// SPDX-License-Identifier: GPL-2.0
/*
 * DRM driver for MIPI DBI compatible display panels
 *
 * Copyright 2022 Noralf Trønnes
 */

#include <linux/backlight.h>
#include <linux/delay.h>
#include <linux/firmware.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>

#include <drm/drm_atomic_helper.h>
#include <drm/drm_drv.h>
#include <drm/drm_fbdev_dma.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_gem_dma_helper.h>
#include <drm/drm_managed.h>
#include <drm/drm_mipi_dbi.h>
#include <drm/drm_modes.h>
#include <drm/drm_modeset_helper.h>

#include <video/mipi_display.h>

struct panel_mipi_dbi_format {
	const char *name;
	u32 fourcc;
	unsigned int bpp;
};

static const struct panel_mipi_dbi_format panel_mipi_dbi_formats[] = {
	{ "r5g6b5", DRM_FORMAT_RGB565, 16 },
	{ "b6x2g6x2r6x2", DRM_FORMAT_RGB888, 24 },
};

static int panel_mipi_dbi_get_format(struct device *dev, u32 *formats, unsigned int *bpp)
{
	const char *format_name;
	unsigned int i;
	int ret;

	formats[1] = DRM_FORMAT_XRGB8888;

	ret = device_property_read_string(dev, "format", &format_name);
	if (ret) {
		/* Old Device Trees don't have this property */
		formats[0] = DRM_FORMAT_RGB565;
		*bpp = 16;
		return 0;
	}

	for (i = 0; i < ARRAY_SIZE(panel_mipi_dbi_formats); i++) {
		const struct panel_mipi_dbi_format *format = &panel_mipi_dbi_formats[i];

		if (strcmp(format_name, format->name))
			continue;

		formats[0] = format->fourcc;
		*bpp = format->bpp;
		return 0;
	}

	dev_err(dev, "Pixel format is not supported: '%s'\n", format_name);

	return -EINVAL;
}

static const u8 panel_mipi_dbi_magic[15] = { 'M', 'I', 'P', 'I', ' ', 'D', 'B', 'I',
					     0, 0, 0, 0, 0, 0, 0 };

/*
 * The display controller configuration is stored in a firmware file.
 * The Device Tree 'compatible' property value with a '.bin' suffix is passed
 * to request_firmware() to fetch this file.
 */
struct panel_mipi_dbi_config {
	/* Magic string: panel_mipi_dbi_magic */
	u8 magic[15];

	/* Config file format version */
	u8 file_format_version;

	/*
	 * MIPI commands to execute when the display pipeline is enabled.
	 * This is used to configure the display controller.
	 *
	 * The commands are stored in a byte array with the format:
	 *     command, num_parameters, [ parameter, ...], command, ...
	 *
	 * Some commands require a pause before the next command can be received.
	 * Inserting a delay in the command sequence is done by using the NOP command with one
	 * parameter: delay in miliseconds (the No Operation command is part of the MIPI Display
	 * Command Set where it has no parameters).
	 *
	 * Example:
	 *     command 0x11
	 *     sleep 120ms
	 *     command 0xb1 parameters 0x01, 0x2c, 0x2d
	 *     command 0x29
	 *
	 * Byte sequence:
	 *     0x11 0x00
	 *     0x00 0x01 0x78
	 *     0xb1 0x03 0x01 0x2c 0x2d
	 *     0x29 0x00
	 */
	u8 commands[];
};

struct panel_mipi_dbi_commands {
	const u8 *buf;
	size_t len;
};

static struct panel_mipi_dbi_commands *
panel_mipi_dbi_check_commands(struct device *dev, const struct firmware *fw)
{
	const struct panel_mipi_dbi_config *config = (struct panel_mipi_dbi_config *)fw->data;
	struct panel_mipi_dbi_commands *commands;
	size_t size = fw->size, commands_len;
	unsigned int i = 0;

