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->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
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_TYPE_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