drivers/video/console_truetype.c - u-boot-mtk - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (c) 2016 Google, Inc
  */

 #include <common.h>
 #include <dm.h>
 #include <video.h>
 #include <video_console.h>

 /* Functions needed by stb_truetype.h */
 static int tt_floor(double val)
 {
 	if (val < 0)
 		return (int)(val - 0.999);

 	return (int)val;
 }

 static int tt_ceil(double val)
 {
 	if (val < 0)
 		return (int)val;

 	return (int)(val + 0.999);
 }

 static double frac(double val)
 {
 	return val - tt_floor(val);
 }

 static double tt_fabs(double x)
 {
 	return x < 0 ? -x : x;
 }

  /*
   * Simple square root algorithm. This is from:
   * http://stackoverflow.com/questions/1623375/writing-your-own-square-root-function
   * Written by Chihung Yu
   * Creative Commons license
   * http://creativecommons.org/licenses/by-sa/3.0/legalcode
   * It has been modified to compile correctly, and for U-Boot style.
   */
 static double tt_sqrt(double value)
 {
 	double lo = 1.0;
 	double hi = value;

 	while (hi - lo > 0.00001) {
 		double mid = lo + (hi - lo) / 2;

 		if (mid * mid - value > 0.00001)
 			hi = mid;
 		else
 			lo = mid;
 	}

 	return lo;
 }

 #define STBTT_ifloor		tt_floor
 #define STBTT_iceil		tt_ceil
 #define STBTT_fabs		tt_fabs
 #define STBTT_sqrt		tt_sqrt
 #define STBTT_malloc(size, u)	((void)(u), malloc(size))
 #define STBTT_free(size, u)	((void)(u), free(size))
 #define STBTT_assert(x)
 #define STBTT_strlen(x)		strlen(x)
 #define STBTT_memcpy		memcpy
 #define STBTT_memset		memset

 #define STB_TRUETYPE_IMPLEMENTATION
 #include "stb_truetype.h"

 /**
  * struct pos_info - Records a cursor position
  *
  * @xpos_frac:	Fractional X position in pixels (multiplied by VID_FRAC_DIV)
  * @ypos:	Y position (pixels from the top)
  */
 struct pos_info {
 	int xpos_frac;
 	int ypos;
 };

 /*
  * Allow one for each character on the command line plus one for each newline.
  * This is just an estimate, but it should not be exceeded.
  */
 #define POS_HISTORY_SIZE	(CONFIG_SYS_CBSIZE * 11 / 10)

 /**
  * struct console_tt_priv - Private data for this driver
  *
  * @font_size:	Vertical font size in pixels
  * @font_data:	Pointer to TrueType font file contents
  * @font:	TrueType font information for the current font
  * @pos:	List of cursor positions for each character written. This is
  *		used to handle backspace. We clear the frame buffer between
  *		the last position and the current position, thus erasing the
  *		last character. We record enough characters to go back to the
  *		start of the current command line.
  * @pos_ptr:	Current position in the position history
  * @baseline:	Pixel offset of the font's baseline from the cursor position.
  *		This is the 'ascent' of the font, scaled to pixel coordinates.
  *		It measures the distance from the baseline to the top of the
  *		font.
  * @scale:	Scale of the font. This is calculated from the pixel height
  *		of the font. It is used by the STB library to generate images
  *		of the correct size.
  */
 struct console_tt_priv {
 	int font_size;
 	u8 *font_data;
 	stbtt_fontinfo font;
 	struct pos_info pos[POS_HISTORY_SIZE];
 	int pos_ptr;
 	int baseline;
 	double scale;
 };

 static int console_truetype_set_row(struct udevice *dev, uint row, int clr)
 {
 	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
 	struct console_tt_priv *priv = dev_get_priv(dev);
 	void *line;
 	int pixels = priv->font_size * vid_priv->line_length;
 	int i;

 	line = vid_priv->fb + row * priv->font_size * vid_priv->line_length;
 	switch (vid_priv->bpix) {
 #ifdef CONFIG_VIDEO_BPP8
 	case VIDEO_BPP8: {
 		uint8_t *dst = line;

 		for (i = 0; i < pixels; i++)
 			*dst++ = clr;
 		break;
 	}
 #endif
 #ifdef CONFIG_VIDEO_BPP16
 	case VIDEO_BPP16: {
 		uint16_t *dst = line;

