// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * MIPI Display Bus Interface (DBI) LCD controller support
 *
 * Copyright 2016 Noralf Trønnes
 */

#define pr_fmt(fmt) "mipi-dbi: " fmt

#include <common.h>
#include <dma.h>
#include <linux/kernel.h>
#include <linux/sizes.h>
#include <linux/gpio/consumer.h>
#include <regulator.h>
#include <spi/spi.h>
#include <video/backlight.h>
#include <video/mipi_dbi.h>

#include <video/vpl.h>
#include <video/mipi_display.h>
#include <video/fourcc.h>

#define MIPI_DBI_MAX_SPI_READ_SPEED 2000000 /* 2MHz */

#define DCS_POWER_MODE_DISPLAY			BIT(2)
#define DCS_POWER_MODE_DISPLAY_NORMAL_MODE	BIT(3)
#define DCS_POWER_MODE_SLEEP_MODE		BIT(4)
#define DCS_POWER_MODE_PARTIAL_MODE		BIT(5)
#define DCS_POWER_MODE_IDLE_MODE		BIT(6)
#define DCS_POWER_MODE_RESERVED_MASK		(BIT(0) | BIT(1) | BIT(7))

LIST_HEAD(mipi_dbi_list);
EXPORT_SYMBOL(mipi_dbi_list);

/**
 * DOC: overview
 *
 * This library provides helpers for MIPI Display Bus Interface (DBI)
 * compatible display controllers.
 *
 * Many controllers for tiny lcd displays are MIPI compliant and can use this
 * library. If a controller uses registers 0x2A and 0x2B to set the area to
 * update and uses register 0x2C to write to frame memory, it is most likely
 * MIPI compliant.
 *
 * Only MIPI Type 1 displays are supported since a full frame memory is needed.
 *
 * There are 3 MIPI DBI implementation types:
 *
 * A. Motorola 6800 type parallel bus
 *
 * B. Intel 8080 type parallel bus
 *
 * C. SPI type with 3 options:
 *
 *    1. 9-bit with the Data/Command signal as the ninth bit
 *    2. Same as above except it's sent as 16 bits
 *    3. 8-bit with the Data/Command signal as a separate D/CX pin
 *
 * Currently barebox mipi_dbi only supports Type C option 3 with
 * mipi_dbi_spi_init().
 */

#define MIPI_DBI_DEBUG_COMMAND(cmd, data, len) \
({ \
	if (!len) \
		pr_debug("cmd=%02x\n", cmd); \
	else if (len <= 32) \
		pr_debug("cmd=%02x, par=%*ph\n", cmd, (int)len, data);\
	else \
		pr_debug("cmd=%02x, len=%zu\n", cmd, len); \
})

static const u8 mipi_dbi_dcs_read_commands[] = {
	MIPI_DCS_GET_DISPLAY_ID,
	MIPI_DCS_GET_RED_CHANNEL,
	MIPI_DCS_GET_GREEN_CHANNEL,
	MIPI_DCS_GET_BLUE_CHANNEL,
	MIPI_DCS_GET_DISPLAY_STATUS,
	MIPI_DCS_GET_POWER_MODE,
	MIPI_DCS_GET_ADDRESS_MODE,
	MIPI_DCS_GET_PIXEL_FORMAT,
	MIPI_DCS_GET_DISPLAY_MODE,
	MIPI_DCS_GET_SIGNAL_MODE,
	MIPI_DCS_GET_DIAGNOSTIC_RESULT,
	MIPI_DCS_READ_MEMORY_START,
	MIPI_DCS_READ_MEMORY_CONTINUE,
	MIPI_DCS_GET_SCANLINE,
	MIPI_DCS_GET_DISPLAY_BRIGHTNESS,
	MIPI_DCS_GET_CONTROL_DISPLAY,
	MIPI_DCS_GET_POWER_SAVE,
	MIPI_DCS_GET_CABC_MIN_BRIGHTNESS,
	MIPI_DCS_READ_DDB_START,
	MIPI_DCS_READ_DDB_CONTINUE,
	0, /* sentinel */
};

bool mipi_dbi_command_is_read(struct mipi_dbi *dbi, u8 cmd)
{
	unsigned int i;

