staging: iio: adc: new driver for AD7745/6/7 devices

Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 747 insertions, 2 deletions

diff --git a/drivers/staging/iio/adc/Kconfig b/drivers/staging/iio/adc/Kconfig
index 4e7b6a8..34c6822 100644
--- a/drivers/staging/iio/adc/Kconfig
+++ b/drivers/staging/iio/adc/Kconfig
@@ -85,9 +85,9 @@ config AD799X_RING_BUFFER
 config AD7476
 	tristate "Analog Devices AD7475/6/7/8 AD7466/7/8 and AD7495 ADC driver"
 	depends on SPI
-	select IIO_RING_BUFFER	
+	select IIO_RING_BUFFER
 	select IIO_SW_RING
-	select IIO_TRIGGER 	
+	select IIO_TRIGGER
 	help
 	  Say yes here to build support for Analog Devices
 	  AD7475, AD7476, AD7477, AD7478, AD7466, AD7467, AD7468, AD7495
@@ -96,3 +96,13 @@ config AD7476
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad7476.
+
+config AD7745
+	tristate "Analog Devices AD7745, AD7746 AD7747 capacitive sensor driver"
+	depends on I2C
+	help
+	  Say yes here to build support for Analog Devices capacitive sensors.
+	  (AD7745, AD7746, AD7747) Provides direct access via sysfs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad7745.
diff --git a/drivers/staging/iio/adc/Makefile b/drivers/staging/iio/adc/Makefile
index 36e66f9..ac83bad 100644
--- a/drivers/staging/iio/adc/Makefile
+++ b/drivers/staging/iio/adc/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_AD7152) += ad7152.o
 obj-$(CONFIG_AD7291) += ad7291.o
 obj-$(CONFIG_AD7298) += ad7298.o
 obj-$(CONFIG_AD7314) += ad7314.o
+obj-$(CONFIG_AD7745) += ad7745.o
diff --git a/drivers/staging/iio/adc/ad7745.c b/drivers/staging/iio/adc/ad7745.c
new file mode 100644
index 0000000..ab7ef84
--- /dev/null
+++ b/drivers/staging/iio/adc/ad7745.c
@@ -0,0 +1,734 @@
+/*
+ * AD774X capacitive sensor driver supporting AD7745/6/7
+ *
+ * Copyright 2010 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/gpio.h>
+#include <linux/workqueue.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/list.h>
+#include <linux/i2c.h>
+#include <linux/rtc.h>
+
+#include "../iio.h"
+#include "../sysfs.h"
+
+/*
+ * AD774X registers definition
+ */
+
+#define AD774X_STATUS		0
+#define AD774X_STATUS_RDY	(1 << 2)
+#define AD774X_STATUS_RDYVT	(1 << 1)
+#define AD774X_STATUS_RDYCAP	(1 << 0)
+#define AD774X_CAP_DATA_HIGH	1
+#define AD774X_CAP_DATA_MID	2
+#define AD774X_CAP_DATA_LOW	3
+#define AD774X_VT_DATA_HIGH	4
+#define AD774X_VT_DATA_MID	5
+#define AD774X_VT_DATA_LOW	6
+#define AD774X_CAP_SETUP	7
+#define AD774X_VT_SETUP		8
+#define AD774X_EXEC_SETUP	9
+#define AD774X_CFG		10
+#define AD774X_CAPDACA		11
+#define AD774X_CAPDACB		12
+#define AD774X_CAPDAC_EN	(1 << 7)
+#define AD774X_CAP_OFFH		13
+#define AD774X_CAP_OFFL		14
+#define AD774X_CAP_GAINH	15
+#define AD774X_CAP_GAINL	16
+#define AD774X_VOLT_GAINH	17
+#define AD774X_VOLT_GAINL	18
+
