[mirror_ubuntu-artful-kernel.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"
#include <linux/module.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 & RC_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	= RC_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"
7a707b89	16	#include <linux/module.h>
784a4931 DH	17
	18	/*
	19	* This decoder currently supports:
	20	* RC6-0-16 (standard toggle bit in header)
	21	* RC6-6A-24 (no toggle bit)
	22	* RC6-6A-32 (MCE version with toggle bit in body)
	23	*/
	24
	25	#define RC6_UNIT 444444 /* us */
	26	#define RC6_HEADER_NBITS 4 /* not including toggle bit */
	27	#define RC6_0_NBITS 16
	28	#define RC6_6A_SMALL_NBITS 24
	29	#define RC6_6A_LARGE_NBITS 32
e40b1127 DH	30	#define RC6_PREFIX_PULSE (6 * RC6_UNIT)
	31	#define RC6_PREFIX_SPACE (2 * RC6_UNIT)
	32	#define RC6_BIT_START (1 * RC6_UNIT)
	33	#define RC6_BIT_END (1 * RC6_UNIT)
	34	#define RC6_TOGGLE_START (2 * RC6_UNIT)
	35	#define RC6_TOGGLE_END (2 * RC6_UNIT)
784a4931 DH	36	#define RC6_MODE_MASK 0x07 /* for the header bits */
	37	#define RC6_STARTBIT_MASK 0x08 /* for the header bits */
	38	#define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */
	39
784a4931 DH	40	enum rc6_mode {
	41	RC6_MODE_0,
	42	RC6_MODE_6A,
	43	RC6_MODE_UNKNOWN,
	44	};
	45
	46	enum rc6_state {
	47	STATE_INACTIVE,
	48	STATE_PREFIX_SPACE,
	49	STATE_HEADER_BIT_START,
	50	STATE_HEADER_BIT_END,
	51	STATE_TOGGLE_START,
	52	STATE_TOGGLE_END,
	53	STATE_BODY_BIT_START,
	54	STATE_BODY_BIT_END,
	55	STATE_FINISHED,
	56	};
	57
c216369e	58	static enum rc6_mode rc6_mode(struct rc6_dec *data)
784a4931	59	{
784a4931 DH	60	switch (data->header & RC6_MODE_MASK) {
	61	case 0:
	62	return RC6_MODE_0;
	63	case 6:
	64	if (!data->toggle)
	65	return RC6_MODE_6A;
	66	/* fall through */
	67	default:
	68	return RC6_MODE_UNKNOWN;
	69	}
	70	}
	71
	72	/**
	73	* ir_rc6_decode() - Decode one RC6 pulse or space
d8b4b582	74	* @dev: the struct rc_dev descriptor of the device
e40b1127	75	* @ev: the struct ir_raw_event descriptor of the pulse/space
784a4931 DH	76	*
	77	* This function returns -EINVAL if the pulse violates the state machine
	78	*/
d8b4b582	79	static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
784a4931	80	{
d8b4b582	81	struct rc6_dec *data = &dev->raw->rc6;
784a4931 DH	82	u32 scancode;
784a4931 DH	83	u8 toggle;
784a4931	84
52b66144	85	if (!(dev->raw->enabled_protocols & RC_TYPE_RC6))
784a4931 DH	86	return 0;
784a4931 DH	87
4651918a ML	88	if (!is_timing_event(ev)) {
	89	if (ev.reset)
	90	data->state = STATE_INACTIVE;
784a4931 DH	91	return 0;
	92	}
	93
e40b1127	94	if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
784a4931 DH	95	goto out;
	96
	97	again:
e40b1127 DH	98	IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
e40b1127 DH	99	data->state, TO_US(ev.duration), TO_STR(ev.pulse));
784a4931	100
e40b1127	101	if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
784a4931 DH	102	return 0;
	103
	104	switch (data->state) {
	105
	106	case STATE_INACTIVE:
e40b1127 DH	107	if (!ev.pulse)
	108	break;
	109
	110	/* Note: larger margin on first pulse since each RC6_UNIT
	111	is quite short and some hardware takes some time to
	112	adjust to the signal */
	113	if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
	114	break;
	115
	116	data->state = STATE_PREFIX_SPACE;
	117	data->count = 0;
	118	return 0;
784a4931 DH	119
784a4931 DH	120	case STATE_PREFIX_SPACE:
e40b1127 DH	121	if (ev.pulse)
	122	break;
	123
	124	if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
	125	break;
	126
	127	data->state = STATE_HEADER_BIT_START;
	128	return 0;
784a4931 DH	129
784a4931 DH	130	case STATE_HEADER_BIT_START:
e40b1127 DH	131	if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
	132	break;
	133
	134	data->header <<= 1;
	135	if (ev.pulse)
	136	data->header \|= 1;
	137	data->count++;
e40b1127 DH	138	data->state = STATE_HEADER_BIT_END;
e40b1127 DH	139	return 0;
784a4931 DH	140
784a4931 DH	141	case STATE_HEADER_BIT_END:
d8b4b582	142	if (!is_transition(&ev, &dev->raw->prev_ev))
e40b1127	143	break;
784a4931	144
e40b1127 DH	145	if (data->count == RC6_HEADER_NBITS)
