drivers/media/IR/ir-rc5-decoder.c - kernel/skids - Git at Google

 /* ir-rc5-decoder.c - handle RC5(x) IR Pulse/Space protocol
  *
  * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
  *
  * 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.
  */

 /*
  * This code handles 14 bits RC5 protocols and 20 bits RC5x protocols.
  * There are other variants that use a different number of bits.
  * This is currently unsupported.
  * It considers a carrier of 36 kHz, with a total of 14/20 bits, where
  * the first two bits are start bits, and a third one is a filing bit
  */

 #include "ir-core-priv.h"

 #define RC5_NBITS		14
 #define RC5X_NBITS		20
 #define CHECK_RC5X_NBITS	8
 #define RC5_UNIT		888888 /* ns */
 #define RC5_BIT_START		(1 * RC5_UNIT)
 #define RC5_BIT_END		(1 * RC5_UNIT)
 #define RC5X_SPACE		(4 * RC5_UNIT)

 /* Used to register rc5_decoder clients */
 static LIST_HEAD(decoder_list);
 static DEFINE_SPINLOCK(decoder_lock);

 enum rc5_state {
 	STATE_INACTIVE,
 	STATE_BIT_START,
 	STATE_BIT_END,
 	STATE_CHECK_RC5X,
 	STATE_FINISHED,
 };

 struct decoder_data {
 	struct list_head	list;
 	struct ir_input_dev	*ir_dev;
 	int			enabled:1;

 	/* State machine control */
 	enum rc5_state		state;
 	u32			rc5_bits;
 	struct ir_raw_event	prev_ev;
 	unsigned		count;
 	unsigned		wanted_bits;
 };


 /**
  * get_decoder_data()	- gets decoder data
  * @input_dev:	input device
  *
  * Returns the struct decoder_data that corresponds to a device
  */

 static struct decoder_data *get_decoder_data(struct  ir_input_dev *ir_dev)
 {
 	struct decoder_data *data = NULL;

 	spin_lock(&decoder_lock);
 	list_for_each_entry(data, &decoder_list, list) {
 		if (data->ir_dev == ir_dev)
 			break;
 	}
 	spin_unlock(&decoder_lock);
 	return data;
 }

 static ssize_t store_enabled(struct device *d,
 			     struct device_attribute *mattr,
 			     const char *buf,
 			     size_t len)
 {
 	unsigned long value;
 	struct ir_input_dev *ir_dev = dev_get_drvdata(d);
 	struct decoder_data *data = get_decoder_data(ir_dev);

 	if (!data)
 		return -EINVAL;

 	if (strict_strtoul(buf, 10, &value) || value > 1)
 		return -EINVAL;

 	data->enabled = value;

 	return len;
 }

 static ssize_t show_enabled(struct device *d,
 			     struct device_attribute *mattr, char *buf)
 {
 	struct ir_input_dev *ir_dev = dev_get_drvdata(d);
 	struct decoder_data *data = get_decoder_data(ir_dev);

 	if (!data)
 		return -EINVAL;

 	if (data->enabled)
 		return sprintf(buf, "1\n");
 	else
 	return sprintf(buf, "0\n");
 }

 static DEVICE_ATTR(enabled, S_IRUGO | S_IWUSR, show_enabled, store_enabled);

 static struct attribute *decoder_attributes[] = {
 	&dev_attr_enabled.attr,
 	NULL
 };

 static struct attribute_group decoder_attribute_group = {
 	.name	= "rc5_decoder",
 	.attrs	= decoder_attributes,
 };

 /**
  * ir_rc5_decode() - Decode one RC-5 pulse or space
  * @input_dev:	the struct input_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_rc5_decode(struct input_dev *input_dev, struct ir_raw_event ev)
 {
 	struct decoder_data *data;
 	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 	u8 toggle;
 	u32 scancode;

 	data = get_decoder_data(ir_dev);
 	if (!data)
 		return -EINVAL;

 	if (!data->enabled)
 		return 0;

 	if (IS_RESET(ev)) {
 		data->state = STATE_INACTIVE;
 		return 0;
 	}

 	if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
 		goto out;

 again:
 	IR_dprintk(2, "RC5(x) decode started at state %i (%uus %s)\n",
 		   data->state, TO_US(ev.duration), TO_STR(ev.pulse));

