1 /* ir-rc6-decoder.c - A decoder for the RC6 IR protocol 2 * 3 * Copyright (C) 2010 by David Härdeman <david@hardeman.nu> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation version 2 of the License. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 */ 14 15 #include "rc-core-priv.h" 16 #include <linux/module.h> 17 18 /* 19 * This decoder currently supports: 20 * RC6-0-16 (standard toggle bit in header) 21 * RC6-6A-20 (no toggle bit) 22 * RC6-6A-24 (no toggle bit) 23 * RC6-6A-32 (MCE version with toggle bit in body) 24 */ 25 26 #define RC6_UNIT 444444 /* nanosecs */ 27 #define RC6_HEADER_NBITS 4 /* not including toggle bit */ 28 #define RC6_0_NBITS 16 29 #define RC6_6A_32_NBITS 32 30 #define RC6_6A_NBITS 128 /* Variable 8..128 */ 31 #define RC6_PREFIX_PULSE (6 * RC6_UNIT) 32 #define RC6_PREFIX_SPACE (2 * RC6_UNIT) 33 #define RC6_BIT_START (1 * RC6_UNIT) 34 #define RC6_BIT_END (1 * RC6_UNIT) 35 #define RC6_TOGGLE_START (2 * RC6_UNIT) 36 #define RC6_TOGGLE_END (2 * RC6_UNIT) 37 #define RC6_SUFFIX_SPACE (6 * RC6_UNIT) 38 #define RC6_MODE_MASK 0x07 /* for the header bits */ 39 #define RC6_STARTBIT_MASK 0x08 /* for the header bits */ 40 #define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */ 41 #define RC6_6A_LCC_MASK 0xffff0000 /* RC6-6A-32 long customer code mask */ 42 #define RC6_6A_MCE_CC 0x800f0000 /* MCE customer code */ 43 #ifndef CHAR_BIT 44 #define CHAR_BIT 8 /* Normally in <limits.h> */ 45 #endif 46 47 enum rc6_mode { 48 RC6_MODE_0, 49 RC6_MODE_6A, 50 RC6_MODE_UNKNOWN, 51 }; 52 53 enum rc6_state { 54 STATE_INACTIVE, 55 STATE_PREFIX_SPACE, 56 STATE_HEADER_BIT_START, 57 STATE_HEADER_BIT_END, 58 STATE_TOGGLE_START, 59 STATE_TOGGLE_END, 60 STATE_BODY_BIT_START, 61 STATE_BODY_BIT_END, 62 STATE_FINISHED, 63 }; 64 65 static enum rc6_mode rc6_mode(struct rc6_dec *data) 66 { 67 switch (data->header & RC6_MODE_MASK) { 68 case 0: 69 return RC6_MODE_0; 70 case 6: 71 if (!data->toggle) 72 return RC6_MODE_6A; 73 /* fall through */ 74 default: 75 return RC6_MODE_UNKNOWN; 76 } 77 } 78 79 /** 80 * ir_rc6_decode() - Decode one RC6 pulse or space 81 * @dev: the struct rc_dev descriptor of the device 82 * @ev: the struct ir_raw_event descriptor of the pulse/space 83 * 84 * This function returns -EINVAL if the pulse violates the state machine 85 */ 86 static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev) 87 { 88 struct rc6_dec *data = &dev->raw->rc6; 89 u32 scancode; 90 u8 toggle; 91 enum rc_type protocol; 92 93 if (!(dev->enabled_protocols & 94 (RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 | RC_BIT_RC6_6A_24 | 95 RC_BIT_RC6_6A_32 | RC_BIT_RC6_MCE))) 96 return 0; 97 98 if (!is_timing_event(ev)) { 99 if (ev.reset) 100 data->state = STATE_INACTIVE; 101 return 0; 102 } 103 104 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) 105 goto out; 106 107 again: 108 IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n", 109 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 110 111 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) 112 return 0; 113 114 switch (data->state) { 115 116 case STATE_INACTIVE: 117 if (!ev.pulse) 118 break; 119 120 /* Note: larger margin on first pulse since each RC6_UNIT 121 is quite short and some hardware takes some time to 122 adjust to the signal */ 123 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT)) 124 break; 125 126 data->state = STATE_PREFIX_SPACE; 127 data->count = 0; 128 return 0; 129 130 case STATE_PREFIX_SPACE: 131 if (ev.pulse) 132 break; 133 134 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2)) 135 break; 136 137 data->state = STATE_HEADER_BIT_START; 138 data->header = 0; 139 return 0; 140 141 case STATE_HEADER_BIT_START: 142 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) 143 break; 144 145 data->header <<= 1; 146 if (ev.pulse) 147 data->header |= 1; 148 data->count++; 