aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/media/rc/ir-nec-decoder.c
blob: a95d09acc22a56a81f63260a8fecb7ecb216fe6c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
/* ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
 *
 * Copyright (C) 2010 by Mauro Carvalho Chehab
 *
 * This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation version 2 of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 */

#include <linux/bitrev.h>
#include <linux/module.h>
#include "rc-core-priv.h"

#define NEC_NBITS		32
#define NEC_UNIT		562500  /* ns */
#define NEC_HEADER_PULSE	(16 * NEC_UNIT)
#define NECX_HEADER_PULSE	(8  * NEC_UNIT) /* Less common NEC variant */
#define NEC_HEADER_SPACE	(8  * NEC_UNIT)
#define NEC_REPEAT_SPACE	(4  * NEC_UNIT)
#define NEC_BIT_PULSE		(1  * NEC_UNIT)
#define NEC_BIT_0_SPACE		(1  * NEC_UNIT)
#define NEC_BIT_1_SPACE		(3  * NEC_UNIT)
#define	NEC_TRAILER_PULSE	(1  * NEC_UNIT)
#define	NEC_TRAILER_SPACE	(10 * NEC_UNIT) /* even longer in reality */
#define NECX_REPEAT_BITS	1

enum nec_state {
	STATE_INACTIVE,
	STATE_HEADER_SPACE,
	STATE_BIT_PULSE,
	STATE_BIT_SPACE,
	STATE_TRAILER_PULSE,
	STATE_TRAILER_SPACE,
};

/**
 * ir_nec_decode() - Decode one NEC pulse or space
 * @dev:	the struct rc_dev descriptor of the device
 * @duration:	the struct ir_raw_event descriptor of the pulse/space
 *
 * This function returns -EINVAL if the pulse violates the state machine
 */
static int ir_nec_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
	struct nec_dec *data = &dev->raw->nec;
	u32 scancode;
	enum rc_proto rc_proto;
	u8 address, not_address, command, not_command;

	if (!is_timing_event(ev)) {
		if (ev.reset)
			data->state = STATE_INACTIVE;
		return 0;
	}

	IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n",
		   data->state, TO_US(ev.duration), TO_STR(ev.pulse));

	switch (data->state) {

	case STATE_INACTIVE:
		if (!ev.pulse)
			break;

		if (eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT * 2)) {
			data->is_nec_x = false;
			data->necx_repeat = false;
		} else if (eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2))
			data->is_nec_x = true;
		else
			break;

		data->count = 0;
		data->state = STATE_HEADER_SPACE;
		return 0;

	case STATE_HEADER_SPACE:
		if (ev.pulse)
			break;

		if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT)) {
			data->state = STATE_BIT_PULSE;
			return 0;
		} else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) {
			data->state = STATE_TRAILER_PULSE;
			return 0;
		}

		break;

	case STATE_BIT_PULSE:
		if (!ev.pulse)
			break;

		if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2))
			break;

		data->state = STATE_BIT_SPACE;
		return 0;

	case STATE_BIT_SPACE:
		if (ev.pulse)
			break;

		if (data->necx_repeat && data->count == NECX_REPEAT_BITS &&
			geq_margin(ev.duration,
			NEC_TRAILER_SPACE, NEC_UNIT / 2)) {
				IR_dprintk(1, "Repeat last key\n");
				rc_repeat(dev);
				data->state = STATE_INACTIVE;
				return 0;

		} else if (data->count > NECX_REPEAT_BITS)
			data->necx_repeat = false;

		data->bits <<= 1;
		if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2))
			data->bits |= 1;
		else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2))
			break;
		data->count++;

		if (data->count == NEC_NBITS)
			data->state = STATE_TRAILER_PULSE;
		else
			data->state = STATE_BIT_PULSE;

		return 0;

	case STATE_TRAILER_PULSE:
		if (!ev.pulse)
			break;

		if (!eq_margin(ev.duration, NEC_TRAILER_PULSE, NEC_UNIT / 2))
			break;

		data->state = STATE_TRAILER_SPACE;
		return 0;

	case STATE_TRAILER_SPACE:
		if (ev.pulse)
			break;

		if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2))
			break;

		if (data->count == NEC_NBITS) {
			address     = bitrev8((data->bits >> 24) & 0xff);
			not_address = bitrev8((data->bits >> 16) & 0xff);
			command	    = bitrev8((data->bits >>  8) & 0xff);
			not_command = bitrev8((data->bits >>  0) & 0xff);

			scancode = ir_nec_bytes_to_scancode(address,
							    not_address,
							    command,
							    not_command,
							    &rc_proto);

			if (data->is_nec_x)
				data->necx_repeat = true;

			rc_keydown(dev, rc_proto, scancode, 0);
		} else {
			rc_repeat(dev);
		}

		data->state = STATE_INACTIVE;
		return 0;
	}

	IR_dprintk(1, "NEC decode failed at count %d state %d (%uus %s)\n",
		   data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse));
	data->state = STATE_INACTIVE;
	return -EINVAL;
}

