drm_format_helper.c

// SPDX-License-Identifier: GPL-2.0 or MIT
/*
 * 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/io.h>
#include <linux/iosys-map.h>
#include <linux/module.h>
#include <linux/slab.h>

#include <drm/drm_device.h>
#include <drm/drm_format_helper.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_print.h>
#include <drm/drm_rect.h>

static unsigned int clip_offset(const struct drm_rect *clip, unsigned int pitch, unsigned int cpp)
{
	return clip->y1 * pitch + clip->x1 * cpp;
}

/**
 * drm_fb_clip_offset - Returns the clipping rectangles byte-offset in a framebuffer
 * @pitch: Framebuffer line pitch in byte
 * @format: Framebuffer format
 * @clip: Clip rectangle
 *
 * Returns:
 * The byte offset of the clip rectangle's top-left corner within the framebuffer.
 */
unsigned int drm_fb_clip_offset(unsigned int pitch, const struct drm_format_info *format,
				const struct drm_rect *clip)
{
	return clip_offset(clip, pitch, format->cpp[0]);
}
EXPORT_SYMBOL(drm_fb_clip_offset);

/* TODO: Make this functon work with multi-plane formats. */
static int drm_fb_xfrm(void *dst, unsigned long dst_pitch, unsigned long dst_pixsize,
		       const void *vaddr, const struct drm_framebuffer *fb,
		       const struct drm_rect *clip, bool vaddr_cached_hint,
		       void (*xfrm_line)(void *dbuf, const void *sbuf, unsigned int npixels))
{
	unsigned long linepixels = drm_rect_width(clip);
	unsigned long lines = drm_rect_height(clip);
	size_t sbuf_len = linepixels * fb->format->cpp[0];
	void *stmp = NULL;
	unsigned long i;
	const void *sbuf;

	/*
	 * Some source buffers, such as DMA memory, use write-combine
	 * caching, so reads are uncached. Speed up access by fetching
	 * one line at a time.
	 */
	if (!vaddr_cached_hint) {
		stmp = kmalloc(sbuf_len, GFP_KERNEL);
		if (!stmp)
			return -ENOMEM;
	}

	if (!dst_pitch)
		dst_pitch = drm_rect_width(clip) * dst_pixsize;
	vaddr += clip_offset(clip, fb->pitches[0], fb->format->cpp[0]);

	for (i = 0; i < lines; ++i) {
		if (stmp)
			sbuf = memcpy(stmp, vaddr, sbuf_len);
		else
			sbuf = vaddr;
		xfrm_line(dst, sbuf, linepixels);
		vaddr += fb->pitches[0];
		dst += dst_pitch;
	}

	kfree(stmp);

	return 0;
}

/* TODO: Make this functon work with multi-plane formats. */
static int drm_fb_xfrm_toio(void __iomem *dst, unsigned long dst_pitch, unsigned long dst_pixsize,
			    const void *vaddr, const struct drm_framebuffer *fb,
			    const struct drm_rect *clip, bool vaddr_cached_hint,
			    void (*xfrm_line)(void *dbuf, const void *sbuf, unsigned int npixels))
{
	unsigned long linepixels = drm_rect_width(clip);
	unsigned long lines = drm_rect_height(clip);
	size_t dbuf_len = linepixels * dst_pixsize;
	size_t stmp_off = round_up(dbuf_len, ARCH_KMALLOC_MINALIGN); /* for sbuf alignment */
	size_t sbuf_len = linepixels * fb->format->cpp[0];
	void *stmp = NULL;
	unsigned long i;
	const void *sbuf;
	void *dbuf;

	if (vaddr_cached_hint) {
		dbuf = kmalloc(dbuf_len, GFP_KERNEL);
	} else {
		dbuf = kmalloc(stmp_off + sbuf_len, GFP_KERNEL);
		stmp = dbuf + stmp_off;
	}
	if (!dbuf)
		return -ENOMEM;

	if (!dst_pitch)
		dst_pitch = linepixels * dst_pixsize;
	vaddr += clip_offset(clip, fb->pitches[0], fb->format->cpp[0]);

