Input: add support for the STMicroelectronics FingerTip touchscreen

The stmfts (ST-Microelectronics FingerTip S) touchscreen device is a
capacitive multi-touch controller mainly for mobile use.  It's connected
through i2c bus at the address 0x49 and it interfaces with userspace
through input event interface.

At the current state it provides a touchscreen multitouch functionality up
to 10 fingers. Each finger is enumerated with a distinctive id (from 0 to
9).

If enabled the device can support single "touch" hovering, by providing
three coordinates, x, y and distance.

It is possible to select the touchkey functionality which provides a basic
two keys interface for "home" and "back" menu, typical in mobile phones.

Signed-off-by: Andi Shyti <andi.shyti@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/touchscreen/st,stmfts.txt

@@ -0,0 +1,43 @@
+* ST-Microelectronics FingerTip touchscreen controller
+
+The ST-Microelectronics FingerTip device provides a basic touchscreen
+functionality. Along with it the user can enable the touchkey which can work as
+a basic HOME and BACK key for phones.
+
+The driver supports also hovering as an absolute single touch event with x, y, z
+coordinates.
+
+Required properties:
+- compatible		: must be "st,stmfts"
+- reg			: I2C slave address, (e.g. 0x49)
+- interrupt-parent	: the phandle to the interrupt controller which provides
+			  the interrupt
+- interrupts		: interrupt specification
+- avdd-supply		: analogic power supply
+- vdd-supply		: power supply
+- touchscreen-size-x	: see touchscreen.txt
+- touchscreen-size-y	: see touchscreen.txt
+
+Optional properties:
+- touch-key-connected	: specifies whether the touchkey feature is connected
+- ledvdd-supply		: power supply to the touch key leds
+
+Example:
+
+i2c@00000000 {
+
+	/* ... */
+
+	touchscreen@49 {
+		compatible = "st,stmfts";
+		reg = <0x49>;
+		interrupt-parent = <&gpa1>;
+		interrupts = <1 IRQ_TYPE_NONE>;
+		touchscreen-size-x = <1599>;
+		touchscreen-size-y = <2559>;
+		touch-key-connected;
+		avdd-supply = <&ldo30_reg>;
+		vdd-supply = <&ldo31_reg>;
+		ledvdd-supply = <&ldo33_reg>;
+	};
+};

drivers/input/touchscreen/Kconfig

@@ -1114,6 +1114,17 @@ config TOUCHSCREEN_ST1232
 	  To compile this driver as a module, choose M here: the
 	  module will be called st1232_ts.
 
+config TOUCHSCREEN_STMFTS
+	tristate "STMicroelectronics STMFTS touchscreen"
+	depends on I2C
+	depends on LEDS_CLASS
+	help
+	  Say Y here if you want support for STMicroelectronics
+	  STMFTS touchscreen.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called stmfts.
+
 config TOUCHSCREEN_STMPE
 	tristate "STMicroelectronics STMPE touchscreens"
 	depends on MFD_STMPE

drivers/input/touchscreen/Makefile

@@ -67,6 +67,7 @@ obj-$(CONFIG_TOUCHSCREEN_S3C2410)	+= s3c2410_ts.o
 obj-$(CONFIG_TOUCHSCREEN_SILEAD)	+= silead.o
 obj-$(CONFIG_TOUCHSCREEN_SIS_I2C)	+= sis_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_ST1232)	+= st1232.o
+obj-$(CONFIG_TOUCHSCREEN_STMFTS)	+= stmfts.o
 obj-$(CONFIG_TOUCHSCREEN_STMPE)		+= stmpe-ts.o
 obj-$(CONFIG_TOUCHSCREEN_SUN4I)		+= sun4i-ts.o
 obj-$(CONFIG_TOUCHSCREEN_SUR40)		+= sur40.o

drivers/input/touchscreen/stmfts.c

@@ -0,0 +1,822 @@
+/*
+ * Copyright (c) 2017 Samsung Electronics Co., Ltd.
