Null Pointer Function

panel-samsung-ams495qa01.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Samsung ams495qa01 MIPI-DSI panel driver
 * Copyright (C) 2022 Chris Morgan
 */

#include <drm/drm_mipi_dbi.h>
#include <drm/drm_mipi_dsi.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/of.h>
#include <linux/of_device.h>
#include <linux/of_graph.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>

#include <video/mipi_display.h>

struct ams495qa01_panel_info {
	/** @display_modes: the supported display modes */
	const struct drm_display_mode *display_modes;
	/** @num_modes: the number of supported display modes */
	unsigned int num_modes;
	/** @width_mm: panel width in mm */
	u16 width_mm;
	/** @height_mm: panel height in mm */
	u16 height_mm;
	/** @bus_flags: drm bus flags for panel */
	u32 bus_flags;
};

struct ams495qa01 {
	/** @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;
	/** @reset: reset GPIO line */
	struct gpio_desc *reset;
	/** @enable: enable GPIO line */
	struct gpio_desc *enable;
	/** @reg_vdd: VDD supply regulator for panel logic */
	struct regulator *reg_vdd;
	/** @reg_elvdd: ELVDD supply regulator for panel display */
	struct regulator *reg_elvdd;
	/** @dsi_dev: DSI child device (panel) */
	struct mipi_dsi_device *dsi_dev;
	/** @bl_dev: pseudo-backlight device for oled panel */
	struct backlight_device *bl_dev;
	/** @panel_info: struct containing panel timing and info */
	const struct ams495qa01_panel_info *panel_info;
};

#define NUM_GAMMA_LEVELS	16
#define GAMMA_TABLE_COUNT	23
#define MAX_BRIGHTNESS		(NUM_GAMMA_LEVELS - 1)

/* Table of gamma values provided in datasheet */
static u8 ams495qa01_gamma[NUM_GAMMA_LEVELS][GAMMA_TABLE_COUNT] = {
	{0x01, 0x79, 0x78, 0x8d, 0xd9, 0xdf, 0xd5, 0xcb, 0xcf, 0xc5,
	 0xe5, 0xe0, 0xe4, 0xdc, 0xb8, 0xd4, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x7d, 0x7c, 0x92, 0xd7, 0xdd, 0xd2, 0xcb, 0xd0, 0xc6,
	 0xe5, 0xe1, 0xe3, 0xda, 0xbd, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x7f, 0x7e, 0x95, 0xd7, 0xde, 0xd2, 0xcb, 0xcf, 0xc5,
	 0xe5, 0xe3, 0xe3, 0xda, 0xbf, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x82, 0x81, 0x99, 0xd6, 0xdd, 0xd1, 0xca, 0xcf, 0xc3,
	 0xe4, 0xe3, 0xe3, 0xda, 0xc2, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x84, 0x83, 0x9b, 0xd7, 0xde, 0xd2, 0xc8, 0xce, 0xc2,
	 0xe4, 0xe3, 0xe2, 0xd9, 0xc3, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x87, 0x86, 0x9f, 0xd6, 0xdd, 0xd1, 0xc7, 0xce, 0xc1,
	 0xe4, 0xe3, 0xe2, 0xd9, 0xc6, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x89, 0x89, 0xa2, 0xd5, 0xdb, 0xcf, 0xc8, 0xcf, 0xc2,
	 0xe3, 0xe3, 0xe1, 0xd9, 0xc7, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x8b, 0x8b, 0xa5, 0xd5, 0xdb, 0xcf, 0xc7, 0xce, 0xc0,
	 0xe3, 0xe3, 0xe1, 0xd8, 0xc7, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x8d, 0x8d, 0xa7, 0xd5, 0xdb, 0xcf, 0xc6, 0xce, 0xc0,
	 0xe4, 0xe4, 0xe1, 0xd7, 0xc8, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x8f, 0x8f, 0xaa, 0xd4, 0xdb, 0xce, 0xc6, 0xcd, 0xbf,
	 0xe3, 0xe3, 0xe1, 0xd7, 0xca, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x91, 0x91, 0xac, 0xd3, 0xda, 0xce, 0xc5, 0xcd, 0xbe,
	 0xe3, 0xe3, 0xe0, 0xd7, 0xca, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x93, 0x93, 0xaf, 0xd3, 0xda, 0xcd, 0xc5, 0xcd, 0xbe,
	 0xe2, 0xe3, 0xdf, 0xd6, 0xca, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x95, 0x95, 0xb1, 0xd2, 0xd9, 0xcc, 0xc4, 0xcd, 0xbe,
	 0xe2, 0xe3, 0xdf, 0xd7, 0xcc, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x99, 0x99, 0xb6, 0xd1, 0xd9, 0xcc, 0xc3, 0xcb, 0xbc,
	 0xe2, 0xe4, 0xdf, 0xd6, 0xcc, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x9c, 0x9c, 0xba, 0xd0, 0xd8, 0xcb, 0xc3, 0xcb, 0xbb,
	 0xe2, 0xe4, 0xdf, 0xd6, 0xce, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
	{0x01, 0x9f, 0x9f, 0xbe, 0xcf, 0xd7, 0xc9, 0xc2, 0xcb, 0xbb,
	 0xe1, 0xe3, 0xde, 0xd6, 0xd0, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
	 0x00, 0x2f},
};

