drivers/media/rc/ir-rc6-decoder.c - kernel/mindspeed - Git at Google

 /* 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");
	/* 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");