1/* ir-jvc-decoder.c - handle JVC IR Pulse/Space protocol
2 *
3 * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation version 2 of the License.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 * GNU General Public License for more details.
13 */
14
15#include <linux/bitrev.h>
16#include <linux/module.h>
17#include "rc-core-priv.h"
18
19#define JVC_NBITS		16		/* dev(8) + func(8) */
20#define JVC_UNIT		525000		/* ns */
21#define JVC_HEADER_PULSE	(16 * JVC_UNIT) /* lack of header -> repeat */
22#define JVC_HEADER_SPACE	(8  * JVC_UNIT)
23#define JVC_BIT_PULSE		(1  * JVC_UNIT)
24#define JVC_BIT_0_SPACE		(1  * JVC_UNIT)
25#define JVC_BIT_1_SPACE		(3  * JVC_UNIT)
26#define JVC_TRAILER_PULSE	(1  * JVC_UNIT)
27#define	JVC_TRAILER_SPACE	(35 * JVC_UNIT)
28
29enum jvc_state {
30	STATE_INACTIVE,
31	STATE_HEADER_SPACE,
32	STATE_BIT_PULSE,
33	STATE_BIT_SPACE,
34	STATE_TRAILER_PULSE,
35	STATE_TRAILER_SPACE,
36	STATE_CHECK_REPEAT,
37};
38
39/**
40 * ir_jvc_decode() - Decode one JVC pulse or space
41 * @dev:	the struct rc_dev descriptor of the device
42 * @duration:   the struct ir_raw_event descriptor of the pulse/space
43 *
44 * This function returns -EINVAL if the pulse violates the state machine
45 */
46static int ir_jvc_decode(struct rc_dev *dev, struct ir_raw_event ev)
47{
48	struct jvc_dec *data = &dev->raw->jvc;
49
50	if (!(dev->raw->enabled_protocols & RC_TYPE_JVC))
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, JVC_UNIT, JVC_UNIT / 2))
60		goto out;
61
62	IR_dprintk(2, "JVC decode started at state %d (%uus %s)\n",
63		   data->state, TO_US(ev.duration), TO_STR(ev.pulse));
64
65again:
66	switch (data->state) {
67
68	case STATE_INACTIVE:
69		if (!ev.pulse)
70			break;
71
72		if (!eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
73			break;
74
75		data->count = 0;
76		data->first = true;
77		data->toggle = !data->toggle;
78		data->state = STATE_HEADER_SPACE;
79		return 0;
80
81	case STATE_HEADER_SPACE:
82		if (ev.pulse)
83			break;
84
85		if (!eq_margin(ev.duration, JVC_HEADER_SPACE, JVC_UNIT / 2))
86			break;
87
88		data->state = STATE_BIT_PULSE;
89		return 0;
90
91	case STATE_BIT_PULSE:
92		if (!ev.pulse)
93			break;
94
95		if (!eq_margin(ev.duration, JVC_BIT_PULSE, JVC_UNIT / 2))
96			break;
97
98		data->state = STATE_BIT_SPACE;
99		return 0;
100
101	case STATE_BIT_SPACE:
102		if (ev.pulse)
103			break;
104
105		data->bits <<= 1;
106		if (eq_margin(ev.duration, JVC_BIT_1_SPACE, JVC_UNIT / 2)) {
107			data->bits |= 1;
108			decrease_duration(&ev, JVC_BIT_1_SPACE);
109		} else if (eq_margin(ev.duration, JVC_BIT_0_SPACE, JVC_UNIT / 2))
110			decrease_duration(&ev, JVC_BIT_0_SPACE);
111		else
112			break;
113		data->count++;
114
115		if (data->count == JVC_NBITS)
116			data->state = STATE_TRAILER_PULSE;
117		else
118			data->state = STATE_BIT_PULSE;
119		return 0;
120
121	case STATE_TRAILER_PULSE:
122		if (!ev.pulse)
123			break;
124
125		if (!eq_margin(ev.duration, JVC_TRAILER_PULSE, JVC_UNIT / 2))
126			break;
127
128		data->state = STATE_TRAILER_SPACE;
129		return 0;
130
131	case STATE_TRAILER_SPACE:
132		if (ev.pulse)
133			break;
134
135		if (!geq_margin(ev.duration, JVC_TRAILER_SPACE, JVC_UNIT / 2))
136			break;
137
138		if (data->first) {
139			u32 scancode;
140			scancode = (bitrev8((data->bits >> 8) & 0xff) << 8) |
141				   (bitrev8((data->bits >> 0) & 0xff) << 0);
142			IR_dprintk(1, "JVC scancode 0x%04x\n", scancode);
143			rc_keydown(dev, scancode, data->toggle);
144			data->first = false;
145			data->old_bits = data->bits;
146		} else if (data->bits == data->old_bits) {
147			IR_dprintk(1, "JVC repeat\n");
148			rc_repeat(dev);
149		} else {
150			IR_dprintk(1, "JVC invalid repeat msg\n");
151			break;
152		}
153
154		data->count = 0;
155		data->state = STATE_CHECK_REPEAT;
156		return 0;
157
158	case STATE_CHECK_REPEAT:
159		if (!ev.pulse)
160			break;
161
162		if (eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
163			data->state = STATE_INACTIVE;
164  else
165			data->state = STATE_BIT_PULSE;
166		goto again;
167	}
168
169out:
170	IR_dprintk(1, "JVC decode failed at state %d (%uus %s)\n",
171		   data->state, TO_US(ev.duration), TO_STR(ev.pulse));
172	data->state = STATE_INACTIVE;
173	return -EINVAL;
174}
175
176static struct ir_raw_handler jvc_handler = {
177	.protocols	= RC_TYPE_JVC,
178	.decode		= ir_jvc_decode,
179};
180
181static int __init ir_jvc_decode_init(void)
182{
183	ir_raw_handler_register(&jvc_handler);
184
185	printk(KERN_INFO "IR JVC protocol handler initialized\n");
186	return 0;
187}
188
189static void __exit ir_jvc_decode_exit(void)
190{
191	ir_raw_handler_unregister(&jvc_handler);
192}
193
194module_init(ir_jvc_decode_init);
195module_exit(ir_jvc_decode_exit);
196
197MODULE_LICENSE("GPL");
198MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
199MODULE_DESCRIPTION("JVC IR protocol decoder");
200