2015-09-05 10:32:09 -07:00
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/*
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* Toradex Colibri VF50 Touchscreen driver
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*
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* Copyright 2015 Toradex AG
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*
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* Originally authored by Stefan Agner for 3.0 kernel
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/gpio.h>
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#include <linux/gpio/consumer.h>
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#include <linux/iio/consumer.h>
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#include <linux/iio/types.h>
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#include <linux/input.h>
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#include <linux/interrupt.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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2016-02-09 11:32:53 -07:00
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#include <linux/of.h>
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2015-09-05 10:32:09 -07:00
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#include <linux/pinctrl/consumer.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#define DRIVER_NAME "colibri-vf50-ts"
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#define VF_ADC_MAX ((1 << 12) - 1)
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#define COLI_TOUCH_MIN_DELAY_US 1000
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#define COLI_TOUCH_MAX_DELAY_US 2000
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#define COLI_PULLUP_MIN_DELAY_US 10000
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#define COLI_PULLUP_MAX_DELAY_US 11000
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#define COLI_TOUCH_NO_OF_AVGS 5
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#define COLI_TOUCH_REQ_ADC_CHAN 4
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struct vf50_touch_device {
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struct platform_device *pdev;
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struct input_dev *ts_input;
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struct iio_channel *channels;
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struct gpio_desc *gpio_xp;
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struct gpio_desc *gpio_xm;
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struct gpio_desc *gpio_yp;
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struct gpio_desc *gpio_ym;
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int pen_irq;
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int min_pressure;
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bool stop_touchscreen;
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};
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/*
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* Enables given plates and measures touch parameters using ADC
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*/
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static int adc_ts_measure(struct iio_channel *channel,
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struct gpio_desc *plate_p, struct gpio_desc *plate_m)
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{
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int i, value = 0, val = 0;
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int error;
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gpiod_set_value(plate_p, 1);
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gpiod_set_value(plate_m, 1);
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usleep_range(COLI_TOUCH_MIN_DELAY_US, COLI_TOUCH_MAX_DELAY_US);
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for (i = 0; i < COLI_TOUCH_NO_OF_AVGS; i++) {
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error = iio_read_channel_raw(channel, &val);
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if (error < 0) {
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value = error;
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goto error_iio_read;
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}
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value += val;
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}
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value /= COLI_TOUCH_NO_OF_AVGS;
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error_iio_read:
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gpiod_set_value(plate_p, 0);
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gpiod_set_value(plate_m, 0);
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return value;
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}
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/*
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* Enable touch detection using falling edge detection on XM
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*/
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static void vf50_ts_enable_touch_detection(struct vf50_touch_device *vf50_ts)
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{
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/* Enable plate YM (needs to be strong GND, high active) */
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gpiod_set_value(vf50_ts->gpio_ym, 1);
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/*
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* Let the platform mux to idle state in order to enable
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* Pull-Up on GPIO
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*/
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pinctrl_pm_select_idle_state(&vf50_ts->pdev->dev);
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/* Wait for the pull-up to be stable on high */
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usleep_range(COLI_PULLUP_MIN_DELAY_US, COLI_PULLUP_MAX_DELAY_US);
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}
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/*
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* ADC touch screen sampling bottom half irq handler
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*/
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static irqreturn_t vf50_ts_irq_bh(int irq, void *private)
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{
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struct vf50_touch_device *vf50_ts = private;
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struct device *dev = &vf50_ts->pdev->dev;
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int val_x, val_y, val_z1, val_z2, val_p = 0;
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bool discard_val_on_start = true;
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/* Disable the touch detection plates */
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gpiod_set_value(vf50_ts->gpio_ym, 0);
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/* Let the platform mux to default state in order to mux as ADC */
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pinctrl_pm_select_default_state(dev);
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while (!vf50_ts->stop_touchscreen) {
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/* X-Direction */
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val_x = adc_ts_measure(&vf50_ts->channels[0],
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vf50_ts->gpio_xp, vf50_ts->gpio_xm);
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if (val_x < 0)
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break;
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/* Y-Direction */
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val_y = adc_ts_measure(&vf50_ts->channels[1],
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vf50_ts->gpio_yp, vf50_ts->gpio_ym);
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if (val_y < 0)
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break;
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/*
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* Touch pressure
