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_ZOTAC_CC         0x80340000 /* Zotac customer code */
  44 #define RC6_6A_KATHREIN_CC      0x80460000 /* Kathrein RCU-676 customer code */
  45 #ifndef CHAR_BIT
  46 #define CHAR_BIT 8      /* Normally in <limits.h> */
  47 #endif
  48
  49 enum rc6_mode {
  50         RC6_MODE_0,
  51         RC6_MODE_6A,
  52         RC6_MODE_UNKNOWN,
  53 };
  54
  55 enum rc6_state {
  56         STATE_INACTIVE,
  57         STATE_PREFIX_SPACE,
  58         STATE_HEADER_BIT_START,
  59         STATE_HEADER_BIT_END,
  60         STATE_TOGGLE_START,
  61         STATE_TOGGLE_END,
  62         STATE_BODY_BIT_START,
  63         STATE_BODY_BIT_END,
  64         STATE_FINISHED,
  65 };
  66
  67 static enum rc6_mode rc6_mode(struct rc6_dec *data)
  68 {
  69         switch (data->header & RC6_MODE_MASK) {
  70         case 0:
  71                 return RC6_MODE_0;
  72         case 6:
  73                 if (!data->toggle)
  74                         return RC6_MODE_6A;
  75                 /* fall through */
  76         default:
  77                 return RC6_MODE_UNKNOWN;
  78         }
  79 }
  80
  81 /**
  82  * ir_rc6_decode() - Decode one RC6 pulse or space
  83  * @dev:        the struct rc_dev descriptor of the device
  84  * @ev:         the struct ir_raw_event descriptor of the pulse/space
  85  *
  86  * This function returns -EINVAL if the pulse violates the state machine
  87  */
  88 static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
  89 {
  90         struct rc6_dec *data = &dev->raw->rc6;
  91         u32 scancode;
  92         u8 toggle;
  93         enum rc_proto protocol;
  94
  95         if (!is_timing_event(ev)) {
  96                 if (ev.reset)
  97                         data->state = STATE_INACTIVE;
  98                 return 0;
  99         }
 100
 101         if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
 102                 goto out;
 103
 104 again:
 105         dev_dbg(&dev->dev, "RC6 decode started at state %i (%uus %s)\n",
 106                 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 107
 108         if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
 109                 return 0;
 110
 111         switch (data->state) {
 112
 113         case STATE_INACTIVE:
 114                 if (!ev.pulse)
 115                         break;
 116
 117                 /* Note: larger margin on first pulse since each RC6_UNIT
 118                    is quite short and some hardware takes some time to
 119                    adjust to the signal */
 120                 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
 121                         break;
 122
 123                 data->state = STATE_PREFIX_SPACE;
 124                 data->count = 0;
 125                 return 0;
 126
 127         case STATE_PREFIX_SPACE:
 128                 if (ev.pulse)
 129                         break;
 130
 131                 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
 132                         break;
 133
 134                 data->state = STATE_HEADER_BIT_START;
 135                 data->header = 0;
 136                 return 0;
 137
 138         case STATE_HEADER_BIT_START:
 139                 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
 140                         break;
 141
 142                 data->header <<= 1;
 143                 if (ev.pulse)
 144                         data->header |= 1;
 145                 data->count++;
 146                 data->state = STATE_HEADER_BIT_END;
 147                 return 0;
 148
 149         case STATE_HEADER_BIT_END:
 150                 if (data->count == RC6_HEADER_NBITS)
 151                         data->state = STATE_TOGGLE_START;
 152                 else
 153                         data->state = STATE_HEADER_BIT_START;
 154
 155                 decrease_duration(&ev, RC6_BIT_END);
 156                 goto again;
 157
 158         case STATE_TOGGLE_START:
 159                 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
 160                         break;
 161
 162                 data->toggle = ev.pulse;
 163                 data->state = STATE_TOGGLE_END;
 164                 return 0;
 165
 166         case STATE_TOGGLE_END:
 167                 if (!(data->header & RC6_STARTBIT_MASK)) {
 168                         dev_dbg(&dev->dev, "RC6 invalid start bit\n");
 169                         break;
 170                 }
 171
 172                 data->state = STATE_BODY_BIT_START;
 173                 decrease_duration(&ev, RC6_TOGGLE_END);
 174                 data->count = 0;
 175                 data->body = 0;
 176
 177                 switch (rc6_mode(data)) {
 178                 case RC6_MODE_0:
 179                         data->wanted_bits = RC6_0_NBITS;
 180                         break;
 181                 case RC6_MODE_6A:
 182                         data->wanted_bits = RC6_6A_NBITS;
 183                         break;
 184                 default:
 185                         dev_dbg(&dev->dev, "RC6 unknown mode\n");
 186                         goto out;
 187                 }
 188                 goto again;
 189
 190         case STATE_BODY_BIT_START:
 191                 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {
 192                         /* Discard LSB's that won't fit in data->body */