 		for (i = 0; i < pixels; i++)
 			*dst++ = clr;
 		break;
 	}
 #endif
 #ifdef CONFIG_VIDEO_BPP32
 	case VIDEO_BPP32: {
 		uint32_t *dst = line;

 		for (i = 0; i < pixels; i++)
 			*dst++ = clr;
 		break;
 	}
 #endif
 	default:
 		return -ENOSYS;
 	}

 	return 0;
 }

 static int console_truetype_move_rows(struct udevice *dev, uint rowdst,
 				     uint rowsrc, uint count)
 {
 	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
 	struct console_tt_priv *priv = dev_get_priv(dev);
 	void *dst;
 	void *src;
 	int i, diff;

 	dst = vid_priv->fb + rowdst * priv->font_size * vid_priv->line_length;
 	src = vid_priv->fb + rowsrc * priv->font_size * vid_priv->line_length;
 	memmove(dst, src, priv->font_size * vid_priv->line_length * count);

 	/* Scroll up our position history */
 	diff = (rowsrc - rowdst) * priv->font_size;
 	for (i = 0; i < priv->pos_ptr; i++)
 		priv->pos[i].ypos -= diff;

 	return 0;
 }

 static int console_truetype_putc_xy(struct udevice *dev, uint x, uint y,
 				    char ch)
 {
 	struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
 	struct udevice *vid = dev->parent;
 	struct video_priv *vid_priv = dev_get_uclass_priv(vid);
 	struct console_tt_priv *priv = dev_get_priv(dev);
 	stbtt_fontinfo *font = &priv->font;
 	int width, height, xoff, yoff;
 	double xpos, x_shift;
 	int lsb;
 	int width_frac, linenum;
 	struct pos_info *pos;
 	u8 *bits, *data;
 	int advance;
 	void *line;
 	int row;

 	/* First get some basic metrics about this character */
 	stbtt_GetCodepointHMetrics(font, ch, &advance, &lsb);

 	/*
 	 * First out our current X position in fractional pixels. If we wrote
 	 * a character previously, using kerning to fine-tune the position of
 	 * this character */
 	xpos = frac(VID_TO_PIXEL((double)x));
 	if (vc_priv->last_ch) {
 		xpos += priv->scale * stbtt_GetCodepointKernAdvance(font,
 							vc_priv->last_ch, ch);
 	}

 	/*
 	 * Figure out where the cursor will move to after this character, and
 	 * abort if we are out of space on this line. Also calculate the
 	 * effective width of this character, which will be our return value:
 	 * it dictates how much the cursor will move forward on the line.
 	 */
 	x_shift = xpos - (double)tt_floor(xpos);
 	xpos += advance * priv->scale;
 	width_frac = (int)VID_TO_POS(xpos);
 	if (x + width_frac >= vc_priv->xsize_frac)
 		return -EAGAIN;

 	/* Write the current cursor position into history */
 	if (priv->pos_ptr < POS_HISTORY_SIZE) {
 		pos = &priv->pos[priv->pos_ptr];
 		pos->xpos_frac = vc_priv->xcur_frac;
 		pos->ypos = vc_priv->ycur;
 		priv->pos_ptr++;
 	}

 	/*
 	 * Figure out how much past the start of a pixel we are, and pass this
 	 * information into the render, which will return a 8-bit-per-pixel
 	 * image of the character. For empty characters, like ' ', data will
 	 * return NULL;
 	 */
 	data = stbtt_GetCodepointBitmapSubpixel(font, priv->scale, priv->scale,
 						x_shift, 0, ch, &width, &height,
 						&xoff, &yoff);
 	if (!data)
 		return width_frac;

 	/* Figure out where to write the character in the frame buffer */
 	bits = data;
 	line = vid_priv->fb + y * vid_priv->line_length +
 		VID_TO_PIXEL(x) * VNBYTES(vid_priv->bpix);
 	linenum = priv->baseline + yoff;
 	if (linenum > 0)
 		line += linenum * vid_priv->line_length;

