb9, 0xb7,
	0xab, 0xbe, 0x00, 0x90, 0x00, 0xb0, 0xb6, 0xab, 0xbf, 0x00, 0x97 },
	{ 0xf9, 0x00, 0xa2, 0xb9, 0xaf, 0xc2, 0x00, 0x7a, 0x00, 0xb9, 0xb7,
	0xaa, 0xbd, 0x00, 0x94, 0x00, 0xb0, 0xb5, 0xab, 0xbf, 0x00, 0x9a },
	{ 0xf9, 0x00, 0xa4, 0xb9, 0xaf, 0xc1, 0x00, 0x7d, 0x00, 0xb9, 0xb6,
	0xaa, 0xbb, 0x00, 0x97, 0x00, 0xb1, 0xb5, 0xaa, 0xbf, 0x00, 0x9d },
	{ 0xf9, 0x00, 0xa4, 0xb8, 0xb0, 0xbf, 0x00, 0x80, 0x00, 0xb8, 0xb6,
	0xaa, 0xbc, 0x00, 0x9a, 0x00, 0xb0, 0xb5, 0xab, 0xbd, 0x00, 0xa0 },
	{ 0xf9, 0x00, 0xa8, 0xb8, 0xae, 0xbe, 0x00, 0x84, 0x00, 0xb9, 0xb7,
	0xa8, 0xbc, 0x00, 0x9d, 0x00, 0xb2, 0xb5, 0xaa, 0xbc, 0x00, 0xa4 },
	{ 0xf9, 0x00, 0xa9, 0xb6, 0xad, 0xbf, 0x00, 0x86, 0x00, 0xb8, 0xb5,
	0xa8, 0xbc, 0x00, 0xa0, 0x00, 0xb3, 0xb3, 0xa9, 0xbc, 0x00, 0xa7 },
	{ 0xf9, 0x00, 0xa9, 0xb7, 0xae, 0xbd, 0x00, 0x89, 0x00, 0xb7, 0xb6,
	0xa8, 0xba, 0x00, 0xa4, 0x00, 0xb1, 0xb4, 0xaa, 0xbb, 0x00, 0xaa },
	{ 0xf9, 0x00, 0xa7, 0xb4, 0xae, 0xbf, 0x00, 0x91, 0x00, 0xb2, 0xb4,
	0xaa, 0xbb, 0x00, 0xac, 0x00, 0xb3, 0xb1, 0xaa, 0xbc, 0x00, 0xb3 },
	};

	struct ld9040 {
	struct device *dev;
	struct drm_panel panel;

	struct regulator_bulk_data supplies[2];
	struct gpio_desc *reset_gpio;
	u32 power_on_delay;
	u32 reset_delay;
	struct videomode vm;
	u32 width_mm;
	u32 height_mm;

	int brightness;

	/* This field is tested by functions directly accessing bus before
	* transfer, transfer is skipped if it is set. In case of transfer
	* failure or unexpected response the field is set to error value.
	* Such construct allows to eliminate many checks in higher level
	* functions.
	*/
	int error;
	};

	#define panel_to_ld9040(p) container_of(p, struct ld9040, panel)

	static int ld9040_clear_error(struct ld9040 *ctx)
	{
	int ret = ctx->error;

	ctx->error = 0;
	return ret;
	}

	static int ld9040_spi_write_word(struct ld9040 *ctx, u16 data)
	{
	struct spi_device *spi = to_spi_device(ctx->dev);
	struct spi_transfer xfer = {
	.len = 2,
	.tx_buf = &data,
	};
	struct spi_message msg;

	spi_message_init(&msg);
	spi_message_add_tail(&xfer, &msg);

	return spi_sync(spi, &msg);
	}

	static void ld9040_dcs_write(struct ld9040 ctx, const u8 data, size_t len)
	{
	int ret = 0;

	if (ctx->error < 0 \|\| len == 0)
	return;

	dev_dbg(ctx->dev, "writing dcs seq: %*ph\n", len, data);
	ret = ld9040_spi_write_word(ctx, *data);

