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

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * 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/devices/rotary-encoder.rst for more information
  */

 #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/consumer.h>
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/pm.h>
 #include <linux/property.h>

 #define DRV_NAME "rotary-encoder"

 enum rotary_encoder_encoding {
 	ROTENC_GRAY,
 	ROTENC_BINARY,
 };

 struct rotary_encoder {
 	struct input_dev *input;

 	struct mutex access_mutex;

 	u32 steps;
 	u32 axis;
 	bool relative_axis;
 	bool rollover;
 	enum rotary_encoder_encoding encoding;

 	unsigned int pos;

 	struct gpio_descs *gpios;

 	unsigned int *irq;

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

 	unsigned int last_stable;
 };

 static unsigned int rotary_encoder_get_state(struct rotary_encoder *encoder)
 {
 	int i;
 	unsigned int ret = 0;

 	for (i = 0; i < encoder->gpios->ndescs; ++i) {
 		int val = gpiod_get_value_cansleep(encoder->gpios->desc[i]);

 		/* convert from gray encoding to normal */
 		if (encoder->encoding == ROTENC_GRAY && ret & 1)
 			val = !val;

 		ret = ret << 1 | val;
 	}

 	return ret & 3;
 }

 static void rotary_encoder_report_event(struct rotary_encoder *encoder)
 {
 	if (encoder->relative_axis) {
 		input_report_rel(encoder->input,
 				 encoder->axis, encoder->dir);
 	} else {
 		unsigned int pos = encoder->pos;

 		if (encoder->dir < 0) {
 			/* turning counter-clockwise */
 			if (encoder->rollover)
 				pos += encoder->steps;
 			if (pos)
 				pos--;
 		} else {
 			/* turning clockwise */
 			if (encoder->rollover || pos < encoder->steps)
 				pos++;
 		}

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

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

 	input_sync(encoder->input);
 }

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

 	mutex_lock(&encoder->access_mutex);

 	state = rotary_encoder_get_state(encoder);

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

 	case 0x1:
 	case 0x3:
 		if (encoder->armed)
 			encoder->dir = 2 - state;
 		break;

 	case 0x2:
 		encoder->armed = true;
 		break;
 	}

 	mutex_unlock(&encoder->access_mutex);

 	return IRQ_HANDLED;
 }

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

 	mutex_lock(&encoder->access_mutex);

 	state = rotary_encoder_get_state(encoder);

 	if (state & 1) {
 		encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1;
 	} else {
 		if (state != encoder->last_stable) {
 			rotary_encoder_report_event(encoder);
 			encoder->last_stable = state;
 		}
 	}

 	mutex_unlock(&encoder->access_mutex);

 	return IRQ_HANDLED;
 }

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

 	mutex_lock(&encoder->access_mutex);

 	state = rotary_encoder_get_state(encoder);

 	if ((encoder->last_stable + 1) % 4 == state)
 		encoder->dir = 1;
 	else if (encoder->last_stable == (state + 1) % 4)
 		encoder->dir = -1;
 	else
 		goto out;

 	rotary_encoder_report_event(encoder);

 out:
 	encoder->last_stable = state;
 	mutex_unlock(&encoder->access_mutex);

 	return IRQ_HANDLED;
 }

 static int rotary_encoder_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct rotary_encoder *encoder;
 	struct input_dev *input;
 	irq_handler_t handler;
 	u32 steps_per_period;
 	unsigned int i;
 	int err;

 	encoder = devm_kzalloc(dev, sizeof(struct rotary_encoder), GFP_KERNEL);
 	if (!encoder)
 		return -ENOMEM;

 	mutex_init(&encoder->access_mutex);

 	device_property_read_u32(dev, "rotary-encoder,steps", &encoder->steps);

 	err = device_property_read_u32(dev, "rotary-encoder,steps-per-period",
 				       &steps_per_period);
 	if (err) {
 		/*
 		 * 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
 		 * neither property is present we fall back to the one step
 		 * per period behavior.
 		 */
 		steps_per_period = device_property_read_bool(dev,
 					"rotary-encoder,half-period") ? 2 : 1;
 	}

 	encoder->rollover =
 		device_property_read_bool(dev, "rotary-encoder,rollover");

 	if (!device_property_present(dev, "rotary-encoder,encoding") ||
 	    !device_property_match_string(dev, "rotary-encoder,encoding",
 					  "gray")) {
 		dev_info(dev, "gray");
 		encoder->encoding = ROTENC_GRAY;
 	} else if (!device_property_match_string(dev, "rotary-encoder,encoding",
 						 "binary")) {
 		dev_info(dev, "binary");
 		encoder->encoding = ROTENC_BINARY;
 	} else {
 		dev_err(dev, "unknown encoding setting\n");
 		return -EINVAL;
 	}

 	device_property_read_u32(dev, "linux,axis", &encoder->axis);
 	encoder->relative_axis =
 		device_property_read_bool(dev, "rotary-encoder,relative-axis");

 	encoder->gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
 	if (IS_ERR(encoder->gpios)) {
 		err = PTR_ERR(encoder->gpios);
 		if (err != -EPROBE_DEFER)
 			dev_err(dev, "unable to get gpios: %d\n", err);
 		return err;
 	}
 	if (encoder->gpios->ndescs < 2) {
 		dev_err(dev, "not enough gpios found\n");
 		return -EINVAL;
 	}

 	input = devm_input_allocate_device(dev);
 	if (!input)
 		return -ENOMEM;

 	encoder->input = input;