+ * Author: Andi Shyti <andi.shyti@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * STMicroelectronics FTS Touchscreen device driver
+ */
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
+
+/* I2C commands */
+#define STMFTS_READ_INFO			0x80
+#define STMFTS_READ_STATUS			0x84
+#define STMFTS_READ_ONE_EVENT			0x85
+#define STMFTS_READ_ALL_EVENT			0x86
+#define STMFTS_LATEST_EVENT			0x87
+#define STMFTS_SLEEP_IN				0x90
+#define STMFTS_SLEEP_OUT			0x91
+#define STMFTS_MS_MT_SENSE_OFF			0x92
+#define STMFTS_MS_MT_SENSE_ON			0x93
+#define STMFTS_SS_HOVER_SENSE_OFF		0x94
+#define STMFTS_SS_HOVER_SENSE_ON		0x95
+#define STMFTS_MS_KEY_SENSE_OFF			0x9a
+#define STMFTS_MS_KEY_SENSE_ON			0x9b
+#define STMFTS_SYSTEM_RESET			0xa0
+#define STMFTS_CLEAR_EVENT_STACK		0xa1
+#define STMFTS_FULL_FORCE_CALIBRATION		0xa2
+#define STMFTS_MS_CX_TUNING			0xa3
+#define STMFTS_SS_CX_TUNING			0xa4
+
+/* events */
+#define STMFTS_EV_NO_EVENT			0x00
+#define STMFTS_EV_MULTI_TOUCH_DETECTED		0x02
+#define STMFTS_EV_MULTI_TOUCH_ENTER		0x03
+#define STMFTS_EV_MULTI_TOUCH_LEAVE		0x04
+#define STMFTS_EV_MULTI_TOUCH_MOTION		0x05
+#define STMFTS_EV_HOVER_ENTER			0x07
+#define STMFTS_EV_HOVER_LEAVE			0x08
+#define STMFTS_EV_HOVER_MOTION			0x09
+#define STMFTS_EV_KEY_STATUS			0x0e
+#define STMFTS_EV_ERROR				0x0f
+#define STMFTS_EV_CONTROLLER_READY		0x10
+#define STMFTS_EV_SLEEP_OUT_CONTROLLER_READY	0x11
+#define STMFTS_EV_STATUS			0x16
+#define STMFTS_EV_DEBUG				0xdb
+
+/* multi touch related event masks */
+#define STMFTS_MASK_EVENT_ID			0x0f
+#define STMFTS_MASK_TOUCH_ID			0xf0
+#define STMFTS_MASK_LEFT_EVENT			0x0f
+#define STMFTS_MASK_X_MSB			0x0f
+#define STMFTS_MASK_Y_LSB			0xf0
+
+/* key related event masks */
+#define STMFTS_MASK_KEY_NO_TOUCH		0x00
+#define STMFTS_MASK_KEY_MENU			0x01
+#define STMFTS_MASK_KEY_BACK			0x02
+
+#define STMFTS_EVENT_SIZE	8
+#define STMFTS_STACK_DEPTH	32
+#define STMFTS_DATA_MAX_SIZE	(STMFTS_EVENT_SIZE * STMFTS_STACK_DEPTH)
+#define STMFTS_MAX_FINGERS	10
+#define STMFTS_DEV_NAME		"stmfts"
+
+enum stmfts_regulators {
+	STMFTS_REGULATOR_VDD,
+	STMFTS_REGULATOR_AVDD,
+};
+
+struct stmfts_data {
+	struct i2c_client *client;
+	struct input_dev *input;
+	struct led_classdev led_cdev;
+	struct mutex mutex;
+
+	struct touchscreen_properties prop;
+
+	struct regulator_bulk_data regulators[2];
+
+	/*
+	 * Presence of ledvdd will be used also to check
+	 * whether the LED is supported.