 	/*
 	 * Write a row at a time, converting the 8bpp image into the colour
 	 * depth of the display. We only expect white-on-black or the reverse
 	 * so the code only handles this simple case.
 	 */
 	for (row = 0; row < height; row++) {
 		switch (vid_priv->bpix) {
 #ifdef CONFIG_VIDEO_BPP16
 		case VIDEO_BPP16: {
 			uint16_t *dst = (uint16_t *)line + xoff;
 			int i;

 			for (i = 0; i < width; i++) {
 				int val = *bits;
 				int out;

 				if (vid_priv->colour_bg)
 					val = 255 - val;
 				out = val >> 3 |
 					(val >> 2) << 5 |
 					(val >> 3) << 11;
 				if (vid_priv->colour_fg)
 					*dst++ |= out;
 				else
 					*dst++ &= out;
 				bits++;
 			}
 			break;
 		}
 #endif
 		default:
 			free(data);
 			return -ENOSYS;
 		}

 		line += vid_priv->line_length;
 	}
 	free(data);

 	return width_frac;
 }

 /**
  * console_truetype_erase() - Erase a character
  *
  * This is used for backspace. We erase a square of the display within the
  * given bounds.
  *
  * @dev:	Device to update
  * @xstart:	X start position in pixels from the left
  * @ystart:	Y start position in pixels from the top
  * @xend:	X end position in pixels from the left
  * @yend:	Y end position  in pixels from the top
  * @clr:	Value to write
  * @return 0 if OK, -ENOSYS if the display depth is not supported
  */
 static int console_truetype_erase(struct udevice *dev, int xstart, int ystart,
 				  int xend, int yend, int clr)
 {
 	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
 	void *line;
 	int pixels = xend - xstart;
 	int row, i;

 	line = vid_priv->fb + ystart * vid_priv->line_length;
 	line += xstart * VNBYTES(vid_priv->bpix);
 	for (row = ystart; row < yend; row++) {
 		switch (vid_priv->bpix) {
 #ifdef CONFIG_VIDEO_BPP8
 		case VIDEO_BPP8: {
 			uint8_t *dst = line;

 			for (i = 0; i < pixels; i++)
 				*dst++ = clr;
 			break;
 		}
 #endif
 #ifdef CONFIG_VIDEO_BPP16
 		case VIDEO_BPP16: {
 			uint16_t *dst = line;

 			for (i = 0; i < pixels; i++)
 				*dst++ = clr;
 			break;
 		}
 #endif
 #ifdef CONFIG_VIDEO_BPP32
 		case VIDEO_BPP32: {
 			uint32_t *dst = line;

 			for (i = 0; i < pixels; i++)
 				*dst++ = clr;
 			break;
 		}
 #endif
 		default:
 			return -ENOSYS;
 		}
 		line += vid_priv->line_length;
 	}

 	return 0;
 }

 /**
  * console_truetype_backspace() - Handle a backspace operation
  *
  * This clears the previous character so that the console looks as if it had
  * not been entered.
  *
  * @dev:	Device to update
  * @return 0 if OK, -ENOSYS if not supported
  */
 static int console_truetype_backspace(struct udevice *dev)
 {
 	struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
 	struct console_tt_priv *priv = dev_get_priv(dev);
 	struct udevice *vid_dev = dev->parent;
 	struct video_priv *vid_priv = dev_get_uclass_priv(vid_dev);
 	struct pos_info *pos;
 	int xend;

 	/*
 	 * This indicates a very strange error higher in the stack. The caller
 	 * has sent out n character and n + 1 backspaces.
 	 */
 	if (!priv->pos_ptr)
 		return -ENOSYS;

 	/* Pop the last cursor position off the stack */
 	pos = &priv->pos[--priv->pos_ptr];

 	/*
 	 * Figure out the end position for clearing. Normlly it is the current
 	 * cursor position, but if we are clearing a character on the previous
 	 * line, we clear from the end of the line.
 	 */
 	if (pos->ypos == vc_priv->ycur)
 		xend = VID_TO_PIXEL(vc_priv->xcur_frac);
 	else
 		xend = vid_priv->xsize;

 	console_truetype_erase(dev, VID_TO_PIXEL(pos->xpos_frac), pos->ypos,
 			       xend, pos->ypos + vc_priv->y_charsize,
 			       vid_priv->colour_bg);

 	/* Move the cursor back to where it was when we pushed this record */
 	vc_priv->xcur_frac = pos->xpos_frac;
 	vc_priv->ycur = pos->ypos;

 	return 0;
 }

 static int console_truetype_entry_start(struct udevice *dev)
 {
 	struct console_tt_priv *priv = dev_get_priv(dev);

