drivers/input/misc/rotary_encoder.c - kernel/panda - 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/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");
	/*
	* 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");