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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* ir-sharp-decoder.c - handle Sharp IR Pulse/Space protocol
   3  *
   4  * Copyright (C) 2013-2014 Imagination Technologies Ltd.
   5  *
   6  * Based on NEC decoder:
   7  * Copyright (C) 2010 by Mauro Carvalho Chehab
   8  */
   9
  10 #include <linux/bitrev.h>
  11 #include <linux/module.h>
  12 #include "rc-core-priv.h"
  13
  14 #define SHARP_NBITS             15
  15 #define SHARP_UNIT              40  /* us */
  16 #define SHARP_BIT_PULSE         (8    * SHARP_UNIT) /* 320us */
  17 #define SHARP_BIT_0_PERIOD      (25   * SHARP_UNIT) /* 1ms (680us space) */
  18 #define SHARP_BIT_1_PERIOD      (50   * SHARP_UNIT) /* 2ms (1680ms space) */
  19 #define SHARP_ECHO_SPACE        (1000 * SHARP_UNIT) /* 40 ms */
  20 #define SHARP_TRAILER_SPACE     (125  * SHARP_UNIT) /* 5 ms (even longer) */
  21
  22 enum sharp_state {
  23         STATE_INACTIVE,
  24         STATE_BIT_PULSE,
  25         STATE_BIT_SPACE,
  26         STATE_TRAILER_PULSE,
  27         STATE_ECHO_SPACE,
  28         STATE_TRAILER_SPACE,
  29 };
  30
  31 /**
  32  * ir_sharp_decode() - Decode one Sharp pulse or space
  33  * @dev:        the struct rc_dev descriptor of the device
  34  * @ev:         the struct ir_raw_event descriptor of the pulse/space
  35  *
  36  * This function returns -EINVAL if the pulse violates the state machine
  37  */
  38 static int ir_sharp_decode(struct rc_dev *dev, struct ir_raw_event ev)
  39 {
  40         struct sharp_dec *data = &dev->raw->sharp;
  41         u32 msg, echo, address, command, scancode;
  42
  43         if (!is_timing_event(ev)) {
  44                 if (ev.overflow)
  45                         data->state = STATE_INACTIVE;
  46                 return 0;
  47         }
  48
  49         dev_dbg(&dev->dev, "Sharp decode started at state %d (%uus %s)\n",
  50                 data->state, ev.duration, TO_STR(ev.pulse));
  51
  52         switch (data->state) {
  53
  54         case STATE_INACTIVE:
  55                 if (!ev.pulse)
  56                         break;
  57
  58                 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
  59                                SHARP_BIT_PULSE / 2))
  60                         break;
  61
  62                 data->count = 0;
  63                 data->pulse_len = ev.duration;
  64                 data->state = STATE_BIT_SPACE;
  65                 return 0;
  66
  67         case STATE_BIT_PULSE:
  68                 if (!ev.pulse)
  69                         break;
  70
  71                 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
  72                                SHARP_BIT_PULSE / 2))
  73                         break;
  74
  75                 data->pulse_len = ev.duration;
  76                 data->state = STATE_BIT_SPACE;
  77                 return 0;
  78
  79         case STATE_BIT_SPACE:
  80                 if (ev.pulse)
  81                         break;
  82
  83                 data->bits <<= 1;
  84                 if (eq_margin(data->pulse_len + ev.duration, SHARP_BIT_1_PERIOD,
  85                               SHARP_BIT_PULSE * 2))
  86                         data->bits |= 1;
  87                 else if (!eq_margin(data->pulse_len + ev.duration,
  88                                     SHARP_BIT_0_PERIOD, SHARP_BIT_PULSE * 2))
  89                         break;
  90                 data->count++;
  91
  92                 if (data->count == SHARP_NBITS ||
  93                     data->count == SHARP_NBITS * 2)
  94                         data->state = STATE_TRAILER_PULSE;
  95                 else
  96                         data->state = STATE_BIT_PULSE;
  97
  98                 return 0;
  99
 100         case STATE_TRAILER_PULSE:
 101                 if (!ev.pulse)
 102                         break;
 103
 104                 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
 105                                SHARP_BIT_PULSE / 2))
 106                         break;
 107
 108                 if (data->count == SHARP_NBITS) {
 109                         /* exp,chk bits should be 1,0 */
 110                         if ((data->bits & 0x3) != 0x2 &&
 111                         /* DENON variant, both chk bits 0 */
 112                             (data->bits & 0x3) != 0x0)
 113                                 break;
 114                         data->state = STATE_ECHO_SPACE;
 115                 } else {
 116                         data->state = STATE_TRAILER_SPACE;
 117                 }
