Input: qt1050 - add Microchip AT42QT1050 support

Add initial support for the AT42QT1050 (QT1050) device. The device
supports up to five input keys, dependent on the mode. Since it adds only
the initial support, the "1 to 4 keys plus Guard Channel" mode isn't
supported.
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/microchip,qt1050.txt

+Microchip AT42QT1050 Five-channel Touch Sensor IC
+
+The AT42QT1050 (QT1050) is a QTouchADC sensor device. The device can sense from
+one to five keys, dependent on mode. The QT1050 includes all signal processing
+functions necessary to provide stable sensing under a wide variety of changing
+conditions, and the outputs are fully debounced.
+
+The touchkey device node should be placed inside an I2C bus node.
+
+Required properties:
+- compatible: Must be "microchip,qt1050"
+- reg: The I2C address of the device
+- interrupts: The sink for the touchpad's IRQ output,
+  see ../interrupt-controller/interrupts.txt
+
+Optional properties:
+- wakeup-source: touch keys can be used as a wakeup source
+
+Each button (key) is represented as a sub-node:
+
+Each not specified key or key with linux,code set to KEY_RESERVED gets disabled
+in HW.
+
+Subnode properties:
+- linux,code: Keycode to emit.
+- reg: The key number. Valid values: 0, 1, 2, 3, 4.
+
+Optional subnode-properties:
+
+If a optional property is missing or has a invalid value the default value is
+taken.
+
+- microchip,pre-charge-time-ns:
+  Each touchpad need some time to precharge. The value depends on the mechanical
+  layout.
+  Valid value range: 0 - 637500; values must be a multiple of 2500;
+  default is 0.
+- microchip,average-samples:
+  Number of data samples which are averaged for each read.
+  Valid values: 1, 4, 16, 64, 256, 1024, 4096, 16384; default is 1.
+- microchip,average-scaling:
+  The scaling factor which is used to scale the average-samples.
+  Valid values: 1, 2, 4, 8, 16, 32, 64, 128; default is 1.
+- microchip,threshold:
+  Number of counts to register a touch detection.
+  Valid value range: 0 - 255; default is 20.
+
+Example:
+QT1050 with 3 non continuous keys, key2 and key4 are disabled.
+
+touchkeys@41 {
+	compatible = "microchip,qt1050";
+	reg = <0x41>;
+	interrupt-parent = <&gpio0>;
+	interrupts = <17 IRQ_TYPE_EDGE_FALLING>;
+
+	up@0 {
+		reg = <0>;
+		linux,code = <KEY_UP>;
+		microchip,average-samples = <64>;
+		microchip,average-scaling = <16>;
+		microchip,pre-charge-time-ns = <10000>;
+	};
+
+	right@1 {
+		reg = <1>;
+		linux,code = <KEY_RIGHT>;
+		microchip,average-samples = <64>;
+		microchip,average-scaling = <8>;
+	};
+
+	down@3 {
+		reg = <3>;
+		linux,code = <KEY_DOWN>;
+		microchip,average-samples = <256>;
+		microchip,average-scaling = <16>;
+	};
+};

drivers/input/keyboard/Kconfig

@@ -137,6 +137,17 @@ config KEYBOARD_ATKBD_RDI_KEYCODES
 	  right-hand column will be interpreted as the key shown in the
 	  left-hand column.
 
+config KEYBOARD_QT1050
+	tristate "Microchip AT42QT1050 Touch Sensor Chip"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  Say Y here if you want to use Microchip AT42QT1050 QTouch
+	  Sensor chip as input device.
