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

   1 /* ir-jvc-decoder.c - handle JVC IR Pulse/Space 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 <linux/bitrev.h>
  16 #include <linux/module.h>
  17 #include "rc-core-priv.h"
  18
  19 #define JVC_NBITS               16              /* dev(8) + func(8) */
  20 #define JVC_UNIT                525000          /* ns */
  21 #define JVC_HEADER_PULSE        (16 * JVC_UNIT) /* lack of header -> repeat */
  22 #define JVC_HEADER_SPACE        (8  * JVC_UNIT)
  23 #define JVC_BIT_PULSE           (1  * JVC_UNIT)
  24 #define JVC_BIT_0_SPACE         (1  * JVC_UNIT)
  25 #define JVC_BIT_1_SPACE         (3  * JVC_UNIT)
  26 #define JVC_TRAILER_PULSE       (1  * JVC_UNIT)
  27 #define JVC_TRAILER_SPACE       (35 * JVC_UNIT)
  28
  29 enum jvc_state {
  30         STATE_INACTIVE,
  31         STATE_HEADER_SPACE,
  32         STATE_BIT_PULSE,
  33         STATE_BIT_SPACE,
  34         STATE_TRAILER_PULSE,
  35         STATE_TRAILER_SPACE,
  36         STATE_CHECK_REPEAT,
  37 };
  38
  39 /**
  40  * ir_jvc_decode() - Decode one JVC 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_jvc_decode(struct rc_dev *dev, struct ir_raw_event ev)
  47 {
  48         struct jvc_dec *data = &dev->raw->jvc;
  49
  50         if (!(dev->raw->enabled_protocols & RC_TYPE_JVC))
  51                 return 0;
  52
  53         if (!is_timing_event(ev)) {
  54                 if (ev.reset)
  55                         data->state = STATE_INACTIVE;
  56                 return 0;
  57         }
  58
  59         if (!geq_margin(ev.duration, JVC_UNIT, JVC_UNIT / 2))
  60                 goto out;
  61
  62         IR_dprintk(2, "JVC decode started at state %d (%uus %s)\n",
  63                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
  64
  65 again:
  66         switch (data->state) {
  67
  68         case STATE_INACTIVE:
  69                 if (!ev.pulse)
  70                         break;
  71
  72                 if (!eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
  73                         break;
  74
  75                 data->count = 0;
  76                 data->first = true;
  77                 data->toggle = !data->toggle;
  78                 data->state = STATE_HEADER_SPACE;
  79                 return 0;
  80
  81         case STATE_HEADER_SPACE:
  82                 if (ev.pulse)
  83                         break;
  84
  85                 if (!eq_margin(ev.duration, JVC_HEADER_SPACE, JVC_UNIT / 2))
  86                         break;
  87
  88                 data->state = STATE_BIT_PULSE;
  89                 return 0;
  90
  91         case STATE_BIT_PULSE:
  92                 if (!ev.pulse)
  93                         break;
  94
  95                 if (!eq_margin(ev.duration, JVC_BIT_PULSE, JVC_UNIT / 2))
  96                         break;
  97
  98                 data->state = STATE_BIT_SPACE;
  99                 return 0;
 100
 101         case STATE_BIT_SPACE:
 102                 if (ev.pulse)
 103                         break;
 104
 105                 data->bits <<= 1;
 106                 if (eq_margin(ev.duration, JVC_BIT_1_SPACE, JVC_UNIT / 2)) {
 107                         data->bits |= 1;
 108                         decrease_duration(&ev, JVC_BIT_1_SPACE);
 109                 } else if (eq_margin(ev.duration, JVC_BIT_0_SPACE, JVC_UNIT / 2))
 110                         decrease_duration(&ev, JVC_BIT_0_SPACE);
 111                 else
 112                         break;
 113                 data->count++;
 114
 115                 if (data->count == JVC_NBITS)
 116                         data->state = STATE_TRAILER_PULSE;
 117                 else
 118                         data->state = STATE_BIT_PULSE;
 119                 return 0;
 120
 121         case STATE_TRAILER_PULSE:
 122                 if (!ev.pulse)
 123                         break;
 124
 125                 if (!eq_margin(ev.duration, JVC_TRAILER_PULSE, JVC_UNIT / 2))
 126                         break;
 127
 128                 data->state = STATE_TRAILER_SPACE;
 129                 return 0;
 130
 131         case STATE_TRAILER_SPACE:
 132                 if (ev.pulse)
 133                         break;
 134
 135                 if (!geq_margin(ev.duration, JVC_TRAILER_SPACE, JVC_UNIT / 2))
 136                         break;
 137
 138                 if (data->first) {
 139                         u32 scancode;
 140                         scancode = (bitrev8((data->bits >> 8) & 0xff) << 8) |
 141                                    (bitrev8((data->bits >> 0) & 0xff) << 0);
 142                         IR_dprintk(1, "JVC scancode 0x%04x\n", scancode);
 143                         rc_keydown(dev, scancode, data->toggle);
 144                         data->first = false;
 145                         data->old_bits = data->bits;
 146                 } else if (data->bits == data->old_bits) {
 147                         IR_dprintk(1, "JVC repeat\n");
 148                         rc_repeat(dev);
 149                 } else {
 150                         IR_dprintk(1, "JVC invalid repeat msg\n");
 151                         break;
 152                 }
 153
 154                 data->count = 0;
 155                 data->state = STATE_CHECK_REPEAT;
 156                 return 0;
 157
 158         case STATE_CHECK_REPEAT:
 159                 if (!ev.pulse)
 160                         break;
 161
 162                 if (eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
 163                         data->state = STATE_INACTIVE;
 164   else
 165                         data->state = STATE_BIT_PULSE;
 166                 goto again;
 167         }
 168
 169 out:
 170         IR_dprintk(1, "JVC decode failed at state %d (%uus %s)\n",
 171                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 172         data->state = STATE_INACTIVE;
 173         return -EINVAL;
 174 }
 175
 176 static struct ir_raw_handler jvc_handler = {
 177         .protocols      = RC_TYPE_JVC,
 178         .decode         = ir_jvc_decode,
 179 };
 180
 181 static int __init ir_jvc_decode_init(void)
 182 {
 183         ir_raw_handler_register(&jvc_handler);
 184
 185         printk(KERN_INFO "IR JVC protocol handler initialized\n");
 186         return 0;
 187 }
 188
 189 static void __exit ir_jvc_decode_exit(void)
 190 {
 191         ir_raw_handler_unregister(&jvc_handler);
 192 }
 193
 194 module_init(ir_jvc_decode_init);
 195 module_exit(ir_jvc_decode_exit);
 196
 197 MODULE_LICENSE("GPL");
 198 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
 199 MODULE_DESCRIPTION("JVC IR protocol decoder");