drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c - third_party/dump-capture-kernel - Git at Google

 /*
  * Copyright (C) 2016 Noralf Trønnes
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  */

 #include <linux/backlight.h>
 #include <linux/dma-buf.h>
 #include <linux/pm.h>
 #include <linux/spi/spi.h>
 #include <linux/swab.h>

 #include <drm/tinydrm/tinydrm.h>
 #include <drm/tinydrm/tinydrm-helpers.h>

 static unsigned int spi_max;
 module_param(spi_max, uint, 0400);
 MODULE_PARM_DESC(spi_max, "Set a lower SPI max transfer size");

 /**
  * tinydrm_merge_clips - Merge clip rectangles
  * @dst: Destination clip rectangle
  * @src: Source clip rectangle(s)
  * @num_clips: Number of @src clip rectangles
  * @flags: Dirty fb ioctl flags
  * @max_width: Maximum width of @dst
  * @max_height: Maximum height of @dst
  *
  * This function merges @src clip rectangle(s) into @dst. If @src is NULL,
  * @max_width and @min_width is used to set a full @dst clip rectangle.
  *
  * Returns:
  * true if it's a full clip, false otherwise
  */
 bool tinydrm_merge_clips(struct drm_clip_rect *dst,
 			 struct drm_clip_rect *src, unsigned int num_clips,
 			 unsigned int flags, u32 max_width, u32 max_height)
 {
 	unsigned int i;

 	if (!src || !num_clips) {
 		dst->x1 = 0;
 		dst->x2 = max_width;
 		dst->y1 = 0;
 		dst->y2 = max_height;
 		return true;
 	}

 	dst->x1 = ~0;
 	dst->y1 = ~0;
 	dst->x2 = 0;
 	dst->y2 = 0;

 	for (i = 0; i < num_clips; i++) {
 		if (flags & DRM_MODE_FB_DIRTY_ANNOTATE_COPY)
 			i++;
 		dst->x1 = min(dst->x1, src[i].x1);
 		dst->x2 = max(dst->x2, src[i].x2);
 		dst->y1 = min(dst->y1, src[i].y1);
 		dst->y2 = max(dst->y2, src[i].y2);
 	}

 	if (dst->x2 > max_width || dst->y2 > max_height ||
 	    dst->x1 >= dst->x2 || dst->y1 >= dst->y2) {
 		DRM_DEBUG_KMS("Illegal clip: x1=%u, x2=%u, y1=%u, y2=%u\n",
 			      dst->x1, dst->x2, dst->y1, dst->y2);
 		dst->x1 = 0;
 		dst->y1 = 0;
 		dst->x2 = max_width;
 		dst->y2 = max_height;
 	}

 	return (dst->x2 - dst->x1) == max_width &&
 	       (dst->y2 - dst->y1) == max_height;
 }
 EXPORT_SYMBOL(tinydrm_merge_clips);

 /**
  * tinydrm_memcpy - Copy clip buffer
  * @dst: Destination buffer
  * @vaddr: Source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  */
 void tinydrm_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
 		    struct drm_clip_rect *clip)
 {
 	unsigned int cpp = drm_format_plane_cpp(fb->format->format, 0);
 	unsigned int pitch = fb->pitches[0];
 	void *src = vaddr + (clip->y1 * pitch) + (clip->x1 * cpp);
 	size_t len = (clip->x2 - clip->x1) * cpp;
 	unsigned int y;

 	for (y = clip->y1; y < clip->y2; y++) {
 		memcpy(dst, src, len);
 		src += pitch;
 		dst += len;
 	}
 }
 EXPORT_SYMBOL(tinydrm_memcpy);

 /**
  * tinydrm_swab16 - Swap bytes into clip buffer
  * @dst: RGB565 destination buffer
  * @vaddr: RGB565 source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  */
 void tinydrm_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
 		    struct drm_clip_rect *clip)
 {
 	size_t len = (clip->x2 - clip->x1) * sizeof(u16);
 	unsigned int x, y;
 	u16 *src, *buf;