	for (i = 0; i < lines; ++i) {
		if (stmp)
			sbuf = memcpy(stmp, vaddr, sbuf_len);
		else
			sbuf = vaddr;
		xfrm_line(dbuf, sbuf, linepixels);
		memcpy_toio(dst, dbuf, dbuf_len);
		vaddr += fb->pitches[0];
		dst += dst_pitch;
	}

	kfree(dbuf);

	return 0;
}

/**
 * drm_fb_memcpy - Copy clip buffer
 * @dst: Array of destination buffers
 * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
 *             within @dst; can be NULL if scanlines are stored next to each other.
 * @vmap: Array of source buffers
 * @fb: DRM framebuffer
 * @clip: Clip rectangle area to copy
 *
 * This function copies parts of a framebuffer to display memory. Destination and
 * framebuffer formats must match. No conversion takes place. The parameters @dst,
 * @dst_pitch and @vmap refer to arrays. Each array must have at least as many entries
 * as there are planes in @fb's format. Each entry stores the value for the format's
 * respective color plane at the same index.
 *
 * This function does not apply clipping on @dst (i.e. the destination is at the
 * top-left corner).
 */
void drm_fb_memcpy(struct iosys_map *dst, const unsigned int *dst_pitch,
		   const struct iosys_map *vmap, const struct drm_framebuffer *fb,
		   const struct drm_rect *clip)
{
	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
		0, 0, 0, 0
	};

	const struct drm_format_info *format = fb->format;
	unsigned int i, y, lines = drm_rect_height(clip);

	if (!dst_pitch)
		dst_pitch = default_dst_pitch;

	for (i = 0; i < format->num_planes; ++i) {
		unsigned int bpp_i = drm_format_info_bpp(format, i);
		unsigned int cpp_i = DIV_ROUND_UP(bpp_i, 8);
		size_t len_i = DIV_ROUND_UP(drm_rect_width(clip) * bpp_i, 8);
		unsigned int dst_pitch_i = dst_pitch[i];
		struct iosys_map dst_i = dst[i];
		struct iosys_map vmap_i = vmap[i];

		if (!dst_pitch_i)
			dst_pitch_i = len_i;

		iosys_map_incr(&vmap_i, clip_offset(clip, fb->pitches[i], cpp_i));
		for (y = 0; y < lines; y++) {
			/* TODO: handle vmap_i in I/O memory here */
			iosys_map_memcpy_to(&dst_i, 0, vmap_i.vaddr, len_i);
			iosys_map_incr(&vmap_i, fb->pitches[i]);
			iosys_map_incr(&dst_i, dst_pitch_i);
		}
	}
}
EXPORT_SYMBOL(drm_fb_memcpy);

static void drm_fb_swab16_line(void *dbuf, const void *sbuf, unsigned int pixels)
{
	u16 *dbuf16 = dbuf;
	const u16 *sbuf16 = sbuf;
	const u16 *send16 = sbuf16 + pixels;

	while (sbuf16 < send16)
		*dbuf16++ = swab16(*sbuf16++);
}

static void drm_fb_swab32_line(void *dbuf, const void *sbuf, unsigned int pixels)
{
	u32 *dbuf32 = dbuf;
	const u32 *sbuf32 = sbuf;
	const u32 *send32 = sbuf32 + pixels;

