[PATCH v3 3/3] touchscreen: colibri-vf50-ts: Add touchscreen support for Colibri VF50
Dmitry Torokhov
dmitry.torokhov at gmail.com
Fri Aug 14 15:53:46 PDT 2015
Hi Sanchayan,
On Wed, Aug 05, 2015 at 02:25:51PM +0530, Sanchayan Maity wrote:
> The Colibri Vybrid VF50 module supports 4-wire touchscreens using
> FETs and ADC inputs. This driver uses the IIO consumer interface
> and relies on the vf610_adc driver based on the IIO framework.
>
> Signed-off-by: Sanchayan Maity <maitysanchayan at gmail.com>
> ---
> drivers/input/touchscreen/Kconfig | 12 +
> drivers/input/touchscreen/Makefile | 1 +
> drivers/input/touchscreen/colibri-vf50-ts.c | 404 ++++++++++++++++++++++++++++
> 3 files changed, 417 insertions(+)
> create mode 100644 drivers/input/touchscreen/colibri-vf50-ts.c
>
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 80f6386..28948ca 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -1027,4 +1027,16 @@ config TOUCHSCREEN_ZFORCE
> To compile this driver as a module, choose M here: the
> module will be called zforce_ts.
>
> +config TOUCHSCREEN_COLIBRI_VF50
> + tristate "Toradex Colibri on board touchscreen driver"
> + depends on GPIOLIB && IIO && VF610_ADC
> + help
> + Say Y here if you have a Colibri VF50 and plan to use
> + the on-board provided 4-wire touchscreen driver.
> +
> + If unsure, say N.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called colibri_vf50_ts.
> +
> endif
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 44deea7..93746a0 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -84,3 +84,4 @@ obj-$(CONFIG_TOUCHSCREEN_W90X900) += w90p910_ts.o
> obj-$(CONFIG_TOUCHSCREEN_SX8654) += sx8654.o
> obj-$(CONFIG_TOUCHSCREEN_TPS6507X) += tps6507x-ts.o
> obj-$(CONFIG_TOUCHSCREEN_ZFORCE) += zforce_ts.o
> +obj-$(CONFIG_TOUCHSCREEN_COLIBRI_VF50) += colibri-vf50-ts.o
> diff --git a/drivers/input/touchscreen/colibri-vf50-ts.c b/drivers/input/touchscreen/colibri-vf50-ts.c
> new file mode 100644
> index 0000000..d7bc91a
> --- /dev/null
> +++ b/drivers/input/touchscreen/colibri-vf50-ts.c
> @@ -0,0 +1,404 @@
> +/* Copyright 2015 Toradex AG
> + *
> + * Toradex Colibri VF50 Touchscreen driver
> + *
> + * 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/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/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
> +
> +static int min_pressure = 200;
> +
> +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;
> + struct gpio_desc *gpio_pen_detect;
> + int pen_irq;
> + 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 ret;
> +
> + 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 < 5; i++) {
Can we have a #define for 5?
> + ret = iio_read_channel_raw(channel, &val);
> + if (ret < 0) {
> + value = ret;
> + goto error_iio_read;
> + }
> +
> + value += val;
> + }
> +
> + value /= 5;
> +
> +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);
> +}
> +
> +/*
> + * 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 = (struct vf50_touch_device *)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 < 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
> + * 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);
> + }
> +
> + msleep(10);
> + }
> +
> + /* Report no more touch, reenable 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);
> +
> + /* Wait for the pull-up to be stable on high */
> + msleep(10);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int vf50_ts_open(struct input_dev *dev_input)
> +{
> + int ret;
> + 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;
> +
> + ret = gpiod_direction_output(touchdev->gpio_xp, 0);
> + if (ret) {
> + dev_err(dev, "Could not set gpio xp as output %d\n", ret);
> + return ret;
> + }
> +
> + ret = gpiod_direction_output(touchdev->gpio_xm, 0);
> + if (ret) {
> + dev_err(dev, "Could not set gpio xm as output %d\n", ret);
> + return ret;
> + }
> +
> + ret = gpiod_direction_output(touchdev->gpio_yp, 0);
> + if (ret) {
> + dev_err(dev, "Could not set gpio yp as output %d\n", ret);
> + return ret;
> + }
> +
> + ret = gpiod_direction_output(touchdev->gpio_ym, 0);
> + if (ret) {
> + dev_err(dev, "Could not set gpio ym as output %d\n", ret);
> + return ret;
> + }
> +
> + ret = gpiod_direction_input(touchdev->gpio_pen_detect);
> + if (ret) {
> + dev_err(dev,
> + "Could not set gpio pen detect as input %d\n", ret);
> + return ret;
> + }
Why do we do this on every open? You can configure gpios as you request
them.
> +
> + /* Mux detection before request IRQ, wait for pull-up to settle */
> + vf50_ts_enable_touch_detection(touchdev);
> + msleep(10);
> +
> + 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;
I think you also need:
mb();
synchronize_irq(touchdev->irq);
to make sure interrupt routine is not running past close.
