[mirror_ubuntu-bionic-kernel.git] / drivers / gpu / drm / udl / udl_transfer.c

/*
 * Copyright (C) 2012 Red Hat
 * based in parts on udlfb.c:
 * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
 * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
 * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License v2. See the file COPYING in the main directory of this archive for
 * more details.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/prefetch.h>
#include <asm/unaligned.h>

#include <drm/drmP.h>
#include "udl_drv.h"

#define MAX_CMD_PIXELS		255

#define RLX_HEADER_BYTES	7
#define MIN_RLX_PIX_BYTES       4
#define MIN_RLX_CMD_BYTES	(RLX_HEADER_BYTES + MIN_RLX_PIX_BYTES)

#define RLE_HEADER_BYTES	6
#define MIN_RLE_PIX_BYTES	3
#define MIN_RLE_CMD_BYTES	(RLE_HEADER_BYTES + MIN_RLE_PIX_BYTES)

#define RAW_HEADER_BYTES	6
#define MIN_RAW_PIX_BYTES	2
#define MIN_RAW_CMD_BYTES	(RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES)

/*
 * Trims identical data from front and back of line
 * Sets new front buffer address and width
 * And returns byte count of identical pixels
 * Assumes CPU natural alignment (unsigned long)
 * for back and front buffer ptrs and width
 */
#if 0
static int udl_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
{
	int j, k;
	const unsigned long *back = (const unsigned long *) bback;
	const unsigned long *front = (const unsigned long *) *bfront;
	const int width = *width_bytes / sizeof(unsigned long);
	int identical = width;
	int start = width;
	int end = width;

	prefetch((void *) front);
	prefetch((void *) back);

	for (j = 0; j < width; j++) {
		if (back[j] != front[j]) {
			start = j;
			break;
		}
	}

	for (k = width - 1; k > j; k--) {
		if (back[k] != front[k]) {
			end = k+1;
			break;
		}
	}

	identical = start + (width - end);
	*bfront = (u8 *) &front[start];
	*width_bytes = (end - start) * sizeof(unsigned long);

	return identical * sizeof(unsigned long);
}
#endif

static inline u16 pixel32_to_be16(const uint32_t pixel)
{
	return (((pixel >> 3) & 0x001f) |
		((pixel >> 5) & 0x07e0) |
		((pixel >> 8) & 0xf800));
}

static inline u16 get_pixel_val16(const uint8_t *pixel, int bpp)
{
	u16 pixel_val16 = 0;
	if (bpp == 2)
		pixel_val16 = *(const uint16_t *)pixel;
	else if (bpp == 4)
		pixel_val16 = pixel32_to_be16(*(const uint32_t *)pixel);
	return pixel_val16;
}

/*
 * Render a command stream for an encoded horizontal line segment of pixels.
 *
 * A command buffer holds several commands.
 * It always begins with a fresh command header
 * (the protocol doesn't require this, but we enforce it to allow
 * multiple buffers to be potentially encoded and sent in parallel).
 * A single command encodes one contiguous horizontal line of pixels
 *
 * The function relies on the client to do all allocation, so that
 * rendering can be done directly to output buffers (e.g. USB URBs).
 * The function fills the supplied command buffer, providing information
 * on where it left off, so the client may call in again with additional
 * buffers if the line will take several buffers to complete.
 *
 * A single command can transmit a maximum of 256 pixels,
 * regardless of the compression ratio (protocol design limit).
 * To the hardware, 0 for a size byte means 256
 *
 * Rather than 256 pixel commands which are either rl or raw encoded,
 * the rlx command simply assumes alternating raw and rl spans within one cmd.
 * This has a slightly larger header overhead, but produces more even results.
 * It also processes all data (read and write) in a single pass.
 * Performance benchmarks of common cases show it having just slightly better
 * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
 * But for very rl friendly data, will compress not quite as well.
 */
static void udl_compress_hline16(
	const u8 **pixel_start_ptr,
	const u8 *const pixel_end,
	uint32_t *device_address_ptr,
	uint8_t **command_buffer_ptr,
	const uint8_t *const cmd_buffer_end, int bpp)
{
	const u8 *pixel = *pixel_start_ptr;
	uint32_t dev_addr  = *device_address_ptr;
	uint8_t *cmd = *command_buffer_ptr;