	while (sbuf32 < send32)
		*dbuf32++ = swab32(*sbuf32++);
}

/**
 * drm_fb_swab - Swap bytes into clip buffer
 * @dst: Array of destination buffers
 * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
 *             within @dst; can be NULL if scanlines are stored next to each other.
 * @vmap: Array of source buffers
 * @fb: DRM framebuffer
 * @clip: Clip rectangle area to copy
 * @cached: Source buffer is mapped cached (eg. not write-combined)
 *
 * This function copies parts of a framebuffer to display memory and swaps per-pixel
 * bytes during the process. Destination and framebuffer formats must match. The
 * parameters @dst, @dst_pitch and @vmap refer to arrays. Each array must have at
 * least as many entries as there are planes in @fb's format. Each entry stores the
 * value for the format's respective color plane at the same index. If @cached is
 * false a temporary buffer is used to cache one pixel line at a time to speed up
 * slow uncached reads.
 *
 * This function does not apply clipping on @dst (i.e. the destination is at the
 * top-left corner).
 */
void drm_fb_swab(struct iosys_map *dst, const unsigned int *dst_pitch,
		 const struct iosys_map *vmap, const struct drm_framebuffer *fb,
		 const struct drm_rect *clip, bool cached)
{
	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
		0, 0, 0, 0
	};
	const struct drm_format_info *format = fb->format;
	u8 cpp = DIV_ROUND_UP(drm_format_info_bpp(format, 0), 8);
	void (*swab_line)(void *dbuf, const void *sbuf, unsigned int npixels);

	switch (cpp) {
	case 4:
		swab_line = drm_fb_swab32_line;
		break;
	case 2:
		swab_line = drm_fb_swab16_line;
		break;
	default:
		drm_warn_once(fb->dev, "Format %p4cc has unsupported pixel size.\n",
			      &format->format);
		swab_line = NULL;
		break;
	}
	if (!swab_line)
		return;

	if (!dst_pitch)
		dst_pitch = default_dst_pitch;

	/* TODO: handle vmap in I/O memory here */
	if (dst->is_iomem)
		drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], cpp,
				 vmap[0].vaddr, fb, clip, cached, swab_line);
	else
		drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], cpp, vmap[0].vaddr, fb,
			    clip, cached, swab_line);
}
EXPORT_SYMBOL(drm_fb_swab);

static void drm_fb_xrgb8888_to_rgb332_line(void *dbuf, const void *sbuf, unsigned int pixels)
{
	u8 *dbuf8 = dbuf;
	const __le32 *sbuf32 = sbuf;
	unsigned int x;
	u32 pix;

	for (x = 0; x < pixels; x++) {
		pix = le32_to_cpu(sbuf32[x]);
		dbuf8[x] = ((pix & 0x00e00000) >> 16) |
			   ((pix & 0x0000e000) >> 11) |
			   ((pix & 0x000000c0) >> 6);
	}
}

/**
 * drm_fb_xrgb8888_to_rgb332 - Convert XRGB8888 to RGB332 clip buffer
 * @dst: Array of RGB332 destination buffers
 * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
 *             within @dst; can be NULL if scanlines are stored next to each other.
 * @vmap: Array of XRGB8888 source buffers
 * @fb: DRM framebuffer
 * @clip: Clip rectangle area to copy
 *
 * This function copies parts of a framebuffer to display memory and converts the
 * color format during the process. Destination and framebuffer formats must match. The
 * parameters @dst, @dst_pitch and @vmap refer to arrays. Each array must have at
 * least as many entries as there are planes in @fb's format. Each entry stores the
 * value for the format's respective color plane at the same index.
 *
 * This function does not apply clipping on @dst (i.e. the destination is at the
 * top-left corner).
 *
 * Drivers can use this function for RGB332 devices that don't support XRGB8888 natively.
 */
void drm_fb_xrgb8888_to_rgb332(struct iosys_map *dst, const unsigned int *dst_pitch,
			       const struct iosys_map *vmap, const struct drm_framebuffer *fb,
			       const struct drm_rect *clip)
{
	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
		0, 0, 0, 0
	};

	if (!dst_pitch)
		dst_pitch = default_dst_pitch;

	/* TODO: handle vmap in I/O memory here */
	if (dst[0].is_iomem)
		drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], 1, vmap[0].vaddr, fb, clip,
				 false, drm_fb_xrgb8888_to_rgb332_line);
	else
		drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], 1, vmap[0].vaddr, fb, clip,
			    false, drm_fb_xrgb8888_to_rgb332_line);
}
EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb332);

static void drm_fb_xrgb8888_to_rgb565_line(void *dbuf, const void *sbuf, unsigned int pixels)
{
	u16 *dbuf16 = dbuf;
	const __le32 *sbuf32 = sbuf;
	unsigned int x;
	u16 val16;
	u32 pix;