	if (!dbi->read_commands)
		return false;

	for (i = 0; i < 0xff; i++) {
		if (!dbi->read_commands[i])
			return false;
		if (cmd == dbi->read_commands[i])
			return true;
	}

	return false;
}

int mipi_dbi_command_read_len(int cmd)
{
	switch (cmd) {
	case MIPI_DCS_READ_MEMORY_START:
	case MIPI_DCS_READ_MEMORY_CONTINUE:
		return 2;
	case MIPI_DCS_GET_DISPLAY_ID:
		return 3;
	case MIPI_DCS_GET_DISPLAY_STATUS:
		return 4;
	default:
		return 1;
	}
}

/**
 * mipi_dbi_command_read - MIPI DCS read command
 * @dbi: MIPI DBI structure
 * @cmd: Command
 * @val: Value read
 *
 * Send MIPI DCS read command to the controller.
 *
 * Returns:
 * Zero on success, negative error code on failure.
 */
int mipi_dbi_command_read(struct mipi_dbi *dbi, u8 cmd, u8 *val)
{
	if (!dbi->read_commands)
		return -EACCES;

	if (!mipi_dbi_command_is_read(dbi, cmd))
		return -EINVAL;

	return mipi_dbi_command_buf(dbi, cmd, val, 1);
}
EXPORT_SYMBOL(mipi_dbi_command_read);

/**
 * mipi_dbi_command_buf - MIPI DCS command with parameter(s) in an array
 * @dbi: MIPI DBI structure
 * @cmd: Command
 * @data: Parameter buffer
 * @len: Buffer length
 *
 * Returns:
 * Zero on success, negative error code on failure.
 */
int mipi_dbi_command_buf(struct mipi_dbi *dbi, u8 cmd, u8 *data, size_t len)
{
	u8 *cmdbuf;
	int ret;

	/* SPI requires dma-safe buffers */
	cmdbuf = kmemdup(&cmd, 1, GFP_KERNEL);
	if (!cmdbuf)
		return -ENOMEM;

	ret = dbi->command(dbi, cmdbuf, data, len);

	kfree(cmdbuf);

	return ret;
}
EXPORT_SYMBOL(mipi_dbi_command_buf);

/* This should only be used by mipi_dbi_command() */
int mipi_dbi_command_stackbuf(struct mipi_dbi *dbi, u8 cmd, const u8 *data,
			      size_t len)
{
	u8 *buf;
	int ret;

	buf = kmemdup(data, len, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	ret = mipi_dbi_command_buf(dbi, cmd, buf, len);

	kfree(buf);

	return ret;
}
EXPORT_SYMBOL(mipi_dbi_command_stackbuf);

/**
 * mipi_dbi_buf_copy - Copy a framebuffer, transforming it if necessary
 * @dst: The destination buffer
 * @info: The source framebuffer info
 * @clip: Clipping rectangle of the area to be copied
 * @swap: When true, swap MSB/LSB of 16-bit values
 */
static void mipi_dbi_buf_copy(u16 *dst, struct fb_info *info,
			      struct fb_rect *clip, bool swap)
{
	u16 *src = (u16 *)info->screen_base;
	unsigned int height = clip->y2 - clip->y1;
	unsigned int width = clip->x2 - clip->x1;
	int x, y;

	src += clip->y1 * info->xres + clip->x1;
	if (swap) {
		for (y = 0; y < height; y++) {
			for (x = 0; x < width; x++)
				*dst++ = src[x] << 8 | src[x] >> 8;
			src += info->xres;
		}
	} else {
		for (y = 0; y < height; y++) {
			memcpy(dst, src, 2 * width);
			dst += width;
			src += info->xres;
		}
	}
}

static void mipi_dbi_set_window_address(struct mipi_dbi_dev *dbidev,
					unsigned int xs, unsigned int xe,
					unsigned int ys, unsigned int ye)
{
	struct mipi_dbi *dbi = &dbidev->dbi;

	xs += dbidev->mode.left_margin;
	xe += dbidev->mode.left_margin;
	ys += dbidev->mode.upper_margin;
	ye += dbidev->mode.upper_margin;