	if (size < sizeof(*config) + 2) { /* At least 1 command */
		dev_err(dev, "config: file size=%zu is too small\n", size);
		return ERR_PTR(-EINVAL);
	}

	if (memcmp(config->magic, panel_mipi_dbi_magic, sizeof(config->magic))) {
		dev_err(dev, "config: Bad magic: %15ph\n", config->magic);
		return ERR_PTR(-EINVAL);
	}

	if (config->file_format_version != 1) {
		dev_err(dev, "config: version=%u is not supported\n", config->file_format_version);
		return ERR_PTR(-EINVAL);
	}

	drm_dev_dbg(dev, DRM_UT_DRIVER, "size=%zu version=%u\n", size, config->file_format_version);

	commands_len = size - sizeof(*config);

	while ((i + 1) < commands_len) {
		u8 command = config->commands[i++];
		u8 num_parameters = config->commands[i++];
		const u8 *parameters = &config->commands[i];

		i += num_parameters;
		if (i > commands_len) {
			dev_err(dev, "config: command=0x%02x num_parameters=%u overflows\n",
				command, num_parameters);
			return ERR_PTR(-EINVAL);
		}

		if (command == 0x00 && num_parameters == 1)
			drm_dev_dbg(dev, DRM_UT_DRIVER, "sleep %ums\n", parameters[0]);
		else
			drm_dev_dbg(dev, DRM_UT_DRIVER, "command %02x %*ph\n",
				    command, num_parameters, parameters);
	}

	if (i != commands_len) {
		dev_err(dev, "config: malformed command array\n");
		return ERR_PTR(-EINVAL);
	}

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

	commands->len = commands_len;
	commands->buf = devm_kmemdup(dev, config->commands, commands->len, GFP_KERNEL);
	if (!commands->buf)
		return ERR_PTR(-ENOMEM);

	return commands;
}

static struct panel_mipi_dbi_commands *panel_mipi_dbi_commands_from_fw(struct device *dev)
{
	struct panel_mipi_dbi_commands *commands;
	const struct firmware *fw;
	const char *compatible;
	char fw_name[40];
	int ret;

	ret = of_property_read_string_index(dev->of_node, "compatible", 0, &compatible);
	if (ret)
		return ERR_PTR(ret);

	snprintf(fw_name, sizeof(fw_name), "%s.bin", compatible);
	ret = request_firmware(&fw, fw_name, dev);
	if (ret) {
		dev_err(dev, "No config file found for compatible '%s' (error=%d)\n",
			compatible, ret);

		return ERR_PTR(ret);
	}

	commands = panel_mipi_dbi_check_commands(dev, fw);
	release_firmware(fw);

	return commands;
}

static void panel_mipi_dbi_commands_execute(struct mipi_dbi *dbi,
					    struct panel_mipi_dbi_commands *commands)
{
	unsigned int i = 0;

	if (!commands)
		return;

	while (i < commands->len) {
		u8 command = commands->buf[i++];
		u8 num_parameters = commands->buf[i++];
		const u8 *parameters = &commands->buf[i];

		if (command == 0x00 && num_parameters == 1)
			msleep(parameters[0]);
		else if (num_parameters)
			mipi_dbi_command_stackbuf(dbi, command, parameters, num_parameters);
		else
			mipi_dbi_command(dbi, command);

		i += num_parameters;
	}
}

static void panel_mipi_dbi_enable(struct drm_simple_display_pipe *pipe,
				  struct drm_crtc_state *crtc_state,
				  struct drm_plane_state *plane_state)
{
	struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(pipe->crtc.dev);
	struct mipi_dbi *dbi = &dbidev->dbi;
	int ret, idx;

	if (!drm_dev_enter(pipe->crtc.dev, &idx))
		return;

	drm_dbg(pipe->crtc.dev, "\n");

	ret = mipi_dbi_poweron_conditional_reset(dbidev);
	if (ret < 0)
		goto out_exit;
	if (!ret)
		panel_mipi_dbi_commands_execute(dbi, dbidev->driver_private);

	mipi_dbi_enable_flush(dbidev, crtc_state, plane_state);
out_exit:
	drm_dev_exit(idx);
}

static const struct drm_simple_display_pipe_funcs panel_mipi_dbi_pipe_funcs = {
	DRM_MIPI_DBI_SIMPLE_DISPLAY_PIPE_FUNCS(panel_mipi_dbi_enable),
};