+
+	  To compile this driver as a module, choose M here:
+	  the module will be called qt1050
+
 config KEYBOARD_QT1070
        tristate "Atmel AT42QT1070 Touch Sensor Chip"
        depends on I2C

drivers/input/keyboard/Makefile

@@ -50,6 +50,7 @@ obj-$(CONFIG_KEYBOARD_OPENCORES)	+= opencores-kbd.o
 obj-$(CONFIG_KEYBOARD_PMIC8XXX)		+= pmic8xxx-keypad.o
 obj-$(CONFIG_KEYBOARD_PXA27x)		+= pxa27x_keypad.o
 obj-$(CONFIG_KEYBOARD_PXA930_ROTARY)	+= pxa930_rotary.o
+obj-$(CONFIG_KEYBOARD_QT1050)           += qt1050.o
 obj-$(CONFIG_KEYBOARD_QT1070)           += qt1070.o
 obj-$(CONFIG_KEYBOARD_QT2160)		+= qt2160.o
 obj-$(CONFIG_KEYBOARD_SAMSUNG)		+= samsung-keypad.o

drivers/input/keyboard/qt1050.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Microchip AT42QT1050 QTouch Sensor Controller
+ *
+ *  Copyright (C) 2019 Pengutronix, Marco Felsch <kernel@pengutronix.de>
+ *
+ *  Base on AT42QT1070 driver by:
+ *  Bo Shen <voice.shen@atmel.com>
+ *  Copyright (C) 2011 Atmel
+ */
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+
+/* Chip ID */
+#define QT1050_CHIP_ID		0x00
+#define QT1050_CHIP_ID_VER	0x46
+
+/* Firmware version */
+#define QT1050_FW_VERSION	0x01
+
+/* Detection status */
+#define QT1050_DET_STATUS	0x02
+
+/* Key status */
+#define QT1050_KEY_STATUS	0x03
+
+/* Key Signals */
+#define QT1050_KEY_SIGNAL_0_MSB	0x06
+#define QT1050_KEY_SIGNAL_0_LSB	0x07
+#define QT1050_KEY_SIGNAL_1_MSB	0x08
+#define QT1050_KEY_SIGNAL_1_LSB	0x09
+#define QT1050_KEY_SIGNAL_2_MSB	0x0c
+#define QT1050_KEY_SIGNAL_2_LSB	0x0d
+#define QT1050_KEY_SIGNAL_3_MSB	0x0e
+#define QT1050_KEY_SIGNAL_3_LSB	0x0f
+#define QT1050_KEY_SIGNAL_4_MSB	0x10
+#define QT1050_KEY_SIGNAL_4_LSB	0x11
+
+/* Reference data */
+#define QT1050_REF_DATA_0_MSB	0x14
+#define QT1050_REF_DATA_0_LSB	0x15
+#define QT1050_REF_DATA_1_MSB	0x16
+#define QT1050_REF_DATA_1_LSB	0x17
+#define QT1050_REF_DATA_2_MSB	0x1a
+#define QT1050_REF_DATA_2_LSB	0x1b
+#define QT1050_REF_DATA_3_MSB	0x1c
+#define QT1050_REF_DATA_3_LSB	0x1d
+#define QT1050_REF_DATA_4_MSB	0x1e
+#define QT1050_REF_DATA_4_LSB	0x1f
+
+/* Negative threshold level */
+#define QT1050_NTHR_0		0x21
+#define QT1050_NTHR_1		0x22
+#define QT1050_NTHR_2		0x24
+#define QT1050_NTHR_3		0x25
+#define QT1050_NTHR_4		0x26
+
+/* Pulse / Scale  */
+#define QT1050_PULSE_SCALE_0	0x28
+#define QT1050_PULSE_SCALE_1	0x29
+#define QT1050_PULSE_SCALE_2	0x2b
+#define QT1050_PULSE_SCALE_3	0x2c
+#define QT1050_PULSE_SCALE_4	0x2d
+
+/* Detection integrator counter / AKS */
+#define QT1050_DI_AKS_0		0x2f
+#define QT1050_DI_AKS_1		0x30
+#define QT1050_DI_AKS_2		0x32
+#define QT1050_DI_AKS_3		0x33
+#define QT1050_DI_AKS_4		0x34
+
+/* Charge Share Delay */
+#define QT1050_CSD_0		0x36
+#define QT1050_CSD_1		0x37
+#define QT1050_CSD_2		0x39
+#define QT1050_CSD_3		0x3a
+#define QT1050_CSD_4		0x3b
+
+/* Low Power Mode */
+#define QT1050_LPMODE		0x3d
+
+/* Calibration and Reset */
+#define QT1050_RES_CAL		0x3f
+#define QT1050_RES_CAL_RESET		BIT(7)
+#define QT1050_RES_CAL_CALIBRATE	BIT(1)
+
+#define QT1050_MAX_KEYS		5
+#define QT1050_RESET_TIME	255
+
+struct qt1050_key_regs {
+	unsigned int nthr;
+	unsigned int pulse_scale;
+	unsigned int di_aks;
+	unsigned int csd;
+};
+
