diff options
Diffstat (limited to 'drivers/input/touchscreen/colibri-vf50-ts.c')
| -rw-r--r-- | drivers/input/touchscreen/colibri-vf50-ts.c | 383 |
1 files changed, 383 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/colibri-vf50-ts.c b/drivers/input/touchscreen/colibri-vf50-ts.c new file mode 100644 index 000000000..82ca5ab65 --- /dev/null +++ b/drivers/input/touchscreen/colibri-vf50-ts.c @@ -0,0 +1,383 @@ +/* + * 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 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; + } + + 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"); |