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/*
* rotary_encoder.c
*
* (c) 2009 Daniel Mack <daniel@caiaq.de>
*
* 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>
#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 */
};
static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
{
struct rotary_encoder *encoder = dev_id;
struct rotary_encoder_platform_data *pdata = encoder->pdata;
int a = !!gpio_get_value(pdata->gpio_a);
int b = !!gpio_get_value(pdata->gpio_b);
int state;
a ^= pdata->inverted_a;
b ^= pdata->inverted_b;
state = (a << 1) | b;
switch (state) {
case 0x0:
if (!encoder->armed)
break;
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);
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 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;
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_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;
}
/* request the IRQs */
err = request_irq(encoder->irq_a, &rotary_encoder_irq,
IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
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, &rotary_encoder_irq,
IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
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>");
MODULE_LICENSE("GPL v2");
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