149 data->state = STATE_HEADER_BIT_END; 150 return 0; 151 152 case STATE_HEADER_BIT_END: 153 if (!is_transition(&ev, &dev->raw->prev_ev)) 154 break; 155 156 if (data->count == RC6_HEADER_NBITS) 157 data->state = STATE_TOGGLE_START; 158 else 159 data->state = STATE_HEADER_BIT_START; 160 161 decrease_duration(&ev, RC6_BIT_END); 162 goto again; 163 164 case STATE_TOGGLE_START: 165 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2)) 166 break; 167 168 data->toggle = ev.pulse; 169 data->state = STATE_TOGGLE_END; 170 return 0; 171 172 case STATE_TOGGLE_END: 173 if (!is_transition(&ev, &dev->raw->prev_ev) || 174 !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2)) 175 break; 176 177 if (!(data->header & RC6_STARTBIT_MASK)) { 178 IR_dprintk(1, "RC6 invalid start bit\n"); 179 break; 180 } 181 182 data->state = STATE_BODY_BIT_START; 183 decrease_duration(&ev, RC6_TOGGLE_END); 184 data->count = 0; 185 data->body = 0; 186 187 switch (rc6_mode(data)) { 188 case RC6_MODE_0: 189 data->wanted_bits = RC6_0_NBITS; 190 break; 191 case RC6_MODE_6A: 192 data->wanted_bits = RC6_6A_NBITS; 193 break; 194 default: 195 IR_dprintk(1, "RC6 unknown mode\n"); 196 goto out; 197 } 198 goto again; 199 200 case STATE_BODY_BIT_START: 201 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) { 202 /* Discard LSB's that won't fit in data->body */ 203 if (data->count++ < CHAR_BIT * sizeof data->body) { 204 data->body <<= 1; 205 if (ev.pulse) 206 data->body |= 1; 207 } 208 data->state = STATE_BODY_BIT_END; 209 return 0; 210 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse && 211 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) { 212 data->state = STATE_FINISHED; 213 goto again; 214 } 215 break; 216 217 case STATE_BODY_BIT_END: 218 if (!is_transition(&ev, &dev->raw->prev_ev)) 219 break; 220 221 if (data->count == data->wanted_bits) 222 data->state = STATE_FINISHED; 223 else 224 data->state = STATE_BODY_BIT_START; 225 226 decrease_duration(&ev, RC6_BIT_END); 227 goto again; 228 229 case STATE_FINISHED: 230 if (ev.pulse) 231 break; 232 233 switch (rc6_mode(data)) { 234 case RC6_MODE_0: 235 scancode = data->body; 236 toggle = data->toggle; 237 protocol = RC_TYPE_RC6_0; 238 IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n", 239 scancode, toggle); 240 break; 241 242 case RC6_MODE_6A: 243 if (data->count > CHAR_BIT * sizeof data->body) { 244 IR_dprintk(1, "RC6 too many (%u) data bits\n", 245 data->count); 246 goto out; 247 } 248 249 scancode = data->body; 250 switch (data->count) { 251 case 20: 252 protocol = RC_TYPE_RC6_6A_20; 253 toggle = 0; 254 break; 255 case 24: 256 protocol = RC_BIT_RC6_6A_24; 257 toggle = 0; 258 break; 259 case 32: 260 if ((scancode & RC6_6A_LCC_MASK) == RC6_6A_MCE_CC) { 261 protocol = RC_TYPE_RC6_MCE; 262 toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK); 263 scancode &= ~RC6_6A_MCE_TOGGLE_MASK; 264 } else { 265 protocol = RC_BIT_RC6_6A_32; 266 toggle = 0; 267 } 268 break; 269 default: 270 IR_dprintk(1, "RC6(6A) unsupported length\n"); 271 goto out; 272 } 273 274 IR_dprintk(1, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n", 275 protocol, scancode, toggle); 276 break; 277 default: 278 IR_dprintk(1, "RC6 unknown mode\n"); 279 goto out; 280 } 281 282 rc_keydown(dev, protocol, scancode, toggle); 283 data->state = STATE_INACTIVE; 284 return 0; 285 } 286 287 out: 288 IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n", 289 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 290 data->state = STATE_INACTIVE; 291 return -EINVAL; 292 } 293 294 static struct ir_raw_timings_manchester ir_rc6_timings[4] = { 295 { 296 .leader = RC6_PREFIX_PULSE, 297 .pulse_space_start = 0, 298 .clock = RC6_UNIT, 299 .invert = 1, 300 .trailer_space = RC6_PREFIX_SPACE, 301 }, 302 { 303 .clock = RC6_UNIT, 304 .invert = 1, 305 }, 306 { 307 .clock = RC6_UNIT * 2, 308 .invert = 1, 309 }, 310 { 311 .clock = RC6_UNIT, 312 .invert = 1, 313 .trailer_space = RC6_SUFFIX_SPACE, 314 }, 315 }; 316 317 static int ir_rc6_validate_filter(const struct rc_scancode_filter *scancode, 318 unsigned int important_bits) 319 { 320 /* all important bits of scancode should be set in mask */ 321 if (~scancode->mask & important_bits) 322 return -EINVAL; 323 /* extra bits in mask should be zero in data */ 324 if (scancode->mask & scancode->data & ~important_bits) 325 return -EINVAL; 326 return 0; 327 } 328 329 /** 330 * ir_rc6_encode() - Encode a scancode as a stream of raw events 331 * 332 * @protocols: allowed protocols 333 * @scancode: scancode filter describing scancode (helps distinguish between 334 * protocol subtypes when scancode is ambiguous) 335 * @events: array of raw ir events to write into 336 * @max: maximum size of @events 337 * 338 * Returns: The number of events written. 339 * -ENOBUFS if there isn't enough space in the array to fit the 340 * encoding. In this case all @max events will have been written. 341 * -EINVAL if the scancode is ambiguous or invalid. 342 */ 343 static int ir_rc6_encode(u64 protocols, 344 const struct rc_scancode_filter *scancode, 345 struct ir_raw_event *events, unsigned int max) 346 { 347 int ret; 348 struct ir_raw_event *e = events; 349 350 if (protocols & RC_BIT_RC6_0 && 351 !ir_rc6_validate_filter(scancode, 0xffff)) { 352 353 /* Modulate the preamble */ 354 ret = ir_raw_gen_manchester(&e, max, &ir_rc6_timings[0], 0, 0); 355 if (ret < 0) 356 return ret; 357 358 /* Modulate the header (Start Bit & Mode-0) */ 359 ret = ir_raw_gen_manchester(&e, max - (e - events), 360 &ir_rc6_timings[1], 361 RC6_HEADER_NBITS, (1 << 3)); 362 if (ret < 0) 363 return ret; 364 365 /* Modulate Trailer Bit */ 366 ret = ir_raw_gen_manchester(&e, max - (e - events), 367 &ir_rc6_timings[2], 1, 0); 368 if (ret < 0) 369 return ret; 370 371 /* Modulate rest of the data */ 372 ret = ir_raw_gen_manchester(&e, max - (e - events), 373 &ir_rc6_timings[3], RC6_0_NBITS, 374 scancode->data); 375 if (ret < 0) 376 return ret; 377 378 } else if (protocols & (RC_BIT_RC6_6A_20 | RC_BIT_RC6_6A_24 | 379 RC_BIT_RC6_6A_32 | RC_BIT_RC6_MCE) && 380 !ir_rc6_validate_filter(scancode, 0x8fffffff)) { 381 382 /* Modulate the preamble */ 383 ret = ir_raw_gen_manchester(&e, max, &ir_rc6_timings[0], 0, 0); 384 if (ret < 0) 385 return ret; 386 387 /* Modulate the header (Start Bit & Header-version 6 */ 388 ret = ir_raw_gen_manchester(&e, max - (e - events), 389 &ir_rc6_timings[1], 390 RC6_HEADER_NBITS, (1 << 3 | 6)); 391 if (ret < 0) 392 return ret; 393 394 /* Modulate Trailer Bit */ 395 ret = ir_raw_gen_manchester(&e, max - (e - events), 396 &ir_rc6_timings[2], 1, 0); 397 if (ret < 0) 398 return ret; 399 400 /* Modulate rest of the data */ 401 ret = ir_raw_gen_manchester(&e, max - (e - events), 402 &ir_rc6_timings[3], 403 fls(scancode->mask), 404 scancode->data); 405 if (ret < 0) 406 return ret; 407 408 } else { 409 return -EINVAL; 410 } 411 412 return e - events; 413 } 414 415 static struct ir_raw_handler rc6_handler = { 416 .protocols = RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 | 417 RC_BIT_RC6_6A_24 | RC_BIT_RC6_6A_32 | 418 RC_BIT_RC6_MCE, 419 .decode = ir_rc6_decode, 420 .encode = ir_rc6_encode, 421 }; 422 423 static int __init ir_rc6_decode_init(void) 424 { 425 ir_raw_handler_register(&rc6_handler); 426 427 printk(KERN_INFO "IR RC6 protocol handler initialized\n"); 428 return 0; 429 } 430 431 static void __exit ir_rc6_decode_exit(void) 432 { 433 ir_raw_handler_unregister(&rc6_handler); 434 } 435 436 module_init(ir_rc6_decode_init); 437 module_exit(ir_rc6_decode_exit); 438 439 MODULE_LICENSE("GPL"); 440 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>"); 441 MODULE_DESCRIPTION("RC6 IR protocol decoder"); 442