drivers/media/rc/ir-rc5-decoder.c

   1 /* ir-rc5-decoder.c - decoder for RC5(x) and StreamZap protocols
   2  *
   3  * Copyright (C) 2010 by Mauro Carvalho Chehab
   4  * Copyright (C) 2010 by Jarod Wilson <jarod@redhat.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation version 2 of the License.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  */
  15
  16 /*
  17  * This decoder handles the 14 bit RC5 protocol, 15 bit "StreamZap" protocol
  18  * and 20 bit RC5x protocol.
  19  */
  20
  21 #include "rc-core-priv.h"
  22 #include <linux/module.h>
  23
  24 #define RC5_NBITS               14
  25 #define RC5_SZ_NBITS            15
  26 #define RC5X_NBITS              20
  27 #define CHECK_RC5X_NBITS        8
  28 #define RC5_UNIT                888888 /* ns */
  29 #define RC5_BIT_START           (1 * RC5_UNIT)
  30 #define RC5_BIT_END             (1 * RC5_UNIT)
  31 #define RC5X_SPACE              (4 * RC5_UNIT)
  32 #define RC5_TRAILER             (6 * RC5_UNIT) /* In reality, approx 100 */
  33
  34 enum rc5_state {
  35         STATE_INACTIVE,
  36         STATE_BIT_START,
  37         STATE_BIT_END,
  38         STATE_CHECK_RC5X,
  39         STATE_FINISHED,
  40 };
  41
  42 /**
  43  * ir_rc5_decode() - Decode one RC-5 pulse or space
  44  * @dev:        the struct rc_dev descriptor of the device
  45  * @ev:         the struct ir_raw_event descriptor of the pulse/space
  46  *
  47  * This function returns -EINVAL if the pulse violates the state machine
  48  */
  49 static int ir_rc5_decode(struct rc_dev *dev, struct ir_raw_event ev)
  50 {
  51         struct rc5_dec *data = &dev->raw->rc5;
  52         u8 toggle;
  53         u32 scancode;
  54         enum rc_type protocol;
  55
  56         if (!is_timing_event(ev)) {
  57                 if (ev.reset)
  58                         data->state = STATE_INACTIVE;
  59                 return 0;
  60         }
  61
  62         if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
  63                 goto out;
  64
  65 again:
  66         IR_dprintk(2, "RC5(x/sz) decode started at state %i (%uus %s)\n",
  67                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
  68
  69         if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
  70                 return 0;
  71
  72         switch (data->state) {
  73
  74         case STATE_INACTIVE:
  75                 if (!ev.pulse)
  76                         break;
  77
  78                 data->state = STATE_BIT_START;
  79                 data->count = 1;
  80                 decrease_duration(&ev, RC5_BIT_START);
  81                 goto again;
  82
  83         case STATE_BIT_START:
  84                 if (!ev.pulse && geq_margin(ev.duration, RC5_TRAILER, RC5_UNIT / 2)) {
  85                         data->state = STATE_FINISHED;
  86                         goto again;
  87                 }
  88
  89                 if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
  90                         break;
  91
  92                 data->bits <<= 1;
  93                 if (!ev.pulse)
  94                         data->bits |= 1;
  95                 data->count++;
  96                 data->state = STATE_BIT_END;
  97                 return 0;
  98
  99         case STATE_BIT_END:
 100                 if (!is_transition(&ev, &dev->raw->prev_ev))
 101                         break;
 102
 103                 if (data->count == CHECK_RC5X_NBITS)
 104                         data->state = STATE_CHECK_RC5X;
 105                 else
 106                         data->state = STATE_BIT_START;
 107
 108                 decrease_duration(&ev, RC5_BIT_END);
 109                 goto again;
 110
 111         case STATE_CHECK_RC5X:
 112                 if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) {
 113                         data->is_rc5x = true;
 114                         decrease_duration(&ev, RC5X_SPACE);
 115                 } else
 116                         data->is_rc5x = false;
 117                 data->state = STATE_BIT_START;
 118                 goto again;
 119
 120         case STATE_FINISHED:
 121                 if (ev.pulse)
 122                         break;
 123
 124                 if (data->is_rc5x && data->count == RC5X_NBITS) {
 125                         /* RC5X */
