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- /*
- * Toradex Colibri VF50 Touchscreen driver
- *
- * Copyright 2015 Toradex AG
- *
- * Originally authored by Stefan Agner for 3.0 kernel
- *
- * 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; either version 2 of the License, or
- * (at your option) any later version.
- */
- #include <linux/delay.h>
- #include <linux/err.h>
- #include <linux/gpio.h>
- #include <linux/gpio/consumer.h>
- #include <linux/iio/consumer.h>
- #include <linux/iio/types.h>
- #include <linux/input.h>
- #include <linux/interrupt.h>
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/of.h>
- #include <linux/pinctrl/consumer.h>
- #include <linux/platform_device.h>
- #include <linux/slab.h>
- #include <linux/types.h>
- #define DRIVER_NAME "colibri-vf50-ts"
- #define DRV_VERSION "1.0"
- #define VF_ADC_MAX ((1 << 12) - 1)
- #define COLI_TOUCH_MIN_DELAY_US 1000
- #define COLI_TOUCH_MAX_DELAY_US 2000
- #define COLI_PULLUP_MIN_DELAY_US 10000
- #define COLI_PULLUP_MAX_DELAY_US 11000
- #define COLI_TOUCH_NO_OF_AVGS 5
- #define COLI_TOUCH_REQ_ADC_CHAN 4
- struct vf50_touch_device {
- struct platform_device *pdev;
- struct input_dev *ts_input;
- struct iio_channel *channels;
- struct gpio_desc *gpio_xp;
- struct gpio_desc *gpio_xm;
- struct gpio_desc *gpio_yp;
- struct gpio_desc *gpio_ym;
- int pen_irq;
- int min_pressure;
- bool stop_touchscreen;
- };
- /*
- * Enables given plates and measures touch parameters using ADC
- */
- static int adc_ts_measure(struct iio_channel *channel,
- struct gpio_desc *plate_p, struct gpio_desc *plate_m)
- {
- int i, value = 0, val = 0;
- int error;
- gpiod_set_value(plate_p, 1);
- gpiod_set_value(plate_m, 1);
- usleep_range(COLI_TOUCH_MIN_DELAY_US, COLI_TOUCH_MAX_DELAY_US);
- for (i = 0; i < COLI_TOUCH_NO_OF_AVGS; i++) {
- error = iio_read_channel_raw(channel, &val);
- if (error < 0) {
- value = error;
- goto error_iio_read;
- }
- value += val;
- }
- value /= COLI_TOUCH_NO_OF_AVGS;
- error_iio_read:
- gpiod_set_value(plate_p, 0);
- gpiod_set_value(plate_m, 0);
- return value;
- }
- /*
- * Enable touch detection using falling edge detection on XM
- */
- static void vf50_ts_enable_touch_detection(struct vf50_touch_device *vf50_ts)
- {
- /* Enable plate YM (needs to be strong GND, high active) */
- gpiod_set_value(vf50_ts->gpio_ym, 1);
- /*
- * Let the platform mux to idle state in order to enable
- * Pull-Up on GPIO
- */
- pinctrl_pm_select_idle_state(&vf50_ts->pdev->dev);
- /* Wait for the pull-up to be stable on high */
- usleep_range(COLI_PULLUP_MIN_DELAY_US, COLI_PULLUP_MAX_DELAY_US);
- }
- /*
- * ADC touch screen sampling bottom half irq handler
- */
- static irqreturn_t vf50_ts_irq_bh(int irq, void *private)
- {
- struct vf50_touch_device *vf50_ts = private;
- struct device *dev = &vf50_ts->pdev->dev;
- int val_x, val_y, val_z1, val_z2, val_p = 0;
- bool discard_val_on_start = true;
- /* Disable the touch detection plates */
- gpiod_set_value(vf50_ts->gpio_ym, 0);
- /* Let the platform mux to default state in order to mux as ADC */
- pinctrl_pm_select_default_state(dev);
- while (!vf50_ts->stop_touchscreen) {
- /* X-Direction */
- val_x = adc_ts_measure(&vf50_ts->channels[0],
- vf50_ts->gpio_xp, vf50_ts->gpio_xm);
- if (val_x < 0)
- break;
- /* Y-Direction */