	while (!ret && --len) {
	++data;
	ret = ld9040_spi_write_word(ctx, *data \| 0x100);
	}

	if (ret) {
	dev_err(ctx->dev, "error %d writing dcs seq: %*ph\n", ret, len,
	data);
	ctx->error = ret;
	}

	usleep_range(300, 310);
	}

	#define ld9040_dcs_write_seq_static(ctx, seq...) \
	({\
	static const u8 d[] = { seq };\
	ld9040_dcs_write(ctx, d, ARRAY_SIZE(d));\
	})

	static void ld9040_brightness_set(struct ld9040 *ctx)
	{
	ld9040_dcs_write(ctx, ld9040_gammas[ctx->brightness],
	ARRAY_SIZE(ld9040_gammas[ctx->brightness]));

	ld9040_dcs_write_seq_static(ctx, MCS_GAMMA_CTRL, 0x02, 0x5a);
	}

	static void ld9040_init(struct ld9040 *ctx)
	{
	ld9040_dcs_write_seq_static(ctx, MCS_USER_SETTING, 0x5a, 0x5a);
	ld9040_dcs_write_seq_static(ctx, MCS_PANEL_CONDITION,
	0x05, 0x65, 0x96, 0x71, 0x7d, 0x19, 0x3b, 0x0d,
	0x19, 0x7e, 0x0d, 0xe2, 0x00, 0x00, 0x7e, 0x7d,
	0x07, 0x07, 0x20, 0x20, 0x20, 0x02, 0x02);
	ld9040_dcs_write_seq_static(ctx, MCS_DISPCTL,
	0x02, 0x08, 0x08, 0x10, 0x10);
	ld9040_dcs_write_seq_static(ctx, MCS_MANPWR, 0x04);
	ld9040_dcs_write_seq_static(ctx, MCS_ELVSS_ON, 0x0d, 0x00, 0x16);
	ld9040_dcs_write_seq_static(ctx, MCS_GTCON, 0x09, 0x00, 0x00);
	ld9040_brightness_set(ctx);
	ld9040_dcs_write_seq_static(ctx, MIPI_DCS_EXIT_SLEEP_MODE);
	ld9040_dcs_write_seq_static(ctx, MIPI_DCS_SET_DISPLAY_ON);
	}

	static int ld9040_power_on(struct ld9040 *ctx)
	{
	int ret;

	ret = regulator_bulk_enable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
	if (ret < 0)
	return ret;

	msleep(ctx->power_on_delay);
	gpiod_set_value(ctx->reset_gpio, 0);
	msleep(ctx->reset_delay);
	gpiod_set_value(ctx->reset_gpio, 1);
	msleep(ctx->reset_delay);

	return 0;
	}

	static int ld9040_power_off(struct ld9040 *ctx)
	{
	return regulator_bulk_disable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
	}

	static int ld9040_disable(struct drm_panel *panel)
	{
	struct ld9040 *ctx = panel_to_ld9040(panel);

	msleep(120);
	ld9040_dcs_write_seq_static(ctx, MIPI_DCS_SET_DISPLAY_OFF);
	ld9040_dcs_write_seq_static(ctx, MIPI_DCS_ENTER_SLEEP_MODE);
	msleep(40);

	ld9040_clear_error(ctx);

	return ld9040_power_off(ctx);
	}

	static int ld9040_enable(struct drm_panel *panel)
	{
	struct ld9040 *ctx = panel_to_ld9040(panel);
	int ret;

	ret = ld9040_power_on(ctx);
	if (ret < 0)
	return ret;

	ld9040_init(ctx);

	ret = ld9040_clear_error(ctx);

	if (ret < 0)
	ld9040_disable(panel);

	return ret;
	}

	static int ld9040_get_modes(struct drm_panel *panel)
	{
	struct drm_connector *connector = panel->connector;
	struct ld9040 *ctx = panel_to_ld9040(panel);
	struct drm_display_mode *mode;

