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

   1 /* ir-xmp-decoder.c - handle XMP IR Pulse/Space protocol
   2  *
   3  * Copyright (C) 2014 by Marcel Mol
   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  * - Based on info from http://www.hifi-remote.com
  15  * - Ignore Toggle=9 frames
  16  * - Ignore XMP-1 XMP-2 difference, always store 16 bit OBC
  17  */
  18
  19 #include <linux/bitrev.h>
  20 #include <linux/module.h>
  21 #include "rc-core-priv.h"
  22
  23 #define XMP_UNIT                  136000 /* ns */
  24 #define XMP_LEADER                210000 /* ns */
  25 #define XMP_NIBBLE_PREFIX         760000 /* ns */
  26 #define XMP_HALFFRAME_SPACE     13800000 /* ns */
  27 #define XMP_TRAILER_SPACE       20000000 /* should be 80ms but not all dureation supliers can go that high */
  28
  29 enum xmp_state {
  30         STATE_INACTIVE,
  31         STATE_LEADER_PULSE,
  32         STATE_NIBBLE_SPACE,
  33 };
  34
  35 /**
  36  * ir_xmp_decode() - Decode one XMP pulse or space
  37  * @dev:        the struct rc_dev descriptor of the device
  38  * @ev:         the struct ir_raw_event descriptor of the pulse/space
  39  *
  40  * This function returns -EINVAL if the pulse violates the state machine
  41  */
  42 static int ir_xmp_decode(struct rc_dev *dev, struct ir_raw_event ev)
  43 {
  44         struct xmp_dec *data = &dev->raw->xmp;
  45
  46         if (!is_timing_event(ev)) {
  47                 if (ev.reset)
  48                         data->state = STATE_INACTIVE;
  49                 return 0;
  50         }
  51
  52         dev_dbg(&dev->dev, "XMP decode started at state %d %d (%uus %s)\n",
  53                 data->state, data->count, TO_US(ev.duration), TO_STR(ev.pulse));
  54
  55         switch (data->state) {
  56
  57         case STATE_INACTIVE:
  58                 if (!ev.pulse)
  59                         break;
  60
  61                 if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) {
  62                         data->count = 0;
  63                         data->state = STATE_NIBBLE_SPACE;
  64                 }
  65
  66                 return 0;
  67
  68         case STATE_LEADER_PULSE:
  69                 if (!ev.pulse)
  70                         break;
  71
  72                 if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2))
  73                         data->state = STATE_NIBBLE_SPACE;
  74
  75                 return 0;
  76
  77         case STATE_NIBBLE_SPACE:
  78                 if (ev.pulse)
  79                         break;
  80
  81                 if (geq_margin(ev.duration, XMP_TRAILER_SPACE, XMP_NIBBLE_PREFIX)) {
  82                         int divider, i;
  83                         u8 addr, subaddr, subaddr2, toggle, oem, obc1, obc2, sum1, sum2;
  84                         u32 *n;
  85                         u32 scancode;
  86
  87                         if (data->count != 16) {
  88                                 dev_dbg(&dev->dev, "received TRAILER period at index %d: %u\n",
  89                                         data->count, ev.duration);
  90                                 data->state = STATE_INACTIVE;
  91                                 return -EINVAL;
  92                         }
  93
  94                         n = data->durations;
  95                         /*
  96                          * the 4th nibble should be 15 so base the divider on this
  97                          * to transform durations into nibbles. Substract 2000 from
  98                          * the divider to compensate for fluctuations in the signal
  99                          */
 100                         divider = (n[3] - XMP_NIBBLE_PREFIX) / 15 - 2000;
 101                         if (divider < 50) {
 102                                 dev_dbg(&dev->dev, "divider to small %d.\n",
 103                                         divider);
 104                                 data->state = STATE_INACTIVE;
 105                                 return -EINVAL;
 106                         }
 107
 108                         /* convert to nibbles and do some sanity checks */
 109                         for (i = 0; i < 16; i++)
 110                                 n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider;
 111                         sum1 = (15 + n[0] + n[1] + n[2] + n[3] +
 112                                 n[4] + n[5] + n[6] + n[7]) % 16;
 113                         sum2 = (15 + n[8] + n[9] + n[10] + n[11] +
 114                                 n[12] + n[13] + n[14] + n[15]) % 16;
 115
 116                         if (sum1 != 15 || sum2 != 15) {
 117                                 dev_dbg(&dev->dev, "checksum errors sum1=0x%X sum2=0x%X\n",
 118                                         sum1, sum2);