 	/*
 	 * The cma memory is write-combined so reads are uncached.
 	 * Speed up by fetching one line at a time.
 	 */
 	buf = kmalloc(len, GFP_KERNEL);
 	if (!buf)
 		return;

 	for (y = clip->y1; y < clip->y2; y++) {
 		src = vaddr + (y * fb->pitches[0]);
 		src += clip->x1;
 		memcpy(buf, src, len);
 		src = buf;
 		for (x = clip->x1; x < clip->x2; x++)
 			*dst++ = swab16(*src++);
 	}

 	kfree(buf);
 }
 EXPORT_SYMBOL(tinydrm_swab16);

 /**
  * tinydrm_xrgb8888_to_rgb565 - Convert XRGB8888 to RGB565 clip buffer
  * @dst: RGB565 destination buffer
  * @vaddr: XRGB8888 source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  * @swap: Swap bytes
  *
  * Drivers can use this function for RGB565 devices that don't natively
  * support XRGB8888.
  */
 void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
 				struct drm_framebuffer *fb,
 				struct drm_clip_rect *clip, bool swap)
 {
 	size_t len = (clip->x2 - clip->x1) * sizeof(u32);
 	unsigned int x, y;
 	u32 *src, *buf;
 	u16 val16;

 	buf = kmalloc(len, GFP_KERNEL);
 	if (!buf)
 		return;

 	for (y = clip->y1; y < clip->y2; y++) {
 		src = vaddr + (y * fb->pitches[0]);
 		src += clip->x1;
 		memcpy(buf, src, len);
 		src = buf;
 		for (x = clip->x1; x < clip->x2; x++) {
 			val16 = ((*src & 0x00F80000) >> 8) |
 				((*src & 0x0000FC00) >> 5) |
 				((*src & 0x000000F8) >> 3);
 			src++;
 			if (swap)
 				*dst++ = swab16(val16);
 			else
 				*dst++ = val16;
 		}
 	}

 	kfree(buf);
 }
 EXPORT_SYMBOL(tinydrm_xrgb8888_to_rgb565);

 /**
  * tinydrm_xrgb8888_to_gray8 - Convert XRGB8888 to grayscale
  * @dst: 8-bit grayscale destination buffer
  * @vaddr: XRGB8888 source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  *
  * Drm doesn't have native monochrome or grayscale support.
  * Such drivers can announce the commonly supported XR24 format to userspace
  * and use this function to convert to the native format.
  *
  * Monochrome drivers will use the most significant bit,
  * where 1 means foreground color and 0 background color.
  *
  * ITU BT.601 is used for the RGB -> luma (brightness) conversion.
  */
 void tinydrm_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
 			       struct drm_clip_rect *clip)
 {
 	unsigned int len = (clip->x2 - clip->x1) * sizeof(u32);
 	unsigned int x, y;
 	void *buf;
 	u32 *src;

 	if (WARN_ON(fb->format->format != DRM_FORMAT_XRGB8888))
 		return;
 	/*
 	 * The cma memory is write-combined so reads are uncached.
 	 * Speed up by fetching one line at a time.
 	 */
 	buf = kmalloc(len, GFP_KERNEL);
 	if (!buf)
 		return;

 	for (y = clip->y1; y < clip->y2; y++) {
 		src = vaddr + (y * fb->pitches[0]);
 		src += clip->x1;
 		memcpy(buf, src, len);
 		src = buf;
 		for (x = clip->x1; x < clip->x2; x++) {
 			u8 r = (*src & 0x00ff0000) >> 16;
 			u8 g = (*src & 0x0000ff00) >> 8;
 			u8 b =  *src & 0x000000ff;

 			/* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
 			*dst++ = (3 * r + 6 * g + b) / 10;
 			src++;
 		}
 	}

 	kfree(buf);
 }
 EXPORT_SYMBOL(tinydrm_xrgb8888_to_gray8);

