drivers/media/rc/ir-rc6-decoder.c

   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 #define RC6_6A_KATHREIN_CC      0x80460000 /* Kathrein RCU-676 customer code */
  44 #ifndef CHAR_BIT
  45 #define CHAR_BIT 8      /* Normally in <limits.h> */
  46 #endif
  47
  48 enum rc6_mode {
  49         RC6_MODE_0,
  50         RC6_MODE_6A,
  51         RC6_MODE_UNKNOWN,
  52 };
  53
  54 enum rc6_state {
  55         STATE_INACTIVE,
  56         STATE_PREFIX_SPACE,
  57         STATE_HEADER_BIT_START,
  58         STATE_HEADER_BIT_END,
  59         STATE_TOGGLE_START,
  60         STATE_TOGGLE_END,
  61         STATE_BODY_BIT_START,
  62         STATE_BODY_BIT_END,
  63         STATE_FINISHED,
  64 };
  65
  66 static enum rc6_mode rc6_mode(struct rc6_dec *data)
  67 {
  68         switch (data->header & RC6_MODE_MASK) {
  69         case 0:
  70                 return RC6_MODE_0;
  71         case 6:
  72                 if (!data->toggle)
  73                         return RC6_MODE_6A;
  74                 /* fall through */
  75         default:
  76                 return RC6_MODE_UNKNOWN;
  77         }
  78 }
  79
  80 /**
  81  * ir_rc6_decode() - Decode one RC6 pulse or space
  82  * @dev:        the struct rc_dev descriptor of the device
  83  * @ev:         the struct ir_raw_event descriptor of the pulse/space
  84  *
  85  * This function returns -EINVAL if the pulse violates the state machine
  86  */
  87 static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
  88 {
  89         struct rc6_dec *data = &dev->raw->rc6;
  90         u32 scancode;
  91         u8 toggle;
  92         enum rc_proto protocol;
  93
  94         if (!is_timing_event(ev)) {
  95                 if (ev.reset)
  96                         data->state = STATE_INACTIVE;
  97                 return 0;
  98         }
  99
 100         if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
 101                 goto out;
 102
 103 again:
 104         dev_dbg(&dev->dev, "RC6 decode started at state %i (%uus %s)\n",
 105                 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 106
 107         if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
 108                 return 0;
 109
 110         switch (data->state) {
 111
 112         case STATE_INACTIVE:
 113                 if (!ev.pulse)
 114                         break;
 115
 116                 /* Note: larger margin on first pulse since each RC6_UNIT
 117                    is quite short and some hardware takes some time to
 118                    adjust to the signal */
 119                 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
 120                         break;
 121
 122                 data->state = STATE_PREFIX_SPACE;
 123                 data->count = 0;
 124                 return 0;
 125
 126         case STATE_PREFIX_SPACE:
 127                 if (ev.pulse)
 128                         break;
 129
 130                 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
 131                         break;
 132
 133                 data->state = STATE_HEADER_BIT_START;
 134                 data->header = 0;
 135                 return 0;
 136
 137         case STATE_HEADER_BIT_START:
 138                 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
 139                         break;
 140
 141                 data->header <<= 1;
 142                 if (ev.pulse)
 143                         data->header |= 1;
 144                 data->count++;
 145                 data->state = STATE_HEADER_BIT_END;
 146                 return 0;
 147
 148         case STATE_HEADER_BIT_END:
 149                 if (data->count == RC6_HEADER_NBITS)
 150                         data->state = STATE_TOGGLE_START;
 151                 else
 152                         data->state = STATE_HEADER_BIT_START;
 153
 154                 decrease_duration(&ev, RC6_BIT_END);
 155                 goto again;
 156
 157         case STATE_TOGGLE_START:
 158                 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
 159                         break;
 160
 161                 data->toggle = ev.pulse;
 162                 data->state = STATE_TOGGLE_END;
 163                 return 0;
 164
 165         case STATE_TOGGLE_END:
 166                 if (!(data->header & RC6_STARTBIT_MASK)) {
 167                         dev_dbg(&dev->dev, "RC6 invalid start bit\n");
 168                         break;
 169                 }
 170
 171                 data->state = STATE_BODY_BIT_START;
 172                 decrease_duration(&ev, RC6_TOGGLE_END);
 173                 data->count = 0;
 174                 data->body = 0;
 175
 176                 switch (rc6_mode(data)) {
 177                 case RC6_MODE_0:
 178                         data->wanted_bits = RC6_0_NBITS;
 179                         break;
 180                 case RC6_MODE_6A:
 181                         data->wanted_bits = RC6_6A_NBITS;
 182                         break;
 183                 default:
 184                         dev_dbg(&dev->dev, "RC6 unknown mode\n");
 185                         goto out;
 186                 }
 187                 goto again;
 188
 189         case STATE_BODY_BIT_START:
 190                 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {
 191                         /* Discard LSB's that won't fit in data->body */
