1 // SPDX-License-Identifier: GPL-2.0-only 2 /* ir-rc6-decoder.c - A decoder for the RC6 IR protocol 3 * 4 * Copyright (C) 2010 by David Härdeman <david@hardeman.nu> 5 */ 6 7 #include "rc-core-priv.h" 8 #include <linux/module.h> 9 10 /* 11 * This decoder currently supports: 12 * RC6-0-16 (standard toggle bit in header) 13 * RC6-6A-20 (no toggle bit) 14 * RC6-6A-24 (no toggle bit) 15 * RC6-6A-32 (MCE version with toggle bit in body) 16 */ 17 18 #define RC6_UNIT 444444 /* nanosecs */ 19 #define RC6_HEADER_NBITS 4 /* not including toggle bit */ 20 #define RC6_0_NBITS 16 21 #define RC6_6A_32_NBITS 32 22 #define RC6_6A_NBITS 128 /* Variable 8..128 */ 23 #define RC6_PREFIX_PULSE (6 * RC6_UNIT) 24 #define RC6_PREFIX_SPACE (2 * RC6_UNIT) 25 #define RC6_BIT_START (1 * RC6_UNIT) 26 #define RC6_BIT_END (1 * RC6_UNIT) 27 #define RC6_TOGGLE_START (2 * RC6_UNIT) 28 #define RC6_TOGGLE_END (2 * RC6_UNIT) 29 #define RC6_SUFFIX_SPACE (6 * RC6_UNIT) 30 #define RC6_MODE_MASK 0x07 /* for the header bits */ 31 #define RC6_STARTBIT_MASK 0x08 /* for the header bits */ 32 #define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */ 33 #define RC6_6A_LCC_MASK 0xffff0000 /* RC6-6A-32 long customer code mask */ 34 #define RC6_6A_MCE_CC 0x800f0000 /* MCE customer code */ 35 #define RC6_6A_ZOTAC_CC 0x80340000 /* Zotac customer code */ 36 #define RC6_6A_KATHREIN_CC 0x80460000 /* Kathrein RCU-676 customer code */ 37 #ifndef CHAR_BIT 38 #define CHAR_BIT 8 /* Normally in <limits.h> */ 39 #endif 40 41 enum rc6_mode { 42 RC6_MODE_0, 43 RC6_MODE_6A, 44 RC6_MODE_UNKNOWN, 45 }; 46 47 enum rc6_state { 48 STATE_INACTIVE, 49 STATE_PREFIX_SPACE, 50 STATE_HEADER_BIT_START, 51 STATE_HEADER_BIT_END, 52 STATE_TOGGLE_START, 53 STATE_TOGGLE_END, 54 STATE_BODY_BIT_START, 55 STATE_BODY_BIT_END, 56 STATE_FINISHED, 57 }; 58 59 static enum rc6_mode rc6_mode(struct rc6_dec *data) 60 { 61 switch (data->header & RC6_MODE_MASK) { 62 case 0: 63 return RC6_MODE_0; 64 case 6: 65 if (!data->toggle) 66 return RC6_MODE_6A; 67 /* fall through */ 68 default: 69 return RC6_MODE_UNKNOWN; 70 } 71 } 72 73 /** 74 * ir_rc6_decode() - Decode one RC6 pulse or space 75 * @dev: the struct rc_dev descriptor of the device 76 * @ev: the struct ir_raw_event descriptor of the pulse/space 77 * 78 * This function returns -EINVAL if the pulse violates the state machine 79 */ 80 static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev) 81 { 82 struct rc6_dec *data = &dev->raw->rc6; 83 u32 scancode; 84 u8 toggle; 85 enum rc_proto protocol; 86 87 if (!is_timing_event(ev)) { 88 if (ev.reset) 89 data->state = STATE_INACTIVE; 90 return 0; 91 } 92 93 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) 94 goto out; 95 96 again: 97 dev_dbg(&dev->dev, "RC6 decode started at state %i (%uus %s)\n", 98 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 99 100 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) 101 return 0; 102 103 switch (data->state) { 104 105 case STATE_INACTIVE: 106 if (!ev.pulse) 107 break; 108 109 /* Note: larger margin on first pulse since each RC6_UNIT 110 is quite short and some hardware takes some time to 111 adjust to the signal */ 112 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT)) 113 break; 114 115 data->state = STATE_PREFIX_SPACE; 116 data->count = 0; 117 return 0; 118 119 case STATE_PREFIX_SPACE: 120 if (ev.pulse) 121 break; 122 123 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2)) 124 break; 125 126 data->state = STATE_HEADER_BIT_START; 127 