 119                                 data->state = STATE_INACTIVE;
 120                                 return -EINVAL;
 121                         }
 122
 123                         subaddr  = n[0] << 4 | n[2];
 124                         subaddr2 = n[8] << 4 | n[11];
 125                         oem      = n[4] << 4 | n[5];
 126                         addr     = n[6] << 4 | n[7];
 127                         toggle   = n[10];
 128                         obc1 = n[12] << 4 | n[13];
 129                         obc2 = n[14] << 4 | n[15];
 130                         if (subaddr != subaddr2) {
 131                                 dev_dbg(&dev->dev, "subaddress nibbles mismatch 0x%02X != 0x%02X\n",
 132                                         subaddr, subaddr2);
 133                                 data->state = STATE_INACTIVE;
 134                                 return -EINVAL;
 135                         }
 136                         if (oem != 0x44)
 137                                 dev_dbg(&dev->dev, "Warning: OEM nibbles 0x%02X. Expected 0x44\n",
 138                                         oem);
 139
 140                         scancode = addr << 24 | subaddr << 16 |
 141                                    obc1 << 8 | obc2;
 142                         dev_dbg(&dev->dev, "XMP scancode 0x%06x\n", scancode);
 143
 144                         if (toggle == 0) {
 145                                 rc_keydown(dev, RC_PROTO_XMP, scancode, 0);
 146                         } else {
 147                                 rc_repeat(dev);
 148                                 dev_dbg(&dev->dev, "Repeat last key\n");
 149                         }
 150                         data->state = STATE_INACTIVE;
 151
 152                         return 0;
 153
 154                 } else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) {
 155                         /* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */
 156                         if (data->count == 16) {
 157                                 dev_dbg(&dev->dev, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n",
 158                                         data->count, ev.duration);
 159                                 /*
 160                                  * TODO: for now go back to half frame position
 161                                  *       so trailer can be found and key press
 162                                  *       can be handled.
 163                                  */
 164                                 data->count = 8;
 165                         }
 166
 167                         else if (data->count != 8)
 168                                 dev_dbg(&dev->dev, "received half frame pulse at index %d: %u\n",
 169                                         data->count, ev.duration);
 170                         data->state = STATE_LEADER_PULSE;
 171
 172                         return 0;
 173
 174                 } else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) {
 175                         /* store nibble raw data, decode after trailer */
 176                         if (data->count == 16) {
 177                                 dev_dbg(&dev->dev, "to many pulses (%d) ignoring: %u\n",
 178                                         data->count, ev.duration);
 179                                 data->state = STATE_INACTIVE;
 180                                 return -EINVAL;
 181                         }
 182                         data->durations[data->count] = ev.duration;
 183                         data->count++;
 184                         data->state = STATE_LEADER_PULSE;
 185
 186                         return 0;
 187
 188                 }
 189
 190                 break;
 191         }
 192
 193         dev_dbg(&dev->dev, "XMP decode failed at count %d state %d (%uus %s)\n",
 194                 data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 195         data->state = STATE_INACTIVE;
 196         return -EINVAL;
 197 }
 198
 199 static struct ir_raw_handler xmp_handler = {
 200         .protocols      = RC_PROTO_BIT_XMP,
 201         .decode         = ir_xmp_decode,
 202         .min_timeout    = XMP_TRAILER_SPACE,
 203 };
 204
 205 static int __init ir_xmp_decode_init(void)
 206 {
 207         ir_raw_handler_register(&xmp_handler);
 208
 209         printk(KERN_INFO "IR XMP protocol handler initialized\n");
 210         return 0;
 211 }
 212
 213 static void __exit ir_xmp_decode_exit(void)
 214 {
 215         ir_raw_handler_unregister(&xmp_handler);
 216 }
 217
 218 module_init(ir_xmp_decode_init);
 219 module_exit(ir_xmp_decode_exit);
 220
 221 MODULE_LICENSE("GPL");
 222 MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>");
 223 MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)");
 224 MODULE_DESCRIPTION("XMP IR protocol decoder");