	for (x = 0; x < pixels; x++) {
		pix = le32_to_cpu(sbuf32[x]);
		val16 = ((pix & 0x00F80000) >> 8) |
			((pix & 0x0000FC00) >> 5) |
			((pix & 0x000000F8) >> 3);
		dbuf16[x] = val16;
	}
}

static void drm_fb_xrgb8888_to_rgb565_swab_line(void *dbuf, const void *sbuf,
						unsigned int pixels)
{
	u16 *dbuf16 = dbuf;
	const __le32 *sbuf32 = sbuf;
	unsigned int x;
	u16 val16;
	u32 pix;

	for (x = 0; x < pixels; x++) {
		pix = le32_to_cpu(sbuf32[x]);
		val16 = ((pix & 0x00F80000) >> 8) |
			((pix & 0x0000FC00) >> 5) |
			((pix & 0x000000F8) >> 3);
		dbuf16[x] = swab16(val16);
	}
}

/**
 * drm_fb_xrgb8888_to_rgb565 - Convert XRGB8888 to RGB565 clip buffer
 * @dst: Array of RGB565 destination buffers
 * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
 *             within @dst; can be NULL if scanlines are stored next to each other.
 * @vmap: Array of XRGB8888 source buffer
 * @fb: DRM framebuffer
 * @clip: Clip rectangle area to copy
 * @swab: Swap bytes
 *
 * This function copies parts of a framebuffer to display memory and converts the
 * color format during the process. Destination and framebuffer formats must match. The
 * parameters @dst, @dst_pitch and @vmap refer to arrays. Each array must have at
 * least as many entries as there are planes in @fb's format. Each entry stores the
 * value for the format's respective color plane at the same index.
 *
 * This function does not apply clipping on @dst (i.e. the destination is at the
 * top-left corner).
 *
 * Drivers can use this function for RGB565 devices that don't support XRGB8888 natively.
 */
void drm_fb_xrgb8888_to_rgb565(struct iosys_map *dst, const unsigned int *dst_pitch,
			       const struct iosys_map *vmap, const struct drm_framebuffer *fb,
			       const struct drm_rect *clip, bool swab)
{
	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
		0, 0, 0, 0
	};
	void (*xfrm_line)(void *dbuf, const void *sbuf, unsigned int npixels);

	if (swab)
		xfrm_line = drm_fb_xrgb8888_to_rgb565_swab_line;
	else
		xfrm_line = drm_fb_xrgb8888_to_rgb565_line;

	if (!dst_pitch)
		dst_pitch = default_dst_pitch;

	/* TODO: handle vmap in I/O memory here */
	if (dst[0].is_iomem)
		drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], 2, vmap[0].vaddr, fb, clip,
				 false, xfrm_line);
	else
		drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], 2, vmap[0].vaddr, fb, clip,
			    false, xfrm_line);
}
EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb565);

static void drm_fb_xrgb8888_to_rgb888_line(void *dbuf, const void *sbuf, unsigned int pixels)
{
	u8 *dbuf8 = dbuf;
	const __le32 *sbuf32 = sbuf;
	unsigned int x;
	u32 pix;

	for (x = 0; x < pixels; x++) {
		pix = le32_to_cpu(sbuf32[x]);
		*dbuf8++ = (pix & 0x000000FF) >>  0;
		*dbuf8++ = (pix & 0x0000FF00) >>  8;
		*dbuf8++ = (pix & 0x00FF0000) >> 16;
	}
}

/**
 * drm_fb_xrgb8888_to_rgb888 - Convert XRGB8888 to RGB888 clip buffer
 * @dst: Array of RGB888 destination buffers
 * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
 *             within @dst; can be NULL if scanlines are stored next to each other.
 * @vmap: Array of XRGB8888 source buffers
 * @fb: DRM framebuffer
 * @clip: Clip rectangle area to copy
 *
 * This function copies parts of a framebuffer to display memory and converts the
 * color format during the process. Destination and framebuffer formats must match. The
 * parameters @dst, @dst_pitch and @vmap refer to arrays. Each array must have at
 * least as many entries as there are planes in @fb's format. Each entry stores the
 * value for the format's respective color plane at the same index.
 *
 * This function does not apply clipping on @dst (i.e. the destination is at the
 * top-left corner).
 *
 * Drivers can use this function for RGB888 devices that don't natively
 * support XRGB8888.
 */
void drm_fb_xrgb8888_to_rgb888(struct iosys_map *dst, const unsigned int *dst_pitch,
			       const struct iosys_map *vmap, const struct drm_framebuffer *fb,
			       const struct drm_rect *clip)
{
	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
		0, 0, 0, 0
	};

	if (!dst_pitch)
		dst_pitch = default_dst_pitch;