 	/* A new input line has start, so clear our history */
 	priv->pos_ptr = 0;

 	return 0;
 }

 /*
  * Provides a list of fonts which can be obtained at run-time in U-Boot. These
  * are compiled in by the Makefile.
  *
  * At present there is no mechanism to select a particular font - the first
  * one found is the one that is used. But the build system and the code here
  * supports multiple fonts, which may be useful for certain firmware screens.
  */
 struct font_info {
 	char *name;
 	u8 *begin;
 	u8 *end;
 };

 #define FONT_DECL(_name) \
 	extern u8 __ttf_ ## _name ## _begin[]; \
 	extern u8 __ttf_ ## _name ## _end[];

 #define FONT_ENTRY(_name)		{ \
 	.name = #_name, \
 	.begin = __ttf_ ## _name ## _begin, \
 	.end = __ttf_ ## _name ## _end, \
 	}

 FONT_DECL(nimbus_sans_l_regular);
 FONT_DECL(ankacoder_c75_r);
 FONT_DECL(rufscript010);
 FONT_DECL(cantoraone_regular);

 static struct font_info font_table[] = {
 #ifdef CONFIG_CONSOLE_TRUETYPE_NIMBUS
 	FONT_ENTRY(nimbus_sans_l_regular),
 #endif
 #ifdef CONFIG_CONSOLE_TRUETYPE_ANKACODER
 	FONT_ENTRY(ankacoder_c75_r),
 #endif
 #ifdef CONFIG_CONSOLE_TRUETYPE_RUFSCRIPT
 	FONT_ENTRY(rufscript010),
 #endif
 #ifdef CONFIG_CONSOLE_TRUETYPE_CANTORAONE
 	FONT_ENTRY(cantoraone_regular),
 #endif
 	{} /* sentinel */
 };

 #define FONT_BEGIN(name)	__ttf_ ## name ## _begin
 #define FONT_END(name)		__ttf_ ## name ## _end
 #define FONT_IS_VALID(name)	(abs(FONT_END(name) - FONT_BEGIN) > 4)

 /**
  * console_truetype_find_font() - Find a suitable font
  *
  * This searched for the first available font.
  *
  * @return pointer to the font, or NULL if none is found
  */
 static u8 *console_truetype_find_font(void)
 {
 	struct font_info *tab;

 	for (tab = font_table; tab->begin; tab++) {
 		if (abs(tab->begin - tab->end) > 4) {
 			debug("%s: Font '%s', at %p, size %lx\n", __func__,
 			      tab->name, tab->begin,
 			      (ulong)(tab->end - tab->begin));
 			return tab->begin;
 		}
 	}

 	return NULL;
 }

 static int console_truetype_probe(struct udevice *dev)
 {
 	struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
 	struct console_tt_priv *priv = dev_get_priv(dev);
 	struct udevice *vid_dev = dev->parent;
 	struct video_priv *vid_priv = dev_get_uclass_priv(vid_dev);
 	stbtt_fontinfo *font = &priv->font;
 	int ascent;

 	debug("%s: start\n", __func__);
 	if (vid_priv->font_size)
 		priv->font_size = vid_priv->font_size;
 	else
 		priv->font_size = CONFIG_CONSOLE_TRUETYPE_SIZE;
 	priv->font_data = console_truetype_find_font();
 	if (!priv->font_data) {
 		debug("%s: Could not find any fonts\n", __func__);
 		return -EBFONT;
 	}

 	vc_priv->x_charsize = priv->font_size;
 	vc_priv->y_charsize = priv->font_size;
 	vc_priv->xstart_frac = VID_TO_POS(2);
 	vc_priv->cols = vid_priv->xsize / priv->font_size;
 	vc_priv->rows = vid_priv->ysize / priv->font_size;
 	vc_priv->tab_width_frac = VID_TO_POS(priv->font_size) * 8 / 2;

 	if (!stbtt_InitFont(font, priv->font_data, 0)) {
 		debug("%s: Font init failed\n", __func__);
 		return -EPERM;
 	}

 	/* Pre-calculate some things we will need regularly */
 	priv->scale = stbtt_ScaleForPixelHeight(font, priv->font_size);
 	stbtt_GetFontVMetrics(font, &ascent, 0, 0);
 	priv->baseline = (int)(ascent * priv->scale);
 	debug("%s: ready\n", __func__);

 	return 0;
 }

 struct vidconsole_ops console_truetype_ops = {
 	.putc_xy	= console_truetype_putc_xy,
 	.move_rows	= console_truetype_move_rows,
 	.set_row	= console_truetype_set_row,
 	.backspace	= console_truetype_backspace,
 	.entry_start	= console_truetype_entry_start,
 };

