drivers/input/misc/rotary_encoder.c - linux - Git at Google

 /*
  * rotary_encoder.c
  *
  * (c) 2009 Daniel Mack <daniel@caiaq.de>
  * Copyright (C) 2011 Johan Hovold <jhovold@gmail.com>
  *
  * state machine code inspired by code from Tim Ruetz
  *
  * A generic driver for rotary encoders connected to GPIO lines.
  * See file:Documentation/input/rotary-encoder.txt for more information
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/input.h>
 #include <linux/device.h>
 #include <linux/platform_device.h>
 #include <linux/gpio.h>
 #include <linux/rotary_encoder.h>
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/of_gpio.h>
 #include <linux/pm.h>

 #define DRV_NAME "rotary-encoder"

 struct rotary_encoder {
 	struct input_dev *input;
 	const struct rotary_encoder_platform_data *pdata;

 	unsigned int axis;
 	unsigned int pos;

 	unsigned int irq_a;
 	unsigned int irq_b;

 	bool armed;
 	unsigned char dir;	/* 0 - clockwise, 1 - CCW */

 	char last_stable;
 };

 static int rotary_encoder_get_state(const struct rotary_encoder_platform_data *pdata)
 {
 	int a = !!gpio_get_value(pdata->gpio_a);
 	int b = !!gpio_get_value(pdata->gpio_b);

 	a ^= pdata->inverted_a;
 	b ^= pdata->inverted_b;

 	return ((a << 1) | b);
 }

 static void rotary_encoder_report_event(struct rotary_encoder *encoder)
 {
 	const struct rotary_encoder_platform_data *pdata = encoder->pdata;

 	if (pdata->relative_axis) {
 		input_report_rel(encoder->input,
 				 pdata->axis, encoder->dir ? -1 : 1);
 	} else {
 		unsigned int pos = encoder->pos;

 		if (encoder->dir) {
 			/* turning counter-clockwise */
 			if (pdata->rollover)
 				pos += pdata->steps;
 			if (pos)
 				pos--;
 		} else {
 			/* turning clockwise */
 			if (pdata->rollover || pos < pdata->steps)
 				pos++;
 		}

 		if (pdata->rollover)
 			pos %= pdata->steps;

 		encoder->pos = pos;
 		input_report_abs(encoder->input, pdata->axis, encoder->pos);
 	}

 	input_sync(encoder->input);
 }

 static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
 {
 	struct rotary_encoder *encoder = dev_id;
 	int state;

 	state = rotary_encoder_get_state(encoder->pdata);

 	switch (state) {
 	case 0x0:
 		if (encoder->armed) {
 			rotary_encoder_report_event(encoder);
 			encoder->armed = false;
 		}
 		break;

 	case 0x1:
 	case 0x2:
 		if (encoder->armed)
 			encoder->dir = state - 1;
 		break;

 	case 0x3:
 		encoder->armed = true;
 		break;
 	}

 	return IRQ_HANDLED;
 }

 static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
 {
 	struct rotary_encoder *encoder = dev_id;
 	int state;

 	state = rotary_encoder_get_state(encoder->pdata);

 	switch (state) {
 	case 0x00:
 	case 0x03:
 		if (state != encoder->last_stable) {
 			rotary_encoder_report_event(encoder);
 			encoder->last_stable = state;
 		}
 		break;

 	case 0x01:
 	case 0x02:
 		encoder->dir = (encoder->last_stable + state) & 0x01;
 		break;
 	}

 	return IRQ_HANDLED;
 }

 static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
 {
 	struct rotary_encoder *encoder = dev_id;
 	unsigned char sum;
 	int state;

 	state = rotary_encoder_get_state(encoder->pdata);