	/* TODO: handle vmap in I/O memory here */
	if (dst[0].is_iomem)
		drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], 3, vmap[0].vaddr, fb,
				 clip, false, drm_fb_xrgb8888_to_rgb888_line);
	else
		drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], 3, vmap[0].vaddr, fb,
			    clip, false, drm_fb_xrgb8888_to_rgb888_line);
}
EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb888);

static void drm_fb_rgb565_to_xrgb8888_line(void *dbuf, const void *sbuf, unsigned int pixels)
{
	__le32 *dbuf32 = dbuf;
	const __le16 *sbuf16 = sbuf;
	unsigned int x;

	for (x = 0; x < pixels; x++) {
		u16 val16 = le16_to_cpu(sbuf16[x]);
		u32 val32 = ((val16 & 0xf800) << 8) |
			    ((val16 & 0x07e0) << 5) |
			    ((val16 & 0x001f) << 3);
		val32 = 0xff000000 | val32 |
			((val32 >> 3) & 0x00070007) |
			((val32 >> 2) & 0x00000300);
		dbuf32[x] = cpu_to_le32(val32);
	}
}

static void drm_fb_rgb565_to_xrgb8888(struct iosys_map *dst, const unsigned int *dst_pitch,
				      const struct iosys_map *vmap,
				      const struct drm_framebuffer *fb,
				      const struct drm_rect *clip)
{
	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
		0, 0, 0, 0
	};

	if (!dst_pitch)
		dst_pitch = default_dst_pitch;

	/* TODO: handle vmap in I/O memory here */
	if (dst[0].is_iomem)
		drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], 4, vmap[0].vaddr, fb,
				 clip, false, drm_fb_rgb565_to_xrgb8888_line);
	else
		drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], 4, vmap[0].vaddr, fb,
			    clip, false, drm_fb_rgb565_to_xrgb8888_line);
}

static void drm_fb_rgb888_to_xrgb8888_line(void *dbuf, const void *sbuf, unsigned int pixels)
{
	__le32 *dbuf32 = dbuf;
	const u8 *sbuf8 = sbuf;
	unsigned int x;

	for (x = 0; x < pixels; x++) {
		u8 r = *sbuf8++;
		u8 g = *sbuf8++;
		u8 b = *sbuf8++;
		u32 pix = 0xff000000 | (r << 16) | (g << 8) | b;
		dbuf32[x] = cpu_to_le32(pix);
	}
}

static void drm_fb_rgb888_to_xrgb8888(struct iosys_map *dst, const unsigned int *dst_pitch,
				      const struct iosys_map *vmap,
				      const struct drm_framebuffer *fb,
				      const struct drm_rect *clip)
{
	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
		0, 0, 0, 0
	};

	if (!dst_pitch)
		dst_pitch = default_dst_pitch;

	/* TODO: handle vmap in I/O memory here */
	if (dst[0].is_iomem)
		drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], 4, vmap[0].vaddr, fb,
				 clip, false, drm_fb_rgb888_to_xrgb8888_line);
	else
		drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], 4, vmap[0].vaddr, fb,
			    clip, false, drm_fb_rgb888_to_xrgb8888_line);
}

static void drm_fb_xrgb8888_to_xrgb2101010_line(void *dbuf, const void *sbuf, unsigned int pixels)
{
	__le32 *dbuf32 = dbuf;
	const __le32 *sbuf32 = sbuf;
	unsigned int x;
	u32 val32;
	u32 pix;

	for (x = 0; x < pixels; x++) {
		pix = le32_to_cpu(sbuf32[x]);
		val32 = ((pix & 0x000000FF) << 2) |
			((pix & 0x0000FF00) << 4) |
			((pix & 0x00FF0000) << 6);
		pix = val32 | ((val32 >> 8) & 0x00300C03);
		*dbuf32++ = cpu_to_le32(pix);
	}
}