	while ((pixel_end > pixel) &&
	       (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
		uint8_t *raw_pixels_count_byte = NULL;
		uint8_t *cmd_pixels_count_byte = NULL;
		const u8 *raw_pixel_start = NULL;
		const u8 *cmd_pixel_start, *cmd_pixel_end = NULL;
		uint16_t pixel_val16;

		prefetchw((void *) cmd); /* pull in one cache line at least */

		*cmd++ = 0xaf;
		*cmd++ = 0x6b;
		*cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
		*cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
		*cmd++ = (uint8_t) ((dev_addr) & 0xFF);

		cmd_pixels_count_byte = cmd++; /*  we'll know this later */
		cmd_pixel_start = pixel;

		raw_pixels_count_byte = cmd++; /*  we'll know this later */
		raw_pixel_start = pixel;

		cmd_pixel_end = pixel + (min(MAX_CMD_PIXELS + 1,
			min((int)(pixel_end - pixel) / bpp,
			    (int)(cmd_buffer_end - cmd) / 2))) * bpp;

		prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);
		pixel_val16 = get_pixel_val16(pixel, bpp);

		while (pixel < cmd_pixel_end) {
			const u8 *const start = pixel;
			const uint16_t repeating_pixel_val16 = pixel_val16;

			put_unaligned_be16(pixel_val16, cmd);

			cmd += 2;
			pixel += bpp;

			while (pixel < cmd_pixel_end) {
				pixel_val16 = get_pixel_val16(pixel, bpp);
				if (pixel_val16 != repeating_pixel_val16)
					break;
				pixel += bpp;
			}

			if (unlikely(pixel > start + bpp)) {
				/* go back and fill in raw pixel count */
				*raw_pixels_count_byte = (((start -
						raw_pixel_start) / bpp) + 1) & 0xFF;

				/* immediately after raw data is repeat byte */
				*cmd++ = (((pixel - start) / bpp) - 1) & 0xFF;

				/* Then start another raw pixel span */
				raw_pixel_start = pixel;
				raw_pixels_count_byte = cmd++;
			}
		}

		if (pixel > raw_pixel_start) {
			/* finalize last RAW span */
			*raw_pixels_count_byte = ((pixel-raw_pixel_start) / bpp) & 0xFF;
		}

		*cmd_pixels_count_byte = ((pixel - cmd_pixel_start) / bpp) & 0xFF;
		dev_addr += ((pixel - cmd_pixel_start) / bpp) * 2;
	}

	if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
		/* Fill leftover bytes with no-ops */
		if (cmd_buffer_end > cmd)
			memset(cmd, 0xAF, cmd_buffer_end - cmd);
		cmd = (uint8_t *) cmd_buffer_end;
	}

	*command_buffer_ptr = cmd;
	*pixel_start_ptr = pixel;
	*device_address_ptr = dev_addr;

	return;
}

/*
 * There are 3 copies of every pixel: The front buffer that the fbdev
 * client renders to, the actual framebuffer across the USB bus in hardware
 * (that we can only write to, slowly, and can never read), and (optionally)
 * our shadow copy that tracks what's been sent to that hardware buffer.
 */
int udl_render_hline(struct drm_device *dev, int bpp, struct urb **urb_ptr,
		     const char *front, char **urb_buf_ptr,
		     u32 byte_offset, u32 device_byte_offset,
		     u32 byte_width,
		     int *ident_ptr, int *sent_ptr)
{
	const u8 *line_start, *line_end, *next_pixel;
	u32 base16 = 0 + (device_byte_offset / bpp) * 2;
	struct urb *urb = *urb_ptr;
	u8 *cmd = *urb_buf_ptr;
	u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;