 	/*
 	 * We encode the previous and the current state using a byte.
 	 * The previous state in the MSB nibble, the current state in the LSB
 	 * nibble. Then use a table to decide the direction of the turn.
 	 */
 	sum = (encoder->last_stable << 4) + state;
 	switch (sum) {
 	case 0x31:
 	case 0x10:
 	case 0x02:
 	case 0x23:
 		encoder->dir = 0; /* clockwise */
 		break;

 	case 0x13:
 	case 0x01:
 	case 0x20:
 	case 0x32:
 		encoder->dir = 1; /* counter-clockwise */
 		break;

 	default:
 		/*
 		 * Ignore all other values. This covers the case when the
 		 * state didn't change (a spurious interrupt) and the
 		 * cases where the state changed by two steps, making it
 		 * impossible to tell the direction.
 		 *
 		 * In either case, don't report any event and save the
 		 * state for later.
 		 */
 		goto out;
 	}

 	rotary_encoder_report_event(encoder);

 out:
 	encoder->last_stable = state;
 	return IRQ_HANDLED;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id rotary_encoder_of_match[] = {
 	{ .compatible = "rotary-encoder", },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);

 static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct device *dev)
 {
 	const struct of_device_id *of_id =
 				of_match_device(rotary_encoder_of_match, dev);
 	struct device_node *np = dev->of_node;
 	struct rotary_encoder_platform_data *pdata;
 	enum of_gpio_flags flags;
 	int error;

 	if (!of_id || !np)
 		return NULL;

 	pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
 			GFP_KERNEL);
 	if (!pdata)
 		return ERR_PTR(-ENOMEM);

 	of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
 	of_property_read_u32(np, "linux,axis", &pdata->axis);

 	pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
 	pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;

 	pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
 	pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;

 	pdata->relative_axis =
 		of_property_read_bool(np, "rotary-encoder,relative-axis");
 	pdata->rollover = of_property_read_bool(np, "rotary-encoder,rollover");

 	error = of_property_read_u32(np, "rotary-encoder,steps-per-period",
 				     &pdata->steps_per_period);
 	if (error) {
 		/*
 		 * The 'half-period' property has been deprecated, you must use
 		 * 'steps-per-period' and set an appropriate value, but we still
 		 * need to parse it to maintain compatibility.
 		 */
 		if (of_property_read_bool(np, "rotary-encoder,half-period")) {
 			pdata->steps_per_period = 2;
 		} else {
 			/* Fallback to one step per period behavior */
 			pdata->steps_per_period = 1;
 		}
 	}

 	pdata->wakeup_source = of_property_read_bool(np, "wakeup-source");

 	return pdata;
 }
 #else
 static inline struct rotary_encoder_platform_data *
 rotary_encoder_parse_dt(struct device *dev)
 {
 	return NULL;
 }
 #endif

 static int rotary_encoder_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
 	struct rotary_encoder *encoder;
 	struct input_dev *input;
 	irq_handler_t handler;
 	int err;

 	if (!pdata) {
 		pdata = rotary_encoder_parse_dt(dev);
 		if (IS_ERR(pdata))
 			return PTR_ERR(pdata);

 		if (!pdata) {
 			dev_err(dev, "missing platform data\n");
 			return -EINVAL;
 		}
 	}

 	encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
 	input = input_allocate_device();
 	if (!encoder || !input) {
 		err = -ENOMEM;
 		goto exit_free_mem;
 	}

 	encoder->input = input;
 	encoder->pdata = pdata;

 	input->name = pdev->name;
 	input->id.bustype = BUS_HOST;
 	input->dev.parent = dev;

 	if (pdata->relative_axis) {
 		input->evbit[0] = BIT_MASK(EV_REL);
 		input->relbit[0] = BIT_MASK(pdata->axis);
 	} else {
 		input->evbit[0] = BIT_MASK(EV_ABS);
 		input_set_abs_params(encoder->input,
 				     pdata->axis, 0, pdata->steps, 0, 1);
 	}

