// SPDX-License-Identifier: GPL-2.0
/*
 * AU Optronics A030JTN01.0 TFT LCD panel driver
 *
 * Copyright (C) 2023, Paul Cercueil <paul@crapouillou.net>
 * Copyright (C) 2023, Christophe Branchereau <cbranchereau@gmail.com>
 */

#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/media-bus-format.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>

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

#define REG05			0x05
#define REG06			0x06
#define REG07			0x07

#define REG05_STDBY		BIT(0)
#define REG06_VBLK		GENMASK(4, 0)
#define REG07_HBLK		GENMASK(7, 0)


struct a030jtn01_info {
	const struct drm_display_mode *display_modes;
	unsigned int num_modes;
	u16 width_mm, height_mm;
	u32 bus_format, bus_flags;
};

struct a030jtn01 {
	struct drm_panel panel;
	struct spi_device *spi;
	struct regmap *map;

	const struct a030jtn01_info *panel_info;

	struct regulator *supply;
	struct gpio_desc *reset_gpio;
};

static inline struct a030jtn01 *to_a030jtn01(struct drm_panel *panel)
{
	return container_of(panel, struct a030jtn01, panel);
}

static int a030jtn01_prepare(struct drm_panel *panel)
{
	struct a030jtn01 *priv = to_a030jtn01(panel);
	struct device *dev = &priv->spi->dev;
	unsigned int dummy;
	int err;

	err = regulator_enable(priv->supply);
	if (err) {
		dev_err(dev, "Failed to enable power supply: %d\n", err);
		return err;
	}

	usleep_range(1000, 8000);

	/* Reset the chip */
	gpiod_set_value_cansleep(priv->reset_gpio, 1);
	usleep_range(100, 8000);
	gpiod_set_value_cansleep(priv->reset_gpio, 0);
	usleep_range(2000, 8000);

	/*
	 * No idea why, but a register read (doesn't matter which) is needed to
	 * properly initialize the chip after a reset; otherwise, the colors
	 * will be wrong. It doesn't seem to be timing-related as a msleep(200)
	 * doesn't fix it.
	 */
	err = regmap_read(priv->map, REG05, &dummy);
	if (err)
		goto err_disable_regulator;

	/* Use (24 + 6) == 0x1e as the vertical back porch */
	err = regmap_write(priv->map, REG06, FIELD_PREP(REG06_VBLK, 0x1e));
	if (err)
		goto err_disable_regulator;

	/* Use (42 + 30) * 3 == 0xd8 as the horizontal back porch */
	err = regmap_write(priv->map, REG07, FIELD_PREP(REG07_HBLK, 0xd8));
	if (err)
		goto err_disable_regulator;

	return 0;

err_disable_regulator:
	gpiod_set_value_cansleep(priv->reset_gpio, 1);
	regulator_disable(priv->supply);
	return err;
}

static int a030jtn01_unprepare(struct drm_panel *panel)
{
	struct a030jtn01 *priv = to_a030jtn01(panel);

	gpiod_set_value_cansleep(priv->reset_gpio, 1);
	regulator_disable(priv->supply);

	return 0;
}

static int a030jtn01_enable(struct drm_panel *panel)
{
	struct a030jtn01 *priv = to_a030jtn01(panel);
	int ret;

	ret = regmap_set_bits(priv->map, REG05, REG05_STDBY);
	if (ret)
		return ret;

	/* Wait for the picture to be stable */
	if (panel->backlight)
		msleep(100);

	return 0;
}

static int a030jtn01_disable(struct drm_panel *panel)
{
	struct a030jtn01 *priv = to_a030jtn01(panel);

	return regmap_clear_bits(priv->map, REG05, REG05_STDBY);
}

static int a030jtn01_get_modes(struct drm_panel *panel,
				struct drm_connector *connector)
{
	struct a030jtn01 *priv = to_a030jtn01(panel);
	const struct a030jtn01_info *panel_info = priv->panel_info;
	struct drm_display_mode *mode;
	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);

		mode->type = DRM_MODE_TYPE_DRIVER;
		if (panel_info->num_modes == 1)
			mode->type |= DRM_MODE_TYPE_PREFERRED;