	mipi_dbi_command(dbi, MIPI_DCS_SET_COLUMN_ADDRESS, (xs >> 8) & 0xff,
			 xs & 0xff, (xe >> 8) & 0xff, xe & 0xff);
	mipi_dbi_command(dbi, MIPI_DCS_SET_PAGE_ADDRESS, (ys >> 8) & 0xff,
			 ys & 0xff, (ye >> 8) & 0xff, ye & 0xff);
}

static void mipi_dbi_fb_dirty(struct mipi_dbi_dev *dbidev, struct fb_info *info,
			      struct fb_rect *rect)
{
	unsigned int height = rect->y2 - rect->y1;
	unsigned int width = rect->x2 - rect->x1;
	struct mipi_dbi *dbi = &dbidev->dbi;
	bool swap = dbi->swap_bytes;
	int ret;
	bool full;
	void *tr;

	full = width == info->xres && height == info->yres;

	if (!full || swap) {
		tr = dbidev->tx_buf;
		mipi_dbi_buf_copy(tr, info, rect, swap);
	} else {
		tr = info->screen_base;
	}

	mipi_dbi_set_window_address(dbidev, rect->x1, rect->x2 - 1, rect->y1,
				    rect->y2 - 1);

	ret = mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START, tr,
				   width * height * 2);
	if (ret)
		pr_err_once("Failed to update display %d\n", ret);

	dbidev->damage.x1 = 0;
	dbidev->damage.y1 = 0;
	dbidev->damage.x2 = 0;
	dbidev->damage.y2 = 0;
}

/**
 * mipi_dbi_enable_flush - MIPI DBI enable helper
 * @dbidev: MIPI DBI device structure
 * @info: Framebuffer info
 *
 * Flushes the whole framebuffer and enables the backlight. Drivers can use this
 * in their &fb_ops->fb_enable callback.
 */
void mipi_dbi_enable_flush(struct mipi_dbi_dev *dbidev,
			   struct fb_info *info)
{
	struct fb_rect rect = {
		.x1 = 0,
		.y1 = 0,
		.x2 = info->xres,
		.y2 = info->yres
	};

	mipi_dbi_fb_dirty(dbidev, info, &rect);

	if (dbidev->backlight)
		backlight_set_brightness_default(dbidev->backlight);
}
EXPORT_SYMBOL(mipi_dbi_enable_flush);

static void mipi_dbi_blank(struct mipi_dbi_dev *dbidev)
{
	u16 height = dbidev->mode.xres;
	u16 width = dbidev->mode.yres;
	struct mipi_dbi *dbi = &dbidev->dbi;
	size_t len = width * height * 2;

	memset(dbidev->tx_buf, 0, len);

	mipi_dbi_set_window_address(dbidev, 0, width - 1, 0, height - 1);
	mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START, dbidev->tx_buf, len);
}

/**
 * mipi_dbi_fb_disable - MIPI DBI framebuffer disable helper
 * @info: Framebuffer info
 *
 * This function disables backlight if present, if not the display memory is
 * blanked. The regulator is disabled if in use. Drivers can use this as their
 * &fb_ops->fb_disable callback.
 */
void mipi_dbi_fb_disable(struct fb_info *info)
{
	struct mipi_dbi_dev *dbidev = container_of(info, struct mipi_dbi_dev, info);

	if (dbidev->backlight)
		backlight_set_brightness(dbidev->backlight, 0);
	else
		mipi_dbi_blank(dbidev);

	regulator_disable(dbidev->regulator);
	regulator_disable(dbidev->io_regulator);
}
EXPORT_SYMBOL(mipi_dbi_fb_disable);

void mipi_dbi_fb_damage(struct fb_info *info, const struct fb_rect *rect)
{
	struct mipi_dbi_dev *dbidev = container_of(info, struct mipi_dbi_dev, info);

	if (dbidev->damage.x2 && dbidev->damage.y2) {
		dbidev->damage.x1 = min(dbidev->damage.x1, rect->x1);
		dbidev->damage.y1 = min(dbidev->damage.y1, rect->y1);
		dbidev->damage.x2 = max(dbidev->damage.x2, rect->x2);
		dbidev->damage.y2 = max(dbidev->damage.y2, rect->y2);
	} else {
		dbidev->damage = *rect;
	}
}
EXPORT_SYMBOL(mipi_dbi_fb_damage);