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* Measure on XP/YM
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*/
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val_z1 = adc_ts_measure(&vf50_ts->channels[2],
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vf50_ts->gpio_yp, vf50_ts->gpio_xm);
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if (val_z1 < 0)
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break;
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val_z2 = adc_ts_measure(&vf50_ts->channels[3],
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vf50_ts->gpio_yp, vf50_ts->gpio_xm);
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if (val_z2 < 0)
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break;
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/* Validate signal (avoid calculation using noise) */
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if (val_z1 > 64 && val_x > 64) {
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/*
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* Calculate resistance between the plates
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* lower resistance means higher pressure
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*/
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int r_x = (1000 * val_x) / VF_ADC_MAX;
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val_p = (r_x * val_z2) / val_z1 - r_x;
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} else {
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val_p = 2000;
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}
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val_p = 2000 - val_p;
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dev_dbg(dev,
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"Measured values: x: %d, y: %d, z1: %d, z2: %d, p: %d\n",
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val_x, val_y, val_z1, val_z2, val_p);
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/*
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* If touch pressure is too low, stop measuring and reenable
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* touch detection
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*/
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if (val_p < vf50_ts->min_pressure || val_p > 2000)
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break;
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/*
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* The pressure may not be enough for the first x and the
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* second y measurement, but, the pressure is ok when the
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* driver is doing the third and fourth measurement. To
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* take care of this, we drop the first measurement always.
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*/
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if (discard_val_on_start) {
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discard_val_on_start = false;
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} else {
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/*
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* Report touch position and sleep for
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* the next measurement.
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*/
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input_report_abs(vf50_ts->ts_input,
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ABS_X, VF_ADC_MAX - val_x);
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input_report_abs(vf50_ts->ts_input,
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ABS_Y, VF_ADC_MAX - val_y);
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input_report_abs(vf50_ts->ts_input,
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ABS_PRESSURE, val_p);
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input_report_key(vf50_ts->ts_input, BTN_TOUCH, 1);
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input_sync(vf50_ts->ts_input);
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}
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usleep_range(COLI_PULLUP_MIN_DELAY_US,
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COLI_PULLUP_MAX_DELAY_US);
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}
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/* Report no more touch, re-enable touch detection */
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input_report_abs(vf50_ts->ts_input, ABS_PRESSURE, 0);
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input_report_key(vf50_ts->ts_input, BTN_TOUCH, 0);
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input_sync(vf50_ts->ts_input);
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vf50_ts_enable_touch_detection(vf50_ts);
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return IRQ_HANDLED;
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}
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static int vf50_ts_open(struct input_dev *dev_input)
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{
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struct vf50_touch_device *touchdev = input_get_drvdata(dev_input);
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struct device *dev = &touchdev->pdev->dev;
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dev_dbg(dev, "Input device %s opened, starting touch detection\n",
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dev_input->name);
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touchdev->stop_touchscreen = false;
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/* Mux detection before request IRQ, wait for pull-up to settle */
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vf50_ts_enable_touch_detection(touchdev);
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return 0;
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}
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static void vf50_ts_close(struct input_dev *dev_input)
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{
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struct vf50_touch_device *touchdev = input_get_drvdata(dev_input);
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struct device *dev = &touchdev->pdev->dev;
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touchdev->stop_touchscreen = true;
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/* Make sure IRQ is not running past close */
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mb();
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synchronize_irq(touchdev->pen_irq);
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gpiod_set_value(touchdev->gpio_ym, 0);
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pinctrl_pm_select_default_state(dev);
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dev_dbg(dev, "Input device %s closed, disable touch detection\n",
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dev_input->name);
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}
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static int vf50_ts_get_gpiod(struct device *dev, struct gpio_desc **gpio_d,
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const char *con_id, enum gpiod_flags flags)
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{
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int error;
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*gpio_d = devm_gpiod_get(dev, con_id, flags);
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if (IS_ERR(*gpio_d)) {
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error = PTR_ERR(*gpio_d);
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dev_err(dev, "Could not get gpio_%s %d\n", con_id, error);
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return error;
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}
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return 0;
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}
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static void vf50_ts_channel_release(void *data)
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{
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struct iio_channel *channels = data;