 U_BOOT_DRIVER(vidconsole_truetype) = {
 	.name	= "vidconsole_tt",
 	.id	= UCLASS_VIDEO_CONSOLE,
 	.ops	= &console_truetype_ops,
 	.probe	= console_truetype_probe,
 	.priv_auto_alloc_size	= sizeof(struct console_tt_priv),
 };
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Copyright (c) 2016 Google, Inc
	*/

	#include <common.h>
	#include <dm.h>
	#include <video.h>
	#include <video_console.h>

	/* Functions needed by stb_truetype.h */
	static int tt_floor(double val)
	{
	if (val < 0)
	return (int)(val - 0.999);

	return (int)val;
	}

	static int tt_ceil(double val)
	{
	if (val < 0)
	return (int)val;

	return (int)(val + 0.999);
	}

	static double frac(double val)
	{
	return val - tt_floor(val);
	}

	static double tt_fabs(double x)
	{
	return x < 0 ? -x : x;
	}

	/*
	* Simple square root algorithm. This is from:
	* http://stackoverflow.com/questions/1623375/writing-your-own-square-root-function
	* Written by Chihung Yu
	* Creative Commons license
	* http://creativecommons.org/licenses/by-sa/3.0/legalcode
	* It has been modified to compile correctly, and for U-Boot style.
	*/
	static double tt_sqrt(double value)
	{
	double lo = 1.0;
	double hi = value;

	while (hi - lo > 0.00001) {
	double mid = lo + (hi - lo) / 2;

	if (mid * mid - value > 0.00001)
	hi = mid;
	else
	lo = mid;
	}

	return lo;
	}

	#define STBTT_ifloor tt_floor
	#define STBTT_iceil tt_ceil
	#define STBTT_fabs tt_fabs
	#define STBTT_sqrt tt_sqrt
	#define STBTT_malloc(size, u) ((void)(u), malloc(size))
	#define STBTT_free(size, u) ((void)(u), free(size))
	#define STBTT_assert(x)
	#define STBTT_strlen(x) strlen(x)
	#define STBTT_memcpy memcpy
	#define STBTT_memset memset

	#define STB_TRUETYPE_IMPLEMENTATION
	#include "stb_truetype.h"

	/**
	* struct pos_info - Records a cursor position
	*
	* @xpos_frac: Fractional X position in pixels (multiplied by VID_FRAC_DIV)
	* @ypos: Y position (pixels from the top)
	*/
	struct pos_info {
	int xpos_frac;
	int ypos;
	};

	/*
	* Allow one for each character on the command line plus one for each newline.
	* This is just an estimate, but it should not be exceeded.
	*/
	#define POS_HISTORY_SIZE (CONFIG_SYS_CBSIZE * 11 / 10)

	/**
	* struct console_tt_priv - Private data for this driver
	*
	* @font_size: Vertical font size in pixels
	* @font_data: Pointer to TrueType font file contents
	* @font: TrueType font information for the current font
	* @pos: List of cursor positions for each character written. This is
	* used to handle backspace. We clear the frame buffer between
	* the last position and the current position, thus erasing the
	* last character. We record enough characters to go back to the
	* start of the current command line.
	* @pos_ptr: Current position in the position history
	* @baseline: Pixel offset of the font's baseline from the cursor position.
	* This is the 'ascent' of the font, scaled to pixel coordinates.
	* It measures the distance from the baseline to the top of the
	* font.
	* @scale: Scale of the font. This is calculated from the pixel height
	* of the font. It is used by the STB library to generate images
	* of the correct size.
	*/
	struct console_tt_priv {
	int font_size;
	u8 *font_data;
	stbtt_fontinfo font;
	struct pos_info pos[POS_HISTORY_SIZE];
	int pos_ptr;
	int baseline;
	double scale;
	};

	static int console_truetype_set_row(struct udevice *dev, uint row, int clr)
	{
	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
	struct console_tt_priv *priv = dev_get_priv(dev);
	void *line;
	int pixels = priv->font_size * vid_priv->line_length;
	int i;

	line = vid_priv->fb + row * priv->font_size * vid_priv->line_length;
	switch (vid_priv->bpix) {
	#ifdef CONFIG_VIDEO_BPP8
	case VIDEO_BPP8: {
	uint8_t *dst = line;

