drivers/media/rc/img-ir/img-ir-rc6.c

   1 /*
   2  * ImgTec IR Decoder setup for Philips RC-6 protocol.
   3  *
   4  * Copyright 2012-2014 Imagination Technologies Ltd.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2 of the License, or (at your
   9  * option) any later version.
  10  */
  11
  12 #include "img-ir-hw.h"
  13
  14 /* Convert RC6 data to a scancode */
  15 static int img_ir_rc6_scancode(int len, u64 raw, u64 enabled_protocols,
  16                                 struct img_ir_scancode_req *request)
  17 {
  18         unsigned int addr, cmd, mode, trl1, trl2;
  19
  20         /*
  21          * Due to a side effect of the decoder handling the double length
  22          * Trailer bit, the header information is a bit scrambled, and the
  23          * raw data is shifted incorrectly.
  24          * This workaround effectively recovers the header bits.
  25          *
  26          * The Header field should look like this:
  27          *
  28          * StartBit ModeBit2 ModeBit1 ModeBit0 TrailerBit
  29          *
  30          * But what we get is:
  31          *
  32          * ModeBit2 ModeBit1 ModeBit0 TrailerBit1 TrailerBit2
  33          *
  34          * The start bit is not important to recover the scancode.
  35          */
  36
  37         raw     >>= 27;
  38
  39         trl1    = (raw >>  17)  & 0x01;
  40         trl2    = (raw >>  16)  & 0x01;
  41
  42         mode    = (raw >>  18)  & 0x07;
  43         addr    = (raw >>   8)  & 0xff;
  44         cmd     =  raw          & 0xff;
  45
  46         /*
  47          * Due to the above explained irregularity the trailer bits cannot
  48          * have the same value.
  49          */
  50         if (trl1 == trl2)
  51                 return -EINVAL;
  52
  53         /* Only mode 0 supported for now */
  54         if (mode)
  55                 return -EINVAL;
  56
  57         request->protocol = RC_PROTO_RC6_0;
  58         request->scancode = addr << 8 | cmd;
  59         request->toggle   = trl2;
  60         return IMG_IR_SCANCODE;
  61 }
  62
  63 /* Convert RC6 scancode to RC6 data filter */
  64 static int img_ir_rc6_filter(const struct rc_scancode_filter *in,
  65                                  struct img_ir_filter *out, u64 protocols)
  66 {
  67         /* Not supported by the hw. */
  68         return -EINVAL;
  69 }
  70
  71 /*
  72  * RC-6 decoder
  73  * see http://www.sbprojects.com/knowledge/ir/rc6.php
  74  */
  75 struct img_ir_decoder img_ir_rc6 = {
  76         .type           = RC_PROTO_BIT_RC6_0,
  77         .control        = {
  78                 .bitorien       = 1,
  79                 .code_type      = IMG_IR_CODETYPE_BIPHASE,
  80                 .decoden        = 1,
  81                 .decodinpol     = 1,
  82         },
  83         /* main timings */
  84         .tolerance      = 20,
  85         /*
  86          * Due to a quirk in the img-ir decoder, default header values do
  87          * not work, the values described below were extracted from
  88          * successful RTL test cases.
  89          */
  90         .timings        = {
  91                 /* leader symbol */
  92                 .ldr = {
  93                         .pulse  = { 650 },
  94                         .space  = { 660 },
  95                 },
  96                 /* 0 symbol */
  97                 .s00 = {
  98                         .pulse  = { 370 },
  99                         .space  = { 370 },
 100                 },
 101                 /* 01 symbol */
 102                 .s01 = {
 103                         .pulse  = { 370 },
 104                         .space  = { 370 },
 105                 },
 106                 /* free time */
 107                 .ft  = {
 108                         .minlen = 21,
 109                         .maxlen = 21,
 110                         .ft_min = 2666, /* 2.666 ms */
 111                 },
 112         },
 113
 114         /* scancode logic */
 115         .scancode       = img_ir_rc6_scancode,
 116         .filter         = img_ir_rc6_filter,
 117 };