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

   1// SPDX-License-Identifier: GPL-2.0-only
   2/* ir-xmp-decoder.c - handle XMP IR Pulse/Space protocol
   3 *
   4 * Copyright (C) 2014 by Marcel Mol
   5 *
   6 * - Based on info from http://www.hifi-remote.com
   7 * - Ignore Toggle=9 frames
   8 * - Ignore XMP-1 XMP-2 difference, always store 16 bit OBC
   9 */
  10
  11#include <linux/bitrev.h>
  12#include <linux/module.h>
  13#include "rc-core-priv.h"
  14
  15#define XMP_UNIT                  136 /* us */
  16#define XMP_LEADER                210 /* us */
  17#define XMP_NIBBLE_PREFIX         760 /* us */
  18#define XMP_HALFFRAME_SPACE     13800 /* us */
  19/* should be 80ms but not all duration supliers can go that high */
  20#define XMP_TRAILER_SPACE       20000
  21
  22enum xmp_state {
  23        STATE_INACTIVE,
  24        STATE_LEADER_PULSE,
  25        STATE_NIBBLE_SPACE,
  26};
  27
  28/**
  29 * ir_xmp_decode() - Decode one XMP pulse or space
  30 * @dev:        the struct rc_dev descriptor of the device
  31 * @ev:         the struct ir_raw_event descriptor of the pulse/space
  32 *
  33 * This function returns -EINVAL if the pulse violates the state machine
  34 */
  35static int ir_xmp_decode(struct rc_dev *dev, struct ir_raw_event ev)
  36{
  37        struct xmp_dec *data = &dev->raw->xmp;
  38
  39        if (!is_timing_event(ev)) {
  40                if (ev.reset)
  41                        data->state = STATE_INACTIVE;
  42                return 0;
  43        }
  44
  45        dev_dbg(&dev->dev, "XMP decode started at state %d %d (%uus %s)\n",
  46                data->state, data->count, ev.duration, TO_STR(ev.pulse));
  47
  48        switch (data->state) {
  49
  50        case STATE_INACTIVE:
  51                if (!ev.pulse)
  52                        break;
  53
  54                if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) {
  55                        data->count = 0;
  56                        data->state = STATE_NIBBLE_SPACE;
  57                }
  58
  59                return 0;
  60
  61        case STATE_LEADER_PULSE:
  62                if (!ev.pulse)
  63                        break;
  64
  65                if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2))
  66                        data->state = STATE_NIBBLE_SPACE;
  67
  68                return 0;
  69
  70        case STATE_NIBBLE_SPACE:
  71                if (ev.pulse)
  72                        break;
  73
  74                if (geq_margin(ev.duration, XMP_TRAILER_SPACE, XMP_NIBBLE_PREFIX)) {
  75                        int divider, i;
  76                        u8 addr, subaddr, subaddr2, toggle, oem, obc1, obc2, sum1, sum2;
  77                        u32 *n;
  78                        u32 scancode;
  79
  80                        if (data->count != 16) {
  81                                dev_dbg(&dev->dev, "received TRAILER period at index %d: %u\n",
  82                                        data->count, ev.duration);
  83                                data->state = STATE_INACTIVE;
  84                                return -EINVAL;
  85                        }
  86
  87                        n = data->durations;
  88                        /*
  89                         * the 4th nibble should be 15 so base the divider on this
  90                         * to transform durations into nibbles. Subtract 2000 from
  91                         * the divider to compensate for fluctuations in the signal
  92                         */
  93                        divider = (n[3] - XMP_NIBBLE_PREFIX) / 15 - 2000;
  94                        if (divider < 50) {
  95                                dev_dbg(&dev->dev, "divider to small %d.\n",
  96                                        divider);
  97                                data->state = STATE_INACTIVE;
  98                                return -EINVAL;
  99                        }
 100
 101                        /* convert to nibbles and do some sanity checks */
 102                        for (i = 0; i < 16; i++)
 103                                n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider;
 104                        sum1 = (15 + n[0] + n[1] + n[2] + n[3] +
 105                                n[4] + n[5] + n[6] + n[7]) % 16;
 106                        sum2 = (15 + n[8] + n[9] + n[10] + n[11] +
 107                                n[12] + n[13] + n[14] + n[15]) % 16;
 108
 109                        if (sum1 != 15 || sum2 != 15) {
 110                                dev_dbg(&dev->dev, "checksum errors sum1=0x%X sum2=0x%X\n",
 111                                        sum1, sum2);
 112                                data->state = STATE_INACTIVE;