DEFINE_DRM_GEM_DMA_FOPS(panel_mipi_dbi_fops);

static const struct drm_driver panel_mipi_dbi_driver = {
	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
	.fops			= &panel_mipi_dbi_fops,
	DRM_GEM_DMA_DRIVER_OPS_VMAP,
	.debugfs_init		= mipi_dbi_debugfs_init,
	.name			= "panel-mipi-dbi",
	.desc			= "MIPI DBI compatible display panel",
	.date			= "20220103",
	.major			= 1,
	.minor			= 0,
};

static int panel_mipi_dbi_get_mode(struct mipi_dbi_dev *dbidev, struct drm_display_mode *mode)
{
	struct device *dev = dbidev->drm.dev;
	u16 hback_porch, vback_porch;
	int ret;

	ret = of_get_drm_panel_display_mode(dev->of_node, mode, NULL);
	if (ret) {
		dev_err(dev, "%pOF: failed to get panel-timing (error=%d)\n", dev->of_node, ret);
		return ret;
	}

	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;

	hback_porch = mode->htotal - mode->hsync_end;
	vback_porch = mode->vtotal - mode->vsync_end;

	/*
	 * Make sure width and height are set and that only back porch and
	 * pixelclock are set in the other timing values. Also check that
	 * width and height don't exceed the 16-bit value specified by MIPI DCS.
	 */
	if (!mode->hdisplay || !mode->vdisplay || mode->flags ||
	    mode->hsync_end > mode->hdisplay || (hback_porch + mode->hdisplay) > 0xffff ||
	    mode->vsync_end > mode->vdisplay || (vback_porch + mode->vdisplay) > 0xffff) {
		dev_err(dev, "%pOF: panel-timing out of bounds\n", dev->of_node);
		return -EINVAL;
	}

	/* The driver doesn't use the pixel clock but it is mandatory so fake one if not set */
	if (!mode->clock)
		mode->clock = mode->htotal * mode->vtotal * 60 / 1000;

	dbidev->top_offset = vback_porch;
	dbidev->left_offset = hback_porch;

	return 0;
}

static int panel_mipi_dbi_spi_probe(struct spi_device *spi)
{
	struct device *dev = &spi->dev;
	struct drm_display_mode mode;
	struct mipi_dbi_dev *dbidev;
	struct drm_device *drm;
	struct mipi_dbi *dbi;
	struct gpio_desc *dc;
	unsigned int bpp;
	size_t buf_size;
	u32 formats[2];
	int ret;

	dbidev = devm_drm_dev_alloc(dev, &panel_mipi_dbi_driver, struct mipi_dbi_dev, drm);
	if (IS_ERR(dbidev))
		return PTR_ERR(dbidev);

	dbi = &dbidev->dbi;
	drm = &dbidev->drm;

	ret = panel_mipi_dbi_get_mode(dbidev, &mode);
	if (ret)
		return ret;

	dbidev->regulator = devm_regulator_get(dev, "power");
	if (IS_ERR(dbidev->regulator))
		return dev_err_probe(dev, PTR_ERR(dbidev->regulator),
				     "Failed to get regulator 'power'\n");

	dbidev->io_regulator = devm_regulator_get(dev, "io");
	if (IS_ERR(dbidev->io_regulator))
		return dev_err_probe(dev, PTR_ERR(dbidev->io_regulator),
				     "Failed to get regulator 'io'\n");

	dbidev->backlight = devm_of_find_backlight(dev);
	if (IS_ERR(dbidev->backlight))
		return dev_err_probe(dev, PTR_ERR(dbidev->backlight), "Failed to get backlight\n");

	dbi->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
	if (IS_ERR(dbi->reset))
		return dev_err_probe(dev, PTR_ERR(dbi->reset), "Failed to get GPIO 'reset'\n");