	for (i = 0; i < pixels; i++)
	*dst++ = clr;
	break;
	}
	#endif
	#ifdef CONFIG_VIDEO_BPP16
	case VIDEO_BPP16: {
	uint16_t *dst = line;

	for (i = 0; i < pixels; i++)
	*dst++ = clr;
	break;
	}
	#endif
	#ifdef CONFIG_VIDEO_BPP32
	case VIDEO_BPP32: {
	uint32_t *dst = line;

	for (i = 0; i < pixels; i++)
	*dst++ = clr;
	break;
	}
	#endif
	default:
	return -ENOSYS;
	}

	return 0;
	}

	static int console_truetype_move_rows(struct udevice *dev, uint rowdst,
	uint rowsrc, uint count)
	{
	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
	struct console_tt_priv *priv = dev_get_priv(dev);
	void *dst;
	void *src;
	int i, diff;

	dst = vid_priv->fb + rowdst * priv->font_size * vid_priv->line_length;
	src = vid_priv->fb + rowsrc * priv->font_size * vid_priv->line_length;
	memmove(dst, src, priv->font_size * vid_priv->line_length * count);

	/* Scroll up our position history */
	diff = (rowsrc - rowdst) * priv->font_size;
	for (i = 0; i < priv->pos_ptr; i++)
	priv->pos[i].ypos -= diff;

	return 0;
	}

	static int console_truetype_putc_xy(struct udevice *dev, uint x, uint y,
	char ch)
	{
	struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
	struct udevice *vid = dev->parent;
	struct video_priv *vid_priv = dev_get_uclass_priv(vid);
	struct console_tt_priv *priv = dev_get_priv(dev);
	stbtt_fontinfo *font = &priv->font;
	int width, height, xoff, yoff;
	double xpos, x_shift;
	int lsb;
	int width_frac, linenum;
	struct pos_info *pos;
	u8 bits, data;
	int advance;
	void *line;
	int row;

	/* First get some basic metrics about this character */
	stbtt_GetCodepointHMetrics(font, ch, &advance, &lsb);

	/*
	* First out our current X position in fractional pixels. If we wrote
	* a character previously, using kerning to fine-tune the position of
	* this character */
	xpos = frac(VID_TO_PIXEL((double)x));
	if (vc_priv->last_ch) {
	xpos += priv->scale * stbtt_GetCodepointKernAdvance(font,
	vc_priv->last_ch, ch);
	}

	/*
	* Figure out where the cursor will move to after this character, and
	* abort if we are out of space on this line. Also calculate the
	* effective width of this character, which will be our return value:
	* it dictates how much the cursor will move forward on the line.
	*/
	x_shift = xpos - (double)tt_floor(xpos);
	xpos += advance * priv->scale;
	width_frac = (int)VID_TO_POS(xpos);
	if (x + width_frac >= vc_priv->xsize_frac)
	return -EAGAIN;

	/* Write the current cursor position into history */
	if (priv->pos_ptr < POS_HISTORY_SIZE) {
	pos = &priv->pos[priv->pos_ptr];
	pos->xpos_frac = vc_priv->xcur_frac;
	pos->ypos = vc_priv->ycur;
	priv->pos_ptr++;
	}

	/*
	* Figure out how much past the start of a pixel we are, and pass this
	* information into the render, which will return a 8-bit-per-pixel
	* image of the character. For empty characters, like ' ', data will
	* return NULL;
	*/
	data = stbtt_GetCodepointBitmapSubpixel(font, priv->scale, priv->scale,
	x_shift, 0, ch, &width, &height,
	&xoff, &yoff);
	if (!data)
	return width_frac;

	/* Figure out where to write the character in the frame buffer */
	bits = data;
	line = vid_priv->fb + y * vid_priv->line_length +
	VID_TO_PIXEL(x) * VNBYTES(vid_priv->bpix);
	linenum = priv->baseline + yoff;
	if (linenum > 0)
	line += linenum * vid_priv->line_length;

