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// SPDX-License-Identifier: GPL-2.0
/*
* ADC generic resistive touchscreen (GRTS)
* This is a generic input driver that connects to an ADC
* given the channels in device tree, and reports events to the input
* subsystem.
*
* Copyright (C) 2017,2018 Microchip Technology,
* Author: Eugen Hristev <eugen.hristev@microchip.com>
*
*/
#include <linux/input.h>
#include <linux/input/touchscreen.h>
#include <linux/iio/consumer.h>
#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#define DRIVER_NAME "resistive-adc-touch"
#define GRTS_DEFAULT_PRESSURE_MIN 50000
#define GRTS_MAX_POS_MASK GENMASK(11, 0)
/**
* grts_state - generic resistive touch screen information struct
* @pressure_min: number representing the minimum for the pressure
* @pressure: are we getting pressure info or not
* @iio_chans: list of channels acquired
* @iio_cb: iio_callback buffer for the data
* @input: the input device structure that we register
* @prop: touchscreen properties struct
*/
struct grts_state {
u32 pressure_min;
bool pressure;
struct iio_channel *iio_chans;
struct iio_cb_buffer *iio_cb;
struct input_dev *input;
struct touchscreen_properties prop;
};
static int grts_cb(const void *data, void *private)
{
const u16 *touch_info = data;
struct grts_state *st = private;
unsigned int x, y, press = 0x0;
/* channel data coming in buffer in the order below */
x = touch_info[0];
y = touch_info[1];
if (st->pressure)
press = touch_info[2];
if ((!x && !y) || (st->pressure && (press < st->pressure_min))) {
/* report end of touch */
input_report_key(st->input, BTN_TOUCH, 0);
input_sync(st->input);
return 0;
}
/* report proper touch to subsystem*/
touchscreen_report_pos(st->input, &st->prop, x, y, false);
if (st->pressure)
input_report_abs(st->input, ABS_PRESSURE, press);
input_report_key(st->input, BTN_TOUCH, 1);
input_sync(st->input);
return 0;
}
static int grts_open(struct input_dev *dev)
{
int error;
struct grts_state *st = input_get_drvdata(dev);
error = iio_channel_start_all_cb(st->iio_cb);
if (error) {
dev_err(dev->dev.parent, "failed to start callback buffer.\n");
return error;
}
return 0;
}
static void grts_close(struct input_dev *dev)
{
struct grts_state *st = input_get_drvdata(dev);
iio_channel_stop_all_cb(st->iio_cb);
}
static void grts_disable(void *data)
{
iio_channel_release_all_cb(data);
}
static int grts_probe(struct platform_device *pdev)
{
struct grts_state *st;
struct input_dev *input;
struct device *dev = &pdev->dev;
struct iio_channel *chan;
int error;
st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL);
if (!st)
return -ENOMEM;
/* get the channels from IIO device */
st->iio_chans = devm_iio_channel_get_all(dev);
if (IS_ERR(st->iio_chans)) {
error = PTR_ERR(st->iio_chans);
if (error != -EPROBE_DEFER)
dev_err(dev, "can't get iio channels.\n");
return error;
}
chan = &st->iio_chans[0];
st->pressure = false;
while (chan && chan->indio_dev) {
if (!strcmp(chan->channel->datasheet_name, "pressure"))
st->pressure = true;
chan++;
}
if (st->pressure) {
error = device_property_read_u32(dev,
"touchscreen-min-pressure",
&st->pressure_min);
if (error) {
dev_dbg(dev, "can't get touchscreen-min-pressure property.\n");
st->pressure_min = GRTS_DEFAULT_PRESSURE_MIN;
}
}
input = devm_input_allocate_device(dev);
if (!input) {
dev_err(dev, "failed to allocate input device.\n");
return -ENOMEM;
}
input->name = DRIVER_NAME;
input->id.bustype = BUS_HOST;
input->open = grts_open;
input->close = grts_close;
input_set_abs_params(input, ABS_X, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
if (st->pressure)
input_set_abs_params(input, ABS_PRESSURE, st->pressure_min,
0xffff, 0, 0);
input_set_capability(input, EV_KEY, BTN_TOUCH);
/* parse optional device tree properties */
touchscreen_parse_properties(input, false, &st->prop);
st->input = input;
input_set_drvdata(input, st);
error = input_register_device(input);
if (error) {
dev_err(dev, "failed to register input device.");
return error;
}
st->iio_cb = iio_channel_get_all_cb(dev, grts_cb, st);
if (IS_ERR(st->iio_cb)) {
dev_err(dev, "failed to allocate callback buffer.\n");
return PTR_ERR(st->iio_cb);
}
error = devm_add_action_or_reset(dev, grts_disable, st->iio_cb);
if (error) {
dev_err(dev, "failed to add disable action.\n");
return error;
}
return 0;
}
static const struct of_device_id grts_of_match[] = {
{
.compatible = "resistive-adc-touch",
}, {
/* sentinel */
},
};
MODULE_DEVICE_TABLE(of, grts_of_match);
static struct platform_driver grts_driver = {
.probe = grts_probe,
.driver = {
.name = DRIVER_NAME,
.of_match_table = of_match_ptr(grts_of_match),
},
};
module_platform_driver(grts_driver);
MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>");
MODULE_DESCRIPTION("Generic ADC Resistive Touch Driver");
MODULE_LICENSE("GPL v2");
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