 /**
  * tinydrm_of_find_backlight - Find backlight device in device-tree
  * @dev: Device
  *
  * This function looks for a DT node pointed to by a property named 'backlight'
  * and uses of_find_backlight_by_node() to get the backlight device.
  * Additionally if the brightness property is zero, it is set to
  * max_brightness.
  *
  * Returns:
  * NULL if there's no backlight property.
  * Error pointer -EPROBE_DEFER if the DT node is found, but no backlight device
  * is found.
  * If the backlight device is found, a pointer to the structure is returned.
  */
 struct backlight_device *tinydrm_of_find_backlight(struct device *dev)
 {
 	struct backlight_device *backlight;
 	struct device_node *np;

 	np = of_parse_phandle(dev->of_node, "backlight", 0);
 	if (!np)
 		return NULL;

 	backlight = of_find_backlight_by_node(np);
 	of_node_put(np);

 	if (!backlight)
 		return ERR_PTR(-EPROBE_DEFER);

 	if (!backlight->props.brightness) {
 		backlight->props.brightness = backlight->props.max_brightness;
 		DRM_DEBUG_KMS("Backlight brightness set to %d\n",
 			      backlight->props.brightness);
 	}

 	return backlight;
 }
 EXPORT_SYMBOL(tinydrm_of_find_backlight);

 /**
  * tinydrm_enable_backlight - Enable backlight helper
  * @backlight: Backlight device
  *
  * Returns:
  * Zero on success, negative error code on failure.
  */
 int tinydrm_enable_backlight(struct backlight_device *backlight)
 {
 	unsigned int old_state;
 	int ret;

 	if (!backlight)
 		return 0;

 	old_state = backlight->props.state;
 	backlight->props.state &= ~BL_CORE_FBBLANK;
 	DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
 		      backlight->props.state);

 	ret = backlight_update_status(backlight);
 	if (ret)
 		DRM_ERROR("Failed to enable backlight %d\n", ret);

 	return ret;
 }
 EXPORT_SYMBOL(tinydrm_enable_backlight);

 /**
  * tinydrm_disable_backlight - Disable backlight helper
  * @backlight: Backlight device
  *
  * Returns:
  * Zero on success, negative error code on failure.
  */
 int tinydrm_disable_backlight(struct backlight_device *backlight)
 {
 	unsigned int old_state;
 	int ret;

 	if (!backlight)
 		return 0;

 	old_state = backlight->props.state;
 	backlight->props.state |= BL_CORE_FBBLANK;
 	DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
 		      backlight->props.state);
 	ret = backlight_update_status(backlight);
 	if (ret)
 		DRM_ERROR("Failed to disable backlight %d\n", ret);

 	return ret;
 }
 EXPORT_SYMBOL(tinydrm_disable_backlight);

 #if IS_ENABLED(CONFIG_SPI)

 /**
  * tinydrm_spi_max_transfer_size - Determine max SPI transfer size
  * @spi: SPI device
  * @max_len: Maximum buffer size needed (optional)
  *
  * This function returns the maximum size to use for SPI transfers. It checks
  * the SPI master, the optional @max_len and the module parameter spi_max and
  * returns the smallest.
  *
  * Returns:
  * Maximum size for SPI transfers
  */
 size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len)
 {
 	size_t ret;

 	ret = min(spi_max_transfer_size(spi), spi->master->max_dma_len);
 	if (max_len)
 		ret = min(ret, max_len);
 	if (spi_max)
 		ret = min_t(size_t, ret, spi_max);
 	ret &= ~0x3;
 	if (ret < 4)
 		ret = 4;

 	return ret;
 }
 EXPORT_SYMBOL(tinydrm_spi_max_transfer_size);