 192                         if (data->count++ < CHAR_BIT * sizeof data->body) {
 193                                 data->body <<= 1;
 194                                 if (ev.pulse)
 195                                         data->body |= 1;
 196                         }
 197                         data->state = STATE_BODY_BIT_END;
 198                         return 0;
 199                 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&
 200                                 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {
 201                         data->state = STATE_FINISHED;
 202                         goto again;
 203                 }
 204                 break;
 205
 206         case STATE_BODY_BIT_END:
 207                 if (data->count == data->wanted_bits)
 208                         data->state = STATE_FINISHED;
 209                 else
 210                         data->state = STATE_BODY_BIT_START;
 211
 212                 decrease_duration(&ev, RC6_BIT_END);
 213                 goto again;
 214
 215         case STATE_FINISHED:
 216                 if (ev.pulse)
 217                         break;
 218
 219                 switch (rc6_mode(data)) {
 220                 case RC6_MODE_0:
 221                         scancode = data->body;
 222                         toggle = data->toggle;
 223                         protocol = RC_PROTO_RC6_0;
 224                         dev_dbg(&dev->dev, "RC6(0) scancode 0x%04x (toggle: %u)\n",
 225                                 scancode, toggle);
 226                         break;
 227
 228                 case RC6_MODE_6A:
 229                         if (data->count > CHAR_BIT * sizeof data->body) {
 230                                 dev_dbg(&dev->dev, "RC6 too many (%u) data bits\n",
 231                                         data->count);
 232                                 goto out;
 233                         }
 234
 235                         scancode = data->body;
 236                         switch (data->count) {
 237                         case 20:
 238                                 protocol = RC_PROTO_RC6_6A_20;
 239                                 toggle = 0;
 240                                 break;
 241                         case 24:
 242                                 protocol = RC_PROTO_RC6_6A_24;
 243                                 toggle = 0;
 244                                 break;
 245                         case 32:
 246                                 switch (scancode & RC6_6A_LCC_MASK) {
 247                                 case RC6_6A_MCE_CC:
 248                                 case RC6_6A_KATHREIN_CC:
 249                                         protocol = RC_PROTO_RC6_MCE;
 250                                         toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK);
 251                                         scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
 252                                         break;
 253                                 default:
 254                                         protocol = RC_PROTO_RC6_6A_32;
 255                                         toggle = 0;
 256                                         break;
 257                                 }
 258                                 break;
 259                         default:
 260                                 dev_dbg(&dev->dev, "RC6(6A) unsupported length\n");
 261                                 goto out;
 262                         }
 263
 264                         dev_dbg(&dev->dev, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n",
 265                                 protocol, scancode, toggle);
 266                         break;
 267                 default:
 268                         dev_dbg(&dev->dev, "RC6 unknown mode\n");
 269                         goto out;
 270                 }
 271
 272                 rc_keydown(dev, protocol, scancode, toggle);
 273                 data->state = STATE_INACTIVE;
 274                 return 0;
 275         }
 276
 277 out:
 278         dev_dbg(&dev->dev, "RC6 decode failed at state %i (%uus %s)\n",
 279                 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 280         data->state = STATE_INACTIVE;
 281         return -EINVAL;
 282 }
 283
 284 static const struct ir_raw_timings_manchester ir_rc6_timings[4] = {
 285         {
 286                 .leader_pulse           = RC6_PREFIX_PULSE,
 287                 .leader_space           = RC6_PREFIX_SPACE,
 288                 .clock                  = RC6_UNIT,
 289                 .invert                 = 1,
 290         },
 291         {
 292                 .clock                  = RC6_UNIT * 2,
 293                 .invert                 = 1,
 294         },
 295         {
 296                 .clock                  = RC6_UNIT,
 297                 .invert                 = 1,
 298                 .trailer_space          = RC6_SUFFIX_SPACE,
 299         },
 300 };
 301
 302 /**
 303  * ir_rc6_encode() - Encode a scancode as a stream of raw events
 304  *
 305  * @protocol:   protocol to encode
 306  * @scancode:   scancode to encode
 307  * @events:     array of raw ir events to write into
 308  * @max:        maximum size of @events
 309  *
 310  * Returns:     The number of events written.