/*
 * Table of elvss values provided in datasheet and corresponds to
 * gamma values.
 */
static u8 ams495qa01_elvss[NUM_GAMMA_LEVELS] = {
	0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x15,
	0x15, 0x15, 0x14, 0x14, 0x13, 0x12,
};

static inline struct ams495qa01 *to_ams495qa01(struct drm_panel *panel)
{
	return container_of(panel, struct ams495qa01, panel);
}

static int ams495qa01_update_gamma(struct mipi_dbi *dbi, u32 brightness)
{
	u32 tmp = brightness;

	/* Set gamma values */
	mipi_dbi_command_buf(dbi, 0xf9, ams495qa01_gamma[tmp],
			     ARRAY_SIZE(ams495qa01_gamma[tmp]));
	/* Set gamma change */
	mipi_dbi_command(dbi, 0xf9, 0x00);
	/* Undocumented command */
	mipi_dbi_command(dbi, 0x26, 0x00);
	/* Set ELVSS value */
	mipi_dbi_command(dbi, 0xb2, ams495qa01_elvss[tmp]);

	return 0;
}

static int ams495qa01_prepare(struct drm_panel *panel)
{
	struct ams495qa01 *db = to_ams495qa01(panel);
	struct mipi_dbi *dbi = &db->dbi;
	int ret;

	/* Power up */
	ret = regulator_enable(db->reg_vdd);
	if (ret) {
		dev_err(db->dev, "failed to enable vdd regulator: %d\n", ret);
		return ret;
	}

	if (db->reg_elvdd) {
		ret = regulator_enable(db->reg_elvdd);
		if (ret) {
			dev_err(db->dev,
				"failed to enable elvdd regulator: %d\n", ret);
			regulator_disable(db->reg_vdd);
			return ret;
		}
	}

	/* Enable */
	if (db->enable)
		gpiod_set_value_cansleep(db->enable, 1);

	msleep(50);

	/* Reset */
	gpiod_set_value_cansleep(db->reset, 1);
	usleep_range(1000, 5000);
	gpiod_set_value_cansleep(db->reset, 0);
	msleep(20);

	/* Panel Init Sequence */

	/* Password to start command sequence */
	mipi_dbi_command(dbi, 0xf0, 0x5a, 0x5a);
	mipi_dbi_command(dbi, 0xf1, 0x5a, 0x5a);

	/* Undocumented commands */
	mipi_dbi_command(dbi, 0xb0, 0x02);
	mipi_dbi_command(dbi, 0xf3, 0x3b);

