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 };
118