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  * @duration:   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 (!(dev->enabled_protocols & RC_BIT_XMP))
  47                 return 0;
  48
  49         if (!is_timing_event(ev)) {
  50                 if (ev.reset)
  51                         data->state = STATE_INACTIVE;
  52                 return 0;
  53         }
  54
  55         IR_dprintk(2, "XMP decode started at state %d %d (%uus %s)\n",
  56                    data->state, data->count, TO_US(ev.duration), TO_STR(ev.pulse));
  57
  58         switch (data->state) {
  59
  60         case STATE_INACTIVE:
  61                 if (!ev.pulse)
  62                         break;
  63
  64                 if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) {
  65                         data->count = 0;
  66                         data->state = STATE_NIBBLE_SPACE;
  67                 }
  68
  69                 return 0;
  70
  71         case STATE_LEADER_PULSE:
  72                 if (!ev.pulse)
  73                         break;
  74
  75                 if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2))
  76                         data->state = STATE_NIBBLE_SPACE;
  77
  78                 return 0;
  79
  80         case STATE_NIBBLE_SPACE:
  81                 if (ev.pulse)
  82                         break;
  83
  84                 if (geq_margin(ev.duration, XMP_TRAILER_SPACE, XMP_NIBBLE_PREFIX)) {
  85                         int divider, i;
  86                         u8 addr, subaddr, subaddr2, toggle, oem, obc1, obc2, sum1, sum2;
  87                         u32 *n;
  88                         u32 scancode;
  89
  90                         if (data->count != 16) {
  91                                 IR_dprintk(2, "received TRAILER period at index %d: %u\n",
  92                                         data->count, ev.duration);
  93                                 data->state = STATE_INACTIVE;
  94                                 return -EINVAL;
  95                         }
  96
  97                         n = data->durations;
  98                         /*
  99                          * the 4th nibble should be 15 so base the divider on this
 100                          * to transform durations into nibbles. Substract 2000 from
 101                          * the divider to compensate for fluctuations in the signal
 102                          */
 103                         divider = (n[3] - XMP_NIBBLE_PREFIX) / 15 - 2000;
 104                         if (divider < 50) {
 105                                 IR_dprintk(2, "divider to small %d.\n", divider);
 106                                 data->state = STATE_INACTIVE;
 107                                 return -EINVAL;
 108                         }
 109
 110                         /* convert to nibbles and do some sanity checks */
 111                         for (i = 0; i < 16; i++)
 112                                 n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider;
 113                         sum1 = (15 + n[0] + n[1] + n[2] + n[3] +
 114                                 n[4] + n[5] + n[6] + n[7]) % 16;
 115                         sum2 = (15 + n[8] + n[9] + n[10] + n[11] +
 116                                 n[12] + n[13] + n[14] + n[15]) % 16;
 117
 118                         if (sum1 != 15 || sum2 != 15) {
 119                                 IR_dprintk(2, "checksum errors sum1=0x%X sum2=0x%X\n",
 120                                         sum1, sum2);
 121                                 data->state = STATE_INACTIVE;
 122                                 return -EINVAL;
 123                         }
 124
 125                         subaddr  = n[0] << 4 | n[2];
 126                         subaddr2 = n[8] << 4 | n[11];
 127                         oem      = n[4] << 4 | n[5];
 128                         addr     = n[6] << 4 | n[7];
 129                         toggle   = n[10];
 130                         obc1 = n[12] << 4 | n[13];
 131                         obc2 = n[14] << 4 | n[15];
 132                         if (subaddr != subaddr2) {
 133                                 IR_dprintk(2, "subaddress nibbles mismatch 0x%02X != 0x%02X\n",
 134                                         subaddr, subaddr2);
 135                                 data->state = STATE_INACTIVE;
 136                                 return -EINVAL;
 137                         }
 138                         if (oem != 0x44)
 139                                 IR_dprintk(1, "Warning: OEM nibbles 0x%02X. Expected 0x44\n",
 140                                         oem);
 141
 142                         scancode = addr << 24 | subaddr << 16 |
 143                                    obc1 << 8 | obc2;
 144                         IR_dprintk(1, "XMP scancode 0x%06x\n", scancode);
 145
 146                         if (toggle == 0) {
 147                                 rc_keydown(dev, RC_TYPE_XMP, scancode, 0);
 148                         } else {
 149                                 rc_repeat(dev);
 150                                 IR_dprintk(1, "Repeat last key\n");
 151                         }
 152                         data->state = STATE_INACTIVE;
 153
 154                         return 0;
 155
 156                 } else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) {
 157                         /* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */
 158                         if (data->count == 16) {
 159                                 IR_dprintk(2, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n",
 160                                         data->count, ev.duration);
 161                                 /*
 162                                  * TODO: for now go back to half frame position
 163                                  *       so trailer can be found and key press
 164                                  *       can be handled.
 165                                  */
 166                                 data->count = 8;
 167                         }
 168
 169                         else if (data->count != 8)
 170                                 IR_dprintk(2, "received half frame pulse at index %d: %u\n",
 171                                         data->count, ev.duration);
 172                         data->state = STATE_LEADER_PULSE;
 173
 174                         return 0;
 175
 176                 } else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) {
 177                         /* store nibble raw data, decode after trailer */
 178                         if (data->count == 16) {
 179                                 IR_dprintk(2, "to many pulses (%d) ignoring: %u\n",
 180                                         data->count, ev.duration);
 181                                 data->state = STATE_INACTIVE;
 182                                 return -EINVAL;
 183                         }
 184                         data->durations[data->count] = ev.duration;
 185                         data->count++;
 186                         data->state = STATE_LEADER_PULSE;
 187
 188                         return 0;
 189
 190                 }
 191
 192                 break;
 193         }
 194
 195         IR_dprintk(1, "XMP decode failed at count %d state %d (%uus %s)\n",
 196                    data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 197         data->state = STATE_INACTIVE;
 198         return -EINVAL;
 199 }
 200
 201 static struct ir_raw_handler xmp_handler = {
 202         .protocols      = RC_BIT_XMP,
 203         .decode         = ir_xmp_decode,
 204 };
 205
 206 static int __init ir_xmp_decode_init(void)
 207 {
 208         ir_raw_handler_register(&xmp_handler);
 209
 210         printk(KERN_INFO "IR XMP protocol handler initialized\n");
 211         return 0;
 212 }
 213
 214 static void __exit ir_xmp_decode_exit(void)
 215 {
 216         ir_raw_handler_unregister(&xmp_handler);
 217 }
 218
 219 module_init(ir_xmp_decode_init);
 220 module_exit(ir_xmp_decode_exit);
 221
 222 MODULE_LICENSE("GPL");
 223 MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>");
 224 MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)");
 225 MODULE_DESCRIPTION("XMP IR protocol decoder");