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

 	if (encoder->relative_axis)
 		input_set_capability(input, EV_REL, encoder->axis);
 	else
 		input_set_abs_params(input,
 				     encoder->axis, 0, encoder->steps, 0, 1);

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

 	encoder->irq =
 		devm_kcalloc(dev,
 			     encoder->gpios->ndescs, sizeof(*encoder->irq),
 			     GFP_KERNEL);
 	if (!encoder->irq)
 		return -ENOMEM;

 	for (i = 0; i < encoder->gpios->ndescs; ++i) {
 		encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);

 		err = devm_request_threaded_irq(dev, encoder->irq[i],
 				NULL, handler,
 				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
 				IRQF_ONESHOT,
 				DRV_NAME, encoder);
 		if (err) {
 			dev_err(dev, "unable to request IRQ %d (gpio#%d)\n",
 				encoder->irq[i], i);
 			return err;
 		}
 	}

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

 	device_init_wakeup(dev,
 			   device_property_read_bool(dev, "wakeup-source"));

 	platform_set_drvdata(pdev, encoder);

 	return 0;
 }

 static int rotary_encoder_suspend(struct device *dev)
 {
 	struct rotary_encoder *encoder = dev_get_drvdata(dev);
 	unsigned int i;

 	if (device_may_wakeup(dev)) {
 		for (i = 0; i < encoder->gpios->ndescs; ++i)
 			enable_irq_wake(encoder->irq[i]);
 	}

 	return 0;
 }

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

 	if (device_may_wakeup(dev)) {
 		for (i = 0; i < encoder->gpios->ndescs; ++i)
 			disable_irq_wake(encoder->irq[i]);
 	}

 	return 0;
 }

 static DEFINE_SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
 				rotary_encoder_suspend, rotary_encoder_resume);

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

 static struct platform_driver rotary_encoder_driver = {
 	.probe		= rotary_encoder_probe,
 	.driver		= {
 		.name	= DRV_NAME,
 		.pm	= pm_sleep_ptr(&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");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* 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/devices/rotary-encoder.rst for more information
	*/

	#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/consumer.h>
	#include <linux/slab.h>
	#include <linux/of.h>
	#include <linux/pm.h>
	#include <linux/property.h>

	#define DRV_NAME "rotary-encoder"

	enum rotary_encoder_encoding {
	ROTENC_GRAY,
	ROTENC_BINARY,
	};

	struct rotary_encoder {
	struct input_dev *input;

	struct mutex access_mutex;

	u32 steps;
	u32 axis;
	bool relative_axis;
	bool rollover;
	enum rotary_encoder_encoding encoding;

	unsigned int pos;

	struct gpio_descs *gpios;

	unsigned int *irq;

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

	unsigned int last_stable;
	};

	static unsigned int rotary_encoder_get_state(struct rotary_encoder *encoder)
	{
	int i;
	unsigned int ret = 0;

	for (i = 0; i < encoder->gpios->ndescs; ++i) {
	int val = gpiod_get_value_cansleep(encoder->gpios->desc[i]);

	/* convert from gray encoding to normal */
	if (encoder->encoding == ROTENC_GRAY && ret & 1)
	val = !val;

	ret = ret << 1 \| val;
	}

	return ret & 3;
	}

	static void rotary_encoder_report_event(struct rotary_encoder *encoder)
	{
	if (encoder->relative_axis) {
	input_report_rel(encoder->input,
	encoder->axis, encoder->dir);
	} else {
	unsigned int pos = encoder->pos;

	if (encoder->dir < 0) {
	/* turning counter-clockwise */
	if (encoder->rollover)
	pos += encoder->steps;
	if (pos)
	pos--;
	} else {
	/* turning clockwise */
	if (encoder->rollover \|\| pos < encoder->steps)
	pos++;
	}

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

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

	input_sync(encoder->input);
	}

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

	mutex_lock(&encoder->access_mutex);

	state = rotary_encoder_get_state(encoder);

