[linux-2.6-block.git] / drivers / media / rc / ir-rc6-decoder.c

/* ir-rc6-decoder.c - A decoder for the RC6 IR protocol
 *
 * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
 *
 * 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 "rc-core-priv.h"

/*
 * This decoder currently supports:
 * RC6-0-16	(standard toggle bit in header)
 * RC6-6A-24	(no toggle bit)
 * RC6-6A-32	(MCE version with toggle bit in body)
 */

#define RC6_UNIT		444444	/* us */
#define RC6_HEADER_NBITS	4	/* not including toggle bit */
#define RC6_0_NBITS		16
#define RC6_6A_SMALL_NBITS	24
#define RC6_6A_LARGE_NBITS	32
#define RC6_PREFIX_PULSE	(6 * RC6_UNIT)
#define RC6_PREFIX_SPACE	(2 * RC6_UNIT)
#define RC6_BIT_START		(1 * RC6_UNIT)
#define RC6_BIT_END		(1 * RC6_UNIT)
#define RC6_TOGGLE_START	(2 * RC6_UNIT)
#define RC6_TOGGLE_END		(2 * RC6_UNIT)
#define RC6_MODE_MASK		0x07	/* for the header bits */
#define RC6_STARTBIT_MASK	0x08	/* for the header bits */
#define RC6_6A_MCE_TOGGLE_MASK	0x8000	/* for the body bits */

enum rc6_mode {
	RC6_MODE_0,
	RC6_MODE_6A,
	RC6_MODE_UNKNOWN,
};

enum rc6_state {
	STATE_INACTIVE,
	STATE_PREFIX_SPACE,
	STATE_HEADER_BIT_START,
	STATE_HEADER_BIT_END,
	STATE_TOGGLE_START,
	STATE_TOGGLE_END,
	STATE_BODY_BIT_START,
	STATE_BODY_BIT_END,
	STATE_FINISHED,
};

static enum rc6_mode rc6_mode(struct rc6_dec *data)
{
	switch (data->header & RC6_MODE_MASK) {
	case 0:
		return RC6_MODE_0;
	case 6:
		if (!data->toggle)
			return RC6_MODE_6A;
		/* fall through */
	default:
		return RC6_MODE_UNKNOWN;
	}
}

/**
 * ir_rc6_decode() - Decode one RC6 pulse or space
 * @dev:	the struct rc_dev descriptor of the device
 * @ev:		the struct ir_raw_event descriptor of the pulse/space
 *
 * This function returns -EINVAL if the pulse violates the state machine
 */
static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
	struct rc6_dec *data = &dev->raw->rc6;
	u32 scancode;
	u8 toggle;

	if (!(dev->raw->enabled_protocols & IR_TYPE_RC6))
		return 0;

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

	if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
		goto out;

again:
	IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
		   data->state, TO_US(ev.duration), TO_STR(ev.pulse));

	if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
		return 0;

	switch (data->state) {

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

		/* Note: larger margin on first pulse since each RC6_UNIT
		   is quite short and some hardware takes some time to
		   adjust to the signal */
		if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
			break;

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

	case STATE_PREFIX_SPACE:
		if (ev.pulse)
			break;

		if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
			break;

		data->state = STATE_HEADER_BIT_START;
		return 0;

	case STATE_HEADER_BIT_START:
		if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
			break;

		data->header <<= 1;
		if (ev.pulse)
			data->header |= 1;
		data->count++;
		data->state = STATE_HEADER_BIT_END;
		return 0;

	case STATE_HEADER_BIT_END:
		if (!is_transition(&ev, &dev->raw->prev_ev))
			break;

		if (data->count == RC6_HEADER_NBITS)
			data->state = STATE_TOGGLE_START;
		else
			data->state = STATE_HEADER_BIT_START;

		decrease_duration(&ev, RC6_BIT_END);
		goto again;

	case STATE_TOGGLE_START:
		if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
			break;

		data->toggle = ev.pulse;
		data->state = STATE_TOGGLE_END;
		return 0;

	case STATE_TOGGLE_END:
		if (!is_transition(&ev, &dev->raw->prev_ev) ||
		    !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
			break;

		if (!(data->header & RC6_STARTBIT_MASK)) {
			IR_dprintk(1, "RC6 invalid start bit\n");
			break;
		}

		data->state = STATE_BODY_BIT_START;
		decrease_duration(&ev, RC6_TOGGLE_END);
		data->count = 0;