+struct qt1050_key {
+	u32 num;
+	u32 charge_delay;
+	u32 thr_cnt;
+	u32 samples;
+	u32 scale;
+	u32 keycode;
+};
+
+struct qt1050_priv {
+	struct i2c_client	*client;
+	struct input_dev	*input;
+	struct regmap		*regmap;
+	struct qt1050_key	keys[QT1050_MAX_KEYS];
+	unsigned short		keycodes[QT1050_MAX_KEYS];
+	u8			reg_keys;
+	u8			last_keys;
+};
+
+static const struct qt1050_key_regs qt1050_key_regs_data[] = {
+	{
+		.nthr = QT1050_NTHR_0,
+		.pulse_scale = QT1050_PULSE_SCALE_0,
+		.di_aks = QT1050_DI_AKS_0,
+		.csd = QT1050_CSD_0,
+	}, {
+		.nthr = QT1050_NTHR_1,
+		.pulse_scale = QT1050_PULSE_SCALE_1,
+		.di_aks = QT1050_DI_AKS_1,
+		.csd = QT1050_CSD_1,
+	}, {
+		.nthr = QT1050_NTHR_2,
+		.pulse_scale = QT1050_PULSE_SCALE_2,
+		.di_aks = QT1050_DI_AKS_2,
+		.csd = QT1050_CSD_2,
+	}, {
+		.nthr = QT1050_NTHR_3,
+		.pulse_scale = QT1050_PULSE_SCALE_3,
+		.di_aks = QT1050_DI_AKS_3,
+		.csd = QT1050_CSD_3,
+	}, {
+		.nthr = QT1050_NTHR_4,
+		.pulse_scale = QT1050_PULSE_SCALE_4,
+		.di_aks = QT1050_DI_AKS_4,
+		.csd = QT1050_CSD_4,
+	}
+};
+
+static bool qt1050_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case QT1050_DET_STATUS:
+	case QT1050_KEY_STATUS:
+	case QT1050_KEY_SIGNAL_0_MSB:
+	case QT1050_KEY_SIGNAL_0_LSB:
+	case QT1050_KEY_SIGNAL_1_MSB:
+	case QT1050_KEY_SIGNAL_1_LSB:
+	case QT1050_KEY_SIGNAL_2_MSB:
+	case QT1050_KEY_SIGNAL_2_LSB:
+	case QT1050_KEY_SIGNAL_3_MSB:
+	case QT1050_KEY_SIGNAL_3_LSB:
+	case QT1050_KEY_SIGNAL_4_MSB:
+	case QT1050_KEY_SIGNAL_4_LSB:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_range qt1050_readable_ranges[] = {
+	regmap_reg_range(QT1050_CHIP_ID, QT1050_KEY_STATUS),
+	regmap_reg_range(QT1050_KEY_SIGNAL_0_MSB, QT1050_KEY_SIGNAL_1_LSB),
+	regmap_reg_range(QT1050_KEY_SIGNAL_2_MSB, QT1050_KEY_SIGNAL_4_LSB),
+	regmap_reg_range(QT1050_REF_DATA_0_MSB, QT1050_REF_DATA_1_LSB),
+	regmap_reg_range(QT1050_REF_DATA_2_MSB, QT1050_REF_DATA_4_LSB),
+	regmap_reg_range(QT1050_NTHR_0, QT1050_NTHR_1),
+	regmap_reg_range(QT1050_NTHR_2, QT1050_NTHR_4),
+	regmap_reg_range(QT1050_PULSE_SCALE_0, QT1050_PULSE_SCALE_1),
+	regmap_reg_range(QT1050_PULSE_SCALE_2, QT1050_PULSE_SCALE_4),
+	regmap_reg_range(QT1050_DI_AKS_0, QT1050_DI_AKS_1),
+	regmap_reg_range(QT1050_DI_AKS_2, QT1050_DI_AKS_4),
+	regmap_reg_range(QT1050_CSD_0, QT1050_CSD_1),
+	regmap_reg_range(QT1050_CSD_2, QT1050_RES_CAL),
+};
+
+static const struct regmap_access_table qt1050_readable_table = {
+	.yes_ranges = qt1050_readable_ranges,
+	.n_yes_ranges = ARRAY_SIZE(qt1050_readable_ranges),
+};
+
+static const struct regmap_range qt1050_writeable_ranges[] = {
+	regmap_reg_range(QT1050_NTHR_0, QT1050_NTHR_1),
+	regmap_reg_range(QT1050_NTHR_2, QT1050_NTHR_4),
+	regmap_reg_range(QT1050_PULSE_SCALE_0, QT1050_PULSE_SCALE_1),
+	regmap_reg_range(QT1050_PULSE_SCALE_2, QT1050_PULSE_SCALE_4),
+	regmap_reg_range(QT1050_DI_AKS_0, QT1050_DI_AKS_1),
+	regmap_reg_range(QT1050_DI_AKS_2, QT1050_DI_AKS_4),
+	regmap_reg_range(QT1050_CSD_0, QT1050_CSD_1),
+	regmap_reg_range(QT1050_CSD_2, QT1050_RES_CAL),
+};
+
+static const struct regmap_access_table qt1050_writeable_table = {
+	.yes_ranges = qt1050_writeable_ranges,
+	.n_yes_ranges = ARRAY_SIZE(qt1050_writeable_ranges),
+};
+