 /**
  * tinydrm_spi_bpw_supported - Check if bits per word is supported
  * @spi: SPI device
  * @bpw: Bits per word
  *
  * This function checks to see if the SPI master driver supports @bpw.
  *
  * Returns:
  * True if @bpw is supported, false otherwise.
  */
 bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw)
 {
 	u32 bpw_mask = spi->master->bits_per_word_mask;

 	if (bpw == 8)
 		return true;

 	if (!bpw_mask) {
 		dev_warn_once(&spi->dev,
 			      "bits_per_word_mask not set, assume 8-bit only\n");
 		return false;
 	}

 	if (bpw_mask & SPI_BPW_MASK(bpw))
 		return true;

 	return false;
 }
 EXPORT_SYMBOL(tinydrm_spi_bpw_supported);

 static void
 tinydrm_dbg_spi_print(struct spi_device *spi, struct spi_transfer *tr,
 		      const void *buf, int idx, bool tx)
 {
 	u32 speed_hz = tr->speed_hz ? tr->speed_hz : spi->max_speed_hz;
 	char linebuf[3 * 32];

 	hex_dump_to_buffer(buf, tr->len, 16,
 			   DIV_ROUND_UP(tr->bits_per_word, 8),
 			   linebuf, sizeof(linebuf), false);

 	printk(KERN_DEBUG
 	       "    tr(%i): speed=%u%s, bpw=%i, len=%u, %s_buf=[%s%s]\n", idx,
 	       speed_hz > 1000000 ? speed_hz / 1000000 : speed_hz / 1000,
 	       speed_hz > 1000000 ? "MHz" : "kHz", tr->bits_per_word, tr->len,
 	       tx ? "tx" : "rx", linebuf, tr->len > 16 ? " ..." : "");
 }

 /* called through tinydrm_dbg_spi_message() */
 void _tinydrm_dbg_spi_message(struct spi_device *spi, struct spi_message *m)
 {
 	struct spi_transfer *tmp;
 	struct list_head *pos;
 	int i = 0;

 	list_for_each(pos, &m->transfers) {
 		tmp = list_entry(pos, struct spi_transfer, transfer_list);

 		if (tmp->tx_buf)
 			tinydrm_dbg_spi_print(spi, tmp, tmp->tx_buf, i, true);
 		if (tmp->rx_buf)
 			tinydrm_dbg_spi_print(spi, tmp, tmp->rx_buf, i, false);
 		i++;
 	}
 }
 EXPORT_SYMBOL(_tinydrm_dbg_spi_message);

 /**
  * tinydrm_spi_transfer - SPI transfer helper
  * @spi: SPI device
  * @speed_hz: Override speed (optional)
  * @header: Optional header transfer
  * @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 master driver can handle. If the machine is Little Endian and the
  * SPI master driver doesn't support 16 bits per word, it swaps the bytes and
  * does a 8-bit transfer.
  * If @header is set, it is prepended to each SPI message.
  *
  * Returns:
  * Zero on success, negative error code on failure.
  */
 int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,
 			 struct spi_transfer *header, u8 bpw, const void *buf,
 			 size_t len)
 {
 	struct spi_transfer tr = {
 		.bits_per_word = bpw,
 		.speed_hz = speed_hz,
 	};
 	struct spi_message m;
 	u16 *swap_buf = NULL;
 	size_t max_chunk;
 	size_t chunk;
 	int ret = 0;

 	if (WARN_ON_ONCE(bpw != 8 && bpw != 16))
 		return -EINVAL;

 	max_chunk = tinydrm_spi_max_transfer_size(spi, 0);

 	if (drm_debug & DRM_UT_DRIVER)
 		pr_debug("[drm:%s] bpw=%u, max_chunk=%zu, transfers:\n",
 			 __func__, bpw, max_chunk);

 	if (bpw == 16 && !tinydrm_spi_bpw_supported(spi, 16)) {
 		tr.bits_per_word = 8;
 		if (tinydrm_machine_little_endian()) {
 			swap_buf = kmalloc(min(len, max_chunk), GFP_KERNEL);
 			if (!swap_buf)
 				return -ENOMEM;
 		}
 	}

 	spi_message_init(&m);
 	if (header)
 		spi_message_add_tail(header, &m);
 	spi_message_add_tail(&tr, &m);

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

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

 		if (swap_buf) {
 			const u16 *buf16 = buf;
 			unsigned int i;

 			for (i = 0; i < chunk / 2; i++)
 				swap_buf[i] = swab16(buf16[i]);

 			tr.tx_buf = swap_buf;
 		}

 		buf += chunk;
 		len -= chunk;

