// 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 __maybe_unused 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 __maybe_unused 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 SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,			 rotary_encoder_suspend, rotary_encoder_resume); #ifdef CONFIG_OFstatic 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	= &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");