> +
> + dev_dbg(dev, "Input device %s closed, disable touch detection\n",
> + dev_input->name);
> +}
> +
> +static inline int vf50_ts_get_gpiod(struct device *dev,
Drop inline, let compiler decide whether it should be inlined or not.
> + struct gpio_desc **gpio_d, const char *con_id)
> +{
> + int ret;
Personal preference: call this variable "error".
> +
> + *gpio_d = devm_gpiod_get(dev, con_id);
I think you need use GPIOD_OUT_LOW (assuming you do not use the function
for pen detect gpio, see below).
> + if (IS_ERR(*gpio_d)) {
> + ret = PTR_ERR(*gpio_d);
> + dev_err(dev, "Could not get gpio_%s %d\n", con_id, ret);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +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 ret;
Personal preference: call this variable "error".
> +
> + channels = iio_channel_get_all(dev);
> + if (IS_ERR(channels))
> + return PTR_ERR(channels);
Please either introduce devm_iio_channel_get_all() or install
iio_channel_release_all as a custom devm action (devm_add_action).
> +
> + touchdev = devm_kzalloc(dev, sizeof(*touchdev), GFP_KERNEL);
> + if (touchdev == NULL) {
if (!touchdev)
please.
> + ret = -ENOMEM;
> + goto error_release_channels;
> + }
> +
> + input = devm_input_allocate_device(dev);
> + if (!input) {
> + dev_err(dev, "Failed to allocate TS input device\n");
> + ret = -ENOMEM;
> + goto error_release_channels;
> + }
> +
> + platform_set_drvdata(pdev, touchdev);
> +
> + touchdev->pdev = pdev;
> + touchdev->channels = channels;
> +
> + input->name = DRIVER_NAME;
> + input->id.bustype = BUS_HOST;
> + input->dev.parent = dev;
> + input->open = vf50_ts_open;
> + input->close = vf50_ts_close;
> +
> + _set_bit(EV_ABS, input->evbit);
> + _set_bit(EV_KEY, input->evbit);
> + _set_bit(BTN_TOUCH, input->keybit);
input_set_capability(dev, EV_KEY, BTN_TOUCH);
and kill _set_bit()s above.
> + 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);
> + ret = input_register_device(input);
> + if (ret) {
> + dev_err(dev, "Failed to register input device\n");
> + goto error_release_channels;
> + }
> +
> + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_xp, "xp");
> + if (ret)
> + goto error_release_channels;
> +
> + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_xm, "xm");
> + if (ret)
> + goto error_release_channels;
> +
> + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_yp, "yp");
> + if (ret)
> + goto error_release_channels;
> +
> + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_ym, "ym");
> + if (ret)
> + goto error_release_channels;
> +
> + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_pen_detect,
> + "pen-detect");
> + if (ret)
> + goto error_release_channels;
> +
> + touchdev->pen_irq = gpiod_to_irq(touchdev->gpio_pen_detect);
> + if (touchdev->pen_irq < 0) {
> + ret = touchdev->pen_irq;
> + dev_err(dev, "Unable to get IRQ for GPIO\n");
> + goto error_release_channels;
> + }
I do not think you need to specify this as gpio, since you are not
reading it's state. Map it using "interrupts" property instead and do
touchdev->pen_irq = platform_get_irq(pdev, 0);
> +
> + ret = devm_request_threaded_irq(dev, touchdev->pen_irq, NULL,
> + vf50_ts_irq_bh, IRQF_TRIGGER_LOW | IRQF_ONESHOT,
Just use IRQF_ONESHOT here, rely on the platform/OF to read and set up
the trigger properly (via "interrupts" property).
> + "vf50 touch", touchdev);
> + if (ret < 0) {
> + dev_err(dev, "Unable to request IRQ %d\n", touchdev->pen_irq);
> + goto error_release_channels;
> + }
> +
> + return 0;
> +
> +error_release_channels:
> + iio_channel_release_all(channels);
> + return ret;
> +}
> +
> +static int vf50_ts_remove(struct platform_device *pdev)
> +{
> + struct vf50_touch_device *touchdev = platform_get_drvdata(pdev);
> +
> + iio_channel_release_all(touchdev->channels);
This is wrong order, I do not think you want to release channels while
your interrupt routine still running. With custom devm action you can
avoid this and also remove whole vf50_ts_remove.
> +
> + 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,
> + .remove = vf50_ts_remove,
> +};
> +
> +module_platform_driver(vf50_touch_driver);
> +
> +module_param(min_pressure, int, 0600);
> +MODULE_PARM_DESC(min_pressure, "Minimum pressure for touch detection");
Since it is my understanding this is not user preference but rather
property of device, I'd rather this been part of DT binding.
> +MODULE_AUTHOR("Sanchayan Maity");
> +MODULE_DESCRIPTION("Colibri VF50 Touchscreen driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_VERSION(DRV_VERSION);
> --
> 2.5.0
>
Thanks.
--
Dmitry
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