drivers/media/IR/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 "ir-core-priv.h"
  17
  18 #define JVC_NBITS               16              /* dev(8) + func(8) */
  19 #define JVC_UNIT                525000          /* ns */
  20 #define JVC_HEADER_PULSE        (16 * JVC_UNIT) /* lack of header -> repeat */
  21 #define JVC_HEADER_SPACE        (8  * JVC_UNIT)
  22 #define JVC_BIT_PULSE           (1  * JVC_UNIT)
  23 #define JVC_BIT_0_SPACE         (1  * JVC_UNIT)
  24 #define JVC_BIT_1_SPACE         (3  * JVC_UNIT)
  25 #define JVC_TRAILER_PULSE       (1  * JVC_UNIT)
  26 #define JVC_TRAILER_SPACE       (35 * JVC_UNIT)
  27
  28 enum jvc_state {
  29         STATE_INACTIVE,
  30         STATE_HEADER_SPACE,
  31         STATE_BIT_PULSE,
  32         STATE_BIT_SPACE,
  33         STATE_TRAILER_PULSE,
  34         STATE_TRAILER_SPACE,
  35 };
  36
  37 /**
  38  * ir_jvc_decode() - Decode one JVC pulse or space
  39  * @input_dev:  the struct input_dev descriptor of the device
  40  * @duration:   the struct ir_raw_event descriptor of the pulse/space
  41  *
  42  * This function returns -EINVAL if the pulse violates the state machine
  43  */
  44 static int ir_jvc_decode(struct input_dev *input_dev, struct ir_raw_event ev)
  45 {
  46         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
  47         struct jvc_dec *data = &ir_dev->raw->jvc;
  48
  49         if (!(ir_dev->raw->enabled_protocols & IR_TYPE_JVC))
  50                 return 0;
  51
  52         if (IS_RESET(ev)) {
  53                 data->state = STATE_INACTIVE;
  54                 return 0;
  55         }
  56
  57         if (!geq_margin(ev.duration, JVC_UNIT, JVC_UNIT / 2))
  58                 goto out;
  59
  60         IR_dprintk(2, "JVC 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, JVC_HEADER_PULSE, JVC_UNIT / 2))
  70                         break;
  71
  72                 data->count = 0;
  73                 data->first = true;
  74                 data->toggle = !data->toggle;
  75                 data->state = STATE_HEADER_SPACE;
  76                 return 0;
  77
  78         case STATE_HEADER_SPACE:
  79                 if (ev.pulse)
  80                         break;
  81
  82                 if (!eq_margin(ev.duration, JVC_HEADER_SPACE, JVC_UNIT / 2))
  83                         break;
  84
  85                 data->state = STATE_BIT_PULSE;
  86                 return 0;
  87
  88         case STATE_BIT_PULSE:
  89                 if (!ev.pulse)
  90                         break;
  91
  92                 if (!eq_margin(ev.duration, JVC_BIT_PULSE, JVC_UNIT / 2))
  93                         break;
  94
  95                 data->state = STATE_BIT_SPACE;
  96                 return 0;
  97
  98         case STATE_BIT_SPACE:
  99                 if (ev.pulse)
 100                         break;
 101
 102                 data->bits <<= 1;
 103                 if (eq_margin(ev.duration, JVC_BIT_1_SPACE, JVC_UNIT / 2)) {
 104                         data->bits |= 1;
 105                         decrease_duration(&ev, JVC_BIT_1_SPACE);
 106                 } else if (eq_margin(ev.duration, JVC_BIT_0_SPACE, JVC_UNIT / 2))
 107                         decrease_duration(&ev, JVC_BIT_0_SPACE);
 108                 else
 109                         break;
 110                 data->count++;
 111
 112                 if (data->count == JVC_NBITS)
 113                         data->state = STATE_TRAILER_PULSE;
 114                 else
 115                         data->state = STATE_BIT_PULSE;
 116                 return 0;
 117
 118         case STATE_TRAILER_PULSE:
 119                 if (!ev.pulse)
 120                         break;
 121
 122                 if (!eq_margin(ev.duration, JVC_TRAILER_PULSE, JVC_UNIT / 2))
 123                         break;
 124
 125                 data->state = STATE_TRAILER_SPACE;
 126                 return 0;
 127
 128         case STATE_TRAILER_SPACE:
 129                 if (ev.pulse)
 130                         break;
 131
 132                 if (!geq_margin(ev.duration, JVC_TRAILER_SPACE, JVC_UNIT / 2))
 133                         break;
 134
 135                 if (data->first) {
 136                         u32 scancode;
 137                         scancode = (bitrev8((data->bits >> 8) & 0xff) << 8) |
 138                                    (bitrev8((data->bits >> 0) & 0xff) << 0);
 139                         IR_dprintk(1, "JVC scancode 0x%04x\n", scancode);
 140                         ir_keydown(input_dev, scancode, data->toggle);
 141                         data->first = false;
 142                         data->old_bits = data->bits;
 143                 } else if (data->bits == data->old_bits) {
 144                         IR_dprintk(1, "JVC repeat\n");
 145                         ir_repeat(input_dev);
 146                 } else {
 147                         IR_dprintk(1, "JVC invalid repeat msg\n");
 148                         break;
 149                 }
 150
 151                 data->count = 0;
 152                 data->state = STATE_BIT_PULSE;
 153                 return 0;
 154         }
 155
 156 out:
 157         IR_dprintk(1, "JVC decode failed at state %d (%uus %s)\n",
 158                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 159         data->state = STATE_INACTIVE;
 160         return -EINVAL;
 161 }
 162
 163 static struct ir_raw_handler jvc_handler = {
 164         .protocols      = IR_TYPE_JVC,
 165         .decode         = ir_jvc_decode,
 166 };
 167
 168 static int __init ir_jvc_decode_init(void)
 169 {
 170         ir_raw_handler_register(&jvc_handler);
 171
 172         printk(KERN_INFO "IR JVC protocol handler initialized\n");
 173         return 0;
 174 }
 175
 176 static void __exit ir_jvc_decode_exit(void)
 177 {
 178         ir_raw_handler_unregister(&jvc_handler);
 179 }
 180
 181 module_init(ir_jvc_decode_init);
 182 module_exit(ir_jvc_decode_exit);
 183
 184 MODULE_LICENSE("GPL");
 185 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
 186 MODULE_DESCRIPTION("JVC IR protocol decoder");