Loading...
Note: File does not exist in v3.1.
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{
217 const u8 *line_start, *line_end, *next_pixel;
218 u32 base16 = 0 + (device_byte_offset >> log_bpp) * 2;
219 struct urb *urb = *urb_ptr;
220 u8 *cmd = *urb_buf_ptr;
221 u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
222
223 BUG_ON(!(log_bpp == 1 || log_bpp == 2));
224
225 line_start = (u8 *) (front + byte_offset);
226 next_pixel = line_start;
227 line_end = next_pixel + byte_width;
228
229 while (next_pixel < line_end) {
230
231 udl_compress_hline16(&next_pixel,
232 line_end, &base16,
233 (u8 **) &cmd, (u8 *) cmd_end, log_bpp);
234
235 if (cmd >= cmd_end) {
236 int len = cmd - (u8 *) urb->transfer_buffer;
237 int ret = udl_submit_urb(dev, urb, len);
238 if (ret)
239 return ret;
240 urb = udl_get_urb(dev);
241 if (!urb)
242 return -EAGAIN;
243 *urb_ptr = urb;
244 cmd = urb->transfer_buffer;
245 cmd_end = &cmd[urb->transfer_buffer_length];
246 }
247 }
248
249 *urb_buf_ptr = cmd;
250
251 return 0;
252}