void mipi_dbi_fb_flush(struct fb_info *info)
{
	struct mipi_dbi_dev *dbidev = container_of(info, struct mipi_dbi_dev, info);

	if (!dbidev->damage.x2 || !dbidev->damage.y2) {
		dbidev->damage.x1 = 0;
		dbidev->damage.y1 = 0;
		dbidev->damage.x2 = info->xres;
		dbidev->damage.y2 = info->yres;
	}

	mipi_dbi_fb_dirty(dbidev, info, &dbidev->damage);
}
EXPORT_SYMBOL(mipi_dbi_fb_flush);

/**
 * mipi_dbi_dev_init - MIPI DBI device initialization
 * @dbidev: MIPI DBI device structure to initialize
 * @ops: Framebuffer operations
 * @mode: Display mode
 *
 * This function sets up a &fb_info with one fixed &fb_videomode.
 * Additionally &mipi_dbi.tx_buf is allocated.
 *
 * Supported format: RGB565.
 *
 * Returns:
 * Zero on success, negative error code on failure.
 */
int mipi_dbi_dev_init(struct mipi_dbi_dev *dbidev, struct fb_ops *ops,
		      struct fb_videomode *mode)
{
	struct fb_info *info = &dbidev->info;

	info->mode = mode;
	info->fbops = ops;
	info->dev.parent = dbidev->dev;

	info->xres = mode->xres;
	info->yres = mode->yres;
	info->bits_per_pixel = 16;
	info->line_length = info->xres * 2;
	info->screen_size = info->line_length * info->yres;
	info->screen_base = dma_alloc(info->screen_size);
	memset(info->screen_base, 0, info->screen_size);

	info->red.length = 5;
	info->red.offset = 11;
	info->green.length = 6;
	info->green.offset = 5;
	info->blue.length = 5;
	info->blue.offset = 0;

	dbidev->tx_buf = dma_alloc(info->screen_size);

	return 0;
}

/**
 * mipi_dbi_hw_reset - Hardware reset of controller
 * @dbi: MIPI DBI structure
 *
 * Reset controller if the &mipi_dbi->reset gpio is set.
 */
void mipi_dbi_hw_reset(struct mipi_dbi *dbi)
{
	if (!dbi->reset)
		return;

	gpiod_set_value(dbi->reset, 0);
	udelay(20);
	gpiod_set_value(dbi->reset, 1);
	mdelay(120);
}
EXPORT_SYMBOL(mipi_dbi_hw_reset);

/**
 * mipi_dbi_display_is_on - Check if display is on
 * @dbi: MIPI DBI structure
 *
 * This function checks the Power Mode register (if readable) to see if
 * display output is turned on. This can be used to see if the bootloader
 * has already turned on the display avoiding flicker when the pipeline is
 * enabled.
 *
 * Returns:
 * true if the display can be verified to be on, false otherwise.
 */
bool mipi_dbi_display_is_on(struct mipi_dbi *dbi)
{
	u8 val;

	if (mipi_dbi_command_read(dbi, MIPI_DCS_GET_POWER_MODE, &val))
		return false;

	val &= ~DCS_POWER_MODE_RESERVED_MASK;

	/* The poweron/reset value is 08h DCS_POWER_MODE_DISPLAY_NORMAL_MODE */
	if (val != (DCS_POWER_MODE_DISPLAY |
	    DCS_POWER_MODE_DISPLAY_NORMAL_MODE | DCS_POWER_MODE_SLEEP_MODE))
		return false;

	pr_debug("Display is ON\n");

	return true;
}
EXPORT_SYMBOL(mipi_dbi_display_is_on);

static int mipi_dbi_poweron_reset_conditional(struct mipi_dbi_dev *dbidev, bool cond)
{
	struct device *dev = dbidev->dev;
	struct mipi_dbi *dbi = &dbidev->dbi;
	int ret;

	ret = regulator_enable(dbidev->regulator);
	if (ret) {
		dev_err(dev, "Failed to enable regulator (%d)\n", ret);
		return ret;
	}