 	/* request the GPIOs */
 	err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
 	if (err) {
 		dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
 		goto exit_free_mem;
 	}

 	err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
 	if (err) {
 		dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
 		goto exit_free_gpio_a;
 	}

 	encoder->irq_a = gpio_to_irq(pdata->gpio_a);
 	encoder->irq_b = gpio_to_irq(pdata->gpio_b);

 	switch (pdata->steps_per_period) {
 	case 4:
 		handler = &rotary_encoder_quarter_period_irq;
 		encoder->last_stable = rotary_encoder_get_state(pdata);
 		break;
 	case 2:
 		handler = &rotary_encoder_half_period_irq;
 		encoder->last_stable = rotary_encoder_get_state(pdata);
 		break;
 	case 1:
 		handler = &rotary_encoder_irq;
 		break;
 	default:
 		dev_err(dev, "'%d' is not a valid steps-per-period value\n",
 			pdata->steps_per_period);
 		err = -EINVAL;
 		goto exit_free_gpio_b;
 	}

 	err = request_irq(encoder->irq_a, handler,
 			  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 			  DRV_NAME, encoder);
 	if (err) {
 		dev_err(dev, "unable to request IRQ %d\n", encoder->irq_a);
 		goto exit_free_gpio_b;
 	}

 	err = request_irq(encoder->irq_b, handler,
 			  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 			  DRV_NAME, encoder);
 	if (err) {
 		dev_err(dev, "unable to request IRQ %d\n", encoder->irq_b);
 		goto exit_free_irq_a;
 	}

 	err = input_register_device(input);
 	if (err) {
 		dev_err(dev, "failed to register input device\n");
 		goto exit_free_irq_b;
 	}

 	device_init_wakeup(&pdev->dev, pdata->wakeup_source);

 	platform_set_drvdata(pdev, encoder);

 	return 0;

 exit_free_irq_b:
 	free_irq(encoder->irq_b, encoder);
 exit_free_irq_a:
 	free_irq(encoder->irq_a, encoder);
 exit_free_gpio_b:
 	gpio_free(pdata->gpio_b);
 exit_free_gpio_a:
 	gpio_free(pdata->gpio_a);
 exit_free_mem:
 	input_free_device(input);
 	kfree(encoder);
 	if (!dev_get_platdata(&pdev->dev))
 		kfree(pdata);

 	return err;
 }

 static int rotary_encoder_remove(struct platform_device *pdev)
 {
 	struct rotary_encoder *encoder = platform_get_drvdata(pdev);
 	const struct rotary_encoder_platform_data *pdata = encoder->pdata;

 	device_init_wakeup(&pdev->dev, false);

 	free_irq(encoder->irq_a, encoder);
 	free_irq(encoder->irq_b, encoder);
 	gpio_free(pdata->gpio_a);
 	gpio_free(pdata->gpio_b);

 	input_unregister_device(encoder->input);
 	kfree(encoder);

 	if (!dev_get_platdata(&pdev->dev))
 		kfree(pdata);

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static int rotary_encoder_suspend(struct device *dev)
 {
 	struct rotary_encoder *encoder = dev_get_drvdata(dev);

 	if (device_may_wakeup(dev)) {
 		enable_irq_wake(encoder->irq_a);
 		enable_irq_wake(encoder->irq_b);
 	}

 	return 0;
 }

 static int rotary_encoder_resume(struct device *dev)
 {
 	struct rotary_encoder *encoder = dev_get_drvdata(dev);

 	if (device_may_wakeup(dev)) {
 		disable_irq_wake(encoder->irq_a);
 		disable_irq_wake(encoder->irq_b);
 	}

 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
 		 rotary_encoder_suspend, rotary_encoder_resume);

 static struct platform_driver rotary_encoder_driver = {
 	.probe		= rotary_encoder_probe,
 	.remove		= rotary_encoder_remove,
 	.driver		= {
 		.name	= DRV_NAME,
 		.pm	= &rotary_encoder_pm_ops,
 		.of_match_table = of_match_ptr(rotary_encoder_of_match),
 	}
 };
 module_platform_driver(rotary_encoder_driver);

