input: touchscreen: resistive-adc-touch: add generic resistive ADC touchscreen

This adds a generic resistive touchscreen (GRTS) driver, which is based
on an IIO device (an ADC). It must be connected to the channels of an ADC
to receive touch data. Then it will feed the data into the input subsystem
where it registers an input device.
It uses an IIO callback buffer to register to the IIO device

Some parts of this patch are based on initial original work by
Mohamed Jamsheeth Hajanajubudeen and Bandaru Venkateswara Swamy

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Eugen Hristev 2018-05-22 10:52:36 +03:00 committed by Jonathan Cameron
parent 23ec2774f1
commit aa132ffb6b
3 changed files with 218 additions and 0 deletions

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@ -92,6 +92,19 @@ config TOUCHSCREEN_AD7879_SPI
To compile this driver as a module, choose M here: the
module will be called ad7879-spi.
config TOUCHSCREEN_ADC
tristate "Generic ADC based resistive touchscreen"
depends on IIO
select IIO_BUFFER_CB
help
Say Y here if you want to use the generic ADC
resistive touchscreen driver.
If unsure, say N (but it's safe to say "Y").
To compile this driver as a module, choose M here: the
module will be called resistive-adc-touch.ko.
config TOUCHSCREEN_AR1021_I2C
tristate "Microchip AR1020/1021 i2c touchscreen"
depends on I2C && OF

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@ -13,6 +13,7 @@ obj-$(CONFIG_TOUCHSCREEN_AD7877) += ad7877.o
obj-$(CONFIG_TOUCHSCREEN_AD7879) += ad7879.o
obj-$(CONFIG_TOUCHSCREEN_AD7879_I2C) += ad7879-i2c.o
obj-$(CONFIG_TOUCHSCREEN_AD7879_SPI) += ad7879-spi.o
obj-$(CONFIG_TOUCHSCREEN_ADC) += resistive-adc-touch.o
obj-$(CONFIG_TOUCHSCREEN_ADS7846) += ads7846.o
obj-$(CONFIG_TOUCHSCREEN_AR1021_I2C) += ar1021_i2c.o
obj-$(CONFIG_TOUCHSCREEN_ATMEL_MXT) += atmel_mxt_ts.o

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@ -0,0 +1,204 @@
// 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");