	ret = regulator_enable(dbidev->io_regulator);
	if (ret) {
		dev_err(dev, "Failed to enable I/O regulator (%d)\n", ret);
		regulator_disable(dbidev->regulator);
		return ret;
	}

	if (cond && mipi_dbi_display_is_on(dbi))
		return 1;

	mipi_dbi_hw_reset(dbi);
	ret = mipi_dbi_command(dbi, MIPI_DCS_SOFT_RESET);
	if (ret) {
		dev_err(dev, "Failed to send reset command (%d)\n", ret);
		regulator_disable(dbidev->io_regulator);
		regulator_disable(dbidev->regulator);
		return ret;
	}

	/*
	 * If we did a hw reset, we know the controller is in Sleep mode and
	 * per MIPI DSC spec should wait 5ms after soft reset. If we didn't,
	 * we assume worst case and wait 120ms.
	 */
	if (dbi->reset)
		mdelay(5);
	else
		mdelay(120);

	return 0;
}

/**
 * mipi_dbi_poweron_conditional_reset - MIPI DBI poweron and conditional reset
 * @dbidev: MIPI DBI device structure
 *
 * This function enables the regulator if used and if the display is off, it
 * does a hardware and software reset. If mipi_dbi_display_is_on() determines
 * that the display is on, no reset is performed.
 *
 * Returns:
 * Zero if the controller was reset, 1 if the display was already on, or a
 * negative error code.
 */
int mipi_dbi_poweron_conditional_reset(struct mipi_dbi_dev *dbidev)
{
	return mipi_dbi_poweron_reset_conditional(dbidev, true);
}
EXPORT_SYMBOL(mipi_dbi_poweron_conditional_reset);

#if IS_ENABLED(CONFIG_SPI)

/**
 * mipi_dbi_spi_cmd_max_speed - get the maximum SPI bus speed
 * @spi: SPI device
 * @len: The transfer buffer length.
 *
 * Many controllers have a max speed of 10MHz, but can be pushed way beyond
 * that. Increase reliability by running pixel data at max speed and the rest
 * at 10MHz, preventing transfer glitches from messing up the init settings.
 */
u32 mipi_dbi_spi_cmd_max_speed(struct spi_device *spi, size_t len)
{
	if (len > 64)
		return 0; /* use default */

	return min_t(u32, 10000000, spi->max_speed_hz);
}
EXPORT_SYMBOL(mipi_dbi_spi_cmd_max_speed);

static bool mipi_dbi_machine_little_endian(void)
{
#if defined(__LITTLE_ENDIAN)
	return true;
#else
	return false;
#endif
}

/* MIPI DBI Type C Option 3 */

static int mipi_dbi_typec3_command_read(struct mipi_dbi *dbi, u8 *cmd,
					u8 *data, size_t len)
{
	struct spi_device *spi = dbi->spi;
	u32 speed_hz = min_t(u32, MIPI_DBI_MAX_SPI_READ_SPEED,
			     spi->max_speed_hz / 2);
	struct spi_transfer tr[2] = {
		{
			.speed_hz = speed_hz,
			.tx_buf = cmd,
			.len = 1,
		}, {
			.speed_hz = speed_hz,
			.len = len,
		},
	};
	struct spi_message m;
	u8 *buf;
	int ret;

	if (!len)
		return -EINVAL;

	/*
	 * Support non-standard 24-bit and 32-bit Nokia read commands which
	 * start with a dummy clock, so we need to read an extra byte.
	 */
	if (*cmd == MIPI_DCS_GET_DISPLAY_ID ||
	    *cmd == MIPI_DCS_GET_DISPLAY_STATUS) {
		if (!(len == 3 || len == 4))
			return -EINVAL;

		tr[1].len = len + 1;
	}

	buf = kmalloc(tr[1].len, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	tr[1].rx_buf = buf;
	gpiod_set_value(dbi->dc, 0);

	spi_message_init_with_transfers(&m, tr, ARRAY_SIZE(tr));
	ret = spi_sync(spi, &m);
	if (ret)
		goto err_free;

	if (tr[1].len == len) {
		memcpy(data, buf, len);
	} else {
		unsigned int i;