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

 	return 0;
 }
 EXPORT_SYMBOL(tinydrm_spi_transfer);

 #endif /* CONFIG_SPI */
	/*
	* Copyright (C) 2016 Noralf Trønnes
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*/

	#include <linux/backlight.h>
	#include <linux/dma-buf.h>
	#include <linux/pm.h>
	#include <linux/spi/spi.h>
	#include <linux/swab.h>

	#include <drm/tinydrm/tinydrm.h>
	#include <drm/tinydrm/tinydrm-helpers.h>

	static unsigned int spi_max;
	module_param(spi_max, uint, 0400);
	MODULE_PARM_DESC(spi_max, "Set a lower SPI max transfer size");

	/**
	* tinydrm_merge_clips - Merge clip rectangles
	* @dst: Destination clip rectangle
	* @src: Source clip rectangle(s)
	* @num_clips: Number of @src clip rectangles
	* @flags: Dirty fb ioctl flags
	* @max_width: Maximum width of @dst
	* @max_height: Maximum height of @dst
	*
	* This function merges @src clip rectangle(s) into @dst. If @src is NULL,
	* @max_width and @min_width is used to set a full @dst clip rectangle.
	*
	* Returns:
	* true if it's a full clip, false otherwise
	*/
	bool tinydrm_merge_clips(struct drm_clip_rect *dst,
	struct drm_clip_rect *src, unsigned int num_clips,
	unsigned int flags, u32 max_width, u32 max_height)
	{
	unsigned int i;

	if (!src \|\| !num_clips) {
	dst->x1 = 0;
	dst->x2 = max_width;
	dst->y1 = 0;
	dst->y2 = max_height;
	return true;
	}

	dst->x1 = ~0;
	dst->y1 = ~0;
	dst->x2 = 0;
	dst->y2 = 0;

	for (i = 0; i < num_clips; i++) {
	if (flags & DRM_MODE_FB_DIRTY_ANNOTATE_COPY)
	i++;
	dst->x1 = min(dst->x1, src[i].x1);
	dst->x2 = max(dst->x2, src[i].x2);
	dst->y1 = min(dst->y1, src[i].y1);
	dst->y2 = max(dst->y2, src[i].y2);
	}

	if (dst->x2 > max_width \|\| dst->y2 > max_height \|\|
	dst->x1 >= dst->x2 \|\| dst->y1 >= dst->y2) {
	DRM_DEBUG_KMS("Illegal clip: x1=%u, x2=%u, y1=%u, y2=%u\n",
	dst->x1, dst->x2, dst->y1, dst->y2);
	dst->x1 = 0;
	dst->y1 = 0;
	dst->x2 = max_width;
	dst->y2 = max_height;
	}

	return (dst->x2 - dst->x1) == max_width &&
	(dst->y2 - dst->y1) == max_height;
	}
	EXPORT_SYMBOL(tinydrm_merge_clips);

	/**
	* tinydrm_memcpy - Copy clip buffer
	* @dst: Destination buffer
	* @vaddr: Source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	*/
	void tinydrm_memcpy(void dst, void vaddr, struct drm_framebuffer *fb,
	struct drm_clip_rect *clip)
	{
	unsigned int cpp = drm_format_plane_cpp(fb->format->format, 0);
	unsigned int pitch = fb->pitches[0];
	void src = vaddr + (clip->y1 pitch) + (clip->x1 * cpp);
	size_t len = (clip->x2 - clip->x1) * cpp;
	unsigned int y;

	for (y = clip->y1; y < clip->y2; y++) {
	memcpy(dst, src, len);
	src += pitch;
	dst += len;
	}
	}
	EXPORT_SYMBOL(tinydrm_memcpy);

	/**
	* tinydrm_swab16 - Swap bytes into clip buffer
	* @dst: RGB565 destination buffer
	* @vaddr: RGB565 source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	*/
	void tinydrm_swab16(u16 dst, void vaddr, struct drm_framebuffer *fb,
	struct drm_clip_rect *clip)
	{
	size_t len = (clip->x2 - clip->x1) * sizeof(u16);
	unsigned int x, y;
	u16 src, buf;