	146	data->state = STATE_TOGGLE_START;
	147	else
	148	data->state = STATE_HEADER_BIT_START;
	149
	150	decrease_duration(&ev, RC6_BIT_END);
	151	goto again;
784a4931 DH	152
784a4931 DH	153	case STATE_TOGGLE_START:
e40b1127 DH	154	if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
	155	break;
	156
	157	data->toggle = ev.pulse;
e40b1127 DH	158	data->state = STATE_TOGGLE_END;
e40b1127 DH	159	return 0;
784a4931 DH	160
784a4931 DH	161	case STATE_TOGGLE_END:
d8b4b582	162	if (!is_transition(&ev, &dev->raw->prev_ev) \|\|
e40b1127 DH	163	!geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
e40b1127 DH	164	break;
784a4931	165
e40b1127 DH	166	if (!(data->header & RC6_STARTBIT_MASK)) {
	167	IR_dprintk(1, "RC6 invalid start bit\n");
	168	break;
	169	}
784a4931	170
e40b1127	171	data->state = STATE_BODY_BIT_START;
e40b1127 DH	172	decrease_duration(&ev, RC6_TOGGLE_END);
	173	data->count = 0;
	174
	175	switch (rc6_mode(data)) {
	176	case RC6_MODE_0:
	177	data->wanted_bits = RC6_0_NBITS;
	178	break;
	179	case RC6_MODE_6A:
	180	/* This might look weird, but we basically
	181	check the value of the first body bit to
	182	determine the number of bits in mode 6A */
	183	if ((!ev.pulse && !geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) \|\|
	184	geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
	185	data->wanted_bits = RC6_6A_LARGE_NBITS;
	186	else
	187	data->wanted_bits = RC6_6A_SMALL_NBITS;
	188	break;
	189	default:
	190	IR_dprintk(1, "RC6 unknown mode\n");
	191	goto out;
784a4931	192	}
e40b1127	193	goto again;
784a4931 DH	194
784a4931 DH	195	case STATE_BODY_BIT_START:
e40b1127 DH	196	if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
e40b1127 DH	197	break;
784a4931	198
e40b1127 DH	199	data->body <<= 1;
	200	if (ev.pulse)
	201	data->body \|= 1;
	202	data->count++;
e40b1127 DH	203	data->state = STATE_BODY_BIT_END;
e40b1127 DH	204	return 0;
784a4931 DH	205
784a4931 DH	206	case STATE_BODY_BIT_END:
d8b4b582	207	if (!is_transition(&ev, &dev->raw->prev_ev))
e40b1127	208	break;
784a4931	209
e40b1127 DH	210	if (data->count == data->wanted_bits)
	211	data->state = STATE_FINISHED;
	212	else
	213	data->state = STATE_BODY_BIT_START;
	214
	215	decrease_duration(&ev, RC6_BIT_END);
	216	goto again;
784a4931 DH	217
784a4931 DH	218	case STATE_FINISHED:
e40b1127 DH	219	if (ev.pulse)
	220	break;
	221
784a4931 DH	222	switch (rc6_mode(data)) {
	223	case RC6_MODE_0:
	224	scancode = data->body & 0xffff;
	225	toggle = data->toggle;
	226	IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
	227	scancode, toggle);
	228	break;
	229	case RC6_MODE_6A:
	230	if (data->wanted_bits == RC6_6A_LARGE_NBITS) {
	231	toggle = data->body & RC6_6A_MCE_TOGGLE_MASK ? 1 : 0;
	232	scancode = data->body & ~RC6_6A_MCE_TOGGLE_MASK;
	233	} else {
	234	toggle = 0;
	235	scancode = data->body & 0xffffff;
	236	}
	237
	238	IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n",
	239	scancode, toggle);
	240	break;
	241	default:
	242	IR_dprintk(1, "RC6 unknown mode\n");
	243	goto out;
	244	}
	245
ca86674b	246	rc_keydown(dev, scancode, toggle);
784a4931 DH	247	data->state = STATE_INACTIVE;
	248	return 0;
	249	}
	250
	251	out:
e40b1127 DH	252	IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n",
e40b1127 DH	253	data->state, TO_US(ev.duration), TO_STR(ev.pulse));
784a4931 DH	254	data->state = STATE_INACTIVE;
	255	return -EINVAL;
	256	}
	257
784a4931	258	static struct ir_raw_handler rc6_handler = {
52b66144	259	.protocols = RC_TYPE_RC6,
784a4931	260	.decode = ir_rc6_decode,
784a4931 DH	261	};
	262
	263	static int __init ir_rc6_decode_init(void)
	264	{
	265	ir_raw_handler_register(&rc6_handler);
	266
	267	printk(KERN_INFO "IR RC6 protocol handler initialized\n");
	268	return 0;
	269	}
	270
	271	static void __exit ir_rc6_decode_exit(void)
	272	{
	273	ir_raw_handler_unregister(&rc6_handler);
	274	}
	275
	276	module_init(ir_rc6_decode_init);
	277	module_exit(ir_rc6_decode_exit);
	278
	279	MODULE_LICENSE("GPL");
	280	MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
	281	MODULE_DESCRIPTION("RC6 IR protocol decoder");