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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Red Hat
4 * based in parts on udlfb.c:
5 * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
6 * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
7 * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
8 */
9
10#include <asm/unaligned.h>
11
12#include "udl_drv.h"
13
14#define MAX_CMD_PIXELS 255
15
16#define RLX_HEADER_BYTES 7
17#define MIN_RLX_PIX_BYTES 4
18#define MIN_RLX_CMD_BYTES (RLX_HEADER_BYTES + MIN_RLX_PIX_BYTES)
19
20#define RLE_HEADER_BYTES 6
21#define MIN_RLE_PIX_BYTES 3
22#define MIN_RLE_CMD_BYTES (RLE_HEADER_BYTES + MIN_RLE_PIX_BYTES)
23
24#define RAW_HEADER_BYTES 6
25#define MIN_RAW_PIX_BYTES 2
26#define MIN_RAW_CMD_BYTES (RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES)
27
28/*
29 * Trims identical data from front and back of line
30 * Sets new front buffer address and width
31 * And returns byte count of identical pixels
32 * Assumes CPU natural alignment (unsigned long)
33 * for back and front buffer ptrs and width
34 */
35#if 0
36static int udl_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
37{
38 int j, k;
39 const unsigned long *back = (const unsigned long *) bback;
40 const unsigned long *front = (const unsigned long *) *bfront;
41 const int width = *width_bytes / sizeof(unsigned long);
42 int identical = width;
43 int start = width;
44 int end = width;
45
46 for (j = 0; j < width; j++) {
47 if (back[j] != front[j]) {
48 start = j;
49 break;
50 }
51 }
52
53 for (k = width - 1; k > j; k--) {
54 if (back[k] != front[k]) {
55 end = k+1;
56 break;
57 }
58 }
59
60 identical = start + (width - end);
61 *bfront = (u8 *) &front[start];
62 *width_bytes = (end - start) * sizeof(unsigned long);
63
64 return identical * sizeof(unsigned long);
65}
66#endif
67
68static inline u16 pixel32_to_be16(const uint32_t pixel)
69{
70 return (((pixel >> 3) & 0x001f) |
71 ((pixel >> 5) & 0x07e0) |
72 ((pixel >> 8) & 0xf800));
73}
74
75static inline u16 get_pixel_val16(const uint8_t *pixel, int log_bpp)
76{
77 u16 pixel_val16;
78 if (log_bpp == 1)
79 pixel_val16 = *(const uint16_t *)pixel;
80 else
81 pixel_val16 = pixel32_to_be16(*(const uint32_t *)pixel);
82 return pixel_val16;
83}
84
85/*
86 * Render a command stream for an encoded horizontal line segment of pixels.
87 *
88 * A command buffer holds several commands.
89 * It always begins with a fresh command header
90 * (the protocol doesn't require this, but we enforce it to allow
91 * multiple buffers to be potentially encoded and sent in parallel).
92 * A single command encodes one contiguous horizontal line of pixels
93 *
94 * The function relies on the client to do all allocation, so that
95 * rendering can be done directly to output buffers (e.g. USB URBs).
96 * The function fills the supplied command buffer, providing information
97 * on where it left off, so the client may call in again with additional
98 * buffers if the line will take several buffers to complete.
99 *
100 * A single command can transmit a maximum of 256 pixels,
101 * regardless of the compression ratio (protocol design limit).
102 * To the hardware, 0 for a size byte means 256
103 *
104 * Rather than 256 pixel commands which are either rl or raw encoded,
105 * the rlx command simply assumes alternating raw and rl spans within one cmd.
106 * This has a slightly larger header overhead, but produces more even results.
107 * It also processes all data (read and write) in a single pass.
108 * Performance benchmarks of common cases show it having just slightly better
109 * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
110 * But for very rl friendly data, will compress not quite as well.