	BUG_ON(!(bpp == 2 || bpp == 4));

	line_start = (u8 *) (front + byte_offset);
	next_pixel = line_start;
	line_end = next_pixel + byte_width;

	while (next_pixel < line_end) {

		udl_compress_hline16(&next_pixel,
			     line_end, &base16,
			     (u8 **) &cmd, (u8 *) cmd_end, bpp);

		if (cmd >= cmd_end) {
			int len = cmd - (u8 *) urb->transfer_buffer;
			if (udl_submit_urb(dev, urb, len))
				return 1; /* lost pixels is set */
			*sent_ptr += len;
			urb = udl_get_urb(dev);
			if (!urb)
				return 1; /* lost_pixels is set */
			*urb_ptr = urb;
			cmd = urb->transfer_buffer;
			cmd_end = &cmd[urb->transfer_buffer_length];
		}
	}

	*urb_buf_ptr = cmd;

	return 0;
}
Commit	Line	Data
5320918b DA	1	/*
	2	* Copyright (C) 2012 Red Hat
	3	* based in parts on udlfb.c:
	4	* Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
	5	* Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
	6	* Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
	7	*
	8	* This file is subject to the terms and conditions of the GNU General Public
	9	* License v2. See the file COPYING in the main directory of this archive for
	10	* more details.
	11	*/
	12
	13	#include <linux/module.h>
	14	#include <linux/slab.h>
	15	#include <linux/fb.h>
	16	#include <linux/prefetch.h>
0c45b36f	17	#include <asm/unaligned.h>
5320918b	18
760285e7	19	#include <drm/drmP.h>
5320918b DA	20	#include "udl_drv.h"
	21
	22	#define MAX_CMD_PIXELS 255
	23
	24	#define RLX_HEADER_BYTES 7
	25	#define MIN_RLX_PIX_BYTES 4
	26	#define MIN_RLX_CMD_BYTES (RLX_HEADER_BYTES + MIN_RLX_PIX_BYTES)
	27
	28	#define RLE_HEADER_BYTES 6
	29	#define MIN_RLE_PIX_BYTES 3
	30	#define MIN_RLE_CMD_BYTES (RLE_HEADER_BYTES + MIN_RLE_PIX_BYTES)
	31
	32	#define RAW_HEADER_BYTES 6
	33	#define MIN_RAW_PIX_BYTES 2
	34	#define MIN_RAW_CMD_BYTES (RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES)
	35
	36	/*
	37	* Trims identical data from front and back of line
	38	* Sets new front buffer address and width
	39	* And returns byte count of identical pixels
	40	* Assumes CPU natural alignment (unsigned long)
	41	* for back and front buffer ptrs and width
	42	*/
	43	#if 0
	44	static int udl_trim_hline(const u8 bback, const u8 bfront, int width_bytes)
	45	{
	46	int j, k;
	47	const unsigned long back = (const unsigned long ) bback;
	48	const unsigned long front = (const unsigned long ) *bfront;
	49	const int width = *width_bytes / sizeof(unsigned long);
	50	int identical = width;
	51	int start = width;
	52	int end = width;
	53
	54	prefetch((void *) front);
	55	prefetch((void *) back);
	56
	57	for (j = 0; j < width; j++) {
	58	if (back[j] != front[j]) {
	59	start = j;
	60	break;
	61	}
	62	}
	63
	64	for (k = width - 1; k > j; k--) {
	65	if (back[k] != front[k]) {
	66	end = k+1;
	67	break;
	68	}
	69	}
	70
	71	identical = start + (width - end);
	72	bfront = (u8 ) &front[start];
	73	width_bytes = (end - start) sizeof(unsigned long);
	74
	75	return identical * sizeof(unsigned long);
	76	}
	77	#endif
	78
e90a4ea5	79	static inline u16 pixel32_to_be16(const uint32_t pixel)
5320918b	80	{
e90a4ea5 CW	81	return (((pixel >> 3) & 0x001f) \|
	82	((pixel >> 5) & 0x07e0) \|
	83	((pixel >> 8) & 0xf800));
	84	}
5320918b	85
86584444	86	static inline u16 get_pixel_val16(const uint8_t *pixel, int bpp)