 MODULE_ALIAS("platform:" DRV_NAME);
 MODULE_DESCRIPTION("GPIO rotary encoder driver");
 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
 MODULE_LICENSE("GPL v2");
	/*
	* rotary_encoder.c
	*
	* (c) 2009 Daniel Mack <daniel@caiaq.de>
	* Copyright (C) 2011 Johan Hovold <jhovold@gmail.com>
	*
	* state machine code inspired by code from Tim Ruetz
	*
	* A generic driver for rotary encoders connected to GPIO lines.
	* See file:Documentation/input/rotary-encoder.txt for more information
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/input.h>
	#include <linux/device.h>
	#include <linux/platform_device.h>
	#include <linux/gpio.h>
	#include <linux/rotary_encoder.h>
	#include <linux/slab.h>
	#include <linux/of.h>
	#include <linux/of_platform.h>
	#include <linux/of_gpio.h>
	#include <linux/pm.h>

	#define DRV_NAME "rotary-encoder"

	struct rotary_encoder {
	struct input_dev *input;
	const struct rotary_encoder_platform_data *pdata;

	unsigned int axis;
	unsigned int pos;

	unsigned int irq_a;
	unsigned int irq_b;

	bool armed;
	unsigned char dir; /* 0 - clockwise, 1 - CCW */

	char last_stable;
	};

	static int rotary_encoder_get_state(const struct rotary_encoder_platform_data *pdata)
	{
	int a = !!gpio_get_value(pdata->gpio_a);
	int b = !!gpio_get_value(pdata->gpio_b);

	a ^= pdata->inverted_a;
	b ^= pdata->inverted_b;

	return ((a << 1) \| b);
	}

	static void rotary_encoder_report_event(struct rotary_encoder *encoder)
	{
	const struct rotary_encoder_platform_data *pdata = encoder->pdata;

	if (pdata->relative_axis) {
	input_report_rel(encoder->input,
	pdata->axis, encoder->dir ? -1 : 1);
	} else {
	unsigned int pos = encoder->pos;

	if (encoder->dir) {
	/* turning counter-clockwise */
	if (pdata->rollover)
	pos += pdata->steps;
	if (pos)
	pos--;
	} else {
	/* turning clockwise */
	if (pdata->rollover \|\| pos < pdata->steps)
	pos++;
	}

	if (pdata->rollover)
	pos %= pdata->steps;

	encoder->pos = pos;
	input_report_abs(encoder->input, pdata->axis, encoder->pos);
	}

	input_sync(encoder->input);
	}

	static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
	{
	struct rotary_encoder *encoder = dev_id;
	int state;

	state = rotary_encoder_get_state(encoder->pdata);

	switch (state) {
	case 0x0:
	if (encoder->armed) {
	rotary_encoder_report_event(encoder);
	encoder->armed = false;
	}
	break;

	case 0x1:
	case 0x2:
	if (encoder->armed)
	encoder->dir = state - 1;
	break;

	case 0x3:
	encoder->armed = true;
	break;
	}

	return IRQ_HANDLED;
	}

	static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
	{
	struct rotary_encoder *encoder = dev_id;
	int state;

	state = rotary_encoder_get_state(encoder->pdata);

	switch (state) {
	case 0x00:
	case 0x03:
	if (state != encoder->last_stable) {
	rotary_encoder_report_event(encoder);
	encoder->last_stable = state;
	}
	break;

	case 0x01:
	case 0x02:
	encoder->dir = (encoder->last_stable + state) & 0x01;
	break;
	}

	return IRQ_HANDLED;
	}

	static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
	{
	struct rotary_encoder *encoder = dev_id;
	unsigned char sum;
	int state;

	state = rotary_encoder_get_state(encoder->pdata);