	/*
	* Write a row at a time, converting the 8bpp image into the colour
	* depth of the display. We only expect white-on-black or the reverse
	* so the code only handles this simple case.
	*/
	for (row = 0; row < height; row++) {
	switch (vid_priv->bpix) {
	#ifdef CONFIG_VIDEO_BPP16
	case VIDEO_BPP16: {
	uint16_t dst = (uint16_t )line + xoff;
	int i;

	for (i = 0; i < width; i++) {
	int val = *bits;
	int out;

	if (vid_priv->colour_bg)
	val = 255 - val;
	out = val >> 3 \|
	(val >> 2) << 5 \|
	(val >> 3) << 11;
	if (vid_priv->colour_fg)
	*dst++ \|= out;
	else
	*dst++ &= out;
	bits++;
	}
	break;
	}
	#endif
	default:
	free(data);
	return -ENOSYS;
	}

	line += vid_priv->line_length;
	}
	free(data);

	return width_frac;
	}

	/**
	* console_truetype_erase() - Erase a character
	*
	* This is used for backspace. We erase a square of the display within the
	* given bounds.
	*
	* @dev: Device to update
	* @xstart: X start position in pixels from the left
	* @ystart: Y start position in pixels from the top
	* @xend: X end position in pixels from the left
	* @yend: Y end position in pixels from the top
	* @clr: Value to write
	* @return 0 if OK, -ENOSYS if the display depth is not supported
	*/
	static int console_truetype_erase(struct udevice *dev, int xstart, int ystart,
	int xend, int yend, int clr)
	{
	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
	void *line;
	int pixels = xend - xstart;
	int row, i;

	line = vid_priv->fb + ystart * vid_priv->line_length;
	line += xstart * VNBYTES(vid_priv->bpix);
	for (row = ystart; row < yend; row++) {
	switch (vid_priv->bpix) {
	#ifdef CONFIG_VIDEO_BPP8
	case VIDEO_BPP8: {
	uint8_t *dst = line;

	for (i = 0; i < pixels; i++)
	*dst++ = clr;
	break;
	}
	#endif
	#ifdef CONFIG_VIDEO_BPP16
	case VIDEO_BPP16: {
	uint16_t *dst = line;

	for (i = 0; i < pixels; i++)
	*dst++ = clr;
	break;
	}
	#endif
	#ifdef CONFIG_VIDEO_BPP32
	case VIDEO_BPP32: {
	uint32_t *dst = line;

	for (i = 0; i < pixels; i++)
	*dst++ = clr;
	break;
	}
	#endif
	default:
	return -ENOSYS;
	}
	line += vid_priv->line_length;
	}

	return 0;
	}

	/**
	* console_truetype_backspace() - Handle a backspace operation
	*
	* This clears the previous character so that the console looks as if it had
	* not been entered.
	*
	* @dev: Device to update
	* @return 0 if OK, -ENOSYS if not supported
	*/
	static int console_truetype_backspace(struct udevice *dev)
	{
	struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
	struct console_tt_priv *priv = dev_get_priv(dev);
	struct udevice *vid_dev = dev->parent;
	struct video_priv *vid_priv = dev_get_uclass_priv(vid_dev);
	struct pos_info *pos;
	int xend;

	/*
	* This indicates a very strange error higher in the stack. The caller
	* has sent out n character and n + 1 backspaces.
	*/
	if (!priv->pos_ptr)
	return -ENOSYS;

	/* Pop the last cursor position off the stack */
	pos = &priv->pos[--priv->pos_ptr];

	/*
	* Figure out the end position for clearing. Normlly it is the current
	* cursor position, but if we are clearing a character on the previous
	* line, we clear from the end of the line.
	*/
	if (pos->ypos == vc_priv->ycur)
	xend = VID_TO_PIXEL(vc_priv->xcur_frac);
	else
	xend = vid_priv->xsize;

	console_truetype_erase(dev, VID_TO_PIXEL(pos->xpos_frac), pos->ypos,
	xend, pos->ypos + vc_priv->y_charsize,
	vid_priv->colour_bg);

	/* Move the cursor back to where it was when we pushed this record */
	vc_priv->xcur_frac = pos->xpos_frac;
	vc_priv->ycur = pos->ypos;

	return 0;
	}

	static int console_truetype_entry_start(struct udevice *dev)
	{
	struct console_tt_priv *priv = dev_get_priv(dev);

	/* A new input line has start, so clear our history */
	priv->pos_ptr = 0;

	return 0;
	}

	/*
	* Provides a list of fonts which can be obtained at run-time in U-Boot. These
	* are compiled in by the Makefile.
	*
	* At present there is no mechanism to select a particular font - the first
	* one found is the one that is used. But the build system and the code here
	* supports multiple fonts, which may be useful for certain firmware screens.
	*/
	struct font_info {
	char *name;
	u8 *begin;
	u8 *end;
	};