 	if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
 		return 0;

 	switch (data->state) {

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

 		data->state = STATE_BIT_START;
 		data->count = 1;
 		/* We just need enough bits to get to STATE_CHECK_RC5X */
 		data->wanted_bits = RC5X_NBITS;
 		decrease_duration(&ev, RC5_BIT_START);
 		goto again;

 	case STATE_BIT_START:
 		if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
 			break;

 		data->rc5_bits <<= 1;
 		if (!ev.pulse)
 			data->rc5_bits |= 1;
 		data->count++;
 		data->prev_ev = ev;
 		data->state = STATE_BIT_END;
 		return 0;

 	case STATE_BIT_END:
 		if (!is_transition(&ev, &data->prev_ev))
 			break;

 		if (data->count == data->wanted_bits)
 			data->state = STATE_FINISHED;
 		else if (data->count == CHECK_RC5X_NBITS)
 			data->state = STATE_CHECK_RC5X;
 		else
 			data->state = STATE_BIT_START;

 		decrease_duration(&ev, RC5_BIT_END);
 		goto again;

 	case STATE_CHECK_RC5X:
 		if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) {
 			/* RC5X */
 			data->wanted_bits = RC5X_NBITS;
 			decrease_duration(&ev, RC5X_SPACE);
 		} else {
 			/* RC5 */
 			data->wanted_bits = RC5_NBITS;
 		}
 		data->state = STATE_BIT_START;
 		goto again;

 	case STATE_FINISHED:
 		if (ev.pulse)
 			break;

 		if (data->wanted_bits == RC5X_NBITS) {
 			/* RC5X */
 			u8 xdata, command, system;
 			xdata    = (data->rc5_bits & 0x0003F) >> 0;
 			command  = (data->rc5_bits & 0x00FC0) >> 6;
 			system   = (data->rc5_bits & 0x1F000) >> 12;
 			toggle   = (data->rc5_bits & 0x20000) ? 1 : 0;
 			command += (data->rc5_bits & 0x01000) ? 0 : 0x40;
 			scancode = system << 16 | command << 8 | xdata;

 			IR_dprintk(1, "RC5X scancode 0x%06x (toggle: %u)\n",
 				   scancode, toggle);

 		} else {
 			/* RC5 */
 			u8 command, system;
 			command  = (data->rc5_bits & 0x0003F) >> 0;
 			system   = (data->rc5_bits & 0x007C0) >> 6;
 			toggle   = (data->rc5_bits & 0x00800) ? 1 : 0;
 			command += (data->rc5_bits & 0x01000) ? 0 : 0x40;
 			scancode = system << 8 | command;

 			IR_dprintk(1, "RC5 scancode 0x%04x (toggle: %u)\n",
 				   scancode, toggle);
 		}

 		ir_keydown(input_dev, scancode, toggle);
 		data->state = STATE_INACTIVE;
 		return 0;
 	}

 out:
 	IR_dprintk(1, "RC5(x) 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 int ir_rc5_register(struct input_dev *input_dev)
 {
 	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 	struct decoder_data *data;
 	int rc;

 	rc = sysfs_create_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 	if (rc < 0)
 		return rc;

 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data) {
 		sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 		return -ENOMEM;
 	}

 	data->ir_dev = ir_dev;
 	data->enabled = 1;

 	spin_lock(&decoder_lock);
 	list_add_tail(&data->list, &decoder_list);
 	spin_unlock(&decoder_lock);

 	return 0;
 }

 static int ir_rc5_unregister(struct input_dev *input_dev)
 {
 	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 	static struct decoder_data *data;

 	data = get_decoder_data(ir_dev);
 	if (!data)
 		return 0;

 	sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);

 	spin_lock(&decoder_lock);
 	list_del(&data->list);
 	spin_unlock(&decoder_lock);

 	return 0;
 }

 static struct ir_raw_handler rc5_handler = {
 	.decode		= ir_rc5_decode,
 	.raw_register	= ir_rc5_register,
 	.raw_unregister	= ir_rc5_unregister,
 };

 static int __init ir_rc5_decode_init(void)
 {
 	ir_raw_handler_register(&rc5_handler);

 	printk(KERN_INFO "IR RC5(x) protocol handler initialized\n");
 	return 0;
 }

 static void __exit ir_rc5_decode_exit(void)
 {
 	ir_raw_handler_unregister(&rc5_handler);
 }

 module_init(ir_rc5_decode_init);
 module_exit(ir_rc5_decode_exit);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
 MODULE_DESCRIPTION("RC5(x) IR protocol decoder");
	/* ir-rc5-decoder.c - handle RC5(x) IR Pulse/Space protocol
	*
	* Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
	*
	* 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.
	*/