e90a4ea5	87	{
86584444	88	u16 pixel_val16 = 0;
e90a4ea5	89	if (bpp == 2)
86584444 HS	90	pixel_val16 = (const uint16_t )pixel;
	91	else if (bpp == 4)
	92	pixel_val16 = pixel32_to_be16((const uint32_t )pixel);
	93	return pixel_val16;
5320918b DA	94	}
	95
	96	/*
	97	* Render a command stream for an encoded horizontal line segment of pixels.
	98	*
	99	* A command buffer holds several commands.
	100	* It always begins with a fresh command header
	101	* (the protocol doesn't require this, but we enforce it to allow
	102	* multiple buffers to be potentially encoded and sent in parallel).
	103	* A single command encodes one contiguous horizontal line of pixels
	104	*
	105	* The function relies on the client to do all allocation, so that
	106	* rendering can be done directly to output buffers (e.g. USB URBs).
	107	* The function fills the supplied command buffer, providing information
	108	* on where it left off, so the client may call in again with additional
	109	* buffers if the line will take several buffers to complete.
	110	*
	111	* A single command can transmit a maximum of 256 pixels,
	112	* regardless of the compression ratio (protocol design limit).
	113	* To the hardware, 0 for a size byte means 256
	114	*
	115	* Rather than 256 pixel commands which are either rl or raw encoded,
	116	* the rlx command simply assumes alternating raw and rl spans within one cmd.
	117	* This has a slightly larger header overhead, but produces more even results.
	118	* It also processes all data (read and write) in a single pass.
	119	* Performance benchmarks of common cases show it having just slightly better
	120	* compression than 256 pixel raw or rle commands, with similar CPU consumpion.
	121	* But for very rl friendly data, will compress not quite as well.
	122	*/
	123	static void udl_compress_hline16(
	124	const u8 **pixel_start_ptr,
	125	const u8 *const pixel_end,
	126	uint32_t *device_address_ptr,
	127	uint8_t **command_buffer_ptr,
	128	const uint8_t *const cmd_buffer_end, int bpp)
	129	{
	130	const u8 pixel = pixel_start_ptr;
	131	uint32_t dev_addr = *device_address_ptr;
	132	uint8_t cmd = command_buffer_ptr;
	133
	134	while ((pixel_end > pixel) &&
	135	(cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
74401b1d SK	136	uint8_t *raw_pixels_count_byte = NULL;
	137	uint8_t *cmd_pixels_count_byte = NULL;
	138	const u8 *raw_pixel_start = NULL;
	139	const u8 cmd_pixel_start, cmd_pixel_end = NULL;
86584444	140	uint16_t pixel_val16;
5320918b DA	141
	142	prefetchw((void ) cmd); / pull in one cache line at least */
	143
	144	*cmd++ = 0xaf;
	145	*cmd++ = 0x6b;
	146	*cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
	147	*cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
	148	*cmd++ = (uint8_t) ((dev_addr) & 0xFF);
	149
	150	cmd_pixels_count_byte = cmd++; /* we'll know this later */
	151	cmd_pixel_start = pixel;
	152
	153	raw_pixels_count_byte = cmd++; /* we'll know this later */
	154	raw_pixel_start = pixel;
	155
	156	cmd_pixel_end = pixel + (min(MAX_CMD_PIXELS + 1,
	157	min((int)(pixel_end - pixel) / bpp,
	158	(int)(cmd_buffer_end - cmd) / 2))) * bpp;
	159
	160	prefetch_range((void ) pixel, (cmd_pixel_end - pixel) bpp);
86584444	161	pixel_val16 = get_pixel_val16(pixel, bpp);
5320918b DA	162