data->header = 0; 128 return 0; 129 130 case STATE_HEADER_BIT_START: 131 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) 132 break; 133 134 data->header <<= 1; 135 if (ev.pulse) 136 data->header |= 1; 137 data->count++; 138 data->state = STATE_HEADER_BIT_END; 139 return 0; 140 141 case STATE_HEADER_BIT_END: 142 if (data->count == RC6_HEADER_NBITS) 143 data->state = STATE_TOGGLE_START; 144 else 145 data->state = STATE_HEADER_BIT_START; 146 147 decrease_duration(&ev, RC6_BIT_END); 148 goto again; 149 150 case STATE_TOGGLE_START: 151 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2)) 152 break; 153 154 data->toggle = ev.pulse; 155 data->state = STATE_TOGGLE_END; 156 return 0; 157 158 case STATE_TOGGLE_END: 159 if (!(data->header & RC6_STARTBIT_MASK)) { 160 dev_dbg(&dev->dev, "RC6 invalid start bit\n"); 161 break; 162 } 163 164 data->state = STATE_BODY_BIT_START; 165 decrease_duration(&ev, RC6_TOGGLE_END); 166 data->count = 0; 167 data->body = 0; 168 169 switch (rc6_mode(data)) { 170 case RC6_MODE_0: 171 data->wanted_bits = RC6_0_NBITS; 172 break; 173 case RC6_MODE_6A: 174 data->wanted_bits = RC6_6A_NBITS; 175 break; 176 default: 177 dev_dbg(&dev->dev, "RC6 unknown mode\n"); 178 goto out; 179 } 180 goto again; 181 182 case STATE_BODY_BIT_START: 183 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) { 184 /* Discard LSB's that won't fit in data->body */ 185 if (data->count++ < CHAR_BIT * sizeof data->body) { 186 data->body <<= 1; 187 if (ev.pulse) 188 data->body |= 1; 189 } 190 data->state = STATE_BODY_BIT_END; 191 return 0; 192 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse && 193 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) { 194 data->state = STATE_FINISHED; 195 goto again; 196 } 197 break; 198 199 case STATE_BODY_BIT_END: 200 if (data->count == data->wanted_bits) 201 data->state = STATE_FINISHED; 202 else 203 data->state = STATE_BODY_BIT_START; 204 205 decrease_duration(&ev, RC6_BIT_END); 206 goto again; 207 208 case STATE_FINISHED: 209 if (ev.pulse) 210 break; 211 212 switch (rc6_mode(data)) { 213 case RC6_MODE_0: 214 scancode = data->body; 215 toggle = data->toggle; 216 protocol = RC_PROTO_RC6_0; 217 dev_dbg(&dev->dev, "RC6(0) scancode 0x%04x (toggle: %u)\n", 218 scancode, toggle); 219 break; 220 221 case RC6_MODE_6A: 222 if (data->count > CHAR_BIT * sizeof data->body) { 223 dev_dbg(&dev->dev, "RC6 too many (%u) data bits\n", 224 data->count); 225 goto out; 226 } 227 228 scancode = data->body; 229 switch (data->count) { 230 case 20: 231 protocol = RC_PROTO_RC6_6A_20; 232 toggle = 0; 233 break; 234 case 24: 235 protocol = RC_PROTO_RC6_6A_24; 236 toggle = 0; 237 break; 238 case 32: 239 switch (scancode & RC6_6A_LCC_MASK) { 240 case RC6_6A_MCE_CC: 241 case RC6_6A_KATHREIN_CC: 242 case RC6_6A_ZOTAC_CC: 243 protocol = RC_PROTO_RC6_MCE; 244 toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK); 245 scancode &= ~RC6_6A_MCE_TOGGLE_MASK; 246 break; 247 default: 248 protocol = RC_PROTO_RC6_6A_32; 249 toggle = 0; 250 break; 251 } 252 break; 253 default: 254 dev_dbg(&dev->dev, "RC6(6A) unsupported length\n"); 255 goto out; 256 } 257 258 dev_dbg(&dev->dev, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n", 259 protocol, scancode, toggle); 260 break; 261 default: 262 dev_dbg(&dev->dev, "RC6 unknown mode\n"); 263 goto out; 264 } 265 266 rc_keydown(dev, protocol, scancode, toggle); 267 data->state = STATE_INACTIVE; 268 return 0; 269 } 270 271 out: 272 dev_dbg(&dev->dev, "RC6 decode failed