	/* Analog Power condition set */
	mipi_dbi_command(dbi, 0xf4, 0x33, 0x42, 0x00, 0x08);
	mipi_dbi_command(dbi, 0xf5, 0x00, 0x06, 0x26, 0x35, 0x03);

	/* Undocumented commands */
	mipi_dbi_command(dbi, 0xf6, 0x02);
	mipi_dbi_command(dbi, 0xc6, 0x0b, 0x00, 0x00, 0x3c, 0x00, 0x22,
			 0x00, 0x00, 0x00, 0x00);

	/* GTCON set */
	mipi_dbi_command(dbi, 0xf7, 0x20);

	/* TEMP_SWIRE set */
	mipi_dbi_command(dbi, 0xb2, 0x06, 0x06, 0x06, 0x06);

	/* ELVSS_CON set */
	mipi_dbi_command(dbi, 0xb1, 0x07, 0x00, 0x10);

	/* Gateless signal set */
	mipi_dbi_command(dbi, 0xf8, 0x7f, 0x7a, 0x89, 0x67, 0x26, 0x38,
			 0x00, 0x00, 0x09, 0x67, 0x70, 0x88, 0x7a,
			 0x76, 0x05, 0x09, 0x23, 0x23, 0x23);

	/* Undocumented commands */
	mipi_dbi_command(dbi, 0xb5, 0xff, 0xef, 0x35, 0x42, 0x0d, 0xd7,
			 0xff, 0x07, 0xff, 0xff, 0xfd, 0x00, 0x01,
			 0xff, 0x05, 0x12, 0x0f, 0xff, 0xff, 0xff,
			 0xff);
	mipi_dbi_command(dbi, 0xb4, 0x15);
	mipi_dbi_command(dbi, 0xb3, 0x00);

	ams495qa01_update_gamma(dbi, MAX_BRIGHTNESS);

	mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
	msleep(200);
	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);
	usleep_range(10000, 15000);

	return 0;
}

static int ams495qa01_unprepare(struct drm_panel *panel)
{
	struct ams495qa01 *db = to_ams495qa01(panel);
	struct mipi_dbi *dbi = &db->dbi;

	/* Panel Exit Sequence */
	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_OFF);
	msleep(20);
	mipi_dbi_command(dbi, MIPI_DCS_ENTER_SLEEP_MODE);
	usleep_range(10000, 15000);

	if (db->enable)
		gpiod_set_value_cansleep(db->enable, 0);
	if (db->reg_elvdd)
		regulator_disable(db->reg_elvdd);
	regulator_disable(db->reg_vdd);
	msleep(20);

	return 0;
}

static int ams495qa01_get_modes(struct drm_panel *panel,
				struct drm_connector *connector)
{
	struct ams495qa01 *db = to_ams495qa01(panel);
	const struct ams495qa01_panel_info *panel_info = db->panel_info;
	struct drm_display_mode *mode;
	static const u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
	unsigned int i;

	for (i = 0; i < panel_info->num_modes; i++) {
		mode = drm_mode_duplicate(connector->dev,
					  &panel_info->display_modes[i]);
		if (!mode)
			return -ENOMEM;

		drm_mode_set_name(mode);
		drm_mode_probed_add(connector, mode);
	}

	connector->display_info.bpc = 8;
	connector->display_info.width_mm = panel_info->width_mm;
	connector->display_info.height_mm = panel_info->height_mm;
	connector->display_info.bus_flags = panel_info->bus_flags;

	drm_display_info_set_bus_formats(&connector->display_info,
					 &bus_format, 1);

	return 1;
}

static const struct drm_panel_funcs ams495qa01_drm_funcs = {
	.unprepare = ams495qa01_unprepare,
	.prepare = ams495qa01_prepare,
	.get_modes = ams495qa01_get_modes,
};