+	 */
+	struct regulator *ledvdd;
+
+	u16 chip_id;
+	u8 chip_ver;
+	u16 fw_ver;
+	u8 config_id;
+	u8 config_ver;
+
+	u8 data[STMFTS_DATA_MAX_SIZE];
+
+	struct completion cmd_done;
+
+	bool use_key;
+	bool led_status;
+	bool hover_enabled;
+	bool running;
+};
+
+static void stmfts_brightness_set(struct led_classdev *led_cdev,
+					enum led_brightness value)
+{
+	struct stmfts_data *sdata = container_of(led_cdev,
+					struct stmfts_data, led_cdev);
+	int err;
+
+	if (value == sdata->led_status || !sdata->ledvdd)
+		return;
+
+	if (!value) {
+		regulator_disable(sdata->ledvdd);
+	} else {
+		err = regulator_enable(sdata->ledvdd);
+		if (err)
+			dev_warn(&sdata->client->dev,
+				 "failed to disable ledvdd regulator: %d\n",
+				 err);
+	}
+
+	sdata->led_status = value;
+}
+
+static enum led_brightness stmfts_brightness_get(struct led_classdev *led_cdev)
+{
+	struct stmfts_data *sdata = container_of(led_cdev,
+						struct stmfts_data, led_cdev);
+
+	return !!regulator_is_enabled(sdata->ledvdd);
+}
+
+/*
+ * We can't simply use i2c_smbus_read_i2c_block_data because we
+ * need to read more than 255 bytes (
+ */
+static int stmfts_read_events(struct stmfts_data *sdata)
+{
+	u8 cmd = STMFTS_READ_ALL_EVENT;
+	struct i2c_msg msgs[2] = {
+		{
+			.addr	= sdata->client->addr,
+			.len	= 1,
+			.buf	= &cmd,
+		},
+		{
+			.addr	= sdata->client->addr,
+			.flags	= I2C_M_RD,
+			.len	= STMFTS_DATA_MAX_SIZE,
+			.buf	= sdata->data,
+		},
+	};
+	int ret;
+
+	ret = i2c_transfer(sdata->client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret < 0)
+		return ret;
+
+	return ret == ARRAY_SIZE(msgs) ? 0 : -EIO;
+}
+
+static void stmfts_report_contact_event(struct stmfts_data *sdata,
+					const u8 event[])
+{
+	u8 slot_id = (event[0] & STMFTS_MASK_TOUCH_ID) >> 4;
+	u16 x = event[1] | ((event[2] & STMFTS_MASK_X_MSB) << 8);
+	u16 y = (event[2] >> 4) | (event[3] << 4);
+	u8 maj = event[4];
+	u8 min = event[5];
+	u8 orientation = event[6];
+	u8 area = event[7];
+
+	input_mt_slot(sdata->input, slot_id);
+
+	input_mt_report_slot_state(sdata->input, MT_TOOL_FINGER, true);
+	input_report_abs(sdata->input, ABS_MT_POSITION_X, x);
+	input_report_abs(sdata->input, ABS_MT_POSITION_Y, y);
+	input_report_abs(sdata->input, ABS_MT_TOUCH_MAJOR, maj);
+	input_report_abs(sdata->input, ABS_MT_TOUCH_MINOR, min);
+	input_report_abs(sdata->input, ABS_MT_PRESSURE, area);
+	input_report_abs(sdata->input, ABS_MT_ORIENTATION, orientation);
+
+	input_sync(sdata->input);
+}
+
+static void stmfts_report_contact_release(struct stmfts_data *sdata,
+					  const u8 event[])
+{
+	u8 slot_id = (event[0] & STMFTS_MASK_TOUCH_ID) >> 4;
+
+	input_mt_slot(sdata->input, slot_id);
+	input_mt_report_slot_state(sdata->input, MT_TOOL_FINGER, false);
+
+	input_sync(sdata->input);
+}
+
+static void stmfts_report_hover_event(struct stmfts_data *sdata,
+				      const u8 event[])
+{
+	u16 x = (event[2] << 4) | (event[4] >> 4);
+	u16 y = (event[3] << 4) | (event[4] & STMFTS_MASK_Y_LSB);
+	u8 z = event[5];
+
+	input_report_abs(sdata->input, ABS_X, x);