+#define AD774X_MAX_CONV_MODE	6
+
+/*
+ * struct ad774x_chip_info - chip specifc information
+ */
+
+struct ad774x_chip_info {
+	const char *name;
+	struct i2c_client *client;
+	struct iio_dev *indio_dev;
+	struct work_struct thresh_work;
+	bool inter;
+	s64 last_timestamp;
+	u16 cap_offs;                   /* Capacitive offset */
+	u16 cap_gain;                   /* Capacitive gain calibration */
+	u16 volt_gain;                  /* Voltage gain calibration */
+	u8  cap_setup;
+	u8  vt_setup;
+	u8  exec_setup;
+
+	char *conversion_mode;
+};
+
+struct ad774x_conversion_mode {
+	char *name;
+	u8 reg_cfg;
+};
+
+struct ad774x_conversion_mode ad774x_conv_mode_table[AD774X_MAX_CONV_MODE] = {
+	{ "idle", 0 },
+	{ "continuous-conversion", 1 },
+	{ "single-conversion", 2 },
+	{ "power-down", 3 },
+	{ "offset-calibration", 5 },
+	{ "gain-calibration", 6 },
+};
+
+/*
+ * ad774x register access by I2C
+ */
+
+static int ad774x_i2c_read(struct ad774x_chip_info *chip, u8 reg, u8 *data, int len)
+{
+	struct i2c_client *client = chip->client;
+	int ret;
+
+	ret = i2c_master_send(client, &reg, 1);
+	if (ret < 0) {
+		dev_err(&client->dev, "I2C write error\n");
+		return ret;
+	}
+
+	ret = i2c_master_recv(client, data, len);
+	if (ret < 0) {
+		dev_err(&client->dev, "I2C read error\n");
+		return ret;
+	}
+
+	return ret;
+}
+
+static int ad774x_i2c_write(struct ad774x_chip_info *chip, u8 reg, u8 data)
+{
+	struct i2c_client *client = chip->client;
+	int ret;
+
+	u8 tx[2] = {
+		reg,
+		data,
+	};
+
+	ret = i2c_master_send(client, tx, 2);
+	if (ret < 0)
+		dev_err(&client->dev, "I2C write error\n");
+
+	return ret;
+}
+
+/*
+ * sysfs nodes
+ */
+
+#define IIO_DEV_ATTR_AVAIL_CONVERSION_MODES(_show)				\
+	IIO_DEVICE_ATTR(available_conversion_modes, S_IRUGO, _show, NULL, 0)
+#define IIO_DEV_ATTR_CONVERSION_MODE(_mode, _show, _store)              \
+	IIO_DEVICE_ATTR(conversion_mode, _mode, _show, _store, 0)
+#define IIO_DEV_ATTR_CAP_SETUP(_mode, _show, _store)		\
+	IIO_DEVICE_ATTR(cap_setup, _mode, _show, _store, 0)
+#define IIO_DEV_ATTR_VT_SETUP(_mode, _show, _store)              \
+	IIO_DEVICE_ATTR(in0_setup, _mode, _show, _store, 0)
+#define IIO_DEV_ATTR_EXEC_SETUP(_mode, _show, _store)              \
+	IIO_DEVICE_ATTR(exec_setup, _mode, _show, _store, 0)
+#define IIO_DEV_ATTR_VOLT_GAIN(_mode, _show, _store)		\
+	IIO_DEVICE_ATTR(in0_gain, _mode, _show, _store, 0)
+#define IIO_DEV_ATTR_CAP_OFFS(_mode, _show, _store)		\
+	IIO_DEVICE_ATTR(cap_offs, _mode, _show, _store, 0)
+#define IIO_DEV_ATTR_CAP_GAIN(_mode, _show, _store)		\
+	IIO_DEVICE_ATTR(cap_gain, _mode, _show, _store, 0)
+#define IIO_DEV_ATTR_CAP_DATA(_show)		\
+	IIO_DEVICE_ATTR(cap0_raw, S_IRUGO, _show, NULL, 0)
+#define IIO_DEV_ATTR_VT_DATA(_show)		\
+	IIO_DEVICE_ATTR(in0_raw, S_IRUGO, _show, NULL, 0)
+
