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

   1 /* ir-sharp-decoder.c - handle Sharp IR Pulse/Space protocol
   2  *
   3  * Copyright (C) 2013-2014 Imagination Technologies Ltd.
   4  *
   5  * Based on NEC decoder:
   6  * Copyright (C) 2010 by Mauro Carvalho Chehab
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation version 2 of the License.
  11  *
  12  *  This program is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  */
  17
  18 #include <linux/bitrev.h>
  19 #include <linux/module.h>
  20 #include "rc-core-priv.h"
  21
  22 #define SHARP_NBITS             15
  23 #define SHARP_UNIT              40000  /* ns */
  24 #define SHARP_BIT_PULSE         (8    * SHARP_UNIT) /* 320us */
  25 #define SHARP_BIT_0_PERIOD      (25   * SHARP_UNIT) /* 1ms (680us space) */
  26 #define SHARP_BIT_1_PERIOD      (50   * SHARP_UNIT) /* 2ms (1680ms space) */
  27 #define SHARP_ECHO_SPACE        (1000 * SHARP_UNIT) /* 40 ms */
  28 #define SHARP_TRAILER_SPACE     (125  * SHARP_UNIT) /* 5 ms (even longer) */
  29
  30 enum sharp_state {
  31         STATE_INACTIVE,
  32         STATE_BIT_PULSE,
  33         STATE_BIT_SPACE,
  34         STATE_TRAILER_PULSE,
  35         STATE_ECHO_SPACE,
  36         STATE_TRAILER_SPACE,
  37 };
  38
  39 /**
  40  * ir_sharp_decode() - Decode one Sharp pulse or space
  41  * @dev:        the struct rc_dev descriptor of the device
  42  * @duration:   the struct ir_raw_event descriptor of the pulse/space
  43  *
  44  * This function returns -EINVAL if the pulse violates the state machine
  45  */
  46 static int ir_sharp_decode(struct rc_dev *dev, struct ir_raw_event ev)
  47 {
  48         struct sharp_dec *data = &dev->raw->sharp;
  49         u32 msg, echo, address, command, scancode;
  50
  51         if (!rc_protocols_enabled(dev, RC_BIT_SHARP))
  52                 return 0;
  53
  54         if (!is_timing_event(ev)) {
  55                 if (ev.reset)
  56                         data->state = STATE_INACTIVE;
  57                 return 0;
  58         }
  59
  60         IR_dprintk(2, "Sharp decode started at state %d (%uus %s)\n",
  61                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
  62
  63         switch (data->state) {
  64
  65         case STATE_INACTIVE:
  66                 if (!ev.pulse)
  67                         break;
  68
  69                 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
  70                                SHARP_BIT_PULSE / 2))
  71                         break;
  72
  73                 data->count = 0;
  74                 data->pulse_len = ev.duration;
  75                 data->state = STATE_BIT_SPACE;
  76                 return 0;
  77
  78         case STATE_BIT_PULSE:
  79                 if (!ev.pulse)
  80                         break;
  81
  82                 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
  83                                SHARP_BIT_PULSE / 2))
  84                         break;
  85
  86                 data->pulse_len = ev.duration;
  87                 data->state = STATE_BIT_SPACE;
  88                 return 0;
  89
  90         case STATE_BIT_SPACE:
  91                 if (ev.pulse)
  92                         break;
  93
  94                 data->bits <<= 1;
  95                 if (eq_margin(data->pulse_len + ev.duration, SHARP_BIT_1_PERIOD,
  96                               SHARP_BIT_PULSE * 2))
  97                         data->bits |= 1;
  98                 else if (!eq_margin(data->pulse_len + ev.duration,
  99                                     SHARP_BIT_0_PERIOD, SHARP_BIT_PULSE * 2))
 100                         break;
 101                 data->count++;
 102
 103                 if (data->count == SHARP_NBITS ||
 104                     data->count == SHARP_NBITS * 2)
 105                         data->state = STATE_TRAILER_PULSE;
 106                 else
 107                         data->state = STATE_BIT_PULSE;
 108
 109                 return 0;
 110
 111         case STATE_TRAILER_PULSE:
 112                 if (!ev.pulse)
 113                         break;
 114
 115                 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
 116                                SHARP_BIT_PULSE / 2))
 117                         break;
 118
 119                 if (data->count == SHARP_NBITS) {
 120                         /* exp,chk bits should be 1,0 */
 121                         if ((data->bits & 0x3) != 0x2)
 122                                 break;
 123                         data->state = STATE_ECHO_SPACE;
 124                 } else {
 125                         data->state = STATE_TRAILER_SPACE;
 126                 }
 127                 return 0;
 128
 129         case STATE_ECHO_SPACE:
 130                 if (ev.pulse)
 131                         break;
 132
 133                 if (!eq_margin(ev.duration, SHARP_ECHO_SPACE,
 134                                SHARP_ECHO_SPACE / 4))
 135                         break;
 136
 137                 data->state = STATE_BIT_PULSE;
 138
 139                 return 0;
 140
 141         case STATE_TRAILER_SPACE:
 142                 if (ev.pulse)
 143                         break;
 144
 145                 if (!geq_margin(ev.duration, SHARP_TRAILER_SPACE,
 146                                 SHARP_BIT_PULSE / 2))
 147                         break;
 148
 149                 /* Validate - command, ext, chk should be inverted in 2nd */
 150                 msg = (data->bits >> 15) & 0x7fff;
 151                 echo = data->bits & 0x7fff;
 152                 if ((msg ^ echo) != 0x3ff) {
 153                         IR_dprintk(1,
 154                                    "Sharp checksum error: received 0x%04x, 0x%04x\n",
 155                                    msg, echo);
 156                         break;
 157                 }
 158
 159                 address = bitrev8((msg >> 7) & 0xf8);
 160                 command = bitrev8((msg >> 2) & 0xff);
 161
 162                 scancode = address << 8 | command;
 163                 IR_dprintk(1, "Sharp scancode 0x%04x\n", scancode);
 164
 165                 rc_keydown(dev, scancode, 0);
 166                 data->state = STATE_INACTIVE;
 167                 return 0;
 168         }
 169
 170         IR_dprintk(1, "Sharp decode failed at count %d state %d (%uus %s)\n",
 171                    data->count, data->state, TO_US(ev.duration),
 172                    TO_STR(ev.pulse));
 173         data->state = STATE_INACTIVE;
 174         return -EINVAL;
 175 }
 176
 177 static struct ir_raw_handler sharp_handler = {
 178         .protocols      = RC_BIT_SHARP,
 179         .decode         = ir_sharp_decode,
 180 };
 181
 182 static int __init ir_sharp_decode_init(void)
 183 {
 184         ir_raw_handler_register(&sharp_handler);
 185
 186         pr_info("IR Sharp protocol handler initialized\n");
 187         return 0;
 188 }
 189
 190 static void __exit ir_sharp_decode_exit(void)
 191 {
 192         ir_raw_handler_unregister(&sharp_handler);
 193 }
 194
 195 module_init(ir_sharp_decode_init);
 196 module_exit(ir_sharp_decode_exit);
 197
 198 MODULE_LICENSE("GPL");
 199 MODULE_AUTHOR("James Hogan <[email protected]>");
 200 MODULE_DESCRIPTION("Sharp IR protocol decoder");