at state %i (%uus %s)\n", 273 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 274 data->state = STATE_INACTIVE; 275 return -EINVAL; 276 } 277 278 static const struct ir_raw_timings_manchester ir_rc6_timings[4] = { 279 { 280 .leader_pulse = RC6_PREFIX_PULSE, 281 .leader_space = RC6_PREFIX_SPACE, 282 .clock = RC6_UNIT, 283 .invert = 1, 284 }, 285 { 286 .clock = RC6_UNIT * 2, 287 .invert = 1, 288 }, 289 { 290 .clock = RC6_UNIT, 291 .invert = 1, 292 .trailer_space = RC6_SUFFIX_SPACE, 293 }, 294 }; 295 296 /** 297 * ir_rc6_encode() - Encode a scancode as a stream of raw events 298 * 299 * @protocol: protocol to encode 300 * @scancode: scancode to encode 301 * @events: array of raw ir events to write into 302 * @max: maximum size of @events 303 * 304 * Returns: The number of events written. 305 * -ENOBUFS if there isn't enough space in the array to fit the 306 * encoding. In this case all @max events will have been written. 307 * -EINVAL if the scancode is ambiguous or invalid. 308 */ 309 static int ir_rc6_encode(enum rc_proto protocol, u32 scancode, 310 struct ir_raw_event *events, unsigned int max) 311 { 312 int ret; 313 struct ir_raw_event *e = events; 314 315 if (protocol == RC_PROTO_RC6_0) { 316 /* Modulate the header (Start Bit & Mode-0) */ 317 ret = ir_raw_gen_manchester(&e, max - (e - events), 318 &ir_rc6_timings[0], 319 RC6_HEADER_NBITS, (1 << 3)); 320 if (ret < 0) 321 return ret; 322 323 /* Modulate Trailer Bit */ 324 ret = ir_raw_gen_manchester(&e, max - (e - events), 325 &ir_rc6_timings[1], 1, 0); 326 if (ret < 0) 327 return ret; 328 329 /* Modulate rest of the data */ 330 ret = ir_raw_gen_manchester(&e, max - (e - events), 331 &ir_rc6_timings[2], RC6_0_NBITS, 332 scancode); 333 if (ret < 0) 334 return ret; 335 336 } else { 337 int bits; 338 339 switch (protocol) { 340 case RC_PROTO_RC6_MCE: 341 case RC_PROTO_RC6_6A_32: 342 bits = 32; 343 break; 344 case RC_PROTO_RC6_6A_24: 345 bits = 24; 346 break; 347 case RC_PROTO_RC6_6A_20: 348 bits = 20; 349 break; 350 default: 351 return -EINVAL; 352 } 353 354 /* Modulate the header (Start Bit & Header-version 6 */ 355 ret = ir_raw_gen_manchester(&e, max - (e - events), 356 &ir_rc6_timings[0], 357 RC6_HEADER_NBITS, (1 << 3 | 6)); 358 if (ret < 0) 359 return ret; 360 361 /* Modulate Trailer Bit */ 362 ret = ir_raw_gen_manchester(&e, max - (e - events), 363 &ir_rc6_timings[1], 1, 0); 364 if (ret < 0) 365 return ret; 366 367 /* Modulate rest of the data */ 368 ret = ir_raw_gen_manchester(&e, max - (e - events), 369 &ir_rc6_timings[2], 370 bits, 371 scancode); 372 if (ret < 0) 373 return ret; 374 } 375 376 return e - events; 377 } 378 379 static struct ir_raw_handler rc6_handler = { 380 .protocols = RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 | 381 RC_PROTO_BIT_RC6_6A_24 | RC_PROTO_BIT_RC6_6A_32 | 382 RC_PROTO_BIT_RC6_MCE, 383 .decode = ir_rc6_decode, 384 .encode = ir_rc6_encode, 385 .carrier = 36000, 386 .min_timeout = RC6_SUFFIX_SPACE, 387 }; 388 389 static int __init ir_rc6_decode_init(void) 390 { 391 ir_raw_handler_register(&rc6_handler); 392 393 printk(KERN_INFO "IR RC6 protocol handler initialized\n"); 394 return 0; 395 } 396 397 static void __exit ir_rc6_decode_exit(void) 398 { 399 ir_raw_handler_unregister(&rc6_handler); 400 } 401 402 module_init(ir_rc6_decode_init); 403 module_exit(ir_rc6_decode_exit); 404 405 MODULE_LICENSE("GPL"); 406 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>"); 407 MODULE_DESCRIPTION("RC6 IR protocol decoder"); 408