	/*
	* This code handles 14 bits RC5 protocols and 20 bits RC5x protocols.
	* There are other variants that use a different number of bits.
	* This is currently unsupported.
	* It considers a carrier of 36 kHz, with a total of 14/20 bits, where
	* the first two bits are start bits, and a third one is a filing bit
	*/

	#include "ir-core-priv.h"

	#define RC5_NBITS 14
	#define RC5X_NBITS 20
	#define CHECK_RC5X_NBITS 8
	#define RC5_UNIT 888888 /* ns */
	#define RC5_BIT_START (1 * RC5_UNIT)
	#define RC5_BIT_END (1 * RC5_UNIT)
	#define RC5X_SPACE (4 * RC5_UNIT)

	/* Used to register rc5_decoder clients */
	static LIST_HEAD(decoder_list);
	static DEFINE_SPINLOCK(decoder_lock);

	enum rc5_state {
	STATE_INACTIVE,
	STATE_BIT_START,
	STATE_BIT_END,
	STATE_CHECK_RC5X,
	STATE_FINISHED,
	};

	struct decoder_data {
	struct list_head list;
	struct ir_input_dev *ir_dev;
	int enabled:1;

	/* State machine control */
	enum rc5_state state;
	u32 rc5_bits;
	struct ir_raw_event prev_ev;
	unsigned count;
	unsigned wanted_bits;
	};


	/**
	* get_decoder_data() - gets decoder data
	* @input_dev: input device
	*
	* Returns the struct decoder_data that corresponds to a device
	*/

	static struct decoder_data get_decoder_data(struct ir_input_dev ir_dev)
	{
	struct decoder_data *data = NULL;

	spin_lock(&decoder_lock);
	list_for_each_entry(data, &decoder_list, list) {
	if (data->ir_dev == ir_dev)
	break;
	}
	spin_unlock(&decoder_lock);
	return data;
	}

	static ssize_t store_enabled(struct device *d,
	struct device_attribute *mattr,
	const char *buf,
	size_t len)
	{
	unsigned long value;
	struct ir_input_dev *ir_dev = dev_get_drvdata(d);
	struct decoder_data *data = get_decoder_data(ir_dev);

	if (!data)
	return -EINVAL;

	if (strict_strtoul(buf, 10, &value) \|\| value > 1)
	return -EINVAL;

	data->enabled = value;

	return len;
	}

	static ssize_t show_enabled(struct device *d,
	struct device_attribute mattr, char buf)
	{
	struct ir_input_dev *ir_dev = dev_get_drvdata(d);
	struct decoder_data *data = get_decoder_data(ir_dev);

	if (!data)
	return -EINVAL;

	if (data->enabled)
	return sprintf(buf, "1\n");
	else
	return sprintf(buf, "0\n");
	}

	static DEVICE_ATTR(enabled, S_IRUGO \| S_IWUSR, show_enabled, store_enabled);

	static struct attribute *decoder_attributes[] = {
	&dev_attr_enabled.attr,
	NULL
	};

	static struct attribute_group decoder_attribute_group = {
	.name = "rc5_decoder",
	.attrs = decoder_attributes,
	};

	/**
	* ir_rc5_decode() - Decode one RC-5 pulse or space
	* @input_dev: the struct input_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_rc5_decode(struct input_dev *input_dev, struct ir_raw_event ev)
	{
	struct decoder_data *data;
	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
	u8 toggle;
	u32 scancode;

	data = get_decoder_data(ir_dev);
	if (!data)
	return -EINVAL;

	if (!data->enabled)
	return 0;

	if (IS_RESET(ev)) {
	data->state = STATE_INACTIVE;
	return 0;
	}

	if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
	goto out;

	again:
	IR_dprintk(2, "RC5(x) decode started at state %i (%uus %s)\n",
	data->state, TO_US(ev.duration), TO_STR(ev.pulse));

	if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
	return 0;