 126                         u8 xdata, command, system;
 127                         if (!(dev->enabled_protocols & RC_BIT_RC5X_20)) {
 128                                 data->state = STATE_INACTIVE;
 129                                 return 0;
 130                         }
 131                         xdata    = (data->bits & 0x0003F) >> 0;
 132                         command  = (data->bits & 0x00FC0) >> 6;
 133                         system   = (data->bits & 0x1F000) >> 12;
 134                         toggle   = (data->bits & 0x20000) ? 1 : 0;
 135                         command += (data->bits & 0x40000) ? 0 : 0x40;
 136                         scancode = system << 16 | command << 8 | xdata;
 137                         protocol = RC_TYPE_RC5X_20;
 138
 139                 } else if (!data->is_rc5x && data->count == RC5_NBITS) {
 140                         /* RC5 */
 141                         u8 command, system;
 142                         if (!(dev->enabled_protocols & RC_BIT_RC5)) {
 143                                 data->state = STATE_INACTIVE;
 144                                 return 0;
 145                         }
 146                         command  = (data->bits & 0x0003F) >> 0;
 147                         system   = (data->bits & 0x007C0) >> 6;
 148                         toggle   = (data->bits & 0x00800) ? 1 : 0;
 149                         command += (data->bits & 0x01000) ? 0 : 0x40;
 150                         scancode = system << 8 | command;
 151                         protocol = RC_TYPE_RC5;
 152
 153                 } else if (!data->is_rc5x && data->count == RC5_SZ_NBITS) {
 154                         /* RC5 StreamZap */
 155                         u8 command, system;
 156                         if (!(dev->enabled_protocols & RC_BIT_RC5_SZ)) {
 157                                 data->state = STATE_INACTIVE;
 158                                 return 0;
 159                         }
 160                         command  = (data->bits & 0x0003F) >> 0;
 161                         system   = (data->bits & 0x02FC0) >> 6;
 162                         toggle   = (data->bits & 0x01000) ? 1 : 0;
 163                         scancode = system << 6 | command;
 164                         protocol = RC_TYPE_RC5_SZ;
 165
 166                 } else
 167                         break;
 168
 169                 IR_dprintk(1, "RC5(x/sz) scancode 0x%06x (p: %u, t: %u)\n",
 170                            scancode, protocol, toggle);
 171
 172                 rc_keydown(dev, protocol, scancode, toggle);
 173                 data->state = STATE_INACTIVE;
 174                 return 0;
 175         }
 176
 177 out:
 178         IR_dprintk(1, "RC5(x/sz) decode failed at state %i count %d (%uus %s)\n",
 179                    data->state, data->count, TO_US(ev.duration), TO_STR(ev.pulse));
 180         data->state = STATE_INACTIVE;
 181         return -EINVAL;
 182 }
 183
 184 static const struct ir_raw_timings_manchester ir_rc5_timings = {
 185         .leader                 = RC5_UNIT,
 186         .pulse_space_start      = 0,
 187         .clock                  = RC5_UNIT,
 188         .trailer_space          = RC5_UNIT * 10,
 189 };
 190
 191 static const struct ir_raw_timings_manchester ir_rc5x_timings[2] = {
 192         {
 193                 .leader                 = RC5_UNIT,
 194                 .pulse_space_start      = 0,
 195                 .clock                  = RC5_UNIT,
 196                 .trailer_space          = RC5X_SPACE,
 197         },
 198         {
 199                 .clock                  = RC5_UNIT,
 200                 .trailer_space          = RC5_UNIT * 10,
 201         },
 202 };
 203
 204 static const struct ir_raw_timings_manchester ir_rc5_sz_timings = {
 205         .leader                         = RC5_UNIT,
 206         .pulse_space_start              = 0,
 207         .clock                          = RC5_UNIT,
 208         .trailer_space                  = RC5_UNIT * 10,
 209 };
 210
 211 /**
 212  * ir_rc5_encode() - Encode a scancode as a stream of raw events
 213  *
 214  * @protocol:   protocol variant to encode
 215  * @scancode:   scancode to encode
 216  * @events:     array of raw ir events to write into
 217  * @max:        maximum size of @events
 218  *
 219  * Returns:     The number of events written.
