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 */
11 static 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 */
60 static 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  */
71 struct 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