tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/* ir-rc5-sz-decoder.c - handle RC5 Streamzap IR Pulse/Space protocol
2 *
3 * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
4 * Copyright (C) 2010 by Jarod Wilson <jarod@redhat.com>
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
8 * the Free Software Foundation version 2 of the License.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 */
15
16/*
17 * This code handles the 15 bit RC5-ish protocol used by the Streamzap
18 * PC Remote.
19 * It considers a carrier of 36 kHz, with a total of 15 bits, where
20 * the first two bits are start bits, and a third one is a filing bit
21 */
22
23#include "rc-core-priv.h"
24
25#define RC5_SZ_NBITS 15
26#define RC5_UNIT 888888 /* ns */
27#define RC5_BIT_START (1 * RC5_UNIT)
28#define RC5_BIT_END (1 * RC5_UNIT)
29
30enum rc5_sz_state {
31 STATE_INACTIVE,
32 STATE_BIT_START,
33 STATE_BIT_END,
34 STATE_FINISHED,
35};
36
37/**
38 * ir_rc5_sz_decode() - Decode one RC-5 Streamzap pulse or space
39 * @dev: the struct rc_dev descriptor of the device
40 * @ev: the struct ir_raw_event descriptor of the pulse/space
41 *
42 * This function returns -EINVAL if the pulse violates the state machine
43 */
44static int ir_rc5_sz_decode(struct rc_dev *dev, struct ir_raw_event ev)
45{
46 struct rc5_sz_dec *data = &dev->raw->rc5_sz;
47 u8 toggle, command, system;
48 u32 scancode;
49
50 if (!(dev->raw->enabled_protocols & RC_TYPE_RC5_SZ))
51 return 0;
52
53 if (!is_timing_event(ev)) {
54 if (ev.reset)
55 data->state = STATE_INACTIVE;
56 return 0;
57 }
58
59 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
60 goto out;
61
62again:
63 IR_dprintk(2, "RC5-sz decode started at state %i (%uus %s)\n",
64 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
65
66 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
67 return 0;
68
69 switch (data->state) {
70
71 case STATE_INACTIVE:
72 if (!ev.pulse)
73 break;
74
75 data->state = STATE_BIT_START;
76 data->count = 1;
77 data->wanted_bits = RC5_SZ_NBITS;
78 decrease_duration(&ev, RC5_BIT_START);
79 goto again;
80
81 case STATE_BIT_START:
82 if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
83 break;
84
85 data->bits <<= 1;
86 if (!ev.pulse)
87 data->bits |= 1;
88 data->count++;
89 data->state = STATE_BIT_END;
90 return 0;
91
92 case STATE_BIT_END:
93 if (!is_transition(&ev, &dev->raw->prev_ev))
94 break;
95
96 if (data->count == data->wanted_bits)
97 data->state = STATE_FINISHED;
98 else
99 data->state = STATE_BIT_START;
100
101 decrease_duration(&ev, RC5_BIT_END);
102 goto again;
103
104 case STATE_FINISHED:
105 if (ev.pulse)
106 break;
107
108 /* RC5-sz */
109 command = (data->bits & 0x0003F) >> 0;
110 system = (data->bits & 0x02FC0) >> 6;
111 toggle = (data->bits & 0x01000) ? 1 : 0;
112 scancode = system << 6 | command;
113
114 IR_dprintk(1, "RC5-sz scancode 0x%04x (toggle: %u)\n",
115 scancode, toggle);
116
117 rc_keydown(dev, scancode, toggle);
118 data->state = STATE_INACTIVE;
119 return 0;
120 }
121
122out:
123 IR_dprintk(1, "RC5-sz decode failed at state %i (%uus %s)\n",
124 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
125 data->state = STATE_INACTIVE;
126 return -EINVAL;
127}
128
129static struct ir_raw_handler rc5_sz_handler = {
130 .protocols = RC_TYPE_RC5_SZ,
131 .decode = ir_rc5_sz_decode,
132};
133
134static int __init ir_rc5_sz_decode_init(void)
135{
136 ir_raw_handler_register(&rc5_sz_handler);
137
138 printk(KERN_INFO "IR RC5 (streamzap) protocol handler initialized\n");
139 return 0;
140}
141
142static void __exit ir_rc5_sz_decode_exit(void)
143{
144 ir_raw_handler_unregister(&rc5_sz_handler);
145}
146
147module_init(ir_rc5_sz_decode_init);
148module_exit(ir_rc5_sz_decode_exit);
149
150MODULE_LICENSE("GPL");
151MODULE_AUTHOR("Jarod Wilson <jarod@redhat.com>");
152MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
153MODULE_DESCRIPTION("RC5 (streamzap) IR protocol decoder");