/**
 * drm_fb_xrgb8888_to_xrgb2101010 - Convert XRGB8888 to XRGB2101010 clip buffer
 * @dst: Array of XRGB2101010 destination buffers
 * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
 *             within @dst; can be NULL if scanlines are stored next to each other.
 * @vmap: Array of XRGB8888 source buffers
 * @fb: DRM framebuffer
 * @clip: Clip rectangle area to copy
 *
 * This function copies parts of a framebuffer to display memory and converts the
 * color format during the process. Destination and framebuffer formats must match. The
 * parameters @dst, @dst_pitch and @vmap refer to arrays. Each array must have at
 * least as many entries as there are planes in @fb's format. Each entry stores the
 * value for the format's respective color plane at the same index.
 *
 * This function does not apply clipping on @dst (i.e. the destination is at the
 * top-left corner).
 *
 * Drivers can use this function for XRGB2101010 devices that don't support XRGB8888
 * natively.
 */
void drm_fb_xrgb8888_to_xrgb2101010(struct iosys_map *dst, const unsigned int *dst_pitch,
				    const struct iosys_map *vmap, const struct drm_framebuffer *fb,
				    const struct drm_rect *clip)
{
	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
		0, 0, 0, 0
	};

	if (!dst_pitch)
		dst_pitch = default_dst_pitch;

	/* TODO: handle vmap in I/O memory here */
	if (dst[0].is_iomem)
		drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], 4, vmap[0].vaddr, fb,
				 clip, false, drm_fb_xrgb8888_to_xrgb2101010_line);
	else
		drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], 4, vmap[0].vaddr, fb,
			    clip, false, drm_fb_xrgb8888_to_xrgb2101010_line);
}

static void drm_fb_xrgb8888_to_gray8_line(void *dbuf, const void *sbuf, unsigned int pixels)
{
	u8 *dbuf8 = dbuf;
	const __le32 *sbuf32 = sbuf;
	unsigned int x;

	for (x = 0; x < pixels; x++) {
		u32 pix = le32_to_cpu(sbuf32[x]);
		u8 r = (pix & 0x00ff0000) >> 16;
		u8 g = (pix & 0x0000ff00) >> 8;
		u8 b =  pix & 0x000000ff;

		/* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
		*dbuf8++ = (3 * r + 6 * g + b) / 10;
	}
}

/**
 * drm_fb_xrgb8888_to_gray8 - Convert XRGB8888 to grayscale
 * @dst: Array of 8-bit grayscale destination buffers
 * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
 *             within @dst; can be NULL if scanlines are stored next to each other.
 * @vmap: Array of XRGB8888 source buffers
 * @fb: DRM framebuffer
 * @clip: Clip rectangle area to copy
 *
 * This function copies parts of a framebuffer to display memory and converts the
 * color format during the process. Destination and framebuffer formats must match. The
 * parameters @dst, @dst_pitch and @vmap refer to arrays. Each array must have at
 * least as many entries as there are planes in @fb's format. Each entry stores the
 * value for the format's respective color plane at the same index.
 *
 * This function does not apply clipping on @dst (i.e. the destination is at the
 * top-left corner).
 *
 * DRM doesn't have native monochrome or grayscale support. Drivers can use this
 * function for grayscale devices that don't support XRGB8888 natively.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 being used for the RGB -> luma (brightness) conversion.
 */
void drm_fb_xrgb8888_to_gray8(struct iosys_map *dst, const unsigned int *dst_pitch,
			      const struct iosys_map *vmap, const struct drm_framebuffer *fb,
			      const struct drm_rect *clip)
{
	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
		0, 0, 0, 0
	};

	if (!dst_pitch)
		dst_pitch = default_dst_pitch;

