blob: 99a49e4968d2bec4a1cf8d0d02779edd77e55de1 [file] [log] [blame]
/*
* 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>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>
#define DRV_NAME "rotary-encoder"
struct rotary_encoder {
struct input_dev *input;
const 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(const 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)
{
const 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;
}
#ifdef CONFIG_OF
static struct of_device_id rotary_encoder_of_match[] = {
{ .compatible = "rotary-encoder", },
{ },
};
MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
static struct rotary_encoder_platform_data * __devinit
rotary_encoder_parse_dt(struct device *dev)
{
const struct of_device_id *of_id =
of_match_device(rotary_encoder_of_match, dev);
struct device_node *np = dev->of_node;
struct rotary_encoder_platform_data *pdata;
enum of_gpio_flags flags;
if (!of_id || !np)
return NULL;
pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
GFP_KERNEL);
if (!pdata)
return ERR_PTR(-ENOMEM);
of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
of_property_read_u32(np, "linux,axis", &pdata->axis);
pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;
pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;
pdata->relative_axis = !!of_get_property(np,
"rotary-encoder,relative-axis", NULL);
pdata->rollover = !!of_get_property(np,
"rotary-encoder,rollover", NULL);
pdata->half_period = !!of_get_property(np,
"rotary-encoder,half-period", NULL);
return pdata;
}
#else
static inline struct rotary_encoder_platform_data *
rotary_encoder_parse_dt(struct device *dev)
{
return NULL;
}
#endif
static int __devinit rotary_encoder_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
struct rotary_encoder *encoder;
struct input_dev *input;
irq_handler_t handler;
int err;
if (!pdata) {
pdata = rotary_encoder_parse_dt(dev);
if (IS_ERR(pdata))
return PTR_ERR(pdata);
if (!pdata) {
dev_err(dev, "missing platform data\n");
return -EINVAL;
}
}
encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
input = input_allocate_device();
if (!encoder || !input) {
err = -ENOMEM;
goto exit_free_mem;
}
encoder->input = input;
encoder->pdata = pdata;
input->name = pdev->name;
input->id.bustype = BUS_HOST;
input->dev.parent = 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);
}
/* request the GPIOs */
err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
if (err) {
dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
goto exit_free_mem;
}
err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
if (err) {
dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
goto exit_free_gpio_a;
}
encoder->irq_a = gpio_to_irq(pdata->gpio_a);
encoder->irq_b = gpio_to_irq(pdata->gpio_b);
/* 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(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(dev, "unable to request IRQ %d\n", encoder->irq_b);
goto exit_free_irq_a;
}
err = input_register_device(input);
if (err) {
dev_err(dev, "failed to register input device\n");
goto exit_free_irq_b;
}
platform_set_drvdata(pdev, encoder);
return 0;
exit_free_irq_b:
free_irq(encoder->irq_b, encoder);
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_free_mem:
input_free_device(input);
kfree(encoder);
if (!dev_get_platdata(&pdev->dev))
kfree(pdata);
return err;
}
static int __devexit rotary_encoder_remove(struct platform_device *pdev)
{
struct rotary_encoder *encoder = platform_get_drvdata(pdev);
const struct rotary_encoder_platform_data *pdata = encoder->pdata;
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);
kfree(encoder);
if (!dev_get_platdata(&pdev->dev))
kfree(pdata);
platform_set_drvdata(pdev, NULL);
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,
.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");