static int ams495qa01_set_brightness(struct backlight_device *bd)
{
	struct ams495qa01 *db = bl_get_data(bd);
	struct mipi_dbi *dbi = &db->dbi;
	int brightness = bd->props.brightness;

	ams495qa01_update_gamma(dbi, brightness);

	return 0;
}

static const struct backlight_ops ams495qa01_backlight_ops = {
	.update_status	= ams495qa01_set_brightness,
};

static int ams495qa01_backlight_register(struct ams495qa01 *db)
{
	struct backlight_properties props = {
		.type		= BACKLIGHT_RAW,
		.brightness	= MAX_BRIGHTNESS,
		.max_brightness = MAX_BRIGHTNESS,
	};
	struct device *dev = db->dev;
	int ret = 0;

	db->bl_dev = devm_backlight_device_register(dev, "panel", dev, db,
						     &ams495qa01_backlight_ops,
						     &props);
	if (IS_ERR(db->bl_dev)) {
		ret = PTR_ERR(db->bl_dev);
		dev_err(dev, "error registering backlight device (%d)\n", ret);
	}

	return ret;
}

int drm_of_get_dsi_bus(struct device *dev,
			      struct mipi_dsi_host *dsi_host,
			      struct mipi_dsi_device_info *info)
{
	struct device_node *endpoint, *dsi_host_node;

	/*
	 * Get first endpoint child from device.
	 */
	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
	if (IS_ERR(endpoint)) {
		return -ENODEV;
	}

	/*
	 * Follow the first endpoint to get the DSI host node.
	 */
	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
	if (IS_ERR(dsi_host_node)) {
		goto error;
	}

	/*
	 * Get the DSI host from the DSI host node. If we get an error
	 * or the return is null assume we're not ready to probe just
	 * yet. Release the DSI host node since we're done with it.
	 */
	dsi_host = of_find_mipi_dsi_host_by_node(dsi_host_node);
	of_node_put(dsi_host_node);
	if (IS_ERR_OR_NULL(dsi_host)) {
		of_node_put(endpoint);
		return -EPROBE_DEFER;
	}

	/*
	 * Set the node of the mipi_dsi_device_info to the correct node
	 * and then release the endpoint node since we're done with it.
	 */
	info->node = of_graph_get_remote_port(endpoint);
	if (IS_ERR(info->node)) {
		goto error;
	}

	of_node_put(endpoint);
	return 0;

error:
	of_node_put(endpoint);
	return -ENODEV;
}

static int ams495qa01_probe(struct spi_device *spi)
{
	struct device *dev = &spi->dev;
	struct mipi_dsi_host *dsi_host;
	struct ams495qa01 *db;
	int ret;
	struct mipi_dsi_device_info info = {
		.type = "ams495qa01",
		.channel = 0,
		.node = NULL,
	};

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

	spi_set_drvdata(spi, db);

	db->dev = dev;

	db->panel_info = of_device_get_match_data(dev);
	if (!db->panel_info)
		return -EINVAL;

	db->reg_vdd = devm_regulator_get(dev, "vdd");
	if (IS_ERR(db->reg_vdd))
		return dev_err_probe(dev, PTR_ERR(db->reg_vdd),
				     "Failed to get vdd supply\n");

	db->reg_elvdd = devm_regulator_get_optional(dev, "elvdd");
	if (IS_ERR(db->reg_elvdd))
		db->reg_elvdd = NULL;

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

	db->enable = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_LOW);
	if (IS_ERR(db->enable)) {
		ret = PTR_ERR(db->enable);
		return dev_err_probe(dev, ret, "cannot get ENABLE GPIO\n");
	}