111 */
112static void udl_compress_hline16(
113 const u8 **pixel_start_ptr,
114 const u8 *const pixel_end,
115 uint32_t *device_address_ptr,
116 uint8_t **command_buffer_ptr,
117 const uint8_t *const cmd_buffer_end, int log_bpp)
118{
119 const int bpp = 1 << log_bpp;
120 const u8 *pixel = *pixel_start_ptr;
121 uint32_t dev_addr = *device_address_ptr;
122 uint8_t *cmd = *command_buffer_ptr;
123
124 while ((pixel_end > pixel) &&
125 (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
126 uint8_t *raw_pixels_count_byte = NULL;
127 uint8_t *cmd_pixels_count_byte = NULL;
128 const u8 *raw_pixel_start = NULL;
129 const u8 *cmd_pixel_start, *cmd_pixel_end = NULL;
130 uint16_t pixel_val16;
131
132 *cmd++ = 0xaf;
133 *cmd++ = 0x6b;
134 *cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
135 *cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
136 *cmd++ = (uint8_t) ((dev_addr) & 0xFF);
137
138 cmd_pixels_count_byte = cmd++; /* we'll know this later */
139 cmd_pixel_start = pixel;
140
141 raw_pixels_count_byte = cmd++; /* we'll know this later */
142 raw_pixel_start = pixel;
143
144 cmd_pixel_end = pixel + (min3(MAX_CMD_PIXELS + 1UL,
145 (unsigned long)(pixel_end - pixel) >> log_bpp,
146 (unsigned long)(cmd_buffer_end - 1 - cmd) / 2) << log_bpp);
147
148 pixel_val16 = get_pixel_val16(pixel, log_bpp);
149
150 while (pixel < cmd_pixel_end) {
151 const u8 *const start = pixel;
152 const uint16_t repeating_pixel_val16 = pixel_val16;
153
154 put_unaligned_be16(pixel_val16, cmd);
155
156 cmd += 2;
157 pixel += bpp;
158
159 while (pixel < cmd_pixel_end) {
160 pixel_val16 = get_pixel_val16(pixel, log_bpp);
161 if (pixel_val16 != repeating_pixel_val16)
162 break;
163 pixel += bpp;
164 }
165
166 if (unlikely(pixel > start + bpp)) {
167 /* go back and fill in raw pixel count */
168 *raw_pixels_count_byte = (((start -
169 raw_pixel_start) >> log_bpp) + 1) & 0xFF;
170
171 /* immediately after raw data is repeat byte */
172 *cmd++ = (((pixel - start) >> log_bpp) - 1) & 0xFF;
173
174 /* Then start another raw pixel span */
175 raw_pixel_start = pixel;
176 raw_pixels_count_byte = cmd++;
177 }
178 }
179
180 if (pixel > raw_pixel_start) {
181 /* finalize last RAW span */
182 *raw_pixels_count_byte = ((pixel - raw_pixel_start) >> log_bpp) & 0xFF;
183 } else {
184 /* undo unused byte */
185 cmd--;
186 }
187
188 *cmd_pixels_count_byte = ((pixel - cmd_pixel_start) >> log_bpp) & 0xFF;
189 dev_addr += ((pixel - cmd_pixel_start) >> log_bpp) * 2;
190 }
191
192 if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
193 /* Fill leftover bytes with no-ops */
194 if (cmd_buffer_end > cmd)
195 memset(cmd, 0xAF, cmd_buffer_end - cmd);
196 cmd = (uint8_t *) cmd_buffer_end;
197 }
198
199 *command_buffer_ptr = cmd;
200 *pixel_start_ptr = pixel;
201 *device_address_ptr = dev_addr;
202
203 return;
204}
205
206/*
207 * There are 3 copies of every pixel: The front buffer that the fbdev
208 * client renders to, the actual framebuffer across the USB bus in hardware
209 * (that we can only write to, slowly, and can never read), and (optionally)
210 * our shadow copy that tracks what's been sent to that hardware buffer.