 118                 return 0;
 119
 120         case STATE_ECHO_SPACE:
 121                 if (ev.pulse)
 122                         break;
 123
 124                 if (!eq_margin(ev.duration, SHARP_ECHO_SPACE,
 125                                SHARP_ECHO_SPACE / 4))
 126                         break;
 127
 128                 data->state = STATE_BIT_PULSE;
 129
 130                 return 0;
 131
 132         case STATE_TRAILER_SPACE:
 133                 if (ev.pulse)
 134                         break;
 135
 136                 if (!geq_margin(ev.duration, SHARP_TRAILER_SPACE,
 137                                 SHARP_BIT_PULSE / 2))
 138                         break;
 139
 140                 /* Validate - command, ext, chk should be inverted in 2nd */
 141                 msg = (data->bits >> 15) & 0x7fff;
 142                 echo = data->bits & 0x7fff;
 143                 if ((msg ^ echo) != 0x3ff) {
 144                         dev_dbg(&dev->dev,
 145                                 "Sharp checksum error: received 0x%04x, 0x%04x\n",
 146                                 msg, echo);
 147                         break;
 148                 }
 149
 150                 address = bitrev8((msg >> 7) & 0xf8);
 151                 command = bitrev8((msg >> 2) & 0xff);
 152
 153                 scancode = address << 8 | command;
 154                 dev_dbg(&dev->dev, "Sharp scancode 0x%04x\n", scancode);
 155
 156                 rc_keydown(dev, RC_PROTO_SHARP, scancode, 0);
 157                 data->state = STATE_INACTIVE;
 158                 return 0;
 159         }
 160
 161         dev_dbg(&dev->dev, "Sharp decode failed at count %d state %d (%uus %s)\n",
 162                 data->count, data->state, ev.duration, TO_STR(ev.pulse));
 163         data->state = STATE_INACTIVE;
 164         return -EINVAL;
 165 }
 166
 167 static const struct ir_raw_timings_pd ir_sharp_timings = {
 168         .header_pulse  = 0,
 169         .header_space  = 0,
 170         .bit_pulse     = SHARP_BIT_PULSE,
 171         .bit_space[0]  = SHARP_BIT_0_PERIOD,
 172         .bit_space[1]  = SHARP_BIT_1_PERIOD,
 173         .trailer_pulse = SHARP_BIT_PULSE,
 174         .trailer_space = SHARP_ECHO_SPACE,
 175         .msb_first     = 1,
 176 };
 177
 178 /**
 179  * ir_sharp_encode() - Encode a scancode as a stream of raw events
 180  *
 181  * @protocol:   protocol to encode
 182  * @scancode:   scancode to encode
 183  * @events:     array of raw ir events to write into
 184  * @max:        maximum size of @events
 185  *
 186  * Returns:     The number of events written.
 187  *              -ENOBUFS if there isn't enough space in the array to fit the
 188  *              encoding. In this case all @max events will have been written.
 189  */
 190 static int ir_sharp_encode(enum rc_proto protocol, u32 scancode,
 191                            struct ir_raw_event *events, unsigned int max)
 192 {
 193         struct ir_raw_event *e = events;
 194         int ret;
 195         u32 raw;
 196
 197         raw = (((bitrev8(scancode >> 8) >> 3) << 8) & 0x1f00) |
 198                 bitrev8(scancode);
 199         ret = ir_raw_gen_pd(&e, max, &ir_sharp_timings, SHARP_NBITS,
 200                             (raw << 2) | 2);
 201         if (ret < 0)
 202                 return ret;
 203
 204         max -= ret;
 205
 206         raw = (((bitrev8(scancode >> 8) >> 3) << 8) & 0x1f00) |
 207                 bitrev8(~scancode);
 208         ret = ir_raw_gen_pd(&e, max, &ir_sharp_timings, SHARP_NBITS,
 209                             (raw << 2) | 1);
 210         if (ret < 0)
 211                 return ret;
 212
 213         return e - events;
 214 }
 215
 216 static struct ir_raw_handler sharp_handler = {
 217         .protocols      = RC_PROTO_BIT_SHARP,
 218         .decode         = ir_sharp_decode,
 219         .encode         = ir_sharp_encode,
 220         .carrier        = 38000,
 221         .min_timeout    = SHARP_ECHO_SPACE + SHARP_ECHO_SPACE / 4,
 222 };
 223
 224 static int __init ir_sharp_decode_init(void)
 225 {
 226         ir_raw_handler_register(&sharp_handler);
 227
 228         pr_info("IR Sharp protocol handler initialized\n");
 229         return 0;
 230 }
 231
 232 static void __exit ir_sharp_decode_exit(void)
 233 {
 234         ir_raw_handler_unregister(&sharp_handler);
 235 }
 236
 237 module_init(ir_sharp_decode_init);
 238 module_exit(ir_sharp_decode_exit);
 239
 240 MODULE_LICENSE("GPL");
 241 MODULE_AUTHOR("James Hogan <jhogan@kernel.org>");
 242 MODULE_DESCRIPTION("Sharp IR protocol decoder");