+static ssize_t ad774x_show_conversion_modes(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	int i;
+	int len = 0;
+
+	for (i = 0; i < AD774X_MAX_CONV_MODE; i++)
+		len += sprintf(buf + len, "%s ", ad774x_conv_mode_table[i].name);
+
+	len += sprintf(buf + len, "\n");
+
+	return len;
+}
+
+static IIO_DEV_ATTR_AVAIL_CONVERSION_MODES(ad774x_show_conversion_modes);
+
+static ssize_t ad774x_show_conversion_mode(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+
+	return sprintf(buf, "%s\n", chip->conversion_mode);
+}
+
+static ssize_t ad774x_store_conversion_mode(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	u8 cfg;
+	int i;
+
+	ad774x_i2c_read(chip, AD774X_CFG, &cfg, 1);
+
+	for (i = 0; i < AD774X_MAX_CONV_MODE; i++) {
+		if (strncmp(buf, ad774x_conv_mode_table[i].name,
+				strlen(ad774x_conv_mode_table[i].name) - 1) == 0) {
+			chip->conversion_mode = ad774x_conv_mode_table[i].name;
+			cfg |= 0x18 | ad774x_conv_mode_table[i].reg_cfg;
+			ad774x_i2c_write(chip, AD774X_CFG, cfg);
+			return len;
+		}
+	}
+
+	dev_err(dev, "not supported conversion mode\n");
+
+	return -EINVAL;
+}
+
+static IIO_DEV_ATTR_CONVERSION_MODE(S_IRUGO | S_IWUSR,
+		ad774x_show_conversion_mode,
+		ad774x_store_conversion_mode);
+
+static ssize_t ad774x_show_dac_value(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	u8 data;
+
+	ad774x_i2c_read(chip, this_attr->address, &data, 1);
+
+	return sprintf(buf, "%02x\n", data & 0x7F);
+}
+
+static ssize_t ad774x_store_dac_value(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	unsigned long data;
+	int ret;
+
+	ret = strict_strtoul(buf, 10, &data);
+
+	if (!ret) {
+		ad774x_i2c_write(chip, this_attr->address,
+			(data ? AD774X_CAPDAC_EN : 0) | (data & 0x7F));
+		return len;
+	}
+
+	return -EINVAL;
+}
+
+static IIO_DEVICE_ATTR(capdac0_raw, S_IRUGO | S_IWUSR,
+			ad774x_show_dac_value,
+			ad774x_store_dac_value,
+			AD774X_CAPDACA);
+
+static IIO_DEVICE_ATTR(capdac1_raw, S_IRUGO | S_IWUSR,
+			ad774x_show_dac_value,
+			ad774x_store_dac_value,
+			AD774X_CAPDACB);
+
+static ssize_t ad774x_show_cap_setup(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+
+	return sprintf(buf, "0x%02x\n", chip->cap_setup);
+}
+
+static ssize_t ad774x_store_cap_setup(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	unsigned long data;
+	int ret;
+
+	ret = strict_strtoul(buf, 10, &data);
+
+	if ((!ret) && (data < 0x100)) {
+		ad774x_i2c_write(chip, AD774X_CAP_SETUP, data);
+		chip->cap_setup = data;
+		return len;
+	}
+
+	return -EINVAL;
+}
+
+static IIO_DEV_ATTR_CAP_SETUP(S_IRUGO | S_IWUSR,
+		ad774x_show_cap_setup,
+		ad774x_store_cap_setup);
+
+static ssize_t ad774x_show_vt_setup(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+
+	return sprintf(buf, "0x%02x\n", chip->vt_setup);
+}
+
