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 (1680us space) */
  19 #define SHARP_BIT_0_SPACE       (17   * SHARP_UNIT) /* 680us space */
  20 #define SHARP_BIT_1_SPACE       (42   * SHARP_UNIT) /* 1680us space */
  21 #define SHARP_ECHO_SPACE        (1000 * SHARP_UNIT) /* 40 ms */
  22 #define SHARP_TRAILER_SPACE     (125  * SHARP_UNIT) /* 5 ms (even longer) */
  23
  24 enum sharp_state {
  25         STATE_INACTIVE,
  26         STATE_BIT_PULSE,
  27         STATE_BIT_SPACE,
  28         STATE_TRAILER_PULSE,
  29         STATE_ECHO_SPACE,
  30         STATE_TRAILER_SPACE,
  31 };
  32
  33 /**
  34  * ir_sharp_decode() - Decode one Sharp pulse or space
  35  * @dev:        the struct rc_dev descriptor of the device
  36  * @ev:         the struct ir_raw_event descriptor of the pulse/space
  37  *
  38  * This function returns -EINVAL if the pulse violates the state machine
  39  */
  40 static int ir_sharp_decode(struct rc_dev *dev, struct ir_raw_event ev)
  41 {
  42         struct sharp_dec *data = &dev->raw->sharp;
  43         u32 msg, echo, address, command, scancode;
  44
  45         if (!is_timing_event(ev)) {
  46                 if (ev.overflow)
  47                         data->state = STATE_INACTIVE;
  48                 return 0;
  49         }
  50
  51         dev_dbg(&dev->dev, "Sharp decode started at state %d (%uus %s)\n",
  52                 data->state, ev.duration, TO_STR(ev.pulse));
  53
  54         switch (data->state) {
  55
  56         case STATE_INACTIVE:
  57                 if (!ev.pulse)
  58                         break;
  59
  60                 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
  61                                SHARP_BIT_PULSE / 2))
  62                         break;
  63
  64                 data->count = 0;
  65                 data->pulse_len = ev.duration;
  66                 data->state = STATE_BIT_SPACE;
  67                 return 0;
  68
  69         case STATE_BIT_PULSE:
  70                 if (!ev.pulse)
  71                         break;
  72
  73                 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
  74                                SHARP_BIT_PULSE / 2))
  75                         break;
  76
  77                 data->pulse_len = ev.duration;
  78                 data->state = STATE_BIT_SPACE;
  79                 return 0;
  80
  81         case STATE_BIT_SPACE:
  82                 if (ev.pulse)
  83                         break;
  84
  85                 data->bits <<= 1;
  86                 if (eq_margin(data->pulse_len + ev.duration, SHARP_BIT_1_PERIOD,
  87                               SHARP_BIT_PULSE * 2))
  88                         data->bits |= 1;
  89                 else if (!eq_margin(data->pulse_len + ev.duration,
  90                                     SHARP_BIT_0_PERIOD, SHARP_BIT_PULSE * 2))
  91                         break;
  92                 data->count++;
  93
  94                 if (data->count == SHARP_NBITS ||
  95                     data->count == SHARP_NBITS * 2)
  96                         data->state = STATE_TRAILER_PULSE;
  97                 else
  98                         data->state = STATE_BIT_PULSE;
  99
 100                 return 0;
 101
 102         case STATE_TRAILER_PULSE:
 103                 if (!ev.pulse)
 104                         break;
 105
 106                 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
 107                                SHARP_BIT_PULSE / 2))
 108                         break;
 109
 110                 if (data->count == SHARP_NBITS) {
 111                         /* exp,chk bits should be 1,0 */
 112                         if ((data->bits & 0x3) != 0x2 &&
 113                         /* DENON variant, both chk bits 0 */
 114                             (data->bits & 0x3) != 0x0)
 115                                 break;
 116                         data->state = STATE_ECHO_SPACE;
 117                 } else {
 118                         data->state = STATE_TRAILER_SPACE;
 119                 }
 120                 return 0;
 121
 122         case STATE_ECHO_SPACE:
 123                 if (ev.pulse)
 124                         break;
 125
 126                 if (!eq_margin(ev.duration, SHARP_ECHO_SPACE,
 127                                SHARP_ECHO_SPACE / 4))
