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};
114