141 lines
3.5 KiB
C
141 lines
3.5 KiB
C
|
/*
|
||
|
|
* Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU General Public License as
|
||
|
|
* published by the Free Software Foundation version 2.
|
||
|
|
*
|
||
|
|
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
|
||
|
|
* kind, whether express or implied; without even the implied warranty
|
||
|
|
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
* GNU General Public License for more details.
|
||
|
|
*
|
||
|
|
* A generic driver to read multiple gpio lines and translate the
|
||
|
|
* encoded numeric value into an input event.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/device.h>
|
||
|
|
#include <linux/gpio/consumer.h>
|
||
|
|
#include <linux/input.h>
|
||
|
|
#include <linux/kernel.h>
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <linux/of.h>
|
||
|
|
#include <linux/platform_device.h>
|
||
|
|
|
||
|
|
struct gpio_decoder {
|
||
|
|
struct gpio_descs *input_gpios;
|
||
|
|
struct device *dev;
|
||
|
|
u32 axis;
|
||
|
|
u32 last_stable;
|
||
|
|
};
|
||
|
|
|
||
|
|
static int gpio_decoder_get_gpios_state(struct gpio_decoder *decoder)
|
||
|
|
{
|
||
|
|
struct gpio_descs *gpios = decoder->input_gpios;
|
||
|
|
unsigned int ret = 0;
|
||
|
|
int i, val;
|
||
|
|
|
||
|
|
for (i = 0; i < gpios->ndescs; i++) {
|
||
|
|
val = gpiod_get_value_cansleep(gpios->desc[i]);
|
||
|
|
if (val < 0) {
|
||
|
|
dev_err(decoder->dev,
|
||
|
|
"Error reading gpio %d: %d\n",
|
||
|
|
desc_to_gpio(gpios->desc[i]), val);
|
||
|
|
return val;
|
||
|
|
}
|
||
|
|
|
||
|
|
val = !!val;
|
||
|
|
ret = (ret << 1) | val;
|
||
|
|
}
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void gpio_decoder_poll_gpios(struct input_dev *input)
|
||
|
|
{
|
||
|
|
struct gpio_decoder *decoder = input_get_drvdata(input);
|
||
|
|
int state;
|
||
|
|
|
||
|
|
state = gpio_decoder_get_gpios_state(decoder);
|
||
|
|
if (state >= 0 && state != decoder->last_stable) {
|
||
|
|
input_report_abs(input, decoder->axis, state);
|
||
|
|
input_sync(input);
|
||
|
|
decoder->last_stable = state;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
static int gpio_decoder_probe(struct platform_device *pdev)
|
||
|
|
{
|
||
|
|
struct device *dev = &pdev->dev;
|
||
|
|
struct gpio_decoder *decoder;
|
||
|
|
struct input_dev *input;
|
||
|
|
u32 max;
|
||
|
|
int err;
|
||
|
|
|
||
|
|
decoder = devm_kzalloc(dev, sizeof(*decoder), GFP_KERNEL);
|
||
|
|
if (!decoder)
|
||
|
|
return -ENOMEM;
|
||
|
|
|
||
|
|
decoder->dev = dev;
|
||
|
|
device_property_read_u32(dev, "linux,axis", &decoder->axis);
|
||
|
|
|
||
|
|
decoder->input_gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
|
||
|
|
if (IS_ERR(decoder->input_gpios)) {
|
||
|
|
dev_err(dev, "unable to acquire input gpios\n");
|
||
|
|
return PTR_ERR(decoder->input_gpios);
|
||
|
|
}
|
||
|
|
|
||
|
|
if (decoder->input_gpios->ndescs < 2) {
|
||
|
|
dev_err(dev, "not enough gpios found\n");
|
||
|
|
return -EINVAL;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (device_property_read_u32(dev, "decoder-max-value", &max))
|
||
|
|
max = (1U << decoder->input_gpios->ndescs) - 1;
|
||
|
|
|
||
|
|
input = devm_input_allocate_device(dev);
|
||
|
|
if (!input)
|
||
|
|
return -ENOMEM;
|
||
|
|
|
||
|
|
input_set_drvdata(input, decoder);
|
||
|
|
|
||
|
|
input->name = pdev->name;
|
||
|
|
input->id.bustype = BUS_HOST;
|
||
|
|
input_set_abs_params(input, decoder->axis, 0, max, 0, 0);
|
||
|
|
|
||
|
|
err = input_setup_polling(input, gpio_decoder_poll_gpios);
|
||
|
|
if (err) {
|
||
|
|
dev_err(dev, "failed to set up polling\n");
|
||
|
|
return err;
|
||
|
|
}
|
||
|
|
|
||
|
|
err = input_register_device(input);
|
||
|
|
if (err) {
|
||
|
|
dev_err(dev, "failed to register input device\n");
|
||
|
|
return err;
|
||
|
|
}
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
#ifdef CONFIG_OF
|
||
|
|
static const struct of_device_id gpio_decoder_of_match[] = {
|
||
|
|
{ .compatible = "gpio-decoder", },
|
||
|
|
{ },
|
||
|
|
};
|
||
|
|
MODULE_DEVICE_TABLE(of, gpio_decoder_of_match);
|
||
|
|
#endif
|
||
|
|
|
||
|
|
static struct platform_driver gpio_decoder_driver = {
|
||
|
|
.probe = gpio_decoder_probe,
|
||
|
|
.driver = {
|
||
|
|
.name = "gpio-decoder",
|
||
|
|
.of_match_table = of_match_ptr(gpio_decoder_of_match),
|
||
|
|
}
|
||
|
|
};
|
||
|
|
module_platform_driver(gpio_decoder_driver);
|
||
|
|
|
||
|
|
MODULE_DESCRIPTION("GPIO decoder input driver");
|
||
|
|
MODULE_AUTHOR("Vignesh R <vigneshr@ti.com>");
|
||
|
|
MODULE_LICENSE("GPL v2");
|