		for (i = 0; i < len; i++)
			data[i] = (buf[i] << 1) | (buf[i + 1] >> 7);
	}

	MIPI_DBI_DEBUG_COMMAND(*cmd, data, len);

err_free:
	kfree(buf);

	return ret;
}

static int mipi_dbi_typec3_command(struct mipi_dbi *dbi, u8 *cmd,
				   u8 *par, size_t num)
{
	struct spi_device *spi = dbi->spi;
	unsigned int bpw = 8;
	u32 speed_hz;
	int ret;

	if (mipi_dbi_command_is_read(dbi, *cmd))
		return mipi_dbi_typec3_command_read(dbi, cmd, par, num);

	MIPI_DBI_DEBUG_COMMAND(*cmd, par, num);

	gpiod_set_value(dbi->dc, 0);
	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
	ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1);
	if (ret || !num)
		return ret;

	if (*cmd == MIPI_DCS_WRITE_MEMORY_START && !dbi->swap_bytes)
		bpw = 16;

	gpiod_set_value(dbi->dc, 1);
	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);

	return mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num);
}

/**
 * mipi_dbi_spi_init - Initialize MIPI DBI SPI interface
 * @spi: SPI device
 * @dbi: MIPI DBI structure to initialize
 * @dc: D/C gpio
 *
 * This function sets &mipi_dbi->command, enables &mipi_dbi->read_commands for the
 * usual read commands. It should be followed by a call to mipi_dbi_dev_init() or
 * a driver-specific init.
 *
 * Type C Option 3 interface is assumed, Type C Option 1 is not yet supported,
 * because barebox has no generic way yet to require a 9-bit SPI transfer
 *
 * If the SPI master driver doesn't support the necessary bits per word,
 * the following transformation is used:
 *
 * - 9-bit: reorder buffer as 9x 8-bit words, padded with no-op command.
 * - 16-bit: if big endian send as 8-bit, if little endian swap bytes
 *
 * Returns:
 * Zero on success, negative error code on failure.
 */
int mipi_dbi_spi_init(struct spi_device *spi, struct mipi_dbi *dbi,
		      struct gpio_desc *dc)
{
	struct device *dev = &spi->dev;

	dbi->spi = spi;
	dbi->read_commands = mipi_dbi_dcs_read_commands;

	if (!dc) {
		dev_dbg(dev, "MIPI DBI Type-C 1 unsupported\n");
		return -ENOSYS;
	}

	dbi->command = mipi_dbi_typec3_command;
	dbi->dc = dc;
	if (mipi_dbi_machine_little_endian() && !spi_is_bpw_supported(spi, 16))
		dbi->swap_bytes = true;

	dev_dbg(dev, "SPI speed: %uMHz\n", spi->max_speed_hz / 1000000);

	list_add(&dbi->list, &mipi_dbi_list);
	return 0;
}
EXPORT_SYMBOL(mipi_dbi_spi_init);

/**
 * mipi_dbi_spi_transfer - SPI transfer helper
 * @spi: SPI device
 * @speed_hz: Override speed (optional)
 * @bpw: Bits per word
 * @buf: Buffer to transfer
 * @len: Buffer length
 *
 * This SPI transfer helper breaks up the transfer of @buf into chunks which
 * the SPI controller driver can handle.
 *
 * Returns:
 * Zero on success, negative error code on failure.
 */
int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
			  u8 bpw, const void *buf, size_t len)
{
	size_t max_chunk = spi_max_transfer_size(spi);
	struct spi_transfer tr = {
		.bits_per_word = bpw,
		.speed_hz = speed_hz,
	};
	struct spi_message m;
	size_t chunk;
	int ret;

	spi_message_init_with_transfers(&m, &tr, 1);

	while (len) {
		chunk = min(len, max_chunk);

		tr.tx_buf = buf;
		tr.len = chunk;
		buf += chunk;
		len -= chunk;

		ret = spi_sync(spi, &m);
		if (ret)
			return ret;
	}

	return 0;
}
EXPORT_SYMBOL(mipi_dbi_spi_transfer);

#endif /* CONFIG_SPI */

MODULE_LICENSE("GPL");