LXR linux/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
  29enum 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 */
  42static 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
 199static 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
 205static 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
 213static void __exit ir_xmp_decode_exit(void)
 214{
 215        ir_raw_handler_unregister(&xmp_handler);
 216}
 217
 218module_init(ir_xmp_decode_init);
 219module_exit(ir_xmp_decode_exit);
 220
 221MODULE_LICENSE("GPL");
 222MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>");
 223MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)");
 224MODULE_DESCRIPTION("XMP IR protocol decoder");
 225