+static struct regmap_config qt1050_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = QT1050_RES_CAL,
+
+	.cache_type = REGCACHE_RBTREE,
+
+	.wr_table = &qt1050_writeable_table,
+	.rd_table = &qt1050_readable_table,
+	.volatile_reg = qt1050_volatile_reg,
+};
+
+static bool qt1050_identify(struct qt1050_priv *ts)
+{
+	unsigned int val;
+	int err;
+
+	/* Read Chip ID */
+	regmap_read(ts->regmap, QT1050_CHIP_ID, &val);
+	if (val != QT1050_CHIP_ID_VER) {
+		dev_err(&ts->client->dev, "ID %d not supported\n", val);
+		return false;
+	}
+
+	/* Read firmware version */
+	err = regmap_read(ts->regmap, QT1050_FW_VERSION, &val);
+	if (err) {
+		dev_err(&ts->client->dev, "could not read the firmware version\n");
+		return false;
+	}
+
+	dev_info(&ts->client->dev, "AT42QT1050 firmware version %1d.%1d\n",
+		 val >> 4, val & 0xf);
+
+	return true;
+}
+
+static irqreturn_t qt1050_irq_threaded(int irq, void *dev_id)
+{
+	struct qt1050_priv *ts = dev_id;
+	struct input_dev *input = ts->input;
+	unsigned long new_keys, changed;
+	unsigned int val;
+	int i, err;
+
+	/* Read the detected status register, thus clearing interrupt */
+	err = regmap_read(ts->regmap, QT1050_DET_STATUS, &val);
+	if (err) {
+		dev_err(&ts->client->dev, "Fail to read detection status: %d\n",
+			err);
+		return IRQ_NONE;
+	}
+
+	/* Read which key changed, keys are not continuous */
+	err = regmap_read(ts->regmap, QT1050_KEY_STATUS, &val);
+	if (err) {
+		dev_err(&ts->client->dev,
+			"Fail to determine the key status: %d\n", err);
+		return IRQ_NONE;
+	}
+	new_keys = (val & 0x70) >> 2 | (val & 0x6) >> 1;
+	changed = ts->last_keys ^ new_keys;
+	/* Report registered keys only */
+	changed &= ts->reg_keys;
+
+	for_each_set_bit(i, &changed, QT1050_MAX_KEYS)
+		input_report_key(input, ts->keys[i].keycode,
+				 test_bit(i, &new_keys));
+
+	ts->last_keys = new_keys;
+	input_sync(input);
+
+	return IRQ_HANDLED;
+}
+
+static const struct qt1050_key_regs *qt1050_get_key_regs(int key_num)
+{
+	return &qt1050_key_regs_data[key_num];
+}
+
+static int qt1050_set_key(struct regmap *map, int number, int on)
+{
+	const struct qt1050_key_regs *key_regs;
+
+	key_regs = qt1050_get_key_regs(number);
+
+	return regmap_update_bits(map, key_regs->di_aks, 0xfc,
+				  on ? BIT(4) : 0x00);
+}
+
+static int qt1050_apply_fw_data(struct qt1050_priv *ts)
+{
+	struct regmap *map = ts->regmap;
+	struct qt1050_key *button = &ts->keys[0];
+	const struct qt1050_key_regs *key_regs;
+	int i, err;
+
+	/* Disable all keys and enable only the specified ones */
+	for (i = 0; i < QT1050_MAX_KEYS; i++) {
+		err = qt1050_set_key(map, i, 0);
+		if (err)
+			return err;
+	}
+
+	for (i = 0; i < QT1050_MAX_KEYS; i++, button++) {
+		/* Keep KEY_RESERVED keys off */
+		if (button->keycode == KEY_RESERVED)
+			continue;
+
+		err = qt1050_set_key(map, button->num, 1);
+		if (err)
+			return err;
+
+		key_regs = qt1050_get_key_regs(button->num);
+
+		err = regmap_write(map, key_regs->pulse_scale,
+				   (button->samples << 4) | (button->scale));
+		if (err)
+			return err;
+		err = regmap_write(map, key_regs->csd, button->charge_delay);
+		if (err)
+			return err;
