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