	/*
	* We encode the previous and the current state using a byte.
	* The previous state in the MSB nibble, the current state in the LSB
	* nibble. Then use a table to decide the direction of the turn.
	*/
	sum = (encoder->last_stable << 4) + state;
	switch (sum) {
	case 0x31:
	case 0x10:
	case 0x02:
	case 0x23:
	encoder->dir = 0; /* clockwise */
	break;

	case 0x13:
	case 0x01:
	case 0x20:
	case 0x32:
	encoder->dir = 1; /* counter-clockwise */
	break;

	default:
	/*
	* Ignore all other values. This covers the case when the
	* state didn't change (a spurious interrupt) and the
	* cases where the state changed by two steps, making it
	* impossible to tell the direction.
	*
	* In either case, don't report any event and save the
	* state for later.
	*/
	goto out;
	}

	rotary_encoder_report_event(encoder);

	out:
	encoder->last_stable = state;
	return IRQ_HANDLED;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id rotary_encoder_of_match[] = {
	{ .compatible = "rotary-encoder", },
	{ },
	};
	MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);

	static struct rotary_encoder_platform_data rotary_encoder_parse_dt(struct device dev)
	{
	const struct of_device_id *of_id =
	of_match_device(rotary_encoder_of_match, dev);
	struct device_node *np = dev->of_node;
	struct rotary_encoder_platform_data *pdata;
	enum of_gpio_flags flags;
	int error;

	if (!of_id \|\| !np)
	return NULL;

	pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
	GFP_KERNEL);
	if (!pdata)
	return ERR_PTR(-ENOMEM);

	of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
	of_property_read_u32(np, "linux,axis", &pdata->axis);

	pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
	pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;

	pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
	pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;

	pdata->relative_axis =
	of_property_read_bool(np, "rotary-encoder,relative-axis");
	pdata->rollover = of_property_read_bool(np, "rotary-encoder,rollover");

	error = of_property_read_u32(np, "rotary-encoder,steps-per-period",
	&pdata->steps_per_period);
	if (error) {
	/*
	* The 'half-period' property has been deprecated, you must use
	* 'steps-per-period' and set an appropriate value, but we still
	* need to parse it to maintain compatibility.
	*/
	if (of_property_read_bool(np, "rotary-encoder,half-period")) {
	pdata->steps_per_period = 2;
	} else {
	/* Fallback to one step per period behavior */
	pdata->steps_per_period = 1;
	}
	}

	pdata->wakeup_source = of_property_read_bool(np, "wakeup-source");

	return pdata;
	}
	#else
	static inline struct rotary_encoder_platform_data *
	rotary_encoder_parse_dt(struct device *dev)
	{
	return NULL;
	}
	#endif

	static int rotary_encoder_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
	struct rotary_encoder *encoder;
	struct input_dev *input;
	irq_handler_t handler;
	int err;

	if (!pdata) {
	pdata = rotary_encoder_parse_dt(dev);
	if (IS_ERR(pdata))
	return PTR_ERR(pdata);

	if (!pdata) {
	dev_err(dev, "missing platform data\n");
	return -EINVAL;
	}
	}

	encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
	input = input_allocate_device();
	if (!encoder \|\| !input) {
	err = -ENOMEM;
	goto exit_free_mem;
	}

	encoder->input = input;
	encoder->pdata = pdata;

	input->name = pdev->name;
	input->id.bustype = BUS_HOST;
	input->dev.parent = dev;

	if (pdata->relative_axis) {
	input->evbit[0] = BIT_MASK(EV_REL);
	input->relbit[0] = BIT_MASK(pdata->axis);
	} else {
	input->evbit[0] = BIT_MASK(EV_ABS);
	input_set_abs_params(encoder->input,
	pdata->axis, 0, pdata->steps, 0, 1);
	}