+		err = regmap_write(map, key_regs->nthr, button->thr_cnt);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int qt1050_parse_fw(struct qt1050_priv *ts)
+{
+	struct device *dev = &ts->client->dev;
+	struct fwnode_handle *child;
+	int nbuttons;
+
+	nbuttons = device_get_child_node_count(dev);
+	if (nbuttons == 0 || nbuttons > QT1050_MAX_KEYS)
+		return -ENODEV;
+
+	device_for_each_child_node(dev, child) {
+		struct qt1050_key button;
+
+		/* Required properties */
+		if (fwnode_property_read_u32(child, "linux,code",
+					     &button.keycode)) {
+			dev_err(dev, "Button without keycode\n");
+			goto err;
+		}
+		if (button.keycode >= KEY_MAX) {
+			dev_err(dev, "Invalid keycode 0x%x\n",
+				button.keycode);
+			goto err;
+		}
+
+		if (fwnode_property_read_u32(child, "reg",
+					     &button.num)) {
+			dev_err(dev, "Button without pad number\n");
+			goto err;
+		}
+		if (button.num < 0 || button.num > QT1050_MAX_KEYS - 1)
+			goto err;
+
+		ts->reg_keys |= BIT(button.num);
+
+		/* Optional properties */
+		if (fwnode_property_read_u32(child,
+					     "microchip,pre-charge-time-ns",
+					     &button.charge_delay)) {
+			button.charge_delay = 0;
+		} else {
+			if (button.charge_delay % 2500 == 0)
+				button.charge_delay =
+					button.charge_delay / 2500;
+			else
+				button.charge_delay = 0;
+		}
+
+		if (fwnode_property_read_u32(child, "microchip,average-samples",
+					 &button.samples)) {
+			button.samples = 0;
+		} else {
+			if (is_power_of_2(button.samples))
+				button.samples = ilog2(button.samples);
+			else
+				button.samples = 0;
+		}
+
+		if (fwnode_property_read_u32(child, "microchip,average-scaling",
+					     &button.scale)) {
+			button.scale = 0;
+		} else {
+			if (is_power_of_2(button.scale))
+				button.scale = ilog2(button.scale);
+			else
+				button.scale = 0;
+
+		}
+
+		if (fwnode_property_read_u32(child, "microchip,threshold",
+					 &button.thr_cnt)) {
+			button.thr_cnt = 20;
+		} else {
+			if (button.thr_cnt > 255)
+				button.thr_cnt = 20;
+		}
+
+		ts->keys[button.num] = button;
+	}
+
+	return 0;
+
+err:
+	fwnode_handle_put(child);
+	return -EINVAL;
+}
+
+static int qt1050_probe(struct i2c_client *client)
+{
+	struct qt1050_priv *ts;
+	struct input_dev *input;
+	struct device *dev = &client->dev;
+	struct regmap *map;
+	unsigned int status, i;
+	int err;
+
+	/* Check basic functionality */
+	err = i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE);
+	if (!err) {
+		dev_err(&client->dev, "%s adapter not supported\n",
+			dev_driver_string(&client->adapter->dev));
+		return -ENODEV;
+	}
+
+	if (!client->irq) {
+		dev_err(dev, "assign a irq line to this device\n");
+		return -EINVAL;
+	}
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	input = devm_input_allocate_device(dev);
+	if (!input)
+		return -ENOMEM;
+
+	map = devm_regmap_init_i2c(client, &qt1050_regmap_config);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	ts->client = client;
+	ts->input = input;
+	ts->regmap = map;
+
+	i2c_set_clientdata(client, ts);
+
+	/* Identify the qt1050 chip */
+	if (!qt1050_identify(ts))
+		return -ENODEV;
+
+	/* Get pdata */
+	err = qt1050_parse_fw(ts);
+	if (err) {
+		dev_err(dev, "Failed to parse firmware: %d\n", err);
+		return err;
+	}
+
