1 // SPDX-License-Identifier: GPL-2.0-only
2 /* ir-jvc-decoder.c - handle JVC IR Pulse/Space protocol
3  *
4  * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
5  */
6 
7 #include <linux/bitrev.h>
8 #include <linux/module.h>
9 #include "rc-core-priv.h"
10 
11 #define JVC_NBITS		16		/* dev(8) + func(8) */
12 #define JVC_UNIT		525		/* us */
13 #define JVC_HEADER_PULSE	(16 * JVC_UNIT) /* lack of header -> repeat */
14 #define JVC_HEADER_SPACE	(8  * JVC_UNIT)
15 #define JVC_BIT_PULSE		(1  * JVC_UNIT)
16 #define JVC_BIT_0_SPACE		(1  * JVC_UNIT)
17 #define JVC_BIT_1_SPACE		(3  * JVC_UNIT)
18 #define JVC_TRAILER_PULSE	(1  * JVC_UNIT)
19 #define	JVC_TRAILER_SPACE	(35 * JVC_UNIT)
20 
21 enum jvc_state {
22 	STATE_INACTIVE,
23 	STATE_HEADER_SPACE,
24 	STATE_BIT_PULSE,
25 	STATE_BIT_SPACE,
26 	STATE_TRAILER_PULSE,
27 	STATE_TRAILER_SPACE,
28 	STATE_CHECK_REPEAT,
29 };
30 
31 /**
32  * ir_jvc_decode() - Decode one JVC pulse or space
33  * @dev:	the struct rc_dev descriptor of the device
34  * @ev:   the struct ir_raw_event descriptor of the pulse/space
35  *
36  * This function returns -EINVAL if the pulse violates the state machine
37  */
38 static int ir_jvc_decode(struct rc_dev *dev, struct ir_raw_event ev)
39 {
40 	struct jvc_dec *data = &dev->raw->jvc;
41 
42 	if (!is_timing_event(ev)) {
43 		if (ev.reset)
44 			data->state = STATE_INACTIVE;
45 		return 0;
46 	}
47 
48 	if (!geq_margin(ev.duration, JVC_UNIT, JVC_UNIT / 2))
49 		goto out;
50 
51 	dev_dbg(&dev->dev, "JVC decode started at state %d (%uus %s)\n",
52 		data->state, ev.duration, TO_STR(ev.pulse));
53 
54 again:
55 	switch (data->state) {
56 
57 	case STATE_INACTIVE:
58 		if (!ev.pulse)
59 			break;
60 
61 		if (!eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
62 			break;
63 
64 		data->count = 0;
65 		data->first = true;
66 		data->toggle = !data->toggle;
67 		data->state = STATE_HEADER_SPACE;
68 		return 0;
69 
70 	case STATE_HEADER_SPACE:
71 		if (ev.pulse)
72 			break;
73 
74 		if (!eq_margin(ev.duration, JVC_HEADER_SPACE, JVC_UNIT / 2))
75 			break;
76 
77 		data->state = STATE_BIT_PULSE;
78 		return 0;
79 
80 	case STATE_BIT_PULSE:
81 		if (!ev.pulse)
82 			break;
83 
84 		if (!eq_margin(ev.duration, JVC_BIT_PULSE, JVC_UNIT / 2))
85 			break;
86 
87 		data->state = STATE_BIT_SPACE;
88 		return 0;
89 
90 	case STATE_BIT_SPACE:
91 		if (ev.pulse)
92 			break;
93 
94 		data->bits <<= 1;
95 		if (eq_margin(ev.duration, JVC_BIT_1_SPACE, JVC_UNIT / 2)) {
96 			data->bits |= 1;
97 			decrease_duration(&ev, JVC_BIT_1_SPACE);
98 		} else if (eq_margin(ev.duration, JVC_BIT_0_SPACE, JVC_UNIT / 2))
99 			decrease_duration(&ev, JVC_BIT_0_SPACE);
100 		else
101 			break;
102 		data->count++;
103 
104 		if (data->count == JVC_NBITS)
105 			data->state = STATE_TRAILER_PULSE;
106 		else
107 			data->state = STATE_BIT_PULSE;
108 		return 0;
109 
110 	case STATE_TRAILER_PULSE:
111 		if (!ev.pulse)
112 			break;
113 
114 		if (!eq_margin(ev.duration, JVC_TRAILER_PULSE, JVC_UNIT / 2))
115 			break;
116 
117 		data->state = STATE_TRAILER_SPACE;
118 		return 0;
119 
120 	case STATE_TRAILER_SPACE:
121 		if (ev.pulse)
122 			break;
123 