211 */
212int udl_render_hline(struct drm_device *dev, int log_bpp, struct urb **urb_ptr,
213 const char *front, char **urb_buf_ptr,
214 u32 byte_offset, u32 device_byte_offset,
215 u32 byte_width,
216 int *ident_ptr, int *sent_ptr)
217{
218 const u8 *line_start, *line_end, *next_pixel;
219 u32 base16 = 0 + (device_byte_offset >> log_bpp) * 2;
220 struct urb *urb = *urb_ptr;
221 u8 *cmd = *urb_buf_ptr;
222 u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
223
224 BUG_ON(!(log_bpp == 1 || log_bpp == 2));
225
226 line_start = (u8 *) (front + byte_offset);
227 next_pixel = line_start;
228 line_end = next_pixel + byte_width;
229
230 while (next_pixel < line_end) {
231
232 udl_compress_hline16(&next_pixel,
233 line_end, &base16,
234 (u8 **) &cmd, (u8 *) cmd_end, log_bpp);
235
236 if (cmd >= cmd_end) {
237 int len = cmd - (u8 *) urb->transfer_buffer;
238 if (udl_submit_urb(dev, urb, len))
239 return 1; /* lost pixels is set */
240 *sent_ptr += len;
241 urb = udl_get_urb(dev);
242 if (!urb)
243 return 1; /* lost_pixels is set */
244 *urb_ptr = urb;
245 cmd = urb->transfer_buffer;
246 cmd_end = &cmd[urb->transfer_buffer_length];
247 }
248 }
249
250 *urb_buf_ptr = cmd;
251
252 return 0;
253}
254
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>
17
18#include <drm/drmP.h>
19#include "udl_drv.h"
20
21#define MAX_CMD_PIXELS 255
22
23#define RLX_HEADER_BYTES 7
24#define MIN_RLX_PIX_BYTES 4
25#define MIN_RLX_CMD_BYTES (RLX_HEADER_BYTES + MIN_RLX_PIX_BYTES)
26
27#define RLE_HEADER_BYTES 6
28#define MIN_RLE_PIX_BYTES 3
29#define MIN_RLE_CMD_BYTES (RLE_HEADER_BYTES + MIN_RLE_PIX_BYTES)
30
31#define RAW_HEADER_BYTES 6
32#define MIN_RAW_PIX_BYTES 2
33#define MIN_RAW_CMD_BYTES (RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES)
34
35/*
36 * Trims identical data from front and back of line
37 * Sets new front buffer address and width
38 * And returns byte count of identical pixels
39 * Assumes CPU natural alignment (unsigned long)
40 * for back and front buffer ptrs and width
41 */
42#if 0
43static int udl_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
44{
45 int j, k;
46 const unsigned long *back = (const unsigned long *) bback;
47 const unsigned long *front = (const unsigned long *) *bfront;
48 const int width = *width_bytes / sizeof(unsigned long);
49 int identical = width;
50 int start = width;
51 int end = width;
52
53 prefetch((void *) front);
54 prefetch((void *) back);
55
56 for (j = 0; j < width; j++) {
57 if (back[j] != front[j]) {
58 start = j;
59 break;
60 }
61 }
62
63 for (k = width - 1; k > j; k--) {
64 if (back[k] != front[k]) {
65 end = k+1;
66 break;
67 }
68 }
69
70 identical = start + (width - end);
71 *bfront = (u8 *) &front[start];
72 *width_bytes = (end - start) * sizeof(unsigned long);
73
74 return identical * sizeof(unsigned long);
75}
76#endif
77
78static inline u16 pixel32_to_be16(const uint32_t pixel)
79{
80 return (((pixel >> 3) & 0x001f) |
81 ((pixel >> 5) & 0x07e0) |
82 ((pixel >> 8) & 0xf800));
83}
84
85static bool pixel_repeats(const void *pixel, const uint32_t repeat, int bpp)
86{
87 if (bpp == 2)
88 return *(const uint16_t *)pixel == repeat;
89 else
90 return *(const uint32_t *)pixel == repeat;
91}
92
93/*
94 * Render a command stream for an encoded horizontal line segment of pixels.
95 *
96 * A command buffer holds several commands.
97 * It always begins with a fresh command header
98 * (the protocol doesn't require this, but we enforce it to allow
99 * multiple buffers to be potentially encoded and sent in parallel).
100 * A single command encodes one contiguous horizontal line of pixels
101 *
102 * The function relies on the client to do all allocation, so that
103 * rendering can be done directly to output buffers (e.g. USB URBs).