+	input_report_abs(sdata->input, ABS_Y, y);
+	input_report_abs(sdata->input, ABS_DISTANCE, z);
+
+	input_sync(sdata->input);
+}
+
+static void stmfts_report_key_event(struct stmfts_data *sdata, const u8 event[])
+{
+	switch (event[2]) {
+	case 0:
+		input_report_key(sdata->input, KEY_BACK, 0);
+		input_report_key(sdata->input, KEY_MENU, 0);
+		break;
+
+	case STMFTS_MASK_KEY_BACK:
+		input_report_key(sdata->input, KEY_BACK, 1);
+		break;
+
+	case STMFTS_MASK_KEY_MENU:
+		input_report_key(sdata->input, KEY_MENU, 1);
+		break;
+
+	default:
+		dev_warn(&sdata->client->dev,
+			 "unknown key event: %#02x\n", event[2]);
+		break;
+	}
+
+	input_sync(sdata->input);
+}
+
+static void stmfts_parse_events(struct stmfts_data *sdata)
+{
+	int i;
+
+	for (i = 0; i < STMFTS_STACK_DEPTH; i++) {
+		u8 *event = &sdata->data[i * STMFTS_EVENT_SIZE];
+
+		switch (event[0]) {
+
+		case STMFTS_EV_CONTROLLER_READY:
+		case STMFTS_EV_SLEEP_OUT_CONTROLLER_READY:
+		case STMFTS_EV_STATUS:
+			complete(&sdata->cmd_done);
+			/* fall through */
+
+		case STMFTS_EV_NO_EVENT:
+		case STMFTS_EV_DEBUG:
+			return;
+		}
+
+		switch (event[0] & STMFTS_MASK_EVENT_ID) {
+
+		case STMFTS_EV_MULTI_TOUCH_ENTER:
+		case STMFTS_EV_MULTI_TOUCH_MOTION:
+			stmfts_report_contact_event(sdata, event);
+			break;
+
+		case STMFTS_EV_MULTI_TOUCH_LEAVE:
+			stmfts_report_contact_release(sdata, event);
+			break;
+
+		case STMFTS_EV_HOVER_ENTER:
+		case STMFTS_EV_HOVER_LEAVE:
+		case STMFTS_EV_HOVER_MOTION:
+			stmfts_report_hover_event(sdata, event);
+			break;
+
+		case STMFTS_EV_KEY_STATUS:
+			stmfts_report_key_event(sdata, event);
+			break;
+
+		case STMFTS_EV_ERROR:
+			dev_warn(&sdata->client->dev,
+					"error code: 0x%x%x%x%x%x%x",
+					event[6], event[5], event[4],
+					event[3], event[2], event[1]);
+			break;
+
+		default:
+			dev_err(&sdata->client->dev,
+				"unknown event %#02x\n", event[0]);
+		}
+	}
+}
+
+static irqreturn_t stmfts_irq_handler(int irq, void *dev)
+{
+	struct stmfts_data *sdata = dev;
+	int err;
+
+	mutex_lock(&sdata->mutex);
+
+	err = stmfts_read_events(sdata);
+	if (unlikely(err))
+		dev_err(&sdata->client->dev,
+			"failed to read events: %d\n", err);
+	else
+		stmfts_parse_events(sdata);
+
+	mutex_unlock(&sdata->mutex);
+	return IRQ_HANDLED;
+}
+
+static int stmfts_command(struct stmfts_data *sdata, const u8 cmd)
+{
+	int err;
+
+	reinit_completion(&sdata->cmd_done);
+
+	err = i2c_smbus_write_byte(sdata->client, cmd);
+	if (err)
+		return err;
+
+	if (!wait_for_completion_timeout(&sdata->cmd_done,
+					 msecs_to_jiffies(1000)))
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int stmfts_input_open(struct input_dev *dev)
+{
+	struct stmfts_data *sdata = input_get_drvdata(dev);
+	int err;
+
+	err = pm_runtime_get_sync(&sdata->client->dev);
+	if (err < 0)
+		return err;
+
+	err = i2c_smbus_write_byte(sdata->client, STMFTS_MS_MT_SENSE_ON);
+	if (err)
+		return err;
+
+	mutex_lock(&sdata->mutex);
+	sdata->running = true;
+
+	if (sdata->hover_enabled) {
+		err = i2c_smbus_write_byte(sdata->client,
+					   STMFTS_SS_HOVER_SENSE_ON);