+static ssize_t ad774x_store_vt_setup(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	unsigned long data;
+	int ret;
+
+	ret = strict_strtoul(buf, 10, &data);
+
+	if ((!ret) && (data < 0x100)) {
+		ad774x_i2c_write(chip, AD774X_VT_SETUP, data);
+		chip->vt_setup = data;
+		return len;
+	}
+
+	return -EINVAL;
+}
+
+static IIO_DEV_ATTR_VT_SETUP(S_IRUGO | S_IWUSR,
+		ad774x_show_vt_setup,
+		ad774x_store_vt_setup);
+
+static ssize_t ad774x_show_exec_setup(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+
+	return sprintf(buf, "0x%02x\n", chip->exec_setup);
+}
+
+static ssize_t ad774x_store_exec_setup(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	unsigned long data;
+	int ret;
+
+	ret = strict_strtoul(buf, 10, &data);
+
+	if ((!ret) && (data < 0x100)) {
+		ad774x_i2c_write(chip, AD774X_EXEC_SETUP, data);
+		chip->exec_setup = data;
+		return len;
+	}
+
+	return -EINVAL;
+}
+
+static IIO_DEV_ATTR_EXEC_SETUP(S_IRUGO | S_IWUSR,
+		ad774x_show_exec_setup,
+		ad774x_store_exec_setup);
+
+static ssize_t ad774x_show_volt_gain(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+
+	return sprintf(buf, "%d\n", chip->volt_gain);
+}
+
+static ssize_t ad774x_store_volt_gain(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	unsigned long data;
+	int ret;
+
+	ret = strict_strtoul(buf, 10, &data);
+
+	if ((!ret) && (data < 0x10000)) {
+		ad774x_i2c_write(chip, AD774X_VOLT_GAINH, data >> 8);
+		ad774x_i2c_write(chip, AD774X_VOLT_GAINL, data);
+		chip->volt_gain = data;
+		return len;
+	}
+
+	return -EINVAL;
+}
+
+static IIO_DEV_ATTR_VOLT_GAIN(S_IRUGO | S_IWUSR,
+		ad774x_show_volt_gain,
+		ad774x_store_volt_gain);
+
+static ssize_t ad774x_show_cap_data(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	unsigned long data;
+	char tmp[3];
+
+	ad774x_i2c_read(chip, AD774X_CAP_DATA_HIGH, tmp, 3);
+	data = ((int)tmp[0] << 16) | ((int)tmp[1] << 8) | (int)tmp[2];
+
+	return sprintf(buf, "%ld\n", data);
+}
+
+static IIO_DEV_ATTR_CAP_DATA(ad774x_show_cap_data);
+
+static ssize_t ad774x_show_vt_data(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	unsigned long data;
+	char tmp[3];
+
+	ad774x_i2c_read(chip, AD774X_VT_DATA_HIGH, tmp, 3);
+	data = ((int)tmp[0] << 16) | ((int)tmp[1] << 8) | (int)tmp[2];
+
+	return sprintf(buf, "%ld\n", data);
+}
+
+static IIO_DEV_ATTR_VT_DATA(ad774x_show_vt_data);
+
+static ssize_t ad774x_show_cap_offs(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+
+	return sprintf(buf, "%d\n", chip->cap_offs);
+}
+
+static ssize_t ad774x_store_cap_offs(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	unsigned long data;
+	int ret;
+
+	ret = strict_strtoul(buf, 10, &data);
+
+	if ((!ret) && (data < 0x10000)) {
+		ad774x_i2c_write(chip, AD774X_CAP_OFFH, data >> 8);
+		ad774x_i2c_write(chip, AD774X_CAP_OFFL, data);
+		chip->cap_offs = data;
+		return len;