 193                         if (data->count++ < CHAR_BIT * sizeof data->body) {
 194                                 data->body <<= 1;
 195                                 if (ev.pulse)
 196                                         data->body |= 1;
 197                         }
 198                         data->state = STATE_BODY_BIT_END;
 199                         return 0;
 200                 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&
 201                                 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {
 202                         data->state = STATE_FINISHED;
 203                         goto again;
 204                 }
 205                 break;
 206
 207         case STATE_BODY_BIT_END:
 208                 if (data->count == data->wanted_bits)
 209                         data->state = STATE_FINISHED;
 210                 else
 211                         data->state = STATE_BODY_BIT_START;
 212
 213                 decrease_duration(&ev, RC6_BIT_END);
 214                 goto again;
 215
 216         case STATE_FINISHED:
 217                 if (ev.pulse)
 218                         break;
 219
 220                 switch (rc6_mode(data)) {
 221                 case RC6_MODE_0:
 222                         scancode = data->body;
 223                         toggle = data->toggle;
 224                         protocol = RC_PROTO_RC6_0;
 225                         dev_dbg(&dev->dev, "RC6(0) scancode 0x%04x (toggle: %u)\n",
 226                                 scancode, toggle);
 227                         break;
 228
 229                 case RC6_MODE_6A:
 230                         if (data->count > CHAR_BIT * sizeof data->body) {
 231                                 dev_dbg(&dev->dev, "RC6 too many (%u) data bits\n",
 232                                         data->count);
 233                                 goto out;
 234                         }
 235
 236                         scancode = data->body;
 237                         switch (data->count) {
 238                         case 20:
 239                                 protocol = RC_PROTO_RC6_6A_20;
 240                                 toggle = 0;
 241                                 break;
 242                         case 24:
 243                                 protocol = RC_PROTO_RC6_6A_24;
 244                                 toggle = 0;
 245                                 break;
 246                         case 32:
 247                                 switch (scancode & RC6_6A_LCC_MASK) {
 248                                 case RC6_6A_MCE_CC:
 249                                 case RC6_6A_KATHREIN_CC:
 250                                 case RC6_6A_ZOTAC_CC:
 251                                         protocol = RC_PROTO_RC6_MCE;
 252                                         toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK);
 253                                         scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
 254                                         break;
 255                                 default:
 256                                         protocol = RC_PROTO_RC6_6A_32;
 257                                         toggle = 0;
 258                                         break;
 259                                 }
 260                                 break;
 261                         default:
 262                                 dev_dbg(&dev->dev, "RC6(6A) unsupported length\n");
 263                                 goto out;
 264                         }
 265
 266                         dev_dbg(&dev->dev, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n",
 267                                 protocol, scancode, toggle);
 268                         break;
 269                 default:
 270                         dev_dbg(&dev->dev, "RC6 unknown mode\n");
 271                         goto out;
 272                 }
 273
 274                 rc_keydown(dev, protocol, scancode, toggle);
 275                 data->state = STATE_INACTIVE;
 276                 return 0;
 277         }
 278
 279 out:
 280         dev_dbg(&dev->dev, "RC6 decode failed at state %i (%uus %s)\n",
 281                 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 282         data->state = STATE_INACTIVE;
 283         return -EINVAL;
 284 }
 285
 286 static const struct ir_raw_timings_manchester ir_rc6_timings[4] = {
 287         {
 288                 .leader_pulse           = RC6_PREFIX_PULSE,
 289                 .leader_space           = RC6_PREFIX_SPACE,
 290                 .clock                  = RC6_UNIT,
 291                 .invert                 = 1,
 292         },
 293         {
 294                 .clock                  = RC6_UNIT * 2,
 295                 .invert                 = 1,
 296         },
 297         {
 298                 .clock                  = RC6_UNIT,
 299                 .invert                 = 1,
 300                 .trailer_space          = RC6_SUFFIX_SPACE,
 301         },
 302 };
 303
 304 /**
 305  * ir_rc6_encode() - Encode a scancode as a stream of raw events
 306  *
 307  * @protocol:   protocol to encode
 308  * @scancode:   scancode to encode
 309  * @events:     array of raw ir events to write into
 310  * @max:        maximum size of @events
 311  *
 312  * Returns:     The number of events written.