+		if (err)
+			dev_warn(&sdata->client->dev,
+				 "failed to enable hover\n");
+	}
+	mutex_unlock(&sdata->mutex);
+
+	if (sdata->use_key) {
+		err = i2c_smbus_write_byte(sdata->client,
+					   STMFTS_MS_KEY_SENSE_ON);
+		if (err)
+			/* I can still use only the touch screen */
+			dev_warn(&sdata->client->dev,
+				 "failed to enable touchkey\n");
+	}
+
+	return 0;
+}
+
+static void stmfts_input_close(struct input_dev *dev)
+{
+	struct stmfts_data *sdata = input_get_drvdata(dev);
+	int err;
+
+	err = i2c_smbus_write_byte(sdata->client, STMFTS_MS_MT_SENSE_OFF);
+	if (err)
+		dev_warn(&sdata->client->dev,
+			 "failed to disable touchscreen: %d\n", err);
+
+	mutex_lock(&sdata->mutex);
+
+	sdata->running = false;
+
+	if (sdata->hover_enabled) {
+		err = i2c_smbus_write_byte(sdata->client,
+					   STMFTS_SS_HOVER_SENSE_OFF);
+		if (err)
+			dev_warn(&sdata->client->dev,
+				 "failed to disable hover: %d\n", err);
+	}
+	mutex_unlock(&sdata->mutex);
+
+	if (sdata->use_key) {
+		err = i2c_smbus_write_byte(sdata->client,
+					   STMFTS_MS_KEY_SENSE_OFF);
+		if (err)
+			dev_warn(&sdata->client->dev,
+				 "failed to disable touchkey: %d\n", err);
+	}
+
+	pm_runtime_put_sync(&sdata->client->dev);
+}
+
+static ssize_t stmfts_sysfs_chip_id(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%#x\n", sdata->chip_id);
+}
+
+static ssize_t stmfts_sysfs_chip_version(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", sdata->chip_ver);
+}
+
+static ssize_t stmfts_sysfs_fw_ver(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", sdata->fw_ver);
+}
+
+static ssize_t stmfts_sysfs_config_id(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%#x\n", sdata->config_id);
+}
+
+static ssize_t stmfts_sysfs_config_version(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", sdata->config_ver);
+}
+
+static ssize_t stmfts_sysfs_read_status(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+	u8 status[4];
+	int err;
+
+	err = i2c_smbus_read_i2c_block_data(sdata->client, STMFTS_READ_STATUS,
+					    sizeof(status), status);
+	if (err)
+		return err;
+
+	return sprintf(buf, "%#02x\n", status[0]);
+}
+
+static ssize_t stmfts_sysfs_hover_enable_read(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", sdata->hover_enabled);
+}
+
+static ssize_t stmfts_sysfs_hover_enable_write(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t len)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+	unsigned long value;
+	int err = 0;
+
+	if (kstrtoul(buf, 0, &value))
+		return -EINVAL;
+
+	mutex_lock(&sdata->mutex);
+
+	if (value & sdata->hover_enabled)
+		goto out;
+
+	if (sdata->running)
+		err = i2c_smbus_write_byte(sdata->client,
+					   value ? STMFTS_SS_HOVER_SENSE_ON :
+						   STMFTS_SS_HOVER_SENSE_OFF);
+
+	if (!err)
+		sdata->hover_enabled = !!value;
+
+out:
+	mutex_unlock(&sdata->mutex);
+
+	return len;
+}
+
+static DEVICE_ATTR(chip_id, 0444, stmfts_sysfs_chip_id, NULL);
+static DEVICE_ATTR(chip_version, 0444, stmfts_sysfs_chip_version, NULL);
+static DEVICE_ATTR(fw_ver, 0444, stmfts_sysfs_fw_ver, NULL);