	/* TODO: handle vmap in I/O memory here */
	if (dst[0].is_iomem)
		drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], 1, vmap[0].vaddr, fb,
				 clip, false, drm_fb_xrgb8888_to_gray8_line);
	else
		drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], 1, vmap[0].vaddr, fb,
			    clip, false, drm_fb_xrgb8888_to_gray8_line);
}
EXPORT_SYMBOL(drm_fb_xrgb8888_to_gray8);

/**
 * drm_fb_blit - Copy parts of a framebuffer to display memory
 * @dst:	Array of display-memory addresses to copy to
 * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
 *             within @dst; can be NULL if scanlines are stored next to each other.
 * @dst_format:	FOURCC code of the display's color format
 * @vmap:	The framebuffer memory to copy from
 * @fb:		The framebuffer to copy from
 * @clip:	Clip rectangle area to copy
 *
 * This function copies parts of a framebuffer to display memory. If the
 * formats of the display and the framebuffer mismatch, the blit function
 * will attempt to convert between them during the process. The parameters @dst,
 * @dst_pitch and @vmap refer to arrays. Each array must have at least as many
 * entries as there are planes in @dst_format's format. Each entry stores the
 * value for the format's respective color plane at the same index.
 *
 * This function does not apply clipping on @dst (i.e. the destination is at the
 * top-left corner).
 *
 * Returns:
 * 0 on success, or
 * -EINVAL if the color-format conversion failed, or
 * a negative error code otherwise.
 */
int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t dst_format,
		const struct iosys_map *vmap, const struct drm_framebuffer *fb,
		const struct drm_rect *clip)
{
	uint32_t fb_format = fb->format->format;

	/* treat alpha channel like filler bits */
	if (fb_format == DRM_FORMAT_ARGB8888)
		fb_format = DRM_FORMAT_XRGB8888;
	if (dst_format == DRM_FORMAT_ARGB8888)
		dst_format = DRM_FORMAT_XRGB8888;
	if (fb_format == DRM_FORMAT_ARGB2101010)
		fb_format = DRM_FORMAT_XRGB2101010;
	if (dst_format == DRM_FORMAT_ARGB2101010)
		dst_format = DRM_FORMAT_XRGB2101010;

	if (dst_format == fb_format) {
		drm_fb_memcpy(dst, dst_pitch, vmap, fb, clip);
		return 0;

	} else if (dst_format == DRM_FORMAT_RGB565) {
		if (fb_format == DRM_FORMAT_XRGB8888) {
			drm_fb_xrgb8888_to_rgb565(dst, dst_pitch, vmap, fb, clip, false);
			return 0;
		}
	} else if (dst_format == DRM_FORMAT_RGB888) {
		if (fb_format == DRM_FORMAT_XRGB8888) {
			drm_fb_xrgb8888_to_rgb888(dst, dst_pitch, vmap, fb, clip);
			return 0;
		}
	} else if (dst_format == DRM_FORMAT_XRGB8888) {
		if (fb_format == DRM_FORMAT_RGB888) {
			drm_fb_rgb888_to_xrgb8888(dst, dst_pitch, vmap, fb, clip);
			return 0;
		} else if (fb_format == DRM_FORMAT_RGB565) {
			drm_fb_rgb565_to_xrgb8888(dst, dst_pitch, vmap, fb, clip);
			return 0;
		}
	} else if (dst_format == DRM_FORMAT_XRGB2101010) {
		if (fb_format == DRM_FORMAT_XRGB8888) {
			drm_fb_xrgb8888_to_xrgb2101010(dst, dst_pitch, vmap, fb, clip);
			return 0;
		}
	}

	drm_warn_once(fb->dev, "No conversion helper from %p4cc to %p4cc found.\n",
		      &fb_format, &dst_format);

	return -EINVAL;
}
EXPORT_SYMBOL(drm_fb_blit);

static void drm_fb_gray8_to_mono_line(void *dbuf, const void *sbuf, unsigned int pixels)
{
	u8 *dbuf8 = dbuf;
	const u8 *sbuf8 = sbuf;

	while (pixels) {
		unsigned int i, bits = min(pixels, 8U);
		u8 byte = 0;

		for (i = 0; i < bits; i++, pixels--) {
			if (*sbuf8++ >= 128)
				byte |= BIT(i);
		}
		*dbuf8++ = byte;
	}
}