	/* Multiple panels can share the "dc" GPIO, but only if they are on the same SPI bus! */
	dc = devm_gpiod_get_optional(dev, "dc", GPIOD_OUT_LOW | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
	if (IS_ERR(dc))
		return dev_err_probe(dev, PTR_ERR(dc), "Failed to get GPIO 'dc'\n");

	ret = mipi_dbi_spi_init(spi, dbi, dc);
	if (ret)
		return ret;

	if (device_property_present(dev, "write-only"))
		dbi->read_commands = NULL;

	dbidev->driver_private = panel_mipi_dbi_commands_from_fw(dev);
	if (IS_ERR(dbidev->driver_private))
		return PTR_ERR(dbidev->driver_private);

	ret = panel_mipi_dbi_get_format(dev, formats, &bpp);
	if (ret)
		return ret;

	buf_size = DIV_ROUND_UP(mode.hdisplay * mode.vdisplay * bpp, 8);
	ret = mipi_dbi_dev_init_with_formats(dbidev, &panel_mipi_dbi_pipe_funcs,
					     formats, ARRAY_SIZE(formats),
					     &mode, 0, buf_size);
	if (ret)
		return ret;

	drm_mode_config_reset(drm);

	ret = drm_dev_register(drm, 0);
	if (ret)
		return ret;

	spi_set_drvdata(spi, drm);

	drm_fbdev_dma_setup(drm, 0);

	return 0;
}

static void panel_mipi_dbi_spi_remove(struct spi_device *spi)
{
	struct drm_device *drm = spi_get_drvdata(spi);

	drm_dev_unplug(drm);
	drm_atomic_helper_shutdown(drm);
}

static void panel_mipi_dbi_spi_shutdown(struct spi_device *spi)
{
	drm_atomic_helper_shutdown(spi_get_drvdata(spi));
}

static int __maybe_unused panel_mipi_dbi_pm_suspend(struct device *dev)
{
	return drm_mode_config_helper_suspend(dev_get_drvdata(dev));
}

static int __maybe_unused panel_mipi_dbi_pm_resume(struct device *dev)
{
	drm_mode_config_helper_resume(dev_get_drvdata(dev));

	return 0;
}

static const struct dev_pm_ops panel_mipi_dbi_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(panel_mipi_dbi_pm_suspend, panel_mipi_dbi_pm_resume)
};

static const struct of_device_id panel_mipi_dbi_spi_of_match[] = {
	{ .compatible = "panel-mipi-dbi-spi" },
	{},
};
MODULE_DEVICE_TABLE(of, panel_mipi_dbi_spi_of_match);

static const struct spi_device_id panel_mipi_dbi_spi_id[] = {
	{ "panel-mipi-dbi-spi", 0 },
	{ },
};
MODULE_DEVICE_TABLE(spi, panel_mipi_dbi_spi_id);

static struct spi_driver panel_mipi_dbi_spi_driver = {
	.driver = {
		.name = "panel-mipi-dbi-spi",
		.of_match_table = panel_mipi_dbi_spi_of_match,
		.pm = &panel_mipi_dbi_pm_ops,
	},
	.id_table = panel_mipi_dbi_spi_id,
	.probe = panel_mipi_dbi_spi_probe,
	.remove = panel_mipi_dbi_spi_remove,
	.shutdown = panel_mipi_dbi_spi_shutdown,
};
module_spi_driver(panel_mipi_dbi_spi_driver);

MODULE_DESCRIPTION("MIPI DBI compatible display panel driver");
MODULE_AUTHOR("Noralf Trønnes");
MODULE_LICENSE("GPL");