 220  *              -ENOBUFS if there isn't enough space in the array to fit the
 221  *              encoding. In this case all @max events will have been written.
 222  *              -EINVAL if the scancode is ambiguous or invalid.
 223  */
 224 static int ir_rc5_encode(enum rc_type protocol, u32 scancode,
 225                          struct ir_raw_event *events, unsigned int max)
 226 {
 227         int ret;
 228         struct ir_raw_event *e = events;
 229         unsigned int data, xdata, command, commandx, system, pre_space_data;
 230
 231         /* Detect protocol and convert scancode to raw data */
 232         if (protocol == RC_TYPE_RC5) {
 233                 /* decode scancode */
 234                 command  = (scancode & 0x003f) >> 0;
 235                 commandx = (scancode & 0x0040) >> 6;
 236                 system   = (scancode & 0x1f00) >> 8;
 237                 /* encode data */
 238                 data = !commandx << 12 | system << 6 | command;
 239
 240                 /* Modulate the data */
 241                 ret = ir_raw_gen_manchester(&e, max, &ir_rc5_timings,
 242                                             RC5_NBITS, data);
 243                 if (ret < 0)
 244                         return ret;
 245         } else if (protocol == RC_TYPE_RC5X_20) {
 246                 /* decode scancode */
 247                 xdata    = (scancode & 0x00003f) >> 0;
 248                 command  = (scancode & 0x003f00) >> 8;
 249                 commandx = !(scancode & 0x004000);
 250                 system   = (scancode & 0x1f0000) >> 16;
 251
 252                 /* encode data */
 253                 data = commandx << 18 | system << 12 | command << 6 | xdata;
 254
 255                 /* Modulate the data */
 256                 pre_space_data = data >> (RC5X_NBITS - CHECK_RC5X_NBITS);
 257                 ret = ir_raw_gen_manchester(&e, max, &ir_rc5x_timings[0],
 258                                             CHECK_RC5X_NBITS, pre_space_data);
 259                 if (ret < 0)
 260                         return ret;
 261                 ret = ir_raw_gen_manchester(&e, max - (e - events),
 262                                             &ir_rc5x_timings[1],
 263                                             RC5X_NBITS - CHECK_RC5X_NBITS,
 264                                             data);
 265                 if (ret < 0)
 266                         return ret;
 267         } else if (protocol == RC_TYPE_RC5_SZ) {
 268                 /* RC5-SZ scancode is raw enough for Manchester as it is */
 269                 ret = ir_raw_gen_manchester(&e, max, &ir_rc5_sz_timings,
 270                                             RC5_SZ_NBITS, scancode & 0x2fff);
 271                 if (ret < 0)
 272                         return ret;
 273         } else {
 274                 return -EINVAL;
 275         }
 276
 277         return e - events;
 278 }
 279
 280 static struct ir_raw_handler rc5_handler = {
 281         .protocols      = RC_BIT_RC5 | RC_BIT_RC5X_20 | RC_BIT_RC5_SZ,
 282         .decode         = ir_rc5_decode,
 283         .encode         = ir_rc5_encode,
 284 };
 285
 286 static int __init ir_rc5_decode_init(void)
 287 {
 288         ir_raw_handler_register(&rc5_handler);
 289
 290         printk(KERN_INFO "IR RC5(x/sz) protocol handler initialized\n");
 291         return 0;
 292 }
 293
 294 static void __exit ir_rc5_decode_exit(void)
 295 {
 296         ir_raw_handler_unregister(&rc5_handler);
 297 }
 298
 299 module_init(ir_rc5_decode_init);
 300 module_exit(ir_rc5_decode_exit);
 301
 302 MODULE_LICENSE("GPL");
 303 MODULE_AUTHOR("Mauro Carvalho Chehab and Jarod Wilson");
 304 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
 305 MODULE_DESCRIPTION("RC5(x/sz) IR protocol decoder");