[PATCH v2 3/4] touchscreen: colibri-vf50-ts: Add touchscreen support for Colibri VF50
Sanchayan Maity
maitysanchayan at gmail.com
Thu Jul 16 08:13:21 PDT 2015
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 | 451 ++++++++++++++++++++++++++++
3 files changed, 464 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..eb16bdc
--- /dev/null
+++ b/drivers/input/touchscreen/colibri-vf50-ts.c
@@ -0,0 +1,451 @@
+/* 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 <dt-bindings/gpio/gpio.h>
+#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/of_gpio.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 workqueue_struct *ts_workqueue;
+ struct work_struct ts_work;
+ 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;
+ struct gpio_desc *gpio_pen_detect_pullup;
+ 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++) {
+ ret = iio_read_channel_raw(channel, &val);
+ if (ret < 0)
+ return -EINVAL;
+
+ value += val;
+ }
+
+ value /= 5;
+
+ 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 worker function
+ */
+static void vf50_ts_work(struct work_struct *ts_work)
+{
+ struct vf50_touch_device *vf50_ts = container_of(ts_work,
+ struct vf50_touch_device, ts_work);
+ 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;
+
+ 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)
+ continue;
+
+ /* Y-Direction */
+ val_y = adc_ts_measure(&vf50_ts->channels[1],
+ vf50_ts->gpio_yp, vf50_ts->gpio_ym);
+ if (val_y < 0)
+ continue;
+
+ /*
+ * 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)
+ continue;
+ val_z2 = adc_ts_measure(&vf50_ts->channels[3],
+ vf50_ts->gpio_yp, vf50_ts->gpio_xm);
+ if (val_z2 < 0)
+ continue;
+
+ /* 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);
+
+ /* Reenable IRQ to detect touch */
+ enable_irq(vf50_ts->pen_irq);
+
+ dev_dbg(dev, "Reenabled touch detection interrupt\n");
+}
+
+static irqreturn_t vf50_ts_touched(int irq, void *dev_id)
+{
+ struct vf50_touch_device *vf50_ts = (struct vf50_touch_device *)dev_id;
+ struct device *dev = &vf50_ts->pdev->dev;
+
+ dev_dbg(dev, "Touch detected, start worker thread\n");
+
+ disable_irq_nosync(irq);
+
+ /* 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);
+
+ queue_work(vf50_ts->ts_workqueue, &vf50_ts->ts_work);
+
+ 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;
+ }
+
+ ret = gpiod_direction_input(touchdev->gpio_pen_detect_pullup);
+ if (ret) {
+ dev_err(dev,
+ "Could not set pen detect pullup as input %d\n", ret);
+ return ret;
+ }
+
+ /* Mux detection before request IRQ, wait for pull-up to settle */
+ vf50_ts_enable_touch_detection(touchdev);
+ msleep(10);
+
+ touchdev->pen_irq = gpiod_to_irq(touchdev->gpio_pen_detect);
+ if (touchdev->pen_irq < 0) {
+ dev_err(dev, "Unable to get IRQ for GPIO\n");
+ return touchdev->pen_irq;
+ }
+
+ ret = request_irq(touchdev->pen_irq, vf50_ts_touched,
+ IRQF_TRIGGER_FALLING, "touch detected", touchdev);
+ if (ret < 0) {
+ dev_err(dev, "Unable to request IRQ %d\n", touchdev->pen_irq);
+ return ret;
+ }
+
+ 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;
+
+ free_irq(touchdev->pen_irq, touchdev);
+
+ touchdev->stop_touchscreen = true;
+
+ /* Wait until touchscreen thread finishes any possible remnants. */
+ cancel_work_sync(&touchdev->ts_work);
+
+ dev_dbg(dev, "Input device %s closed, disable touch detection\n",
+ dev_input->name);
+}
+
+static inline int vf50_ts_get_gpiod(struct device *dev,
+ struct gpio_desc **gpio_d, const char *con_id)
+{
+ int ret;
+
+ *gpio_d = devm_gpiod_get(dev, con_id);
+ 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 device *dev = &pdev->dev;
+ struct device_node *node = dev->of_node;
+ struct vf50_touch_device *touchdev;
+ struct input_dev *input;
+ int ret = 0;
+
+ if (!node) {
+ dev_err(dev, "Device does not have associated DT data\n");
+ return -EINVAL;
+ }
+
+ touchdev = devm_kzalloc(dev, sizeof(*touchdev), GFP_KERNEL);
+ if (touchdev == NULL)
+ return -ENOMEM;
+
+ input = devm_input_allocate_device(dev);
+ if (!input) {
+ dev_err(dev, "Failed to allocate TS input device\n");
+ ret = -ENOMEM;
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, touchdev);
+
+ touchdev->pdev = pdev;
+
+ 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_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");
+ return ret;
+ }
+
+ ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_xp, "xp");
+ if (ret)
+ return ret;
+
+ ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_xm, "xm");
+ if (ret)
+ return ret;
+
+ ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_yp, "yp");
+ if (ret)
+ return ret;
+
+ ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_ym, "ym");
+ if (ret)
+ return ret;
+
+ ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_pen_detect,
+ "pen-detect");
+ if (ret)
+ return ret;
+
+ ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_pen_detect_pullup,
+ "pen-pullup");
+ if (ret)
+ return ret;
+
+ INIT_WORK(&touchdev->ts_work, vf50_ts_work);
+ touchdev->ts_workqueue = create_singlethread_workqueue("vf50-ts-touch");
+
+ if (!touchdev->ts_workqueue) {
+ ret = PTR_ERR(touchdev->ts_workqueue);
+ dev_err(dev,
+ "Failed creating vf50-ts-touch workqueue %d\n", ret);
+ return ret;
+ }
+
+ touchdev->channels = iio_channel_get_all(dev);
+ if (IS_ERR(touchdev->channels))
+ return PTR_ERR(touchdev->channels);
+
+ dev_info(dev, "Attached colibri-vf50-ts driver successfully\n");
+
+ return 0;
+}
+
+static int vf50_ts_remove(struct platform_device *pdev)
+{
+ struct vf50_touch_device *touchdev = platform_get_drvdata(pdev);
+
+ destroy_workqueue(touchdev->ts_workqueue);
+ iio_channel_release_all(touchdev->channels);
+
+ return 0;
+}
+
+static const struct of_device_id vf50_touch_of_match[] = {
+ { .compatible = "toradex,vf50-touchctrl", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, vf50_touch_of_match);
+
+static struct platform_driver __refdata vf50_touch_driver = {
+ .driver = {
+ .name = "toradex,vf50_touchctrl",
+ .of_match_table = vf50_touch_of_match,
+ },
+ .probe = vf50_ts_probe,
+ .remove = vf50_ts_remove,
+ .prevent_deferred_probe = false,
+};
+
+module_platform_driver(vf50_touch_driver);
+
+module_param(min_pressure, int, 0600);
+MODULE_PARM_DESC(min_pressure, "Minimum pressure for touch detection");
+MODULE_AUTHOR("Sanchayan Maity");
+MODULE_DESCRIPTION("Colibri VF50 Touchscreen driver");
+MODULE_LICENSE("GPL v2");
+MODULE_VERSION(DRV_VERSION);
--
2.4.6
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