+	input->name = "AT42QT1050 QTouch Sensor";
+	input->dev.parent = &client->dev;
+	input->id.bustype = BUS_I2C;
+
+	/* Add the keycode */
+	input->keycode = ts->keycodes;
+	input->keycodesize = sizeof(ts->keycodes[0]);
+	input->keycodemax = QT1050_MAX_KEYS;
+
+	__set_bit(EV_KEY, input->evbit);
+	for (i = 0; i < QT1050_MAX_KEYS; i++) {
+		ts->keycodes[i] = ts->keys[i].keycode;
+		__set_bit(ts->keycodes[i], input->keybit);
+	}
+
+	/* Trigger re-calibration */
+	err = regmap_update_bits(ts->regmap, QT1050_RES_CAL, 0x7f,
+				 QT1050_RES_CAL_CALIBRATE);
+	if (err) {
+		dev_err(dev, "Trigger calibration failed: %d\n", err);
+		return err;
+	}
+	err = regmap_read_poll_timeout(ts->regmap, QT1050_DET_STATUS, status,
+				 status >> 7 == 1, 10000, 200000);
+	if (err) {
+		dev_err(dev, "Calibration failed: %d\n", err);
+		return err;
+	}
+
+	/* Soft reset to set defaults */
+	err = regmap_update_bits(ts->regmap, QT1050_RES_CAL,
+				 QT1050_RES_CAL_RESET, QT1050_RES_CAL_RESET);
+	if (err) {
+		dev_err(dev, "Trigger soft reset failed: %d\n", err);
+		return err;
+	}
+	msleep(QT1050_RESET_TIME);
+
+	/* Set pdata */
+	err = qt1050_apply_fw_data(ts);
+	if (err) {
+		dev_err(dev, "Failed to set firmware data: %d\n", err);
+		return err;
+	}
+
+	err = devm_request_threaded_irq(dev, client->irq, NULL,
+					qt1050_irq_threaded, IRQF_ONESHOT,
+					"qt1050", ts);
+	if (err) {
+		dev_err(&client->dev, "Failed to request irq: %d\n", err);
+		return err;
+	}
+
+	/* Clear #CHANGE line */
+	err = regmap_read(ts->regmap, QT1050_DET_STATUS, &status);
+	if (err) {
+		dev_err(dev, "Failed to clear #CHANGE line level: %d\n", err);
+		return err;
+	}
+
+	/* Register the input device */
+	err = input_register_device(ts->input);
+	if (err) {
+		dev_err(&client->dev, "Failed to register input device: %d\n",
+			err);
+		return err;
+	}
+
+	return 0;
+}
+
+static int __maybe_unused qt1050_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct qt1050_priv *ts = i2c_get_clientdata(client);
+
+	disable_irq(client->irq);
+
+	/*
+	 * Set measurement interval to 1s (125 x 8ms) if wakeup is allowed
+	 * else turn off. The 1s interval seems to be a good compromise between
+	 * low power and response time.
+	 */
+	return regmap_write(ts->regmap, QT1050_LPMODE,
+			    device_may_wakeup(dev) ? 125 : 0);
+}
+
+static int __maybe_unused qt1050_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct qt1050_priv *ts = i2c_get_clientdata(client);
+
+	enable_irq(client->irq);
+
+	/* Set measurement interval back to 16ms (2 x 8ms) */
+	return regmap_write(ts->regmap, QT1050_LPMODE, 2);
+}
+
+static SIMPLE_DEV_PM_OPS(qt1050_pm_ops, qt1050_suspend, qt1050_resume);
+
+static const struct of_device_id __maybe_unused qt1050_of_match[] = {
+	{ .compatible = "microchip,qt1050", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, qt1050_of_match);
+
+static struct i2c_driver qt1050_driver = {
+	.driver	= {
+		.name = "qt1050",
+		.of_match_table = of_match_ptr(qt1050_of_match),
+		.pm = &qt1050_pm_ops,
+	},
+	.probe_new = qt1050_probe,
+};
+
+module_i2c_driver(qt1050_driver);
+
+MODULE_AUTHOR("Marco Felsch <kernel@pengutronix.de");
+MODULE_DESCRIPTION("Driver for AT42QT1050 QTouch sensor");
+MODULE_LICENSE("GPL v2");