/**
 * drm_fb_xrgb8888_to_mono - Convert XRGB8888 to monochrome
 * @dst: Array of monochrome destination buffers (0=black, 1=white)
 * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
 *             within @dst; can be NULL if scanlines are stored next to each other.
 * @vmap: Array of XRGB8888 source buffers
 * @fb: DRM framebuffer
 * @clip: Clip rectangle area to copy
 *
 * This function copies parts of a framebuffer to display memory and converts the
 * color format during the process. Destination and framebuffer formats must match. The
 * parameters @dst, @dst_pitch and @vmap refer to arrays. Each array must have at
 * least as many entries as there are planes in @fb's format. Each entry stores the
 * value for the format's respective color plane at the same index.
 *
 * This function does not apply clipping on @dst (i.e. the destination is at the
 * top-left corner). The first pixel (upper left corner of the clip rectangle) will
 * be converted and copied to the first bit (LSB) in the first byte of the monochrome
 * destination buffer. If the caller requires that the first pixel in a byte must
 * be located at an x-coordinate that is a multiple of 8, then the caller must take
 * care itself of supplying a suitable clip rectangle.
 *
 * DRM doesn't have native monochrome support. Drivers can use this function for
 * monochrome devices that don't support XRGB8888 natively. Such drivers can
 * announce the commonly supported XR24 format to userspace and use this function
 * to convert to the native format.
 *
 * This function uses drm_fb_xrgb8888_to_gray8() to convert to grayscale and
 * then the result is converted from grayscale to monochrome.
 */
void drm_fb_xrgb8888_to_mono(struct iosys_map *dst, const unsigned int *dst_pitch,
			     const struct iosys_map *vmap, const struct drm_framebuffer *fb,
			     const struct drm_rect *clip)
{
	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
		0, 0, 0, 0
	};
	unsigned int linepixels = drm_rect_width(clip);
	unsigned int lines = drm_rect_height(clip);
	unsigned int cpp = fb->format->cpp[0];
	unsigned int len_src32 = linepixels * cpp;
	struct drm_device *dev = fb->dev;
	void *vaddr = vmap[0].vaddr;
	unsigned int dst_pitch_0;
	unsigned int y;
	u8 *mono = dst[0].vaddr, *gray8;
	u32 *src32;

	if (drm_WARN_ON(dev, fb->format->format != DRM_FORMAT_XRGB8888))
		return;

	if (!dst_pitch)
		dst_pitch = default_dst_pitch;
	dst_pitch_0 = dst_pitch[0];

	/*
	 * The mono destination buffer contains 1 bit per pixel
	 */
	if (!dst_pitch_0)
		dst_pitch_0 = DIV_ROUND_UP(linepixels, 8);

	/*
	 * The dma memory is write-combined so reads are uncached.
	 * Speed up by fetching one line at a time.
	 *
	 * Also, format conversion from XR24 to monochrome are done
	 * line-by-line but are converted to 8-bit grayscale as an
	 * intermediate step.
	 *
	 * Allocate a buffer to be used for both copying from the cma
	 * memory and to store the intermediate grayscale line pixels.
	 */
	src32 = kmalloc(len_src32 + linepixels, GFP_KERNEL);
	if (!src32)
		return;

	gray8 = (u8 *)src32 + len_src32;

	vaddr += clip_offset(clip, fb->pitches[0], cpp);
	for (y = 0; y < lines; y++) {
		src32 = memcpy(src32, vaddr, len_src32);
		drm_fb_xrgb8888_to_gray8_line(gray8, src32, linepixels);
		drm_fb_gray8_to_mono_line(mono, gray8, linepixels);
		vaddr += fb->pitches[0];
		mono += dst_pitch_0;
	}

	kfree(src32);
}
EXPORT_SYMBOL(drm_fb_xrgb8888_to_mono);