		switch (rc6_mode(data)) {
		case RC6_MODE_0:
			data->wanted_bits = RC6_0_NBITS;
			break;
		case RC6_MODE_6A:
			/* This might look weird, but we basically
			   check the value of the first body bit to
			   determine the number of bits in mode 6A */
			if ((!ev.pulse && !geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) ||
			    geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
				data->wanted_bits = RC6_6A_LARGE_NBITS;
			else
				data->wanted_bits = RC6_6A_SMALL_NBITS;
			break;
		default:
			IR_dprintk(1, "RC6 unknown mode\n");
			goto out;
		}
		goto again;

	case STATE_BODY_BIT_START:
		if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
			break;

		data->body <<= 1;
		if (ev.pulse)
			data->body |= 1;
		data->count++;
		data->state = STATE_BODY_BIT_END;
		return 0;

	case STATE_BODY_BIT_END:
		if (!is_transition(&ev, &dev->raw->prev_ev))
			break;

		if (data->count == data->wanted_bits)
			data->state = STATE_FINISHED;
		else
			data->state = STATE_BODY_BIT_START;

		decrease_duration(&ev, RC6_BIT_END);
		goto again;

	case STATE_FINISHED:
		if (ev.pulse)
			break;

		switch (rc6_mode(data)) {
		case RC6_MODE_0:
			scancode = data->body & 0xffff;
			toggle = data->toggle;
			IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
				   scancode, toggle);
			break;
		case RC6_MODE_6A:
			if (data->wanted_bits == RC6_6A_LARGE_NBITS) {
				toggle = data->body & RC6_6A_MCE_TOGGLE_MASK ? 1 : 0;
				scancode = data->body & ~RC6_6A_MCE_TOGGLE_MASK;
			} else {
				toggle = 0;
				scancode = data->body & 0xffffff;
			}

			IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n",
				   scancode, toggle);
			break;
		default:
			IR_dprintk(1, "RC6 unknown mode\n");
			goto out;
		}

		rc_keydown(dev, scancode, toggle);
		data->state = STATE_INACTIVE;
		return 0;
	}

out:
	IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n",
		   data->state, TO_US(ev.duration), TO_STR(ev.pulse));
	data->state = STATE_INACTIVE;
	return -EINVAL;
}

static struct ir_raw_handler rc6_handler = {
	.protocols	= IR_TYPE_RC6,
	.decode		= ir_rc6_decode,
};

static int __init ir_rc6_decode_init(void)
{
	ir_raw_handler_register(&rc6_handler);

	printk(KERN_INFO "IR RC6 protocol handler initialized\n");
	return 0;
}

static void __exit ir_rc6_decode_exit(void)
{
	ir_raw_handler_unregister(&rc6_handler);
}