+static DEVICE_ATTR(config_id, 0444, stmfts_sysfs_config_id, NULL);
+static DEVICE_ATTR(config_version, 0444, stmfts_sysfs_config_version, NULL);
+static DEVICE_ATTR(status, 0444, stmfts_sysfs_read_status, NULL);
+static DEVICE_ATTR(hover_enable, 0644, stmfts_sysfs_hover_enable_read,
+					stmfts_sysfs_hover_enable_write);
+
+static struct attribute *stmfts_sysfs_attrs[] = {
+	&dev_attr_chip_id.attr,
+	&dev_attr_chip_version.attr,
+	&dev_attr_fw_ver.attr,
+	&dev_attr_config_id.attr,
+	&dev_attr_config_version.attr,
+	&dev_attr_status.attr,
+	&dev_attr_hover_enable.attr,
+	NULL
+};
+
+static struct attribute_group stmfts_attribute_group = {
+	.attrs = stmfts_sysfs_attrs
+};
+
+static int stmfts_power_on(struct stmfts_data *sdata)
+{
+	int err;
+	u8 reg[8];
+
+	err = regulator_bulk_enable(ARRAY_SIZE(sdata->regulators),
+				    sdata->regulators);
+	if (err)
+		return err;
+
+	/*
+	 * The datasheet does not specify the power on time, but considering
+	 * that the reset time is < 10ms, I sleep 20ms to be sure
+	 */
+	msleep(20);
+
+	err = i2c_smbus_read_i2c_block_data(sdata->client, STMFTS_READ_INFO,
+					    sizeof(reg), reg);
+	if (err < 0)
+		return err;
+	if (err != sizeof(reg))
+		return -EIO;
+
+	sdata->chip_id = be16_to_cpup((__be16 *)&reg[6]);
+	sdata->chip_ver = reg[0];
+	sdata->fw_ver = be16_to_cpup((__be16 *)&reg[2]);
+	sdata->config_id = reg[4];
+	sdata->config_ver = reg[5];
+
+	enable_irq(sdata->client->irq);
+
+	msleep(50);
+
+	err = stmfts_command(sdata, STMFTS_SYSTEM_RESET);
+	if (err)
+		return err;
+
+	err = stmfts_command(sdata, STMFTS_SLEEP_OUT);
+	if (err)
+		return err;
+
+	/* optional tuning */
+	err = stmfts_command(sdata, STMFTS_MS_CX_TUNING);
+	if (err)
+		dev_warn(&sdata->client->dev,
+			 "failed to perform mutual auto tune: %d\n", err);
+
+	/* optional tuning */
+	err = stmfts_command(sdata, STMFTS_SS_CX_TUNING);
+	if (err)
+		dev_warn(&sdata->client->dev,
+			 "failed to perform self auto tune: %d\n", err);
+
+	err = stmfts_command(sdata, STMFTS_FULL_FORCE_CALIBRATION);
+	if (err)
+		return err;
+
+	/*
+	 * At this point no one is using the touchscreen
+	 * and I don't really care about the return value
+	 */
+	(void) i2c_smbus_write_byte(sdata->client, STMFTS_SLEEP_IN);
+
+	return 0;
+}
+
+static void stmfts_power_off(void *data)
+{
+	struct stmfts_data *sdata = data;
+
+	disable_irq(sdata->client->irq);
+	regulator_bulk_disable(ARRAY_SIZE(sdata->regulators),
+						sdata->regulators);
+}
+
+/* This function is void because I don't want to prevent using the touch key
+ * only because the LEDs don't get registered
+ */
+static int stmfts_enable_led(struct stmfts_data *sdata)
+{
+	int err;
+
+	/* get the regulator for powering the leds on */
+	sdata->ledvdd = devm_regulator_get(&sdata->client->dev, "ledvdd");
+	if (IS_ERR(sdata->ledvdd))
+		return PTR_ERR(sdata->ledvdd);
+
+	sdata->led_cdev.name = STMFTS_DEV_NAME;
+	sdata->led_cdev.max_brightness = LED_ON;
+	sdata->led_cdev.brightness = LED_OFF;
+	sdata->led_cdev.brightness_set = stmfts_brightness_set;