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

	case 0x1:
	case 0x3:
	if (encoder->armed)
	encoder->dir = 2 - state;
	break;

	case 0x2:
	encoder->armed = true;
	break;
	}

	mutex_unlock(&encoder->access_mutex);

	return IRQ_HANDLED;
	}

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

	mutex_lock(&encoder->access_mutex);

	state = rotary_encoder_get_state(encoder);

	if (state & 1) {
	encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1;
	} else {
	if (state != encoder->last_stable) {
	rotary_encoder_report_event(encoder);
	encoder->last_stable = state;
	}
	}

	mutex_unlock(&encoder->access_mutex);

	return IRQ_HANDLED;
	}

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

	mutex_lock(&encoder->access_mutex);

	state = rotary_encoder_get_state(encoder);

	if ((encoder->last_stable + 1) % 4 == state)
	encoder->dir = 1;
	else if (encoder->last_stable == (state + 1) % 4)
	encoder->dir = -1;
	else
	goto out;

	rotary_encoder_report_event(encoder);

	out:
	encoder->last_stable = state;
	mutex_unlock(&encoder->access_mutex);

	return IRQ_HANDLED;
	}

	static int rotary_encoder_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct rotary_encoder *encoder;
	struct input_dev *input;
	irq_handler_t handler;
	u32 steps_per_period;
	unsigned int i;
	int err;

	encoder = devm_kzalloc(dev, sizeof(struct rotary_encoder), GFP_KERNEL);
	if (!encoder)
	return -ENOMEM;

	mutex_init(&encoder->access_mutex);

	device_property_read_u32(dev, "rotary-encoder,steps", &encoder->steps);

	err = device_property_read_u32(dev, "rotary-encoder,steps-per-period",
	&steps_per_period);
	if (err) {
	/*
	* 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
	* neither property is present we fall back to the one step
	* per period behavior.
	*/
	steps_per_period = device_property_read_bool(dev,
	"rotary-encoder,half-period") ? 2 : 1;
	}

	encoder->rollover =
	device_property_read_bool(dev, "rotary-encoder,rollover");

	if (!device_property_present(dev, "rotary-encoder,encoding") \|\|
	!device_property_match_string(dev, "rotary-encoder,encoding",
	"gray")) {
	dev_info(dev, "gray");
	encoder->encoding = ROTENC_GRAY;
	} else if (!device_property_match_string(dev, "rotary-encoder,encoding",
	"binary")) {
	dev_info(dev, "binary");
	encoder->encoding = ROTENC_BINARY;
	} else {
	dev_err(dev, "unknown encoding setting\n");
	return -EINVAL;
	}

	device_property_read_u32(dev, "linux,axis", &encoder->axis);
	encoder->relative_axis =
	device_property_read_bool(dev, "rotary-encoder,relative-axis");

	encoder->gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
	if (IS_ERR(encoder->gpios)) {
	err = PTR_ERR(encoder->gpios);
	if (err != -EPROBE_DEFER)
	dev_err(dev, "unable to get gpios: %d\n", err);
	return err;
	}
	if (encoder->gpios->ndescs < 2) {
	dev_err(dev, "not enough gpios found\n");
	return -EINVAL;
	}

	input = devm_input_allocate_device(dev);
	if (!input)
	return -ENOMEM;

	encoder->input = input;

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

	if (encoder->relative_axis)
	input_set_capability(input, EV_REL, encoder->axis);
	else
	input_set_abs_params(input,
	encoder->axis, 0, encoder->steps, 0, 1);

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

	encoder->irq =
	devm_kcalloc(dev,
	encoder->gpios->ndescs, sizeof(*encoder->irq),
	GFP_KERNEL);
	if (!encoder->irq)
	return -ENOMEM;

	for (i = 0; i < encoder->gpios->ndescs; ++i) {
	encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);

	err = devm_request_threaded_irq(dev, encoder->irq[i],
	NULL, handler,
	IRQF_TRIGGER_RISING \| IRQF_TRIGGER_FALLING \|
	IRQF_ONESHOT,
	DRV_NAME, encoder);
	if (err) {
	dev_err(dev, "unable to request IRQ %d (gpio#%d)\n",
	encoder->irq[i], i);
	return err;
	}
	}

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

	device_init_wakeup(dev,
	device_property_read_bool(dev, "wakeup-source"));

	platform_set_drvdata(pdev, encoder);

	return 0;
	}

	static int rotary_encoder_suspend(struct device *dev)
	{
	struct rotary_encoder *encoder = dev_get_drvdata(dev);
	unsigned int i;

	if (device_may_wakeup(dev)) {
	for (i = 0; i < encoder->gpios->ndescs; ++i)
	enable_irq_wake(encoder->irq[i]);
	}

	return 0;
	}

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

	if (device_may_wakeup(dev)) {
	for (i = 0; i < encoder->gpios->ndescs; ++i)
	disable_irq_wake(encoder->irq[i]);
	}

	return 0;
	}

	static DEFINE_SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
	rotary_encoder_suspend, rotary_encoder_resume);

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

	static struct platform_driver rotary_encoder_driver = {
	.probe = rotary_encoder_probe,
	.driver = {
	.name = DRV_NAME,
	.pm = pm_sleep_ptr(&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");