module_init(ir_rc6_decode_init);
module_exit(ir_rc6_decode_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
MODULE_DESCRIPTION("RC6 IR protocol decoder");
Commit	Line	Data
784a4931 DH	1	/* ir-rc6-decoder.c - A decoder for the RC6 IR 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
f62de675	15	#include "rc-core-priv.h"
784a4931 DH	16
	17	/*
	18	* This decoder currently supports:
	19	* RC6-0-16 (standard toggle bit in header)
	20	* RC6-6A-24 (no toggle bit)
	21	* RC6-6A-32 (MCE version with toggle bit in body)
	22	*/
	23
	24	#define RC6_UNIT 444444 /* us */
	25	#define RC6_HEADER_NBITS 4 /* not including toggle bit */
	26	#define RC6_0_NBITS 16
	27	#define RC6_6A_SMALL_NBITS 24
	28	#define RC6_6A_LARGE_NBITS 32
e40b1127 DH	29	#define RC6_PREFIX_PULSE (6 * RC6_UNIT)
	30	#define RC6_PREFIX_SPACE (2 * RC6_UNIT)
	31	#define RC6_BIT_START (1 * RC6_UNIT)
	32	#define RC6_BIT_END (1 * RC6_UNIT)
	33	#define RC6_TOGGLE_START (2 * RC6_UNIT)
	34	#define RC6_TOGGLE_END (2 * RC6_UNIT)
784a4931 DH	35	#define RC6_MODE_MASK 0x07 /* for the header bits */
	36	#define RC6_STARTBIT_MASK 0x08 /* for the header bits */
	37	#define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */
	38
784a4931 DH	39	enum rc6_mode {
	40	RC6_MODE_0,
	41	RC6_MODE_6A,
	42	RC6_MODE_UNKNOWN,
	43	};
	44
	45	enum rc6_state {
	46	STATE_INACTIVE,
	47	STATE_PREFIX_SPACE,
	48	STATE_HEADER_BIT_START,
	49	STATE_HEADER_BIT_END,
	50	STATE_TOGGLE_START,
	51	STATE_TOGGLE_END,
	52	STATE_BODY_BIT_START,
	53	STATE_BODY_BIT_END,
	54	STATE_FINISHED,
	55	};
	56
c216369e	57	static enum rc6_mode rc6_mode(struct rc6_dec *data)
784a4931	58	{
784a4931 DH	59	switch (data->header & RC6_MODE_MASK) {
	60	case 0:
	61	return RC6_MODE_0;
	62	case 6:
	63	if (!data->toggle)
	64	return RC6_MODE_6A;
	65	/* fall through */
	66	default:
	67	return RC6_MODE_UNKNOWN;
	68	}
	69	}
	70
	71	/**
	72	* ir_rc6_decode() - Decode one RC6 pulse or space
d8b4b582	73	* @dev: the struct rc_dev descriptor of the device
e40b1127	74	* @ev: the struct ir_raw_event descriptor of the pulse/space
784a4931 DH	75	*
	76	* This function returns -EINVAL if the pulse violates the state machine
	77	*/
d8b4b582	78	static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
784a4931	79	{
d8b4b582	80	struct rc6_dec *data = &dev->raw->rc6;
784a4931 DH	81	u32 scancode;
784a4931 DH	82	u8 toggle;
784a4931	83
d8b4b582	84	if (!(dev->raw->enabled_protocols & IR_TYPE_RC6))
784a4931 DH	85	return 0;
784a4931 DH	86
4651918a ML	87	if (!is_timing_event(ev)) {
	88	if (ev.reset)
	89	data->state = STATE_INACTIVE;
784a4931 DH	90	return 0;
	91	}
	92
e40b1127	93	if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
784a4931 DH	94	goto out;
	95
	96	again:
e40b1127 DH	97	IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
e40b1127 DH	98	data->state, TO_US(ev.duration), TO_STR(ev.pulse));
784a4931	99
e40b1127	100	if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
784a4931 DH	101	return 0;
	102
	103	switch (data->state) {
	104
	105	case STATE_INACTIVE:
e40b1127 DH	106	if (!ev.pulse)
	107	break;
	108
	109	/* Note: larger margin on first pulse since each RC6_UNIT
	110	is quite short and some hardware takes some time to
	111	adjust to the signal */
	112	if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
	113	break;
	114
	115	data->state = STATE_PREFIX_SPACE;
	116	data->count = 0;
	117	return 0;
784a4931 DH	118
784a4931 DH	119	case STATE_PREFIX_SPACE:
e40b1127 DH	120	if (ev.pulse)
	121	break;
	122
	123	if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
	124	break;
	125
	126	data->state = STATE_HEADER_BIT_START;
	127	return 0;
784a4931 DH	128
784a4931 DH	129	case STATE_HEADER_BIT_START:
e40b1127 DH	130	if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
	131	break;
	132
	133	data->header <<= 1;
	134	if (ev.pulse)
	135	data->header \|= 1;
	136	data->count++;
e40b1127 DH	137	data->state = STATE_HEADER_BIT_END;
e40b1127 DH	138	return 0;
784a4931 DH	139
784a4931 DH	140	case STATE_HEADER_BIT_END:
d8b4b582	141	if (!is_transition(&ev, &dev->raw->prev_ev))
e40b1127	142	break;
784a4931	143