	switch (data->state) {

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

	data->state = STATE_BIT_START;
	data->count = 1;
	/* We just need enough bits to get to STATE_CHECK_RC5X */
	data->wanted_bits = RC5X_NBITS;
	decrease_duration(&ev, RC5_BIT_START);
	goto again;

	case STATE_BIT_START:
	if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
	break;

	data->rc5_bits <<= 1;
	if (!ev.pulse)
	data->rc5_bits \|= 1;
	data->count++;
	data->prev_ev = ev;
	data->state = STATE_BIT_END;
	return 0;

	case STATE_BIT_END:
	if (!is_transition(&ev, &data->prev_ev))
	break;

	if (data->count == data->wanted_bits)
	data->state = STATE_FINISHED;
	else if (data->count == CHECK_RC5X_NBITS)
	data->state = STATE_CHECK_RC5X;
	else
	data->state = STATE_BIT_START;

	decrease_duration(&ev, RC5_BIT_END);
	goto again;

	case STATE_CHECK_RC5X:
	if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) {
	/* RC5X */
	data->wanted_bits = RC5X_NBITS;
	decrease_duration(&ev, RC5X_SPACE);
	} else {
	/* RC5 */
	data->wanted_bits = RC5_NBITS;
	}
	data->state = STATE_BIT_START;
	goto again;

	case STATE_FINISHED:
	if (ev.pulse)
	break;

	if (data->wanted_bits == RC5X_NBITS) {
	/* RC5X */
	u8 xdata, command, system;
	xdata = (data->rc5_bits & 0x0003F) >> 0;
	command = (data->rc5_bits & 0x00FC0) >> 6;
	system = (data->rc5_bits & 0x1F000) >> 12;
	toggle = (data->rc5_bits & 0x20000) ? 1 : 0;
	command += (data->rc5_bits & 0x01000) ? 0 : 0x40;
	scancode = system << 16 \| command << 8 \| xdata;

	IR_dprintk(1, "RC5X scancode 0x%06x (toggle: %u)\n",
	scancode, toggle);

	} else {
	/* RC5 */
	u8 command, system;
	command = (data->rc5_bits & 0x0003F) >> 0;
	system = (data->rc5_bits & 0x007C0) >> 6;
	toggle = (data->rc5_bits & 0x00800) ? 1 : 0;
	command += (data->rc5_bits & 0x01000) ? 0 : 0x40;
	scancode = system << 8 \| command;

	IR_dprintk(1, "RC5 scancode 0x%04x (toggle: %u)\n",
	scancode, toggle);
	}

	ir_keydown(input_dev, scancode, toggle);
	data->state = STATE_INACTIVE;
	return 0;
	}

	out:
	IR_dprintk(1, "RC5(x) 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 int ir_rc5_register(struct input_dev *input_dev)
	{
	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
	struct decoder_data *data;
	int rc;

	rc = sysfs_create_group(&ir_dev->dev.kobj, &decoder_attribute_group);
	if (rc < 0)
	return rc;

	data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (!data) {
	sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
	return -ENOMEM;
	}

	data->ir_dev = ir_dev;
	data->enabled = 1;

	spin_lock(&decoder_lock);
	list_add_tail(&data->list, &decoder_list);
	spin_unlock(&decoder_lock);

	return 0;
	}

	static int ir_rc5_unregister(struct input_dev *input_dev)
	{
	struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
	static struct decoder_data *data;

	data = get_decoder_data(ir_dev);
	if (!data)
	return 0;

	sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);

	spin_lock(&decoder_lock);
	list_del(&data->list);
	spin_unlock(&decoder_lock);

	return 0;
	}

	static struct ir_raw_handler rc5_handler = {
	.decode = ir_rc5_decode,
	.raw_register = ir_rc5_register,
	.raw_unregister = ir_rc5_unregister,
	};

	static int __init ir_rc5_decode_init(void)
	{
	ir_raw_handler_register(&rc5_handler);

	printk(KERN_INFO "IR RC5(x) protocol handler initialized\n");
	return 0;
	}

	static void __exit ir_rc5_decode_exit(void)
	{
	ir_raw_handler_unregister(&rc5_handler);
	}

	module_init(ir_rc5_decode_init);
	module_exit(ir_rc5_decode_exit);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
	MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
	MODULE_DESCRIPTION("RC5(x) IR protocol decoder");