	mode = drm_mode_create(connector->dev);
	if (!mode) {
	DRM_ERROR("failed to create a new display mode\n");
	return 0;
	}

	drm_display_mode_from_videomode(&ctx->vm, mode);
	mode->width_mm = ctx->width_mm;
	mode->height_mm = ctx->height_mm;
	connector->display_info.width_mm = mode->width_mm;
	connector->display_info.height_mm = mode->height_mm;

	mode->type = DRM_MODE_TYPE_DRIVER \| DRM_MODE_TYPE_PREFERRED;
	drm_mode_probed_add(connector, mode);

	return 1;
	}

	static const struct drm_panel_funcs ld9040_drm_funcs = {
	.disable = ld9040_disable,
	.enable = ld9040_enable,
	.get_modes = ld9040_get_modes,
	};

	static int ld9040_parse_dt(struct ld9040 *ctx)
	{
	struct device *dev = ctx->dev;
	struct device_node *np = dev->of_node;
	int ret;

	ret = of_get_videomode(np, &ctx->vm, 0);
	if (ret < 0)
	return ret;

	of_property_read_u32(np, "power-on-delay", &ctx->power_on_delay);
	of_property_read_u32(np, "reset-delay", &ctx->reset_delay);
	of_property_read_u32(np, "panel-width-mm", &ctx->width_mm);
	of_property_read_u32(np, "panel-height-mm", &ctx->height_mm);

	return 0;
	}

	static int ld9040_probe(struct spi_device *spi)
	{
	struct device *dev = &spi->dev;
	struct ld9040 *ctx;
	int ret;

	ctx = devm_kzalloc(dev, sizeof(struct ld9040), GFP_KERNEL);
	if (!ctx)
	return -ENOMEM;

	spi_set_drvdata(spi, ctx);

	ctx->dev = dev;
	ctx->brightness = ARRAY_SIZE(ld9040_gammas) - 1;

	ret = ld9040_parse_dt(ctx);
	if (ret < 0)
	return ret;

	ctx->supplies[0].supply = "vdd3";
	ctx->supplies[1].supply = "vci";
	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(ctx->supplies),
	ctx->supplies);
	if (ret < 0)
	return ret;

	ctx->reset_gpio = devm_gpiod_get(dev, "reset");
	if (IS_ERR(ctx->reset_gpio)) {
	dev_err(dev, "cannot get reset-gpios %ld\n",
	PTR_ERR(ctx->reset_gpio));
	return PTR_ERR(ctx->reset_gpio);
	}
	ret = gpiod_direction_output(ctx->reset_gpio, 1);
	if (ret < 0) {
	dev_err(dev, "cannot configure reset-gpios %d\n", ret);
	return ret;
	}

	spi->bits_per_word = 9;
	ret = spi_setup(spi);
	if (ret < 0) {
	dev_err(dev, "spi setup failed.\n");
	return ret;
	}

	drm_panel_init(&ctx->panel);
	ctx->panel.dev = dev;
	ctx->panel.funcs = &ld9040_drm_funcs;

	return drm_panel_add(&ctx->panel);
	}

	static int ld9040_remove(struct spi_device *spi)
	{
	struct ld9040 *ctx = spi_get_drvdata(spi);

	ld9040_power_off(ctx);
	drm_panel_remove(&ctx->panel);

	return 0;
	}

	static struct of_device_id ld9040_of_match[] = {
	{ .compatible = "samsung,ld9040" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, ld9040_of_match);

	static struct spi_driver ld9040_driver = {
	.probe = ld9040_probe,
	.remove = ld9040_remove,
	.driver = {
	.name = "ld9040",
	.owner = THIS_MODULE,
	.of_match_table = ld9040_of_match,
	},
	};
	module_spi_driver(ld9040_driver);

	MODULE_AUTHOR("Andrzej Hajda <a.hajda@samsung.com>");
	MODULE_DESCRIPTION("ld9040 LCD Driver");
	MODULE_LICENSE("GPL v2");