e40b1127 DH	144	if (data->count == RC6_HEADER_NBITS)
	145	data->state = STATE_TOGGLE_START;
	146	else
	147	data->state = STATE_HEADER_BIT_START;
	148
	149	decrease_duration(&ev, RC6_BIT_END);
	150	goto again;
784a4931 DH	151
784a4931 DH	152	case STATE_TOGGLE_START:
e40b1127 DH	153	if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
	154	break;
	155
	156	data->toggle = ev.pulse;
e40b1127 DH	157	data->state = STATE_TOGGLE_END;
e40b1127 DH	158	return 0;
784a4931 DH	159
784a4931 DH	160	case STATE_TOGGLE_END:
d8b4b582	161	if (!is_transition(&ev, &dev->raw->prev_ev) \|\|
e40b1127 DH	162	!geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
e40b1127 DH	163	break;
784a4931	164
e40b1127 DH	165	if (!(data->header & RC6_STARTBIT_MASK)) {
	166	IR_dprintk(1, "RC6 invalid start bit\n");
	167	break;
	168	}
784a4931	169
e40b1127	170	data->state = STATE_BODY_BIT_START;
e40b1127 DH	171	decrease_duration(&ev, RC6_TOGGLE_END);
	172	data->count = 0;
	173
	174	switch (rc6_mode(data)) {
	175	case RC6_MODE_0:
	176	data->wanted_bits = RC6_0_NBITS;
	177	break;
	178	case RC6_MODE_6A:
	179	/* This might look weird, but we basically
	180	check the value of the first body bit to
	181	determine the number of bits in mode 6A */
	182	if ((!ev.pulse && !geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) \|\|
	183	geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
	184	data->wanted_bits = RC6_6A_LARGE_NBITS;
	185	else
	186	data->wanted_bits = RC6_6A_SMALL_NBITS;
	187	break;
	188	default:
	189	IR_dprintk(1, "RC6 unknown mode\n");
	190	goto out;
784a4931	191	}
e40b1127	192	goto again;
784a4931 DH	193
784a4931 DH	194	case STATE_BODY_BIT_START:
e40b1127 DH	195	if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
e40b1127 DH	196	break;
784a4931	197
e40b1127 DH	198	data->body <<= 1;
	199	if (ev.pulse)
	200	data->body \|= 1;
	201	data->count++;
e40b1127 DH	202	data->state = STATE_BODY_BIT_END;
e40b1127 DH	203	return 0;
784a4931 DH	204
784a4931 DH	205	case STATE_BODY_BIT_END:
d8b4b582	206	if (!is_transition(&ev, &dev->raw->prev_ev))
e40b1127	207	break;
784a4931	208
e40b1127 DH	209	if (data->count == data->wanted_bits)
	210	data->state = STATE_FINISHED;
	211	else
	212	data->state = STATE_BODY_BIT_START;
	213
	214	decrease_duration(&ev, RC6_BIT_END);
	215	goto again;
784a4931 DH	216
784a4931 DH	217	case STATE_FINISHED:
e40b1127 DH	218	if (ev.pulse)
	219	break;
	220
784a4931 DH	221	switch (rc6_mode(data)) {
	222	case RC6_MODE_0:
	223	scancode = data->body & 0xffff;
	224	toggle = data->toggle;
	225	IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
	226	scancode, toggle);
	227	break;
	228	case RC6_MODE_6A:
	229	if (data->wanted_bits == RC6_6A_LARGE_NBITS) {
	230	toggle = data->body & RC6_6A_MCE_TOGGLE_MASK ? 1 : 0;
	231	scancode = data->body & ~RC6_6A_MCE_TOGGLE_MASK;
	232	} else {
	233	toggle = 0;
	234	scancode = data->body & 0xffffff;
	235	}
	236
	237	IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n",
	238	scancode, toggle);
	239	break;
	240	default:
	241	IR_dprintk(1, "RC6 unknown mode\n");
	242	goto out;
	243	}
	244
ca86674b	245	rc_keydown(dev, scancode, toggle);
784a4931 DH	246	data->state = STATE_INACTIVE;
	247	return 0;
	248	}
	249
	250	out:
e40b1127 DH	251	IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n",
e40b1127 DH	252	data->state, TO_US(ev.duration), TO_STR(ev.pulse));
784a4931 DH	253	data->state = STATE_INACTIVE;
	254	return -EINVAL;
	255	}
	256
784a4931	257	static struct ir_raw_handler rc6_handler = {
667c9ebe	258	.protocols = IR_TYPE_RC6,
784a4931	259	.decode = ir_rc6_decode,
784a4931 DH	260	};
	261
	262	static int __init ir_rc6_decode_init(void)
	263	{
	264	ir_raw_handler_register(&rc6_handler);
	265
	266	printk(KERN_INFO "IR RC6 protocol handler initialized\n");
	267	return 0;
	268	}
	269
	270	static void __exit ir_rc6_decode_exit(void)
	271	{
	272	ir_raw_handler_unregister(&rc6_handler);
	273	}
	274
	275	module_init(ir_rc6_decode_init);
	276	module_exit(ir_rc6_decode_exit);
	277
	278	MODULE_LICENSE("GPL");
	279	MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
	280	MODULE_DESCRIPTION("RC6 IR protocol decoder");