img-ir-rc6.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * ImgTec IR Decoder setup for Philips RC-6 protocol.
  4 *
  5 * Copyright 2012-2014 Imagination Technologies Ltd.
  6 */
  7
  8#include "img-ir-hw.h"
  9
 10/* Convert RC6 data to a scancode */
 11static int img_ir_rc6_scancode(int len, u64 raw, u64 enabled_protocols,
 12				struct img_ir_scancode_req *request)
 13{
 14	unsigned int addr, cmd, mode, trl1, trl2;
 15
 16	/*
 17	 * Due to a side effect of the decoder handling the double length
 18	 * Trailer bit, the header information is a bit scrambled, and the
 19	 * raw data is shifted incorrectly.
 20	 * This workaround effectively recovers the header bits.
 21	 *
 22	 * The Header field should look like this:
 23	 *
 24	 * StartBit ModeBit2 ModeBit1 ModeBit0 TrailerBit
 25	 *
 26	 * But what we get is:
 27	 *
 28	 * ModeBit2 ModeBit1 ModeBit0 TrailerBit1 TrailerBit2
 29	 *
 30	 * The start bit is not important to recover the scancode.
 31	 */
 32
 33	raw	>>= 27;
 34
 35	trl1	= (raw >>  17)	& 0x01;
 36	trl2	= (raw >>  16)	& 0x01;
 37
 38	mode	= (raw >>  18)	& 0x07;
 39	addr	= (raw >>   8)	& 0xff;
 40	cmd	=  raw		& 0xff;
 41
 42	/*
 43	 * Due to the above explained irregularity the trailer bits cannot
 44	 * have the same value.
 45	 */
 46	if (trl1 == trl2)
 47		return -EINVAL;
 48
 49	/* Only mode 0 supported for now */
 50	if (mode)
 51		return -EINVAL;
 52
 53	request->protocol = RC_PROTO_RC6_0;
 54	request->scancode = addr << 8 | cmd;
 55	request->toggle	  = trl2;
 56	return IMG_IR_SCANCODE;
 57}
 58
 59/* Convert RC6 scancode to RC6 data filter */
 60static int img_ir_rc6_filter(const struct rc_scancode_filter *in,
 61				 struct img_ir_filter *out, u64 protocols)
 62{
 63	/* Not supported by the hw. */
 64	return -EINVAL;
 65}
 66
 67/*
 68 * RC-6 decoder
 69 * see http://www.sbprojects.com/knowledge/ir/rc6.php
 70 */
 71struct img_ir_decoder img_ir_rc6 = {
 72	.type		= RC_PROTO_BIT_RC6_0,
 73	.control	= {
 74		.bitorien	= 1,
 75		.code_type	= IMG_IR_CODETYPE_BIPHASE,
 76		.decoden	= 1,
 77		.decodinpol	= 1,
 78	},
 79	/* main timings */
 80	.tolerance	= 20,
 81	/*
 82	 * Due to a quirk in the img-ir decoder, default header values do
 83	 * not work, the values described below were extracted from
 84	 * successful RTL test cases.
 85	 */
 86	.timings	= {
 87		/* leader symbol */
 88		.ldr = {
 89			.pulse	= { 650 },
 90			.space	= { 660 },
 91		},
 92		/* 0 symbol */
 93		.s00 = {
 94			.pulse	= { 370 },
 95			.space	= { 370 },
 96		},
 97		/* 01 symbol */
 98		.s01 = {
 99			.pulse	= { 370 },
100			.space	= { 370 },
101		},
102		/* free time */
103		.ft  = {
104			.minlen = 21,
105			.maxlen = 21,
106			.ft_min = 2666,	/* 2.666 ms */
107		},
108	},
109
110	/* scancode logic */
111	.scancode	= img_ir_rc6_scancode,
112	.filter		= img_ir_rc6_filter,
113};