- val_y = adc_ts_measure(&vf50_ts->channels[1],
- vf50_ts->gpio_yp, vf50_ts->gpio_ym);
- if (val_y < 0)
- break;
- /*
- * Touch pressure
- * Measure on XP/YM
- */
- val_z1 = adc_ts_measure(&vf50_ts->channels[2],
- vf50_ts->gpio_yp, vf50_ts->gpio_xm);
- if (val_z1 < 0)
- break;
- val_z2 = adc_ts_measure(&vf50_ts->channels[3],
- vf50_ts->gpio_yp, vf50_ts->gpio_xm);
- if (val_z2 < 0)
- break;
- /* Validate signal (avoid calculation using noise) */
- if (val_z1 > 64 && val_x > 64) {
- /*
- * Calculate resistance between the plates
- * lower resistance means higher pressure
- */
- int r_x = (1000 * val_x) / VF_ADC_MAX;
- val_p = (r_x * val_z2) / val_z1 - r_x;
- } else {
- val_p = 2000;
- }
- val_p = 2000 - val_p;
- dev_dbg(dev,
- "Measured values: x: %d, y: %d, z1: %d, z2: %d, p: %d\n",
- val_x, val_y, val_z1, val_z2, val_p);
- /*
- * If touch pressure is too low, stop measuring and reenable
- * touch detection
- */
- if (val_p < vf50_ts->min_pressure || val_p > 2000)
- break;
- /*
- * The pressure may not be enough for the first x and the
- * second y measurement, but, the pressure is ok when the
- * driver is doing the third and fourth measurement. To
- * take care of this, we drop the first measurement always.
- */
- if (discard_val_on_start) {
- discard_val_on_start = false;
- } else {
- /*
- * Report touch position and sleep for
- * the next measurement.
- */
- input_report_abs(vf50_ts->ts_input,
- ABS_X, VF_ADC_MAX - val_x);
- input_report_abs(vf50_ts->ts_input,
- ABS_Y, VF_ADC_MAX - val_y);
- input_report_abs(vf50_ts->ts_input,
- ABS_PRESSURE, val_p);
- input_report_key(vf50_ts->ts_input, BTN_TOUCH, 1);
- input_sync(vf50_ts->ts_input);
- }
- usleep_range(COLI_PULLUP_MIN_DELAY_US,
- COLI_PULLUP_MAX_DELAY_US);
- }
- /* Report no more touch, re-enable touch detection */
- input_report_abs(vf50_ts->ts_input, ABS_PRESSURE, 0);
- input_report_key(vf50_ts->ts_input, BTN_TOUCH, 0);
- input_sync(vf50_ts->ts_input);
- vf50_ts_enable_touch_detection(vf50_ts);
- return IRQ_HANDLED;
- }
- static int vf50_ts_open(struct input_dev *dev_input)
- {
- struct vf50_touch_device *touchdev = input_get_drvdata(dev_input);
- struct device *dev = &touchdev->pdev->dev;
- dev_dbg(dev, "Input device %s opened, starting touch detection\n",
- dev_input->name);
- touchdev->stop_touchscreen = false;
- /* Mux detection before request IRQ, wait for pull-up to settle */
- vf50_ts_enable_touch_detection(touchdev);
- return 0;
- }
- static void vf50_ts_close(struct input_dev *dev_input)
- {
- struct vf50_touch_device *touchdev = input_get_drvdata(dev_input);
- struct device *dev = &touchdev->pdev->dev;
- touchdev->stop_touchscreen = true;
- /* Make sure IRQ is not running past close */
- mb();
- synchronize_irq(touchdev->pen_irq);
- gpiod_set_value(touchdev->gpio_ym, 0);
- pinctrl_pm_select_default_state(dev);
- dev_dbg(dev, "Input device %s closed, disable touch detection\n",
- dev_input->name);
- }
- static int vf50_ts_get_gpiod(struct device *dev, struct gpio_desc **gpio_d,
- const char *con_id, enum gpiod_flags flags)
- {
- int error;
- *gpio_d = devm_gpiod_get(dev, con_id, flags);
- if (IS_ERR(*gpio_d)) {
- error = PTR_ERR(*gpio_d);
- dev_err(dev, "Could not get gpio_%s %d\n", con_id, error);
- return error;
- }
- return 0;
- }