	/*
	* The cma memory is write-combined so reads are uncached.
	* Speed up by fetching one line at a time.
	*/
	buf = kmalloc(len, GFP_KERNEL);
	if (!buf)
	return;

	for (y = clip->y1; y < clip->y2; y++) {
	src = vaddr + (y * fb->pitches[0]);
	src += clip->x1;
	memcpy(buf, src, len);
	src = buf;
	for (x = clip->x1; x < clip->x2; x++)
	dst++ = swab16(src++);
	}

	kfree(buf);
	}
	EXPORT_SYMBOL(tinydrm_swab16);

	/**
	* tinydrm_xrgb8888_to_rgb565 - Convert XRGB8888 to RGB565 clip buffer
	* @dst: RGB565 destination buffer
	* @vaddr: XRGB8888 source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	* @swap: Swap bytes
	*
	* Drivers can use this function for RGB565 devices that don't natively
	* support XRGB8888.
	*/
	void tinydrm_xrgb8888_to_rgb565(u16 dst, void vaddr,
	struct drm_framebuffer *fb,
	struct drm_clip_rect *clip, bool swap)
	{
	size_t len = (clip->x2 - clip->x1) * sizeof(u32);
	unsigned int x, y;
	u32 src, buf;
	u16 val16;

	buf = kmalloc(len, GFP_KERNEL);
	if (!buf)
	return;

	for (y = clip->y1; y < clip->y2; y++) {
	src = vaddr + (y * fb->pitches[0]);
	src += clip->x1;
	memcpy(buf, src, len);
	src = buf;
	for (x = clip->x1; x < clip->x2; x++) {
	val16 = ((*src & 0x00F80000) >> 8) \|
	((*src & 0x0000FC00) >> 5) \|
	((*src & 0x000000F8) >> 3);
	src++;
	if (swap)
	*dst++ = swab16(val16);
	else
	*dst++ = val16;
	}
	}

	kfree(buf);
	}
	EXPORT_SYMBOL(tinydrm_xrgb8888_to_rgb565);

	/**
	* tinydrm_xrgb8888_to_gray8 - Convert XRGB8888 to grayscale
	* @dst: 8-bit grayscale destination buffer
	* @vaddr: XRGB8888 source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	*
	* Drm doesn't have native monochrome or grayscale support.
	* Such drivers can announce the commonly supported XR24 format to userspace
	* and use this function to convert to the native format.
	*
	* Monochrome drivers will use the most significant bit,
	* where 1 means foreground color and 0 background color.
	*
	* ITU BT.601 is used for the RGB -> luma (brightness) conversion.
	*/
	void tinydrm_xrgb8888_to_gray8(u8 dst, void vaddr, struct drm_framebuffer *fb,
	struct drm_clip_rect *clip)
	{
	unsigned int len = (clip->x2 - clip->x1) * sizeof(u32);
	unsigned int x, y;
	void *buf;
	u32 *src;

	if (WARN_ON(fb->format->format != DRM_FORMAT_XRGB8888))
	return;
	/*
	* The cma memory is write-combined so reads are uncached.
	* Speed up by fetching one line at a time.
	*/
	buf = kmalloc(len, GFP_KERNEL);
	if (!buf)
	return;

	for (y = clip->y1; y < clip->y2; y++) {
	src = vaddr + (y * fb->pitches[0]);
	src += clip->x1;
	memcpy(buf, src, len);
	src = buf;
	for (x = clip->x1; x < clip->x2; x++) {
	u8 r = (*src & 0x00ff0000) >> 16;
	u8 g = (*src & 0x0000ff00) >> 8;
	u8 b = *src & 0x000000ff;

	/* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
	dst++ = (3 r + 6 * g + b) / 10;
	src++;
	}
	}

	kfree(buf);
	}
	EXPORT_SYMBOL(tinydrm_xrgb8888_to_gray8);