 313  *              -ENOBUFS if there isn't enough space in the array to fit the
 314  *              encoding. In this case all @max events will have been written.
 315  *              -EINVAL if the scancode is ambiguous or invalid.
 316  */
 317 static int ir_rc6_encode(enum rc_proto protocol, u32 scancode,
 318                          struct ir_raw_event *events, unsigned int max)
 319 {
 320         int ret;
 321         struct ir_raw_event *e = events;
 322
 323         if (protocol == RC_PROTO_RC6_0) {
 324                 /* Modulate the header (Start Bit & Mode-0) */
 325                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 326                                             &ir_rc6_timings[0],
 327                                             RC6_HEADER_NBITS, (1 << 3));
 328                 if (ret < 0)
 329                         return ret;
 330
 331                 /* Modulate Trailer Bit */
 332                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 333                                             &ir_rc6_timings[1], 1, 0);
 334                 if (ret < 0)
 335                         return ret;
 336
 337                 /* Modulate rest of the data */
 338                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 339                                             &ir_rc6_timings[2], RC6_0_NBITS,
 340                                             scancode);
 341                 if (ret < 0)
 342                         return ret;
 343
 344         } else {
 345                 int bits;
 346
 347                 switch (protocol) {
 348                 case RC_PROTO_RC6_MCE:
 349                 case RC_PROTO_RC6_6A_32:
 350                         bits = 32;
 351                         break;
 352                 case RC_PROTO_RC6_6A_24:
 353                         bits = 24;
 354                         break;
 355                 case RC_PROTO_RC6_6A_20:
 356                         bits = 20;
 357                         break;
 358                 default:
 359                         return -EINVAL;
 360                 }
 361
 362                 /* Modulate the header (Start Bit & Header-version 6 */
 363                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 364                                             &ir_rc6_timings[0],
 365                                             RC6_HEADER_NBITS, (1 << 3 | 6));
 366                 if (ret < 0)
 367                         return ret;
 368
 369                 /* Modulate Trailer Bit */
 370                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 371                                             &ir_rc6_timings[1], 1, 0);
 372                 if (ret < 0)
 373                         return ret;
 374
 375                 /* Modulate rest of the data */
 376                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 377                                             &ir_rc6_timings[2],
 378                                             bits,
 379                                             scancode);
 380                 if (ret < 0)
 381                         return ret;
 382         }
 383
 384         return e - events;
 385 }
 386
 387 static struct ir_raw_handler rc6_handler = {
 388         .protocols      = RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 |
 389                           RC_PROTO_BIT_RC6_6A_24 | RC_PROTO_BIT_RC6_6A_32 |
 390                           RC_PROTO_BIT_RC6_MCE,
 391         .decode         = ir_rc6_decode,
 392         .encode         = ir_rc6_encode,
 393         .carrier        = 36000,
 394         .min_timeout    = RC6_SUFFIX_SPACE,
 395 };
 396
 397 static int __init ir_rc6_decode_init(void)
 398 {
 399         ir_raw_handler_register(&rc6_handler);
 400
 401         printk(KERN_INFO "IR RC6 protocol handler initialized\n");
 402         return 0;
 403 }
 404
 405 static void __exit ir_rc6_decode_exit(void)
 406 {
 407         ir_raw_handler_unregister(&rc6_handler);
 408 }
 409
 410 module_init(ir_rc6_decode_init);
 411 module_exit(ir_rc6_decode_exit);
 412
 413 MODULE_LICENSE("GPL");
 414 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
 415 MODULE_DESCRIPTION("RC6 IR protocol decoder");