		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;

	drm_display_info_set_bus_formats(&connector->display_info,
					 &panel_info->bus_format, 1);
	connector->display_info.bus_flags = panel_info->bus_flags;

	return panel_info->num_modes;
}

static const struct drm_panel_funcs a030jtn01_funcs = {
	.prepare	= a030jtn01_prepare,
	.unprepare	= a030jtn01_unprepare,
	.enable		= a030jtn01_enable,
	.disable	= a030jtn01_disable,
	.get_modes	= a030jtn01_get_modes,
};

static bool a030jtn01_has_reg(struct device *dev, unsigned int reg)
{
	static const u32 a030jtn01_regs_mask = 0x001823f1fb;

	return a030jtn01_regs_mask & BIT(reg);
};

static const struct regmap_config a030jtn01_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.read_flag_mask = 0x40,
	.max_register = 0x1c,
	.readable_reg = a030jtn01_has_reg,
	.writeable_reg = a030jtn01_has_reg,
};

static int a030jtn01_probe(struct spi_device *spi)
{
	struct device *dev = &spi->dev;
	struct a030jtn01 *priv;
	int err;

	spi->mode |= SPI_MODE_3 | SPI_3WIRE;

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

	priv->spi = spi;
	spi_set_drvdata(spi, priv);

	priv->map = devm_regmap_init_spi(spi, &a030jtn01_regmap_config);
	if (IS_ERR(priv->map))
		return dev_err_probe(dev, PTR_ERR(priv->map), "Unable to init regmap");

	priv->panel_info = spi_get_device_match_data(spi);
	if (!priv->panel_info)
		return -EINVAL;

	priv->supply = devm_regulator_get(dev, "power");
	if (IS_ERR(priv->supply))
		return dev_err_probe(dev, PTR_ERR(priv->supply), "Failed to get power supply");

	priv->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
	if (IS_ERR(priv->reset_gpio))
		return dev_err_probe(dev, PTR_ERR(priv->reset_gpio), "Failed to get reset GPIO");

	drm_panel_init(&priv->panel, dev, &a030jtn01_funcs,
		       DRM_MODE_CONNECTOR_DPI);

	err = drm_panel_of_backlight(&priv->panel);
	if (err)
		return err;

	drm_panel_add(&priv->panel);

	return 0;
}

static void a030jtn01_remove(struct spi_device *spi)
{
	struct a030jtn01 *priv = spi_get_drvdata(spi);

	drm_panel_remove(&priv->panel);
	drm_panel_disable(&priv->panel);
	drm_panel_unprepare(&priv->panel);
}

static const struct drm_display_mode a030jtn01_modes[] = {
	{ /* 60 Hz */
		.clock = 14400,
		.hdisplay = 320,
		.hsync_start = 320 + 8,
		.hsync_end = 320 + 8 + 42,
		.htotal = 320 + 8 + 42 + 30,
		.vdisplay = 480,
		.vsync_start = 480 + 90,
		.vsync_end = 480 + 90 + 24,
		.vtotal = 480 + 90 + 24 + 6,
		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
	},
	{ /* 50 Hz */
		.clock = 12000,
		.hdisplay = 320,
		.hsync_start = 320 + 8,
		.hsync_end = 320 + 8 + 42,
		.htotal = 320 + 8 + 42 + 30,
		.vdisplay = 480,
		.vsync_start = 480 + 90,
		.vsync_end = 480 + 90 + 24,
		.vtotal = 480 + 90 + 24 + 6,
		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
	},
};

static const struct a030jtn01_info a030jtn01_info = {
	.display_modes = a030jtn01_modes,
	.num_modes = ARRAY_SIZE(a030jtn01_modes),
	.width_mm = 70,
	.height_mm = 51,
	.bus_format = MEDIA_BUS_FMT_RGB888_3X8_DELTA,
	.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
};

static const struct spi_device_id a030jtn01_id[] = {
	{ "a030jtn01", (kernel_ulong_t) &a030jtn01_info },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(spi, a030jtn01_id);

static const struct of_device_id a030jtn01_of_match[] = {
	{ .compatible = "auo,a030jtn01" },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, a030jtn01_of_match);

static struct spi_driver a030jtn01_driver = {
	.driver = {
		.name = "auo-a030jtn01",
		.of_match_table = a030jtn01_of_match,
	},
	.id_table = a030jtn01_id,
	.probe = a030jtn01_probe,
	.remove = a030jtn01_remove,
};
module_spi_driver(a030jtn01_driver);

MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
MODULE_AUTHOR("Christophe Branchereau <cbranchereau@gmail.com>");
MODULE_LICENSE("GPL");