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Jarod Wilson7a569f52010-08-07 13:31:40 -03001/* 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
Mauro Carvalho Chehabf62de672010-11-09 23:09:57 -030023#include "rc-core-priv.h"
Paul Gortmaker7a707b82011-07-03 14:03:12 -040024#include <linux/module.h>
Jarod Wilson7a569f52010-08-07 13:31:40 -030025
26#define RC5_SZ_NBITS 15
27#define RC5_UNIT 888888 /* ns */
28#define RC5_BIT_START (1 * RC5_UNIT)
29#define RC5_BIT_END (1 * RC5_UNIT)
30
31enum rc5_sz_state {
32 STATE_INACTIVE,
33 STATE_BIT_START,
34 STATE_BIT_END,
35 STATE_FINISHED,
36};
37
38/**
39 * ir_rc5_sz_decode() - Decode one RC-5 Streamzap pulse or space
David Härdemand8b4b582010-10-29 16:08:23 -030040 * @dev: the struct rc_dev descriptor of the device
Jarod Wilson7a569f52010-08-07 13:31:40 -030041 * @ev: the struct ir_raw_event descriptor of the pulse/space
42 *
43 * This function returns -EINVAL if the pulse violates the state machine
44 */
David Härdemand8b4b582010-10-29 16:08:23 -030045static int ir_rc5_sz_decode(struct rc_dev *dev, struct ir_raw_event ev)
Jarod Wilson7a569f52010-08-07 13:31:40 -030046{
David Härdemand8b4b582010-10-29 16:08:23 -030047 struct rc5_sz_dec *data = &dev->raw->rc5_sz;
Jarod Wilson7a569f52010-08-07 13:31:40 -030048 u8 toggle, command, system;
49 u32 scancode;
50
Mauro Carvalho Chehab52b66142010-11-17 14:20:52 -030051 if (!(dev->raw->enabled_protocols & RC_TYPE_RC5_SZ))
Jarod Wilson7a569f52010-08-07 13:31:40 -030052 return 0;
53
Maxim Levitsky46519182010-10-16 19:56:28 -030054 if (!is_timing_event(ev)) {
55 if (ev.reset)
56 data->state = STATE_INACTIVE;
Jarod Wilson7a569f52010-08-07 13:31:40 -030057 return 0;
58 }
59
60 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
61 goto out;
62
63again:
64 IR_dprintk(2, "RC5-sz decode started at state %i (%uus %s)\n",
65 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
66
67 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
68 return 0;
69
70 switch (data->state) {
71
72 case STATE_INACTIVE:
73 if (!ev.pulse)
74 break;
75
76 data->state = STATE_BIT_START;
77 data->count = 1;
78 data->wanted_bits = RC5_SZ_NBITS;
79 decrease_duration(&ev, RC5_BIT_START);
80 goto again;
81
82 case STATE_BIT_START:
83 if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
84 break;
85
86 data->bits <<= 1;
87 if (!ev.pulse)
88 data->bits |= 1;
89 data->count++;
90 data->state = STATE_BIT_END;
91 return 0;
92
93 case STATE_BIT_END:
David Härdemand8b4b582010-10-29 16:08:23 -030094 if (!is_transition(&ev, &dev->raw->prev_ev))
Jarod Wilson7a569f52010-08-07 13:31:40 -030095 break;
96
97 if (data->count == data->wanted_bits)
98 data->state = STATE_FINISHED;
99 else
100 data->state = STATE_BIT_START;
101
102 decrease_duration(&ev, RC5_BIT_END);
103 goto again;
104
105 case STATE_FINISHED:
106 if (ev.pulse)
107 break;
108
109 /* RC5-sz */
110 command = (data->bits & 0x0003F) >> 0;
111 system = (data->bits & 0x02FC0) >> 6;
112 toggle = (data->bits & 0x01000) ? 1 : 0;
113 scancode = system << 6 | command;
114
115 IR_dprintk(1, "RC5-sz scancode 0x%04x (toggle: %u)\n",
116 scancode, toggle);
117
Mauro Carvalho Chehabca866742010-11-17 13:53:11 -0300118 rc_keydown(dev, scancode, toggle);
Jarod Wilson7a569f52010-08-07 13:31:40 -0300119 data->state = STATE_INACTIVE;
120 return 0;
121 }
122
123out:
124 IR_dprintk(1, "RC5-sz decode failed at state %i (%uus %s)\n",
125 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
126 data->state = STATE_INACTIVE;
127 return -EINVAL;
128}
129
130static struct ir_raw_handler rc5_sz_handler = {
Mauro Carvalho Chehab52b66142010-11-17 14:20:52 -0300131 .protocols = RC_TYPE_RC5_SZ,
Jarod Wilson7a569f52010-08-07 13:31:40 -0300132 .decode = ir_rc5_sz_decode,
133};
134
135static int __init ir_rc5_sz_decode_init(void)
136{
137 ir_raw_handler_register(&rc5_sz_handler);
138
139 printk(KERN_INFO "IR RC5 (streamzap) protocol handler initialized\n");
140 return 0;
141}
142
143static void __exit ir_rc5_sz_decode_exit(void)
144{
145 ir_raw_handler_unregister(&rc5_sz_handler);
146}
147
148module_init(ir_rc5_sz_decode_init);
149module_exit(ir_rc5_sz_decode_exit);
150
151MODULE_LICENSE("GPL");
152MODULE_AUTHOR("Jarod Wilson <jarod@redhat.com>");
153MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
154MODULE_DESCRIPTION("RC5 (streamzap) IR protocol decoder");