	#define FONT_DECL(_name) \
	extern u8 __ttf_ ## _name ## _begin[]; \
	extern u8 __ttf_ ## _name ## _end[];

	#define FONT_ENTRY(_name) { \
	.name = #_name, \
	.begin = __ttf_ ## _name ## _begin, \
	.end = __ttf_ ## _name ## _end, \
	}

	FONT_DECL(nimbus_sans_l_regular);
	FONT_DECL(ankacoder_c75_r);
	FONT_DECL(rufscript010);
	FONT_DECL(cantoraone_regular);

	static struct font_info font_table[] = {
	#ifdef CONFIG_CONSOLE_TRUETYPE_NIMBUS
	FONT_ENTRY(nimbus_sans_l_regular),
	#endif
	#ifdef CONFIG_CONSOLE_TRUETYPE_ANKACODER
	FONT_ENTRY(ankacoder_c75_r),
	#endif
	#ifdef CONFIG_CONSOLE_TRUETYPE_RUFSCRIPT
	FONT_ENTRY(rufscript010),
	#endif
	#ifdef CONFIG_CONSOLE_TRUETYPE_CANTORAONE
	FONT_ENTRY(cantoraone_regular),
	#endif
	{} /* sentinel */
	};

	#define FONT_BEGIN(name) __ttf_ ## name ## _begin
	#define FONT_END(name) __ttf_ ## name ## _end
	#define FONT_IS_VALID(name) (abs(FONT_END(name) - FONT_BEGIN) > 4)

	/**
	* console_truetype_find_font() - Find a suitable font
	*
	* This searched for the first available font.
	*
	* @return pointer to the font, or NULL if none is found
	*/
	static u8 *console_truetype_find_font(void)
	{
	struct font_info *tab;

	for (tab = font_table; tab->begin; tab++) {
	if (abs(tab->begin - tab->end) > 4) {
	debug("%s: Font '%s', at %p, size %lx\n", __func__,
	tab->name, tab->begin,
	(ulong)(tab->end - tab->begin));
	return tab->begin;
	}
	}

	return NULL;
	}

	static int console_truetype_probe(struct udevice *dev)
	{
	struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
	struct console_tt_priv *priv = dev_get_priv(dev);
	struct udevice *vid_dev = dev->parent;
	struct video_priv *vid_priv = dev_get_uclass_priv(vid_dev);
	stbtt_fontinfo *font = &priv->font;
	int ascent;

	debug("%s: start\n", __func__);
	if (vid_priv->font_size)
	priv->font_size = vid_priv->font_size;
	else
	priv->font_size = CONFIG_CONSOLE_TRUETYPE_SIZE;
	priv->font_data = console_truetype_find_font();
	if (!priv->font_data) {
	debug("%s: Could not find any fonts\n", __func__);
	return -EBFONT;
	}

	vc_priv->x_charsize = priv->font_size;
	vc_priv->y_charsize = priv->font_size;
	vc_priv->xstart_frac = VID_TO_POS(2);
	vc_priv->cols = vid_priv->xsize / priv->font_size;
	vc_priv->rows = vid_priv->ysize / priv->font_size;
	vc_priv->tab_width_frac = VID_TO_POS(priv->font_size) * 8 / 2;

	if (!stbtt_InitFont(font, priv->font_data, 0)) {
	debug("%s: Font init failed\n", __func__);
	return -EPERM;
	}

	/* Pre-calculate some things we will need regularly */
	priv->scale = stbtt_ScaleForPixelHeight(font, priv->font_size);
	stbtt_GetFontVMetrics(font, &ascent, 0, 0);
	priv->baseline = (int)(ascent * priv->scale);
	debug("%s: ready\n", __func__);

	return 0;
	}

	struct vidconsole_ops console_truetype_ops = {
	.putc_xy = console_truetype_putc_xy,
	.move_rows = console_truetype_move_rows,
	.set_row = console_truetype_set_row,
	.backspace = console_truetype_backspace,
	.entry_start = console_truetype_entry_start,
	};

	U_BOOT_DRIVER(vidconsole_truetype) = {
	.name = "vidconsole_tt",
	.id = UCLASS_VIDEO_CONSOLE,
	.ops = &console_truetype_ops,
	.probe = console_truetype_probe,
	.priv_auto_alloc_size = sizeof(struct console_tt_priv),
	};