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
  22 enum 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  */
  35 static 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
 192 static 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
 198 static 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
 206 static void __exit ir_xmp_decode_exit(void)
 207 {
 208         ir_raw_handler_unregister(&xmp_handler);
 209 }
 210
 211 module_init(ir_xmp_decode_init);
 212 module_exit(ir_xmp_decode_exit);
 213
 214 MODULE_LICENSE("GPL");
 215 MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>");
 216 MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)");
 217 MODULE_DESCRIPTION("XMP IR protocol decoder");