	/**
	* tinydrm_of_find_backlight - Find backlight device in device-tree
	* @dev: Device
	*
	* This function looks for a DT node pointed to by a property named 'backlight'
	* and uses of_find_backlight_by_node() to get the backlight device.
	* Additionally if the brightness property is zero, it is set to
	* max_brightness.
	*
	* Returns:
	* NULL if there's no backlight property.
	* Error pointer -EPROBE_DEFER if the DT node is found, but no backlight device
	* is found.
	* If the backlight device is found, a pointer to the structure is returned.
	*/
	struct backlight_device tinydrm_of_find_backlight(struct device dev)
	{
	struct backlight_device *backlight;
	struct device_node *np;

	np = of_parse_phandle(dev->of_node, "backlight", 0);
	if (!np)
	return NULL;

	backlight = of_find_backlight_by_node(np);
	of_node_put(np);

	if (!backlight)
	return ERR_PTR(-EPROBE_DEFER);

	if (!backlight->props.brightness) {
	backlight->props.brightness = backlight->props.max_brightness;
	DRM_DEBUG_KMS("Backlight brightness set to %d\n",
	backlight->props.brightness);
	}

	return backlight;
	}
	EXPORT_SYMBOL(tinydrm_of_find_backlight);

	/**
	* tinydrm_enable_backlight - Enable backlight helper
	* @backlight: Backlight device
	*
	* Returns:
	* Zero on success, negative error code on failure.
	*/
	int tinydrm_enable_backlight(struct backlight_device *backlight)
	{
	unsigned int old_state;
	int ret;

	if (!backlight)
	return 0;

	old_state = backlight->props.state;
	backlight->props.state &= ~BL_CORE_FBBLANK;
	DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
	backlight->props.state);

	ret = backlight_update_status(backlight);
	if (ret)
	DRM_ERROR("Failed to enable backlight %d\n", ret);

	return ret;
	}
	EXPORT_SYMBOL(tinydrm_enable_backlight);

	/**
	* tinydrm_disable_backlight - Disable backlight helper
	* @backlight: Backlight device
	*
	* Returns:
	* Zero on success, negative error code on failure.
	*/
	int tinydrm_disable_backlight(struct backlight_device *backlight)
	{
	unsigned int old_state;
	int ret;

	if (!backlight)
	return 0;

	old_state = backlight->props.state;
	backlight->props.state \|= BL_CORE_FBBLANK;
	DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
	backlight->props.state);
	ret = backlight_update_status(backlight);
	if (ret)
	DRM_ERROR("Failed to disable backlight %d\n", ret);

	return ret;
	}
	EXPORT_SYMBOL(tinydrm_disable_backlight);

	#if IS_ENABLED(CONFIG_SPI)

	/**
	* tinydrm_spi_max_transfer_size - Determine max SPI transfer size
	* @spi: SPI device
	* @max_len: Maximum buffer size needed (optional)
	*
	* This function returns the maximum size to use for SPI transfers. It checks
	* the SPI master, the optional @max_len and the module parameter spi_max and
	* returns the smallest.
	*
	* Returns:
	* Maximum size for SPI transfers
	*/
	size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len)
	{
	size_t ret;

	ret = min(spi_max_transfer_size(spi), spi->master->max_dma_len);
	if (max_len)
	ret = min(ret, max_len);
	if (spi_max)
	ret = min_t(size_t, ret, spi_max);
	ret &= ~0x3;
	if (ret < 4)
	ret = 4;

	return ret;
	}
	EXPORT_SYMBOL(tinydrm_spi_max_transfer_size);

