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 "rc-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         STATE_CHECK_REPEAT,
  36 };
  37
  38 /**
  39  * ir_jvc_decode() - Decode one JVC pulse or space
  40  * @dev:        the struct rc_dev descriptor of the device
  41  * @duration:   the struct ir_raw_event descriptor of the pulse/space
  42  *
  43  * This function returns -EINVAL if the pulse violates the state machine
  44  */
  45 static int ir_jvc_decode(struct rc_dev *dev, struct ir_raw_event ev)
  46 {
  47         struct jvc_dec *data = &dev->raw->jvc;
  48
  49         if (!(dev->raw->enabled_protocols & RC_TYPE_JVC))
  50                 return 0;
  51
  52         if (!is_timing_event(ev)) {
  53                 if (ev.reset)
  54                         data->state = STATE_INACTIVE;
  55                 return 0;
  56         }
  57
  58         if (!geq_margin(ev.duration, JVC_UNIT, JVC_UNIT / 2))
  59                 goto out;
  60
  61         IR_dprintk(2, "JVC decode started at state %d (%uus %s)\n",
  62                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
  63
  64 again:
  65         switch (data->state) {
  66
  67         case STATE_INACTIVE:
  68                 if (!ev.pulse)
  69                         break;
  70
  71                 if (!eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
  72                         break;
  73
  74                 data->count = 0;
  75                 data->first = true;
  76                 data->toggle = !data->toggle;
  77                 data->state = STATE_HEADER_SPACE;
  78                 return 0;
  79
  80         case STATE_HEADER_SPACE:
  81                 if (ev.pulse)
  82                         break;
  83
  84                 if (!eq_margin(ev.duration, JVC_HEADER_SPACE, JVC_UNIT / 2))
  85                         break;
  86
  87                 data->state = STATE_BIT_PULSE;
  88                 return 0;
  89
  90         case STATE_BIT_PULSE:
  91                 if (!ev.pulse)
  92                         break;
  93
  94                 if (!eq_margin(ev.duration, JVC_BIT_PULSE, JVC_UNIT / 2))
  95                         break;
  96
  97                 data->state = STATE_BIT_SPACE;
  98                 return 0;
  99
 100         case STATE_BIT_SPACE:
 101                 if (ev.pulse)
 102                         break;
 103
 104                 data->bits <<= 1;
 105                 if (eq_margin(ev.duration, JVC_BIT_1_SPACE, JVC_UNIT / 2)) {
 106                         data->bits |= 1;
 107                         decrease_duration(&ev, JVC_BIT_1_SPACE);
 108                 } else if (eq_margin(ev.duration, JVC_BIT_0_SPACE, JVC_UNIT / 2))
 109                         decrease_duration(&ev, JVC_BIT_0_SPACE);
 110                 else
 111                         break;
 112                 data->count++;
 113
 114                 if (data->count == JVC_NBITS)
 115                         data->state = STATE_TRAILER_PULSE;
 116                 else
 117                         data->state = STATE_BIT_PULSE;
 118                 return 0;
 119
 120         case STATE_TRAILER_PULSE:
 121                 if (!ev.pulse)
 122                         break;
 123
 124                 if (!eq_margin(ev.duration, JVC_TRAILER_PULSE, JVC_UNIT / 2))
 125                         break;
 126
 127                 data->state = STATE_TRAILER_SPACE;
 128                 return 0;
 129
 130         case STATE_TRAILER_SPACE:
 131                 if (ev.pulse)
 132                         break;
 133
 134                 if (!geq_margin(ev.duration, JVC_TRAILER_SPACE, JVC_UNIT / 2))
 135                         break;
 136
 137                 if (data->first) {
 138                         u32 scancode;
 139                         scancode = (bitrev8((data->bits >> 8) & 0xff) << 8) |
 140                                    (bitrev8((data->bits >> 0) & 0xff) << 0);
 141                         IR_dprintk(1, "JVC scancode 0x%04x\n", scancode);
 142                         rc_keydown(dev, scancode, data->toggle);
 143                         data->first = false;
 144                         data->old_bits = data->bits;
 145                 } else if (data->bits == data->old_bits) {
 146                         IR_dprintk(1, "JVC repeat\n");
 147                         rc_repeat(dev);
 148                 } else {
 149                         IR_dprintk(1, "JVC invalid repeat msg\n");
 150                         break;
 151                 }
 152
 153                 data->count = 0;
 154                 data->state = STATE_CHECK_REPEAT;
 155                 return 0;
 156
 157         case STATE_CHECK_REPEAT:
 158                 if (!ev.pulse)
 159                         break;
 160
 161                 if (eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
 162                         data->state = STATE_INACTIVE;
 163   else
 164                         data->state = STATE_BIT_PULSE;
 165                 goto again;
 166         }
 167
 168 out:
 169         IR_dprintk(1, "JVC decode failed at state %d (%uus %s)\n",
 170                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 171         data->state = STATE_INACTIVE;
 172         return -EINVAL;
 173 }
 174
 175 static struct ir_raw_handler jvc_handler = {
 176         .protocols      = RC_TYPE_JVC,
 177         .decode         = ir_jvc_decode,
 178 };
 179
 180 static int __init ir_jvc_decode_init(void)
 181 {
 182         ir_raw_handler_register(&jvc_handler);
 183
 184         printk(KERN_INFO "IR JVC protocol handler initialized\n");
 185         return 0;
 186 }
 187
 188 static void __exit ir_jvc_decode_exit(void)
 189 {
 190         ir_raw_handler_unregister(&jvc_handler);
 191 }
 192
 193 module_init(ir_jvc_decode_init);
 194 module_exit(ir_jvc_decode_exit);
 195
 196 MODULE_LICENSE("GPL");
 197 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
 198 MODULE_DESCRIPTION("JVC IR protocol decoder");