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_proto protocol; 92 93 if (!is_timing_event(ev)) { 94 if (ev.reset) 95 data->state = STATE_INACTIVE; 96 return 0; 97 } 98 99 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) 100 goto out; 101 102 again: 103 dev_dbg(&dev->dev, "RC6 decode started at state %i (%uus %s)\n", 104 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 105 106 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) 107 return 0; 108 109 switch (data->state) { 110 111 case STATE_INACTIVE: 112 if (!ev.pulse) 113 break; 114 115 /* Note: larger margin on first pulse since each RC6_UNIT 116 is quite short and some hardware takes some time to 117 adjust to the signal */ 118 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT)) 119 break; 120 121 data->state = STATE_PREFIX_SPACE; 122 data->count = 0; 123 return 0; 124 125 case STATE_PREFIX_SPACE: 126 if (ev.pulse) 127 break; 128 129 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2)) 130 break; 131 132 data->state = STATE_HEADER_BIT_START; 133 data->header = 0; 134 return 0; 135 136 case STATE_HEADER_BIT_START: 137 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) 138 break; 139 140 data->header <<= 1; 141 if (ev.pulse) 142 data->header |= 1; 143 data->count++; 144 data->state = STATE_HEADER_BIT_END; 145 return 0; 146 147 case STATE_HEADER_BIT_END: 148 if (!is_transition(&ev, &dev->raw->prev_ev)) 149 break; 150 151 if (data->count == RC6_HEADER_NBITS) 152 data->state = STATE_TOGGLE_START; 153 else 154 data->state = STATE_HEADER_BIT_START; 155 156 decrease_duration(&ev, RC6_BIT_END); 157 goto again; 158 159 case STATE_TOGGLE_START: 160 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2)) 161 break; 162 163 data->toggle = ev.pulse; 164 data->state = STATE_TOGGLE_END; 165 return 0; 166 167 case STATE_TOGGLE_END: 168 if (!is_transition(&ev, &dev->raw->prev_ev) || 169 !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2)) 170 break; 171 172 if (!(data->header & RC6_STARTBIT_MASK)) { 173 dev_dbg(&dev->dev, "RC6 invalid start bit\n"); 174 break; 175 } 176 177 data->state = STATE_BODY_BIT_START; 178 decrease_duration(&ev, RC6_TOGGLE_END); 179 data->count = 0; 180 data->body = 0; 181 182 switch (rc6_mode(data)) { 183 case RC6_MODE_0: 184 data->wanted_bits = RC6_0_NBITS; 185 break; 186 case RC6_MODE_6A: 187 data->wanted_bits = RC6_6A_NBITS; 188 break; 189 default: 190 dev_dbg(&dev->dev, "RC6 unknown mode\n"); 191 goto out; 192 } 193 goto again; 194 195 case STATE_BODY_BIT_START: 196 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) { 197 /* Discard LSB's that won't fit in data->body */ 198 if (data->count++ < CHAR_BIT * sizeof data->body) { 199 data->body <<= 1; 200 if (ev.pulse) 201 data->body |= 1; 202 } 203 data->state = STATE_BODY_BIT_END; 204 return 0; 205 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse && 206 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) { 207 data->state = STATE_FINISHED; 208 goto again; 209 } 210 break; 211 212 case STATE_BODY_BIT_END: 213 if (!is_transition(&ev, &dev->raw->prev_ev)) 214 break; 215 216 if (data->count == data->wanted_bits) 217 data->state = STATE_FINISHED; 218 else 219 data->state = STATE_BODY_BIT_START; 220 221 decrease_duration(&ev, RC6_BIT_END); 222 goto again; 223 224 case STATE_FINISHED: 225 if (ev.pulse) 226 break; 227 228 switch (rc6_mode(data)) { 229 case RC6_MODE_0: 230 scancode = data->body; 231 toggle = data->toggle; 232 protocol = RC_PROTO_RC6_0; 233 dev_dbg(&dev->dev, "RC6(0) scancode 0x%04x (toggle: %u)\n", 234 scancode, toggle); 235 break; 236 237 case RC6_MODE_6A: 238 if (data->count > CHAR_BIT * sizeof data->body) { 239 dev_dbg(&dev->dev, "RC6 too many (%u) data bits\n", 240 data->count); 241 goto out; 242 } 243 244 scancode = data->body; 245 switch (data->count) { 246 case 20: 247 protocol = RC_PROTO_RC6_6A_20; 248 toggle = 0; 249 break; 250 case 24: 251 protocol = RC_PROTO_RC6_6A_24; 252 toggle = 0; 253 break; 254 case 32: 255 if ((scancode & RC6_6A_LCC_MASK) == RC6_6A_MCE_CC) { 256 protocol = RC_PROTO_RC6_MCE; 257 toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK); 258 scancode &= ~RC6_6A_MCE_TOGGLE_MASK; 259 } else { 260 protocol = RC_PROTO_RC6_6A_32; 261 toggle = 0; 262 } 263 break; 264 default: 265 dev_dbg(&dev->dev, "RC6(6A) unsupported length\n"); 266 goto out; 267 } 268 269 dev_dbg(&dev->dev, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n", 270 protocol, scancode, toggle); 271 break; 272 default: 273 dev_dbg(&dev->dev, "RC6 unknown mode\n"); 274 goto out; 275 } 276 277 rc_keydown(dev, protocol, scancode, toggle); 278 data->state = STATE_INACTIVE; 279 return 0; 280 } 281 282 out: 283 dev_dbg(&dev->dev, "RC6 decode failed at state %i (%uus %s)\n", 284 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 285 data->state = STATE_INACTIVE; 286 return -EINVAL; 287 } 288 289 static const struct ir_raw_timings_manchester ir_rc6_timings[4] = { 290 { 291 .leader_pulse = RC6_PREFIX_PULSE, 292 .leader_space = RC6_PREFIX_SPACE, 293 .clock = RC6_UNIT, 294 .invert = 1, 295 }, 296 { 297 .clock = RC6_UNIT * 2, 298 .invert = 1, 299 }, 300 { 301 .clock = RC6_UNIT, 302 .invert = 1, 303 .trailer_space = RC6_SUFFIX_SPACE, 304 }, 305 }; 306 307 /** 308 * ir_rc6_encode() - Encode a scancode as a stream of raw events 309 * 310 * @protocol: protocol to encode 311 * @scancode: scancode to encode 312 * @events: array of raw ir events to write into 313 * @max: maximum size of @events 314 * 315 * Returns: The number of events written. 316 * -ENOBUFS if there isn't enough space in the array to fit the 317 * encoding. In this case all @max events will have been written. 318 * -EINVAL if the scancode is ambiguous or invalid. 319 */ 320 static int ir_rc6_encode(enum rc_proto protocol, u32 scancode, 321 struct ir_raw_event *events, unsigned int max) 322 { 323 int ret; 324 struct ir_raw_event *e = events; 325 326 if (protocol == RC_PROTO_RC6_0) { 327 /* Modulate the header (Start Bit & Mode-0) */ 328 ret = ir_raw_gen_manchester(&e, max - (e - events), 329 &ir_rc6_timings[0], 330 RC6_HEADER_NBITS, (1 << 3)); 331 if (ret < 0) 332 return ret; 333 334 /* Modulate Trailer Bit */ 335 ret = ir_raw_gen_manchester(&e, max - (e - events), 336 &ir_rc6_timings[1], 1, 0); 337 if (ret < 0) 338 return ret; 339 340 /* Modulate rest of the data */ 341 ret = ir_raw_gen_manchester(&e, max - (e - events), 342 &ir_rc6_timings[2], RC6_0_NBITS, 343 scancode); 344 if (ret < 0) 345 return ret; 346 347 } else { 348 int bits; 349 350 switch (protocol) { 351 case RC_PROTO_RC6_MCE: 352 case RC_PROTO_RC6_6A_32: 353 bits = 32; 354 break; 355 case RC_PROTO_RC6_6A_24: 356 bits = 24; 357 break; 358 case RC_PROTO_RC6_6A_20: 359 bits = 20; 360 break; 361 default: 362 return -EINVAL; 363 } 364 365 /* Modulate the header (Start Bit & Header-version 6 */ 366 ret = ir_raw_gen_manchester(&e, max - (e - events), 367 &ir_rc6_timings[0], 368 RC6_HEADER_NBITS, (1 << 3 | 6)); 369 if (ret < 0) 370 return ret; 371 372 /* Modulate Trailer Bit */ 373 ret = ir_raw_gen_manchester(&e, max - (e - events), 374 &ir_rc6_timings[1], 1, 0); 375 if (ret < 0) 376 return ret; 377 378 /* Modulate rest of the data */ 379 ret = ir_raw_gen_manchester(&e, max - (e - events), 380 &ir_rc6_timings[2], 381 bits, 382 scancode); 383 if (ret < 0) 384 return ret; 385 } 386 387 return e - events; 388 } 389 390 static struct ir_raw_handler rc6_handler = { 391 .protocols = RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 | 392 RC_PROTO_BIT_RC6_6A_24 | RC_PROTO_BIT_RC6_6A_32 | 393 RC_PROTO_BIT_RC6_MCE, 394 .decode = ir_rc6_decode, 395 .encode = ir_rc6_encode, 396 .carrier = 36000, 397 }; 398 399 static int __init ir_rc6_decode_init(void) 400 { 401 ir_raw_handler_register(&rc6_handler); 402 403 printk(KERN_INFO "IR RC6 protocol handler initialized\n"); 404 return 0; 405 } 406 407 static void __exit ir_rc6_decode_exit(void) 408 { 409 ir_raw_handler_unregister(&rc6_handler); 410 } 411 412 module_init(ir_rc6_decode_init); 413 module_exit(ir_rc6_decode_exit); 414 415 MODULE_LICENSE("GPL"); 416 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>"); 417 MODULE_DESCRIPTION("RC6 IR protocol decoder"); 418