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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 
29 enum 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  */
ir_jvc_decode(struct rc_dev * dev,struct ir_raw_event ev)46 static 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->enabled_protocols & RC_BIT_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 
65 again:
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 
169 out:
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 
176 static struct ir_raw_handler jvc_handler = {
177 	.protocols	= RC_BIT_JVC,
178 	.decode		= ir_jvc_decode,
179 };
180 
ir_jvc_decode_init(void)181 static 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 
ir_jvc_decode_exit(void)189 static void __exit ir_jvc_decode_exit(void)
190 {
191 	ir_raw_handler_unregister(&jvc_handler);
192 }
193 
194 module_init(ir_jvc_decode_init);
195 module_exit(ir_jvc_decode_exit);
196 
197 MODULE_LICENSE("GPL");
198 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
199 MODULE_DESCRIPTION("JVC IR protocol decoder");
200