/* * 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/init.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> #define DRV_NAME "rotary-encoder" struct rotary_encoder {	struct input_dev *input;	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(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){	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 int __devinit rotary_encoder_probe(struct platform_device *pdev){	struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;	struct rotary_encoder *encoder;	struct input_dev *input;	irq_handler_t handler;	int err; 	if (!pdata) {		dev_err(&pdev->dev, "missing platform data\n");		return -ENOENT;	} 	encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);	input = input_allocate_device();	if (!encoder || !input) {		dev_err(&pdev->dev, "failed to allocate memory for device\n");		err = -ENOMEM;		goto exit_free_mem;	} 	encoder->input = input;	encoder->pdata = pdata;	encoder->irq_a = gpio_to_irq(pdata->gpio_a);	encoder->irq_b = gpio_to_irq(pdata->gpio_b); 	/* create and register the input driver */	input->name = pdev->name;	input->id.bustype = BUS_HOST;	input->dev.parent = &pdev->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);	} 	err = input_register_device(input);	if (err) {		dev_err(&pdev->dev, "failed to register input device\n");		goto exit_free_mem;	} 	/* request the GPIOs */	err = gpio_request(pdata->gpio_a, DRV_NAME);	if (err) {		dev_err(&pdev->dev, "unable to request GPIO %d\n",			pdata->gpio_a);		goto exit_unregister_input;	} 	err = gpio_direction_input(pdata->gpio_a);	if (err) {		dev_err(&pdev->dev, "unable to set GPIO %d for input\n",			pdata->gpio_a);		goto exit_unregister_input;	} 	err = gpio_request(pdata->gpio_b, DRV_NAME);	if (err) {		dev_err(&pdev->dev, "unable to request GPIO %d\n",			pdata->gpio_b);		goto exit_free_gpio_a;	} 	err = gpio_direction_input(pdata->gpio_b);	if (err) {		dev_err(&pdev->dev, "unable to set GPIO %d for input\n",			pdata->gpio_b);		goto exit_free_gpio_a;	} 	/* request the IRQs */	if (pdata->half_period) {		handler = &rotary_encoder_half_period_irq;		encoder->last_stable = rotary_encoder_get_state(pdata);	} else {		handler = &rotary_encoder_irq;	} 	err = request_irq(encoder->irq_a, handler,			  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,			  DRV_NAME, encoder);	if (err) {		dev_err(&pdev->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(&pdev->dev, "unable to request IRQ %d\n",			encoder->irq_b);		goto exit_free_irq_a;	} 	platform_set_drvdata(pdev, encoder); 	return 0; 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_unregister_input:	input_unregister_device(input);	input = NULL; /* so we don't try to free it */exit_free_mem:	input_free_device(input);	kfree(encoder);	return err;} static int __devexit rotary_encoder_remove(struct platform_device *pdev){	struct rotary_encoder *encoder = platform_get_drvdata(pdev);	struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data; 	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);	platform_set_drvdata(pdev, NULL);	kfree(encoder); 	return 0;} static struct platform_driver rotary_encoder_driver = {	.probe		= rotary_encoder_probe,	.remove		= __devexit_p(rotary_encoder_remove),	.driver		= {		.name	= DRV_NAME,		.owner	= THIS_MODULE,	}}; static int __init rotary_encoder_init(void){	return platform_driver_register(&rotary_encoder_driver);} static void __exit rotary_encoder_exit(void){	platform_driver_unregister(&rotary_encoder_driver);} module_init(rotary_encoder_init);module_exit(rotary_encoder_exit); MODULE_ALIAS("platform:" DRV_NAME);MODULE_DESCRIPTION("GPIO rotary encoder driver");MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");MODULE_LICENSE("GPL v2");