+	sdata->led_cdev.brightness_get = stmfts_brightness_get;
+
+	err = devm_led_classdev_register(&sdata->client->dev, &sdata->led_cdev);
+	if (err) {
+		devm_regulator_put(sdata->ledvdd);
+		return err;
+	}
+
+	return 0;
+}
+
+static int stmfts_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	int err;
+	struct stmfts_data *sdata;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+						I2C_FUNC_SMBUS_BYTE_DATA |
+						I2C_FUNC_SMBUS_I2C_BLOCK))
+		return -ENODEV;
+
+	sdata = devm_kzalloc(&client->dev, sizeof(*sdata), GFP_KERNEL);
+	if (!sdata)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, sdata);
+
+	sdata->client = client;
+	mutex_init(&sdata->mutex);
+	init_completion(&sdata->cmd_done);
+
+	sdata->regulators[STMFTS_REGULATOR_VDD].supply = "vdd";
+	sdata->regulators[STMFTS_REGULATOR_AVDD].supply = "avdd";
+	err = devm_regulator_bulk_get(&client->dev,
+				      ARRAY_SIZE(sdata->regulators),
+				      sdata->regulators);
+	if (err)
+		return err;
+
+	sdata->input = devm_input_allocate_device(&client->dev);
+	if (!sdata->input)
+		return -ENOMEM;
+
+	sdata->input->name = STMFTS_DEV_NAME;
+	sdata->input->id.bustype = BUS_I2C;
+	sdata->input->open = stmfts_input_open;
+	sdata->input->close = stmfts_input_close;
+
+	touchscreen_parse_properties(sdata->input, true, &sdata->prop);
+
+	input_set_abs_params(sdata->input, ABS_MT_POSITION_X, 0,
+						sdata->prop.max_x, 0, 0);
+	input_set_abs_params(sdata->input, ABS_MT_POSITION_Y, 0,
+						sdata->prop.max_y, 0, 0);
+	input_set_abs_params(sdata->input, ABS_MT_TOUCH_MAJOR, 0, 255, 0, 0);
+	input_set_abs_params(sdata->input, ABS_MT_TOUCH_MINOR, 0, 255, 0, 0);
+	input_set_abs_params(sdata->input, ABS_MT_ORIENTATION, 0, 255, 0, 0);
+	input_set_abs_params(sdata->input, ABS_MT_PRESSURE, 0, 255, 0, 0);
+	input_set_abs_params(sdata->input, ABS_DISTANCE, 0, 255, 0, 0);
+
+	sdata->use_key = device_property_read_bool(&client->dev,
+						   "touch-key-connected");
+	if (sdata->use_key) {
+		input_set_capability(sdata->input, EV_KEY, KEY_MENU);
+		input_set_capability(sdata->input, EV_KEY, KEY_BACK);
+	}
+
+	err = input_mt_init_slots(sdata->input,
+				  STMFTS_MAX_FINGERS, INPUT_MT_DIRECT);
+	if (err)
+		return err;
+
+	input_set_drvdata(sdata->input, sdata);
+
+	err = devm_request_threaded_irq(&client->dev, client->irq,
+					NULL, stmfts_irq_handler,
+					IRQF_ONESHOT,
+					"stmfts_irq", sdata);
+	if (err)
+		return err;
+
+	/* stmfts_power_on expects interrupt to be disabled */
+	disable_irq(client->irq);
+
+	dev_dbg(&client->dev, "initializing ST-Microelectronics FTS...\n");
+
+	err = stmfts_power_on(sdata);
+	if (err)
+		return err;
+
+	err = devm_add_action_or_reset(&client->dev, stmfts_power_off, sdata);
+	if (err)
+		return err;
+
+	err = input_register_device(sdata->input);
+	if (err)
+		return err;
+
+	if (sdata->use_key) {
+		err = stmfts_enable_led(sdata);
+		if (err) {
+			/*
+			 * Even if the LEDs have failed to be initialized and
+			 * used in the driver, I can still use the device even
+			 * without LEDs. The ledvdd regulator pointer will be
+			 * used as a flag.