124 		if (!geq_margin(ev.duration, JVC_TRAILER_SPACE, JVC_UNIT / 2))
125 			break;
126 
127 		if (data->first) {
128 			u32 scancode;
129 			scancode = (bitrev8((data->bits >> 8) & 0xff) << 8) |
130 				   (bitrev8((data->bits >> 0) & 0xff) << 0);
131 			dev_dbg(&dev->dev, "JVC scancode 0x%04x\n", scancode);
132 			rc_keydown(dev, RC_PROTO_JVC, scancode, data->toggle);
133 			data->first = false;
134 			data->old_bits = data->bits;
135 		} else if (data->bits == data->old_bits) {
136 			dev_dbg(&dev->dev, "JVC repeat\n");
137 			rc_repeat(dev);
138 		} else {
139 			dev_dbg(&dev->dev, "JVC invalid repeat msg\n");
140 			break;
141 		}
142 
143 		data->count = 0;
144 		data->state = STATE_CHECK_REPEAT;
145 		return 0;
146 
147 	case STATE_CHECK_REPEAT:
148 		if (!ev.pulse)
149 			break;
150 
151 		if (eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
152 			data->state = STATE_INACTIVE;
153   else
154 			data->state = STATE_BIT_PULSE;
155 		goto again;
156 	}
157 
158 out:
159 	dev_dbg(&dev->dev, "JVC decode failed at state %d (%uus %s)\n",
160 		data->state, ev.duration, TO_STR(ev.pulse));
161 	data->state = STATE_INACTIVE;
162 	return -EINVAL;
163 }
164 
165 static const struct ir_raw_timings_pd ir_jvc_timings = {
166 	.header_pulse  = JVC_HEADER_PULSE,
167 	.header_space  = JVC_HEADER_SPACE,
168 	.bit_pulse     = JVC_BIT_PULSE,
169 	.bit_space[0]  = JVC_BIT_0_SPACE,
170 	.bit_space[1]  = JVC_BIT_1_SPACE,
171 	.trailer_pulse = JVC_TRAILER_PULSE,
172 	.trailer_space = JVC_TRAILER_SPACE,
173 	.msb_first     = 1,
174 };
175 
176 /**
177  * ir_jvc_encode() - Encode a scancode as a stream of raw events
178  *
179  * @protocol:	protocol to encode
180  * @scancode:	scancode to encode
181  * @events:	array of raw ir events to write into
182  * @max:	maximum size of @events
183  *
184  * Returns:	The number of events written.
185  *		-ENOBUFS if there isn't enough space in the array to fit the
186  *		encoding. In this case all @max events will have been written.
187  */
188 static int ir_jvc_encode(enum rc_proto protocol, u32 scancode,
189 			 struct ir_raw_event *events, unsigned int max)
190 {
191 	struct ir_raw_event *e = events;
192 	int ret;
193 	u32 raw = (bitrev8((scancode >> 8) & 0xff) << 8) |
194 		  (bitrev8((scancode >> 0) & 0xff) << 0);
195 
196 	ret = ir_raw_gen_pd(&e, max, &ir_jvc_timings, JVC_NBITS, raw);
197 	if (ret < 0)
198 		return ret;
199 
200 	return e - events;
201 }
202 
203 static struct ir_raw_handler jvc_handler = {
204 	.protocols	= RC_PROTO_BIT_JVC,
205 	.decode		= ir_jvc_decode,
206 	.encode		= ir_jvc_encode,
207 	.carrier	= 38000,
208 	.min_timeout	= JVC_TRAILER_SPACE,
209 };
210 
211 static int __init ir_jvc_decode_init(void)
212 {
213 	ir_raw_handler_register(&jvc_handler);
214 
215 	printk(KERN_INFO "IR JVC protocol handler initialized\n");
216 	return 0;
217 }
218 
219 static void __exit ir_jvc_decode_exit(void)
220 {
221 	ir_raw_handler_unregister(&jvc_handler);
222 }
223 
224 module_init(ir_jvc_decode_init);
225 module_exit(ir_jvc_decode_exit);
226 
227 MODULE_LICENSE("GPL");
228 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
229 MODULE_DESCRIPTION("JVC IR protocol decoder");
230