 128                         break;
 129
 130                 data->state = STATE_BIT_PULSE;
 131
 132                 return 0;
 133
 134         case STATE_TRAILER_SPACE:
 135                 if (ev.pulse)
 136                         break;
 137
 138                 if (!geq_margin(ev.duration, SHARP_TRAILER_SPACE,
 139                                 SHARP_BIT_PULSE / 2))
 140                         break;
 141
 142                 /* Validate - command, ext, chk should be inverted in 2nd */
 143                 msg = (data->bits >> 15) & 0x7fff;
 144                 echo = data->bits & 0x7fff;
 145                 if ((msg ^ echo) != 0x3ff) {
 146                         dev_dbg(&dev->dev,
 147                                 "Sharp checksum error: received 0x%04x, 0x%04x\n",
 148                                 msg, echo);
 149                         break;
 150                 }
 151
 152                 address = bitrev8((msg >> 7) & 0xf8);
 153                 command = bitrev8((msg >> 2) & 0xff);
 154
 155                 scancode = address << 8 | command;
 156                 dev_dbg(&dev->dev, "Sharp scancode 0x%04x\n", scancode);
 157
 158                 rc_keydown(dev, RC_PROTO_SHARP, scancode, 0);
 159                 data->state = STATE_INACTIVE;
 160                 return 0;
 161         }
 162
 163         dev_dbg(&dev->dev, "Sharp decode failed at count %d state %d (%uus %s)\n",
 164                 data->count, data->state, ev.duration, TO_STR(ev.pulse));
 165         data->state = STATE_INACTIVE;
 166         return -EINVAL;
 167 }
 168
 169 static const struct ir_raw_timings_pd ir_sharp_timings = {
 170         .header_pulse  = 0,
 171         .header_space  = 0,
 172         .bit_pulse     = SHARP_BIT_PULSE,
 173         .bit_space[0]  = SHARP_BIT_0_SPACE,
 174         .bit_space[1]  = SHARP_BIT_1_SPACE,
 175         .trailer_pulse = SHARP_BIT_PULSE,
 176         .trailer_space = SHARP_ECHO_SPACE,
 177         .msb_first     = 1,
 178 };
 179
 180 /**
 181  * ir_sharp_encode() - Encode a scancode as a stream of raw events
 182  *
 183  * @protocol:   protocol to encode
 184  * @scancode:   scancode to encode
 185  * @events:     array of raw ir events to write into
 186  * @max:        maximum size of @events
 187  *
 188  * Returns:     The number of events written.
 189  *              -ENOBUFS if there isn't enough space in the array to fit the
 190  *              encoding. In this case all @max events will have been written.
 191  */
 192 static int ir_sharp_encode(enum rc_proto protocol, u32 scancode,
 193                            struct ir_raw_event *events, unsigned int max)
 194 {
 195         struct ir_raw_event *e = events;
 196         int ret;
 197         u32 raw;
 198
 199         raw = (((bitrev8(scancode >> 8) >> 3) << 8) & 0x1f00) |
 200                 bitrev8(scancode);
 201         ret = ir_raw_gen_pd(&e, max, &ir_sharp_timings, SHARP_NBITS,
 202                             (raw << 2) | 2);
 203         if (ret < 0)
 204                 return ret;
 205
 206         max -= ret;
 207
 208         raw = (((bitrev8(scancode >> 8) >> 3) << 8) & 0x1f00) |
 209                 bitrev8(~scancode);
 210         ret = ir_raw_gen_pd(&e, max, &ir_sharp_timings, SHARP_NBITS,
 211                             (raw << 2) | 1);
 212         if (ret < 0)
 213                 return ret;
 214
 215         return e - events;
 216 }
 217
 218 static struct ir_raw_handler sharp_handler = {
 219         .protocols      = RC_PROTO_BIT_SHARP,
 220         .decode         = ir_sharp_decode,
 221         .encode         = ir_sharp_encode,
 222         .carrier        = 38000,
 223         .min_timeout    = SHARP_ECHO_SPACE + SHARP_ECHO_SPACE / 4,
 224 };
 225
 226 static int __init ir_sharp_decode_init(void)
 227 {
 228         ir_raw_handler_register(&sharp_handler);
 229
 230         pr_info("IR Sharp protocol handler initialized\n");
 231         return 0;
 232 }
 233
 234 static void __exit ir_sharp_decode_exit(void)
 235 {
 236         ir_raw_handler_unregister(&sharp_handler);
 237 }
 238
 239 module_init(ir_sharp_decode_init);
 240 module_exit(ir_sharp_decode_exit);
 241
 242 MODULE_LICENSE("GPL");
 243 MODULE_AUTHOR("James Hogan <jhogan@kernel.org>");
 244 MODULE_DESCRIPTION("Sharp IR protocol decoder");