+			 */
+			dev_warn(&client->dev, "unable to use touchkey leds\n");
+			sdata->ledvdd = NULL;
+		}
+	}
+
+	err = sysfs_create_group(&sdata->client->dev.kobj,
+				 &stmfts_attribute_group);
+	if (err)
+		return err;
+
+	pm_runtime_enable(&client->dev);
+
+	return 0;
+}
+
+static int stmfts_remove(struct i2c_client *client)
+{
+	pm_runtime_disable(&client->dev);
+	sysfs_remove_group(&client->dev.kobj, &stmfts_attribute_group);
+
+	return 0;
+}
+
+static int stmfts_runtime_suspend(struct device *dev)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+	int ret;
+
+	ret = i2c_smbus_write_byte(sdata->client, STMFTS_SLEEP_IN);
+	if (ret)
+		dev_warn(dev, "failed to suspend device: %d\n", ret);
+
+	return ret;
+}
+
+static int stmfts_runtime_resume(struct device *dev)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+	int ret;
+
+	ret = i2c_smbus_write_byte(sdata->client, STMFTS_SLEEP_OUT);
+	if (ret)
+		dev_err(dev, "failed to resume device: %d\n", ret);
+
+	return ret;
+}
+
+static int __maybe_unused stmfts_suspend(struct device *dev)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+
+	stmfts_power_off(sdata);
+
+	return 0;
+}
+
+static int __maybe_unused stmfts_resume(struct device *dev)
+{
+	struct stmfts_data *sdata = dev_get_drvdata(dev);
+
+	return stmfts_power_on(sdata);
+}
+
+static const struct dev_pm_ops stmfts_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(stmfts_suspend, stmfts_resume)
+	SET_RUNTIME_PM_OPS(stmfts_runtime_suspend, stmfts_runtime_resume, NULL)
+};
+
+#ifdef CONFIG_OF
+static const struct of_device_id stmfts_of_match[] = {
+	{ .compatible = "st,stmfts", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, stmfts_of_match);
+#endif
+
+static const struct i2c_device_id stmfts_id[] = {
+	{ "stmfts", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, stmfts_id);
+
+static struct i2c_driver stmfts_driver = {
+	.driver = {
+		.name = STMFTS_DEV_NAME,
+		.of_match_table = of_match_ptr(stmfts_of_match),
+		.pm = &stmfts_pm_ops,
+	},
+	.probe = stmfts_probe,
+	.remove = stmfts_remove,
+	.id_table = stmfts_id,
+};
+
+module_i2c_driver(stmfts_driver);
+
+MODULE_AUTHOR("Andi Shyti <andi.shyti@samsung.com>");
+MODULE_DESCRIPTION("STMicroelectronics FTS Touch Screen");
+MODULE_LICENSE("GPL v2");