5320918b DA	163	while (pixel < cmd_pixel_end) {
e90a4ea5	164	const u8 *const start = pixel;
86584444 HS	165	const uint16_t repeating_pixel_val16 = pixel_val16;
86584444 HS	166
0c45b36f	167	put_unaligned_be16(pixel_val16, cmd);
5320918b DA	168
	169	cmd += 2;
	170	pixel += bpp;
	171
86584444 HS	172	while (pixel < cmd_pixel_end) {
	173	pixel_val16 = get_pixel_val16(pixel, bpp);
	174	if (pixel_val16 != repeating_pixel_val16)
	175	break;
	176	pixel += bpp;
	177	}
	178
	179	if (unlikely(pixel > start + bpp)) {
5320918b	180	/* go back and fill in raw pixel count */
e90a4ea5	181	*raw_pixels_count_byte = (((start -
5320918b DA	182	raw_pixel_start) / bpp) + 1) & 0xFF;
5320918b DA	183
5320918b	184	/* immediately after raw data is repeat byte */
e90a4ea5	185	*cmd++ = (((pixel - start) / bpp) - 1) & 0xFF;
5320918b DA	186
	187	/* Then start another raw pixel span */
	188	raw_pixel_start = pixel;
	189	raw_pixels_count_byte = cmd++;
	190	}
	191	}
	192
	193	if (pixel > raw_pixel_start) {
	194	/* finalize last RAW span */
	195	*raw_pixels_count_byte = ((pixel-raw_pixel_start) / bpp) & 0xFF;
	196	}
	197
	198	*cmd_pixels_count_byte = ((pixel - cmd_pixel_start) / bpp) & 0xFF;
	199	dev_addr += ((pixel - cmd_pixel_start) / bpp) * 2;
	200	}
	201
	202	if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
	203	/* Fill leftover bytes with no-ops */
	204	if (cmd_buffer_end > cmd)
	205	memset(cmd, 0xAF, cmd_buffer_end - cmd);
	206	cmd = (uint8_t *) cmd_buffer_end;
	207	}
	208
	209	*command_buffer_ptr = cmd;
	210	*pixel_start_ptr = pixel;
	211	*device_address_ptr = dev_addr;
	212
	213	return;
	214	}
	215
	216	/*
	217	* There are 3 copies of every pixel: The front buffer that the fbdev
	218	* client renders to, the actual framebuffer across the USB bus in hardware
	219	* (that we can only write to, slowly, and can never read), and (optionally)
	220	* our shadow copy that tracks what's been sent to that hardware buffer.
	221	*/
	222	int udl_render_hline(struct drm_device dev, int bpp, struct urb *urb_ptr,
	223	const char front, char *urb_buf_ptr,
3916e1d7 DA	224	u32 byte_offset, u32 device_byte_offset,
3916e1d7 DA	225	u32 byte_width,
5320918b DA	226	int ident_ptr, int sent_ptr)
	227	{
	228	const u8 line_start, line_end, *next_pixel;
3916e1d7	229	u32 base16 = 0 + (device_byte_offset / bpp) * 2;
5320918b DA	230	struct urb urb = urb_ptr;
	231	u8 cmd = urb_buf_ptr;
	232	u8 cmd_end = (u8 ) urb->transfer_buffer + urb->transfer_buffer_length;
	233
e90a4ea5 CW	234	BUG_ON(!(bpp == 2 \|\| bpp == 4));
e90a4ea5 CW	235
5320918b DA	236	line_start = (u8 *) (front + byte_offset);
	237	next_pixel = line_start;
	238	line_end = next_pixel + byte_width;
	239
	240	while (next_pixel < line_end) {
	241
	242	udl_compress_hline16(&next_pixel,
	243	line_end, &base16,
	244	(u8 *) &cmd, (u8 ) cmd_end, bpp);
	245
	246	if (cmd >= cmd_end) {
	247	int len = cmd - (u8 *) urb->transfer_buffer;
	248	if (udl_submit_urb(dev, urb, len))
	249	return 1; /* lost pixels is set */
	250	*sent_ptr += len;
	251	urb = udl_get_urb(dev);
	252	if (!urb)
	253	return 1; /* lost_pixels is set */
	254	*urb_ptr = urb;
	255	cmd = urb->transfer_buffer;
	256	cmd_end = &cmd[urb->transfer_buffer_length];
	257	}
	258	}
	259
	260	*urb_buf_ptr = cmd;
	261
	262	return 0;
	263	}
	264