 113                                return -EINVAL;
 114                        }
 115
 116                        subaddr  = n[0] << 4 | n[2];
 117                        subaddr2 = n[8] << 4 | n[11];
 118                        oem      = n[4] << 4 | n[5];
 119                        addr     = n[6] << 4 | n[7];
 120                        toggle   = n[10];
 121                        obc1 = n[12] << 4 | n[13];
 122                        obc2 = n[14] << 4 | n[15];
 123                        if (subaddr != subaddr2) {
 124                                dev_dbg(&dev->dev, "subaddress nibbles mismatch 0x%02X != 0x%02X\n",
 125                                        subaddr, subaddr2);
 126                                data->state = STATE_INACTIVE;
 127                                return -EINVAL;
 128                        }
 129                        if (oem != 0x44)
 130                                dev_dbg(&dev->dev, "Warning: OEM nibbles 0x%02X. Expected 0x44\n",
 131                                        oem);
 132
 133                        scancode = addr << 24 | subaddr << 16 |
 134                                   obc1 << 8 | obc2;
 135                        dev_dbg(&dev->dev, "XMP scancode 0x%06x\n", scancode);
 136
 137                        if (toggle == 0) {
 138                                rc_keydown(dev, RC_PROTO_XMP, scancode, 0);
 139                        } else {
 140                                rc_repeat(dev);
 141                                dev_dbg(&dev->dev, "Repeat last key\n");
 142                        }
 143                        data->state = STATE_INACTIVE;
 144
 145                        return 0;
 146
 147                } else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) {
 148                        /* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */
 149                        if (data->count == 16) {
 150                                dev_dbg(&dev->dev, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n",
 151                                        data->count, ev.duration);
 152                                /*
 153                                 * TODO: for now go back to half frame position
 154                                 *       so trailer can be found and key press
 155                                 *       can be handled.
 156                                 */
 157                                data->count = 8;
 158                        }
 159
 160                        else if (data->count != 8)
 161                                dev_dbg(&dev->dev, "received half frame pulse at index %d: %u\n",
 162                                        data->count, ev.duration);
 163                        data->state = STATE_LEADER_PULSE;
 164
 165                        return 0;
 166
 167                } else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) {
 168                        /* store nibble raw data, decode after trailer */
 169                        if (data->count == 16) {
 170                                dev_dbg(&dev->dev, "too many pulses (%d) ignoring: %u\n",
 171                                        data->count, ev.duration);
 172                                data->state = STATE_INACTIVE;
 173                                return -EINVAL;
 174                        }
 175                        data->durations[data->count] = ev.duration;
 176                        data->count++;
 177                        data->state = STATE_LEADER_PULSE;
 178
 179                        return 0;
 180
 181                }
 182
 183                break;
 184        }
 185
 186        dev_dbg(&dev->dev, "XMP decode failed at count %d state %d (%uus %s)\n",
 187                data->count, data->state, ev.duration, TO_STR(ev.pulse));
 188        data->state = STATE_INACTIVE;
 189        return -EINVAL;
 190}
 191
 192static struct ir_raw_handler xmp_handler = {
 193        .protocols      = RC_PROTO_BIT_XMP,
 194        .decode         = ir_xmp_decode,
 195        .min_timeout    = XMP_TRAILER_SPACE,
 196};
 197
 198static int __init ir_xmp_decode_init(void)
 199{
 200        ir_raw_handler_register(&xmp_handler);
 201
 202        printk(KERN_INFO "IR XMP protocol handler initialized\n");
 203        return 0;
 204}
 205
 206static void __exit ir_xmp_decode_exit(void)
 207{
 208        ir_raw_handler_unregister(&xmp_handler);
 209}
 210
 211module_init(ir_xmp_decode_init);
 212module_exit(ir_xmp_decode_exit);
 213
 214MODULE_LICENSE("GPL");
 215MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>");
 216MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)");
 217MODULE_DESCRIPTION("XMP IR protocol decoder");
 218