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 (!is_timing_event(ev)) {
  47                 if (ev.reset)
  48                         data->state = STATE_INACTIVE;
  49                 return 0;
  50         }
  51
  52         IR_dprintk(2, "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                                 IR_dprintk(2, "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                                 IR_dprintk(2, "divider to small %d.\n", divider);
 103                                 data->state = STATE_INACTIVE;
 104                                 return -EINVAL;
 105                         }
 106
 107                         /* convert to nibbles and do some sanity checks */
 108                         for (i = 0; i < 16; i++)
 109                                 n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider;
 110                         sum1 = (15 + n[0] + n[1] + n[2] + n[3] +
 111                                 n[4] + n[5] + n[6] + n[7]) % 16;
 112                         sum2 = (15 + n[8] + n[9] + n[10] + n[11] +
 113                                 n[12] + n[13] + n[14] + n[15]) % 16;
 114
 115                         if (sum1 != 15 || sum2 != 15) {
 116                                 IR_dprintk(2, "checksum errors sum1=0x%X sum2=0x%X\n",
 117                                         sum1, sum2);
 118                                 data->state = STATE_INACTIVE;
 119                                 return -EINVAL;
 120                         }
 121
 122                         subaddr  = n[0] << 4 | n[2];
 123                         subaddr2 = n[8] << 4 | n[11];
 124                         oem      = n[4] << 4 | n[5];
 125                         addr     = n[6] << 4 | n[7];
 126                         toggle   = n[10];
 127                         obc1 = n[12] << 4 | n[13];
 128                         obc2 = n[14] << 4 | n[15];
 129                         if (subaddr != subaddr2) {
 130                                 IR_dprintk(2, "subaddress nibbles mismatch 0x%02X != 0x%02X\n",
 131                                         subaddr, subaddr2);
 132                                 data->state = STATE_INACTIVE;
 133                                 return -EINVAL;
 134                         }
 135                         if (oem != 0x44)
 136                                 IR_dprintk(1, "Warning: OEM nibbles 0x%02X. Expected 0x44\n",
 137                                         oem);
 138
 139                         scancode = addr << 24 | subaddr << 16 |
 140                                    obc1 << 8 | obc2;
 141                         IR_dprintk(1, "XMP scancode 0x%06x\n", scancode);
 142
 143                         if (toggle == 0) {
 144                                 rc_keydown(dev, RC_PROTO_XMP, scancode, 0);
 145                         } else {
 146                                 rc_repeat(dev);
 147                                 IR_dprintk(1, "Repeat last key\n");
 148                         }
 149                         data->state = STATE_INACTIVE;
 150
 151                         return 0;
 152
 153                 } else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) {
 154                         /* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */
 155                         if (data->count == 16) {
 156                                 IR_dprintk(2, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n",
 157                                         data->count, ev.duration);
 158                                 /*
 159                                  * TODO: for now go back to half frame position
 160                                  *       so trailer can be found and key press
 161                                  *       can be handled.
 162                                  */
 163                                 data->count = 8;
 164                         }
 165
 166                         else if (data->count != 8)
 167                                 IR_dprintk(2, "received half frame pulse at index %d: %u\n",
 168                                         data->count, ev.duration);
 169                         data->state = STATE_LEADER_PULSE;
 170
 171                         return 0;
 172
 173                 } else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) {
 174                         /* store nibble raw data, decode after trailer */
 175                         if (data->count == 16) {
 176                                 IR_dprintk(2, "to many pulses (%d) ignoring: %u\n",
 177                                         data->count, ev.duration);
 178                                 data->state = STATE_INACTIVE;
 179                                 return -EINVAL;
 180                         }
 181                         data->durations[data->count] = ev.duration;
 182                         data->count++;
 183                         data->state = STATE_LEADER_PULSE;
 184
 185                         return 0;
 186
 187                 }
 188
 189                 break;
 190         }
 191
 192         IR_dprintk(1, "XMP decode failed at count %d state %d (%uus %s)\n",
 193                    data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 194         data->state = STATE_INACTIVE;
 195         return -EINVAL;
 196 }
 197
 198 static struct ir_raw_handler xmp_handler = {
 199         .protocols      = RC_PROTO_BIT_XMP,
 200         .decode         = ir_xmp_decode,
 201 };
 202
 203 static int __init ir_xmp_decode_init(void)
 204 {
 205         ir_raw_handler_register(&xmp_handler);
 206
 207         printk(KERN_INFO "IR XMP protocol handler initialized\n");
 208         return 0;
 209 }
 210
 211 static void __exit ir_xmp_decode_exit(void)
 212 {
 213         ir_raw_handler_unregister(&xmp_handler);
 214 }
 215
 216 module_init(ir_xmp_decode_init);
 217 module_exit(ir_xmp_decode_exit);
 218
 219 MODULE_LICENSE("GPL");
 220 MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>");
 221 MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)");
 222 MODULE_DESCRIPTION("XMP IR protocol decoder");