	/* request the GPIOs */
	err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
	if (err) {
	dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
	goto exit_free_mem;
	}

	err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
	if (err) {
	dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
	goto exit_free_gpio_a;
	}

	encoder->irq_a = gpio_to_irq(pdata->gpio_a);
	encoder->irq_b = gpio_to_irq(pdata->gpio_b);

	switch (pdata->steps_per_period) {
	case 4:
	handler = &rotary_encoder_quarter_period_irq;
	encoder->last_stable = rotary_encoder_get_state(pdata);
	break;
	case 2:
	handler = &rotary_encoder_half_period_irq;
	encoder->last_stable = rotary_encoder_get_state(pdata);
	break;
	case 1:
	handler = &rotary_encoder_irq;
	break;
	default:
	dev_err(dev, "'%d' is not a valid steps-per-period value\n",
	pdata->steps_per_period);
	err = -EINVAL;
	goto exit_free_gpio_b;
	}

	err = request_irq(encoder->irq_a, handler,
	IRQF_TRIGGER_RISING \| IRQF_TRIGGER_FALLING,
	DRV_NAME, encoder);
	if (err) {
	dev_err(dev, "unable to request IRQ %d\n", encoder->irq_a);
	goto exit_free_gpio_b;
	}

	err = request_irq(encoder->irq_b, handler,
	IRQF_TRIGGER_RISING \| IRQF_TRIGGER_FALLING,
	DRV_NAME, encoder);
	if (err) {
	dev_err(dev, "unable to request IRQ %d\n", encoder->irq_b);
	goto exit_free_irq_a;
	}

	err = input_register_device(input);
	if (err) {
	dev_err(dev, "failed to register input device\n");
	goto exit_free_irq_b;
	}

	device_init_wakeup(&pdev->dev, pdata->wakeup_source);

	platform_set_drvdata(pdev, encoder);

	return 0;

	exit_free_irq_b:
	free_irq(encoder->irq_b, encoder);
	exit_free_irq_a:
	free_irq(encoder->irq_a, encoder);
	exit_free_gpio_b:
	gpio_free(pdata->gpio_b);
	exit_free_gpio_a:
	gpio_free(pdata->gpio_a);
	exit_free_mem:
	input_free_device(input);
	kfree(encoder);
	if (!dev_get_platdata(&pdev->dev))
	kfree(pdata);

	return err;
	}

	static int rotary_encoder_remove(struct platform_device *pdev)
	{
	struct rotary_encoder *encoder = platform_get_drvdata(pdev);
	const struct rotary_encoder_platform_data *pdata = encoder->pdata;

	device_init_wakeup(&pdev->dev, false);

	free_irq(encoder->irq_a, encoder);
	free_irq(encoder->irq_b, encoder);
	gpio_free(pdata->gpio_a);
	gpio_free(pdata->gpio_b);

	input_unregister_device(encoder->input);
	kfree(encoder);

	if (!dev_get_platdata(&pdev->dev))
	kfree(pdata);

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static int rotary_encoder_suspend(struct device *dev)
	{
	struct rotary_encoder *encoder = dev_get_drvdata(dev);

	if (device_may_wakeup(dev)) {
	enable_irq_wake(encoder->irq_a);
	enable_irq_wake(encoder->irq_b);
	}

	return 0;
	}

	static int rotary_encoder_resume(struct device *dev)
	{
	struct rotary_encoder *encoder = dev_get_drvdata(dev);

	if (device_may_wakeup(dev)) {
	disable_irq_wake(encoder->irq_a);
	disable_irq_wake(encoder->irq_b);
	}

	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
	rotary_encoder_suspend, rotary_encoder_resume);

	static struct platform_driver rotary_encoder_driver = {
	.probe = rotary_encoder_probe,
	.remove = rotary_encoder_remove,
	.driver = {
	.name = DRV_NAME,
	.pm = &rotary_encoder_pm_ops,
	.of_match_table = of_match_ptr(rotary_encoder_of_match),
	}
	};
	module_platform_driver(rotary_encoder_driver);

	MODULE_ALIAS("platform:" DRV_NAME);
	MODULE_DESCRIPTION("GPIO rotary encoder driver");
	MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
	MODULE_LICENSE("GPL v2");