 311  *              -ENOBUFS if there isn't enough space in the array to fit the
 312  *              encoding. In this case all @max events will have been written.
 313  *              -EINVAL if the scancode is ambiguous or invalid.
 314  */
 315 static int ir_rc6_encode(enum rc_proto protocol, u32 scancode,
 316                          struct ir_raw_event *events, unsigned int max)
 317 {
 318         int ret;
 319         struct ir_raw_event *e = events;
 320
 321         if (protocol == RC_PROTO_RC6_0) {
 322                 /* Modulate the header (Start Bit & Mode-0) */
 323                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 324                                             &ir_rc6_timings[0],
 325                                             RC6_HEADER_NBITS, (1 << 3));
 326                 if (ret < 0)
 327                         return ret;
 328
 329                 /* Modulate Trailer Bit */
 330                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 331                                             &ir_rc6_timings[1], 1, 0);
 332                 if (ret < 0)
 333                         return ret;
 334
 335                 /* Modulate rest of the data */
 336                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 337                                             &ir_rc6_timings[2], RC6_0_NBITS,
 338                                             scancode);
 339                 if (ret < 0)
 340                         return ret;
 341
 342         } else {
 343                 int bits;
 344
 345                 switch (protocol) {
 346                 case RC_PROTO_RC6_MCE:
 347                 case RC_PROTO_RC6_6A_32:
 348                         bits = 32;
 349                         break;
 350                 case RC_PROTO_RC6_6A_24:
 351                         bits = 24;
 352                         break;
 353                 case RC_PROTO_RC6_6A_20:
 354                         bits = 20;
 355                         break;
 356                 default:
 357                         return -EINVAL;
 358                 }
 359
 360                 /* Modulate the header (Start Bit & Header-version 6 */
 361                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 362                                             &ir_rc6_timings[0],
 363                                             RC6_HEADER_NBITS, (1 << 3 | 6));
 364                 if (ret < 0)
 365                         return ret;
 366
 367                 /* Modulate Trailer Bit */
 368                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 369                                             &ir_rc6_timings[1], 1, 0);
 370                 if (ret < 0)
 371                         return ret;
 372
 373                 /* Modulate rest of the data */
 374                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 375                                             &ir_rc6_timings[2],
 376                                             bits,
 377                                             scancode);
 378                 if (ret < 0)
 379                         return ret;
 380         }
 381
 382         return e - events;
 383 }
 384
 385 static struct ir_raw_handler rc6_handler = {
 386         .protocols      = RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 |
 387                           RC_PROTO_BIT_RC6_6A_24 | RC_PROTO_BIT_RC6_6A_32 |
 388                           RC_PROTO_BIT_RC6_MCE,
 389         .decode         = ir_rc6_decode,
 390         .encode         = ir_rc6_encode,
 391         .carrier        = 36000,
 392         .min_timeout    = RC6_SUFFIX_SPACE,
 393 };
 394
 395 static int __init ir_rc6_decode_init(void)
 396 {
 397         ir_raw_handler_register(&rc6_handler);
 398
 399         printk(KERN_INFO "IR RC6 protocol handler initialized\n");
 400         return 0;
 401 }
 402
 403 static void __exit ir_rc6_decode_exit(void)
 404 {
 405         ir_raw_handler_unregister(&rc6_handler);
 406 }
 407
 408 module_init(ir_rc6_decode_init);
 409 module_exit(ir_rc6_decode_exit);
 410
 411 MODULE_LICENSE("GPL");
 412 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
 413 MODULE_DESCRIPTION("RC6 IR protocol decoder");