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 36 static 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 68 static 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 75 static 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 */ 112 static 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 */ 212 int 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 } 253