Merge remote branch 'jwb/next' into next
[pandora-kernel.git] / drivers / media / rc / ir-rc5-sz-decoder.c
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
30 enum 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  */
44 static 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
62 again:
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
122 out:
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
129 static struct ir_raw_handler rc5_sz_handler = {
130         .protocols      = RC_TYPE_RC5_SZ,
131         .decode         = ir_rc5_sz_decode,
132 };
133
134 static 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
142 static void __exit ir_rc5_sz_decode_exit(void)
143 {
144         ir_raw_handler_unregister(&rc5_sz_handler);
145 }
146
147 module_init(ir_rc5_sz_decode_init);
148 module_exit(ir_rc5_sz_decode_exit);
149
150 MODULE_LICENSE("GPL");
151 MODULE_AUTHOR("Jarod Wilson <jarod@redhat.com>");
152 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
153 MODULE_DESCRIPTION("RC5 (streamzap) IR protocol decoder");