- static void vf50_ts_channel_release(void *data)
- {
- struct iio_channel *channels = data;
- iio_channel_release_all(channels);
- }
- static int vf50_ts_probe(struct platform_device *pdev)
- {
- struct input_dev *input;
- struct iio_channel *channels;
- struct device *dev = &pdev->dev;
- struct vf50_touch_device *touchdev;
- int num_adc_channels;
- int error;
- channels = iio_channel_get_all(dev);
- if (IS_ERR(channels))
- return PTR_ERR(channels);
- error = devm_add_action(dev, vf50_ts_channel_release, channels);
- if (error) {
- iio_channel_release_all(channels);
- dev_err(dev, "Failed to register iio channel release action");
- return error;
- }
- num_adc_channels = 0;
- while (channels[num_adc_channels].indio_dev)
- num_adc_channels++;
- if (num_adc_channels != COLI_TOUCH_REQ_ADC_CHAN) {
- dev_err(dev, "Inadequate ADC channels specified\n");
- return -EINVAL;
- }
- touchdev = devm_kzalloc(dev, sizeof(*touchdev), GFP_KERNEL);
- if (!touchdev)
- return -ENOMEM;
- touchdev->pdev = pdev;
- touchdev->channels = channels;
- error = of_property_read_u32(dev->of_node, "vf50-ts-min-pressure",
- &touchdev->min_pressure);
- if (error)
- return error;
- input = devm_input_allocate_device(dev);
- if (!input) {
- dev_err(dev, "Failed to allocate TS input device\n");
- return -ENOMEM;
- }
- platform_set_drvdata(pdev, touchdev);
- input->name = DRIVER_NAME;
- input->id.bustype = BUS_HOST;
- input->dev.parent = dev;
- input->open = vf50_ts_open;
- input->close = vf50_ts_close;
- input_set_capability(input, EV_KEY, BTN_TOUCH);
- input_set_abs_params(input, ABS_X, 0, VF_ADC_MAX, 0, 0);
- input_set_abs_params(input, ABS_Y, 0, VF_ADC_MAX, 0, 0);
- input_set_abs_params(input, ABS_PRESSURE, 0, VF_ADC_MAX, 0, 0);
- touchdev->ts_input = input;
- input_set_drvdata(input, touchdev);
- error = input_register_device(input);
- if (error) {
- dev_err(dev, "Failed to register input device\n");
- return error;
- }
- error = vf50_ts_get_gpiod(dev, &touchdev->gpio_xp, "xp", GPIOD_OUT_LOW);
- if (error)
- return error;
- error = vf50_ts_get_gpiod(dev, &touchdev->gpio_xm,
- "xm", GPIOD_OUT_LOW);
- if (error)
- return error;
- error = vf50_ts_get_gpiod(dev, &touchdev->gpio_yp, "yp", GPIOD_OUT_LOW);
- if (error)
- return error;
- error = vf50_ts_get_gpiod(dev, &touchdev->gpio_ym, "ym", GPIOD_OUT_LOW);
- if (error)
- return error;
- touchdev->pen_irq = platform_get_irq(pdev, 0);
- if (touchdev->pen_irq < 0)
- return touchdev->pen_irq;
- error = devm_request_threaded_irq(dev, touchdev->pen_irq,
- NULL, vf50_ts_irq_bh, IRQF_ONESHOT,
- "vf50 touch", touchdev);
- if (error) {
- dev_err(dev, "Failed to request IRQ %d: %d\n",
- touchdev->pen_irq, error);
- return error;
- }
- return 0;
- }
- static const struct of_device_id vf50_touch_of_match[] = {
- { .compatible = "toradex,vf50-touchscreen", },
- { }
- };
- MODULE_DEVICE_TABLE(of, vf50_touch_of_match);
- static struct platform_driver vf50_touch_driver = {
- .driver = {
- .name = "toradex,vf50_touchctrl",
- .of_match_table = vf50_touch_of_match,
- },
- .probe = vf50_ts_probe,
- };
- module_platform_driver(vf50_touch_driver);
- MODULE_AUTHOR("Sanchayan Maity");
- MODULE_DESCRIPTION("Colibri VF50 Touchscreen driver");
- MODULE_LICENSE("GPL");
- MODULE_VERSION(DRV_VERSION);
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