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

	ret = drm_of_get_dsi_bus(dev, dsi_host, &info);
	if (ret)
		return dev_err_probe(dev, ret, "Error attaching DSI bus\n");

	db->dsi_dev = devm_mipi_dsi_device_register_full(dev, dsi_host, &info);
	if (IS_ERR(db->dsi_dev)) {
		dev_err(dev, "failed to register dsi device: %ld\n",
			PTR_ERR(db->dsi_dev));
		ret = PTR_ERR(db->dsi_dev);
	}

	db->dsi_dev->lanes = 2;
	db->dsi_dev->format = MIPI_DSI_FMT_RGB888;
	db->dsi_dev->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
			  MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_NO_EOT_PACKET;

	drm_panel_init(&db->panel, dev, &ams495qa01_drm_funcs,
		       DRM_MODE_CONNECTOR_DSI);

	ret = ams495qa01_backlight_register(db);
	if (ret < 0)
		return ret;

	drm_panel_add(&db->panel);

	ret = devm_mipi_dsi_attach(dev, db->dsi_dev);
	if (ret < 0) {
		dev_err(dev, "mipi_dsi_attach failed: %d\n", ret);
		drm_panel_remove(&db->panel);
		return ret;
	}

	return 0;
}

static void ams495qa01_shutdown(struct spi_device *spi)
{
	struct ams495qa01 *db = spi_get_drvdata(spi);
	int ret;

	ret = drm_panel_unprepare(&db->panel);
	if (ret < 0)
		dev_err(&spi->dev, "Failed to unprepare panel: %d\n", ret);

	ret = drm_panel_disable(&db->panel);
	if (ret < 0)
		dev_err(&spi->dev, "Failed to disable panel: %d\n", ret);
}

static void ams495qa01_remove(struct spi_device *spi)
{
	struct ams495qa01 *db = spi_get_drvdata(spi);

	ams495qa01_shutdown(spi);

	drm_panel_remove(&db->panel);
}

static const struct drm_display_mode ams495qa01_modes[] = {
	{ /* 60hz */
		.clock = 33500,
		.hdisplay = 960,
		.hsync_start = 960 + 10,
		.hsync_end = 960 + 10 + 2,
		.htotal = 960 + 10 + 2 + 10,
		.vdisplay = 544,
		.vsync_start = 544 + 10,
		.vsync_end = 544 + 10 + 2,
		.vtotal = 544 + 10 + 2 + 10,
		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
		.type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
		},
	{ /* 50hz */
		.clock = 27800,
		.hdisplay = 960,
		.hsync_start = 960 + 10,
		.hsync_end = 960 + 10 + 2,
		.htotal = 960 + 10 + 2 + 10,
		.vdisplay = 544,
		.vsync_start = 544 + 10,
		.vsync_end = 544 + 10 + 2,
		.vtotal = 544 + 10 + 2 + 10,
		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
		.type = DRM_MODE_TYPE_DRIVER,
	},
};

static const struct ams495qa01_panel_info ams495qa01_info = {
	.display_modes = ams495qa01_modes,
	.num_modes = ARRAY_SIZE(ams495qa01_modes),
	.width_mm = 117,
	.height_mm = 74,
	.bus_flags = DRM_BUS_FLAG_DE_LOW | DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
};

static const struct of_device_id ams495qa01_match[] = {
	{ .compatible = "samsung,ams495qa01", .data = &ams495qa01_info },
	{},
};
MODULE_DEVICE_TABLE(of, ams495qa01_match);

static const struct spi_device_id ams495qa01_ids[] = {
	{ "ams495qa01", 0 },
	{},
};
MODULE_DEVICE_TABLE(spi, ams495qa01_ids);

static struct spi_driver ams495qa01_driver = {
	.driver		= {
		.name	= "ams495qa01-panel",
		.of_match_table = ams495qa01_match,
	},
	.id_table	= ams495qa01_ids,
	.probe		= ams495qa01_probe,
	.remove		= ams495qa01_remove,
	.shutdown	= ams495qa01_shutdown,
};
module_spi_driver(ams495qa01_driver);

MODULE_AUTHOR("Chris Morgan <macromorgan@hotmail.com>");
MODULE_DESCRIPTION("Samsung ams495qa01 panel driver");
MODULE_LICENSE("GPL");