drivers/media/rc/ir-nec-decoder.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 // ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
 //
 // Copyright (C) 2010 by Mauro Carvalho Chehab

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

 #define NEC_NBITS		32
 #define NEC_UNIT		563  /* us */
 #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
  * @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_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.overflow)
 			data->state = STATE_INACTIVE;
 		return 0;
 	}

 	dev_dbg(&dev->dev, "NEC decode started at state %d (%uus %s)\n",
 		data->state, 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)) {
 			dev_dbg(&dev->dev, "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;
 	}

 	dev_dbg(&dev->dev, "NEC decode failed at count %d state %d (%uus %s)\n",
 		data->count, data->state, 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.
  */
 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,
 	.carrier	= 38000,
 	.min_timeout	= NEC_TRAILER_SPACE,
 };

 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 v2");
 MODULE_AUTHOR("Mauro Carvalho Chehab");
 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
 MODULE_DESCRIPTION("NEC IR protocol decoder");
	// SPDX-License-Identifier: GPL-2.0
	// ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
	//
	// Copyright (C) 2010 by Mauro Carvalho Chehab

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

	#define NEC_NBITS 32
	#define NEC_UNIT 563 /* us */
	#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
	* @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_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.overflow)
	data->state = STATE_INACTIVE;
	return 0;
	}

	dev_dbg(&dev->dev, "NEC decode started at state %d (%uus %s)\n",
	data->state, 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)) {
	dev_dbg(&dev->dev, "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;
	}

	dev_dbg(&dev->dev, "NEC decode failed at count %d state %d (%uus %s)\n",
	data->count, data->state, 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.
	*/
	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,
	.carrier = 38000,
	.min_timeout = NEC_TRAILER_SPACE,
	};

	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 v2");
	MODULE_AUTHOR("Mauro Carvalho Chehab");
	MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
	MODULE_DESCRIPTION("NEC IR protocol decoder");