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iio_channel_release_all(channels);
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}
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static int vf50_ts_probe(struct platform_device *pdev)
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{
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struct input_dev *input;
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struct iio_channel *channels;
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struct device *dev = &pdev->dev;
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struct vf50_touch_device *touchdev;
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int num_adc_channels;
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int error;
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channels = iio_channel_get_all(dev);
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if (IS_ERR(channels))
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return PTR_ERR(channels);
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error = devm_add_action(dev, vf50_ts_channel_release, channels);
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if (error) {
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iio_channel_release_all(channels);
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dev_err(dev, "Failed to register iio channel release action");
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return error;
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}
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num_adc_channels = 0;
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while (channels[num_adc_channels].indio_dev)
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num_adc_channels++;
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if (num_adc_channels != COLI_TOUCH_REQ_ADC_CHAN) {
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dev_err(dev, "Inadequate ADC channels specified\n");
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return -EINVAL;
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}
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touchdev = devm_kzalloc(dev, sizeof(*touchdev), GFP_KERNEL);
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if (!touchdev)
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return -ENOMEM;
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touchdev->pdev = pdev;
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touchdev->channels = channels;
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error = of_property_read_u32(dev->of_node, "vf50-ts-min-pressure",
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&touchdev->min_pressure);
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if (error)
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return error;
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input = devm_input_allocate_device(dev);
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if (!input) {
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dev_err(dev, "Failed to allocate TS input device\n");
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return -ENOMEM;
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}
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input->name = DRIVER_NAME;
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input->id.bustype = BUS_HOST;
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input->dev.parent = dev;
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input->open = vf50_ts_open;
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input->close = vf50_ts_close;
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input_set_capability(input, EV_KEY, BTN_TOUCH);
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input_set_abs_params(input, ABS_X, 0, VF_ADC_MAX, 0, 0);
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input_set_abs_params(input, ABS_Y, 0, VF_ADC_MAX, 0, 0);
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input_set_abs_params(input, ABS_PRESSURE, 0, VF_ADC_MAX, 0, 0);
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touchdev->ts_input = input;
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input_set_drvdata(input, touchdev);
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error = input_register_device(input);
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if (error) {
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dev_err(dev, "Failed to register input device\n");
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return error;
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}
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error = vf50_ts_get_gpiod(dev, &touchdev->gpio_xp, "xp", GPIOD_OUT_LOW);
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if (error)
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return error;
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error = vf50_ts_get_gpiod(dev, &touchdev->gpio_xm,
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"xm", GPIOD_OUT_LOW);
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if (error)
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return error;
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error = vf50_ts_get_gpiod(dev, &touchdev->gpio_yp, "yp", GPIOD_OUT_LOW);
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if (error)
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return error;
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error = vf50_ts_get_gpiod(dev, &touchdev->gpio_ym, "ym", GPIOD_OUT_LOW);
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if (error)
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return error;
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touchdev->pen_irq = platform_get_irq(pdev, 0);
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if (touchdev->pen_irq < 0)
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return touchdev->pen_irq;
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error = devm_request_threaded_irq(dev, touchdev->pen_irq,
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NULL, vf50_ts_irq_bh, IRQF_ONESHOT,
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"vf50 touch", touchdev);
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if (error) {
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dev_err(dev, "Failed to request IRQ %d: %d\n",
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touchdev->pen_irq, error);
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return error;
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}
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return 0;
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}
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static const struct of_device_id vf50_touch_of_match[] = {
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{ .compatible = "toradex,vf50-touchscreen", },
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{ }
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};
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MODULE_DEVICE_TABLE(of, vf50_touch_of_match);
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static struct platform_driver vf50_touch_driver = {
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|
|
.driver = {
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|
|
.name = "toradex,vf50_touchctrl",
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|
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.of_match_table = vf50_touch_of_match,
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|
|
},
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|
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.probe = vf50_ts_probe,
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|
|
};
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module_platform_driver(vf50_touch_driver);
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|
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MODULE_AUTHOR("Sanchayan Maity");
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|
|
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MODULE_DESCRIPTION("Colibri VF50 Touchscreen driver");
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|
|
|
MODULE_LICENSE("GPL");
|