/**
 * ir_nec_scancode_to_raw() - encode an NEC scancode ready for modulation.
 * @protocol:	specific protocol to use
 * @scancode:	a single NEC scancode.
 * @raw:	raw data to be modulated.
 */
static u32 ir_nec_scancode_to_raw(enum rc_proto protocol, u32 scancode)
{
	unsigned int addr, addr_inv, data, data_inv;

	data = scancode & 0xff;

	if (protocol == RC_PROTO_NEC32) {
		/* 32-bit NEC (used by Apple and TiVo remotes) */
		/* scan encoding: aaAAddDD */
		addr_inv   = (scancode >> 24) & 0xff;
		addr       = (scancode >> 16) & 0xff;
		data_inv   = (scancode >>  8) & 0xff;
	} else if (protocol == RC_PROTO_NECX) {
		/* Extended NEC */
		/* scan encoding AAaaDD */
		addr       = (scancode >> 16) & 0xff;
		addr_inv   = (scancode >>  8) & 0xff;
		data_inv   = data ^ 0xff;
	} else {
		/* Normal NEC */
		/* scan encoding: AADD */
		addr       = (scancode >>  8) & 0xff;
		addr_inv   = addr ^ 0xff;
		data_inv   = data ^ 0xff;
	}

	/* raw encoding: ddDDaaAA */
	return data_inv << 24 |
	       data     << 16 |
	       addr_inv <<  8 |
	       addr;
}

static const struct ir_raw_timings_pd ir_nec_timings = {
	.header_pulse	= NEC_HEADER_PULSE,
	.header_space	= NEC_HEADER_SPACE,
	.bit_pulse	= NEC_BIT_PULSE,
	.bit_space[0]	= NEC_BIT_0_SPACE,
	.bit_space[1]	= NEC_BIT_1_SPACE,
	.trailer_pulse	= NEC_TRAILER_PULSE,
	.trailer_space	= NEC_TRAILER_SPACE,
	.msb_first	= 0,
};

/**
 * ir_nec_encode() - Encode a scancode as a stream of raw events
 *
 * @protocol:	protocol to encode
 * @scancode:	scancode to encode
 * @events:	array of raw ir events to write into
 * @max:	maximum size of @events
 *
 * Returns:	The number of events written.
 *		-ENOBUFS if there isn't enough space in the array to fit the
 *		encoding. In this case all @max events will have been written.
 */
static int ir_nec_encode(enum rc_proto protocol, u32 scancode,
			 struct ir_raw_event *events, unsigned int max)
{
	struct ir_raw_event *e = events;
	int ret;
	u32 raw;

	/* Convert a NEC scancode to raw NEC data */
	raw = ir_nec_scancode_to_raw(protocol, scancode);

	/* Modulate the raw data using a pulse distance modulation */
	ret = ir_raw_gen_pd(&e, max, &ir_nec_timings, NEC_NBITS, raw);
	if (ret < 0)
		return ret;

	return e - events;
}

static struct ir_raw_handler nec_handler = {
	.protocols	= RC_PROTO_BIT_NEC | RC_PROTO_BIT_NECX |
							RC_PROTO_BIT_NEC32,
	.decode		= ir_nec_decode,
	.encode		= ir_nec_encode,
};

static int __init ir_nec_decode_init(void)
{
	ir_raw_handler_register(&nec_handler);

	printk(KERN_INFO "IR NEC protocol handler initialized\n");
	return 0;
}

static void __exit ir_nec_decode_exit(void)
{
	ir_raw_handler_unregister(&nec_handler);
}

module_init(ir_nec_decode_init);
module_exit(ir_nec_decode_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mauro Carvalho Chehab");
MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
MODULE_DESCRIPTION("NEC IR protocol decoder");