104 * The function fills the supplied command buffer, providing information
105 * on where it left off, so the client may call in again with additional
106 * buffers if the line will take several buffers to complete.
107 *
108 * A single command can transmit a maximum of 256 pixels,
109 * regardless of the compression ratio (protocol design limit).
110 * To the hardware, 0 for a size byte means 256
111 *
112 * Rather than 256 pixel commands which are either rl or raw encoded,
113 * the rlx command simply assumes alternating raw and rl spans within one cmd.
114 * This has a slightly larger header overhead, but produces more even results.
115 * It also processes all data (read and write) in a single pass.
116 * Performance benchmarks of common cases show it having just slightly better
117 * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
118 * But for very rl friendly data, will compress not quite as well.
119 */
120static void udl_compress_hline16(
121 const u8 **pixel_start_ptr,
122 const u8 *const pixel_end,
123 uint32_t *device_address_ptr,
124 uint8_t **command_buffer_ptr,
125 const uint8_t *const cmd_buffer_end, int bpp)
126{
127 const u8 *pixel = *pixel_start_ptr;
128 uint32_t dev_addr = *device_address_ptr;
129 uint8_t *cmd = *command_buffer_ptr;
130
131 while ((pixel_end > pixel) &&
132 (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
133 uint8_t *raw_pixels_count_byte = NULL;
134 uint8_t *cmd_pixels_count_byte = NULL;
135 const u8 *raw_pixel_start = NULL;
136 const u8 *cmd_pixel_start, *cmd_pixel_end = NULL;
137
138 prefetchw((void *) cmd); /* pull in one cache line at least */
139
140 *cmd++ = 0xaf;
141 *cmd++ = 0x6b;
142 *cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
143 *cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
144 *cmd++ = (uint8_t) ((dev_addr) & 0xFF);
145
146 cmd_pixels_count_byte = cmd++; /* we'll know this later */
147 cmd_pixel_start = pixel;
148
149 raw_pixels_count_byte = cmd++; /* we'll know this later */
150 raw_pixel_start = pixel;
151
152 cmd_pixel_end = pixel + (min(MAX_CMD_PIXELS + 1,
153 min((int)(pixel_end - pixel) / bpp,
154 (int)(cmd_buffer_end - cmd) / 2))) * bpp;
155
156 prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);
157
158 while (pixel < cmd_pixel_end) {
159 const u8 *const start = pixel;
160 u32 repeating_pixel;
161
162 if (bpp == 2) {
163 repeating_pixel = *(uint16_t *)pixel;
164 *(uint16_t *)cmd = cpu_to_be16(repeating_pixel);
165 } else {
166 repeating_pixel = *(uint32_t *)pixel;
167 *(uint16_t *)cmd = cpu_to_be16(pixel32_to_be16(repeating_pixel));
168 }
169
170 cmd += 2;
171 pixel += bpp;
172
173 if (unlikely((pixel < cmd_pixel_end) &&
174 (pixel_repeats(pixel, repeating_pixel, bpp)))) {
175 /* go back and fill in raw pixel count */
176 *raw_pixels_count_byte = (((start -
177 raw_pixel_start) / bpp) + 1) & 0xFF;
178
179 while ((pixel < cmd_pixel_end) &&
180 (pixel_repeats(pixel, repeating_pixel, bpp))) {
181 pixel += bpp;
182 }
183
184 /* immediately after raw data is repeat byte */
185 *cmd++ = (((pixel - start) / bpp) - 1) & 0xFF;
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 */
222int udl_render_hline(struct drm_device *dev, int bpp, struct urb **urb_ptr,
223 const char *front, char **urb_buf_ptr,
224 u32 byte_offset, u32 device_byte_offset,
225 u32 byte_width,
226 int *ident_ptr, int *sent_ptr)
227{
228 const u8 *line_start, *line_end, *next_pixel;
229 u32 base16 = 0 + (device_byte_offset / bpp) * 2;
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
234 BUG_ON(!(bpp == 2 || bpp == 4));
235
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