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 #include <linux/module.h>
25
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
31 enum 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
40 * @dev: the struct rc_dev descriptor of the device
41 * @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 */
ir_rc5_sz_decode(struct rc_dev * dev,struct ir_raw_event ev)45 static int ir_rc5_sz_decode(struct rc_dev *dev, struct ir_raw_event ev)
46 {
47 struct rc5_sz_dec *data = &dev->raw->rc5_sz;
48 u8 toggle, command, system;
49 u32 scancode;
50
51 if (!(dev->raw->enabled_protocols & RC_TYPE_RC5_SZ))
52 return 0;
53
54 if (!is_timing_event(ev)) {
55 if (ev.reset)
56 data->state = STATE_INACTIVE;
57 return 0;
58 }
59
60 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
61 goto out;
62
63 again:
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:
94 if (!is_transition(&ev, &dev->raw->prev_ev))
95 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
118 rc_keydown(dev, scancode, toggle);
119 data->state = STATE_INACTIVE;
120 return 0;
121 }
122
123 out:
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
130 static struct ir_raw_handler rc5_sz_handler = {
131 .protocols = RC_TYPE_RC5_SZ,
132 .decode = ir_rc5_sz_decode,
133 };
134
ir_rc5_sz_decode_init(void)135 static 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
ir_rc5_sz_decode_exit(void)143 static void __exit ir_rc5_sz_decode_exit(void)
144 {
145 ir_raw_handler_unregister(&rc5_sz_handler);
146 }
147
148 module_init(ir_rc5_sz_decode_init);
149 module_exit(ir_rc5_sz_decode_exit);
150
151 MODULE_LICENSE("GPL");
152 MODULE_AUTHOR("Jarod Wilson <jarod@redhat.com>");
153 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
154 MODULE_DESCRIPTION("RC5 (streamzap) IR protocol decoder");
155