	/**
	* tinydrm_spi_bpw_supported - Check if bits per word is supported
	* @spi: SPI device
	* @bpw: Bits per word
	*
	* This function checks to see if the SPI master driver supports @bpw.
	*
	* Returns:
	* True if @bpw is supported, false otherwise.
	*/
	bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw)
	{
	u32 bpw_mask = spi->master->bits_per_word_mask;

	if (bpw == 8)
	return true;

	if (!bpw_mask) {
	dev_warn_once(&spi->dev,
	"bits_per_word_mask not set, assume 8-bit only\n");
	return false;
	}

	if (bpw_mask & SPI_BPW_MASK(bpw))
	return true;

	return false;
	}
	EXPORT_SYMBOL(tinydrm_spi_bpw_supported);

	static void
	tinydrm_dbg_spi_print(struct spi_device spi, struct spi_transfer tr,
	const void *buf, int idx, bool tx)
	{
	u32 speed_hz = tr->speed_hz ? tr->speed_hz : spi->max_speed_hz;
	char linebuf[3 * 32];

	hex_dump_to_buffer(buf, tr->len, 16,
	DIV_ROUND_UP(tr->bits_per_word, 8),
	linebuf, sizeof(linebuf), false);

	printk(KERN_DEBUG
	" tr(%i): speed=%u%s, bpw=%i, len=%u, %s_buf=[%s%s]\n", idx,
	speed_hz > 1000000 ? speed_hz / 1000000 : speed_hz / 1000,
	speed_hz > 1000000 ? "MHz" : "kHz", tr->bits_per_word, tr->len,
	tx ? "tx" : "rx", linebuf, tr->len > 16 ? " ..." : "");
	}

	/* called through tinydrm_dbg_spi_message() */
	void _tinydrm_dbg_spi_message(struct spi_device spi, struct spi_message m)
	{
	struct spi_transfer *tmp;
	struct list_head *pos;
	int i = 0;

	list_for_each(pos, &m->transfers) {
	tmp = list_entry(pos, struct spi_transfer, transfer_list);

	if (tmp->tx_buf)
	tinydrm_dbg_spi_print(spi, tmp, tmp->tx_buf, i, true);
	if (tmp->rx_buf)
	tinydrm_dbg_spi_print(spi, tmp, tmp->rx_buf, i, false);
	i++;
	}
	}
	EXPORT_SYMBOL(_tinydrm_dbg_spi_message);

	/**
	* tinydrm_spi_transfer - SPI transfer helper
	* @spi: SPI device
	* @speed_hz: Override speed (optional)
	* @header: Optional header transfer
	* @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 master driver can handle. If the machine is Little Endian and the
	* SPI master driver doesn't support 16 bits per word, it swaps the bytes and
	* does a 8-bit transfer.
	* If @header is set, it is prepended to each SPI message.
	*
	* Returns:
	* Zero on success, negative error code on failure.
	*/
	int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,
	struct spi_transfer header, u8 bpw, const void buf,
	size_t len)
	{
	struct spi_transfer tr = {
	.bits_per_word = bpw,
	.speed_hz = speed_hz,
	};
	struct spi_message m;
	u16 *swap_buf = NULL;
	size_t max_chunk;
	size_t chunk;
	int ret = 0;

	if (WARN_ON_ONCE(bpw != 8 && bpw != 16))
	return -EINVAL;

	max_chunk = tinydrm_spi_max_transfer_size(spi, 0);

	if (drm_debug & DRM_UT_DRIVER)
	pr_debug("[drm:%s] bpw=%u, max_chunk=%zu, transfers:\n",
	__func__, bpw, max_chunk);

	if (bpw == 16 && !tinydrm_spi_bpw_supported(spi, 16)) {
	tr.bits_per_word = 8;
	if (tinydrm_machine_little_endian()) {
	swap_buf = kmalloc(min(len, max_chunk), GFP_KERNEL);
	if (!swap_buf)
	return -ENOMEM;
	}
	}

	spi_message_init(&m);
	if (header)
	spi_message_add_tail(header, &m);
	spi_message_add_tail(&tr, &m);

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

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

	if (swap_buf) {
	const u16 *buf16 = buf;
	unsigned int i;

	for (i = 0; i < chunk / 2; i++)
	swap_buf[i] = swab16(buf16[i]);

	tr.tx_buf = swap_buf;
	}

	buf += chunk;
	len -= chunk;

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

	return 0;
	}
	EXPORT_SYMBOL(tinydrm_spi_transfer);

	#endif /* CONFIG_SPI */