6946416164
Add a driver to read group of GPIO lines and provide its status as a numerical value as input event to the system. This will help in interfacing devices, that can be connected over GPIOs, that provide input to the system by driving GPIO lines connected to them like a rotary dial or a switch. For example, a rotary switch can be connected to four GPIO lines. The status of the GPIO lines reflect the actual position of the rotary switch dial. For example, if dial points to 9, then the four GPIO lines connected to the switch will read HLLH(0b'1001 = 9). This value can be reported as an ABS_* event to the input subsystem. Signed-off-by: Vignesh R <vigneshr@ti.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
138 lines
3.6 KiB
C
138 lines
3.6 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/input-polldev.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/of.h>
|
|
#include <linux/platform_device.h>
|
|
|
|
struct gpio_decoder {
|
|
struct input_polled_dev *poll_dev;
|
|
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_polled_dev *poll_dev)
|
|
{
|
|
struct gpio_decoder *decoder = poll_dev->private;
|
|
int state;
|
|
|
|
state = gpio_decoder_get_gpios_state(decoder);
|
|
if (state >= 0 && state != decoder->last_stable) {
|
|
input_report_abs(poll_dev->input, decoder->axis, state);
|
|
input_sync(poll_dev->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_polled_dev *poll_dev;
|
|
u32 max;
|
|
int err;
|
|
|
|
decoder = devm_kzalloc(dev, sizeof(struct gpio_decoder), GFP_KERNEL);
|
|
if (!decoder)
|
|
return -ENOMEM;
|
|
|
|
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;
|
|
|
|
decoder->dev = dev;
|
|
poll_dev = devm_input_allocate_polled_device(decoder->dev);
|
|
if (!poll_dev)
|
|
return -ENOMEM;
|
|
|
|
poll_dev->private = decoder;
|
|
poll_dev->poll = gpio_decoder_poll_gpios;
|
|
decoder->poll_dev = poll_dev;
|
|
|
|
poll_dev->input->name = pdev->name;
|
|
poll_dev->input->id.bustype = BUS_HOST;
|
|
input_set_abs_params(poll_dev->input, decoder->axis, 0, max, 0, 0);
|
|
|
|
err = input_register_polled_device(poll_dev);
|
|
if (err) {
|
|
dev_err(dev, "failed to register polled device\n");
|
|
return err;
|
|
}
|
|
platform_set_drvdata(pdev, decoder);
|
|
|
|
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");
|