ir-jvc-decoder.c

  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
 21enum 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 */
 38static 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.overflow)
 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
 54again:
 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
158out:
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
165static 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 */
188static 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
203static 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
211static 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
219static void __exit ir_jvc_decode_exit(void)
220{
221	ir_raw_handler_unregister(&jvc_handler);
222}
223
224module_init(ir_jvc_decode_init);
225module_exit(ir_jvc_decode_exit);
226
227MODULE_LICENSE("GPL");
228MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
229MODULE_DESCRIPTION("JVC IR protocol decoder");