+	}
+
+	return -EINVAL;
+}
+
+static IIO_DEV_ATTR_CAP_OFFS(S_IRUGO | S_IWUSR,
+		ad774x_show_cap_offs,
+		ad774x_store_cap_offs);
+
+static ssize_t ad774x_show_cap_gain(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+
+	return sprintf(buf, "%d\n", chip->cap_gain);
+}
+
+static ssize_t ad774x_store_cap_gain(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	unsigned long data;
+	int ret;
+
+	ret = strict_strtoul(buf, 10, &data);
+
+	if ((!ret) && (data < 0x10000)) {
+		ad774x_i2c_write(chip, AD774X_CAP_GAINH, data >> 8);
+		ad774x_i2c_write(chip, AD774X_CAP_GAINL, data);
+		chip->cap_gain = data;
+		return len;
+	}
+
+	return -EINVAL;
+}
+
+static IIO_DEV_ATTR_CAP_GAIN(S_IRUGO | S_IWUSR,
+		ad774x_show_cap_gain,
+		ad774x_store_cap_gain);
+
+static ssize_t ad774x_show_name(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+	return sprintf(buf, "%s\n", chip->name);
+}
+
+static IIO_DEVICE_ATTR(name, S_IRUGO, ad774x_show_name, NULL, 0);
+
+static struct attribute *ad774x_attributes[] = {
+	&iio_dev_attr_available_conversion_modes.dev_attr.attr,
+	&iio_dev_attr_conversion_mode.dev_attr.attr,
+	&iio_dev_attr_cap_setup.dev_attr.attr,
+	&iio_dev_attr_in0_setup.dev_attr.attr,
+	&iio_dev_attr_exec_setup.dev_attr.attr,
+	&iio_dev_attr_cap_offs.dev_attr.attr,
+	&iio_dev_attr_cap_gain.dev_attr.attr,
+	&iio_dev_attr_in0_gain.dev_attr.attr,
+	&iio_dev_attr_in0_raw.dev_attr.attr,
+	&iio_dev_attr_cap0_raw.dev_attr.attr,
+	&iio_dev_attr_capdac0_raw.dev_attr.attr,
+	&iio_dev_attr_capdac1_raw.dev_attr.attr,
+	&iio_dev_attr_name.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ad774x_attribute_group = {
+	.attrs = ad774x_attributes,
+};
+
+/*
+ * data ready events
+ */
+
+#define IIO_EVENT_CODE_CAP_RDY     IIO_BUFFER_EVENT_CODE(0)
+#define IIO_EVENT_CODE_VT_RDY      IIO_BUFFER_EVENT_CODE(1)
+
+#define IIO_EVENT_ATTR_CAP_RDY_SH(_evlist, _show, _store, _mask)	\
+	IIO_EVENT_ATTR_SH(cap_rdy, _evlist, _show, _store, _mask)
+
+#define IIO_EVENT_ATTR_VT_RDY_SH(_evlist, _show, _store, _mask)	\
+	IIO_EVENT_ATTR_SH(vt_rdy, _evlist, _show, _store, _mask)
+
+static void ad774x_interrupt_handler_bh(struct work_struct *work_s)
+{
+	struct ad774x_chip_info *chip =
+		container_of(work_s, struct ad774x_chip_info, thresh_work);
+	u8 int_status;
+
+	enable_irq(chip->client->irq);
+
+	ad774x_i2c_read(chip, AD774X_STATUS, &int_status, 1);
+
+	if (int_status & AD774X_STATUS_RDYCAP)
+		iio_push_event(chip->indio_dev, 0,
+				IIO_EVENT_CODE_CAP_RDY,
+				chip->last_timestamp);
+
+	if (int_status & AD774X_STATUS_RDYVT)
+		iio_push_event(chip->indio_dev, 0,
+				IIO_EVENT_CODE_VT_RDY,
+				chip->last_timestamp);
+}
+
+static int ad774x_interrupt_handler_th(struct iio_dev *dev_info,
+		int index,
+		s64 timestamp,
+		int no_test)
+{
+	struct ad774x_chip_info *chip = dev_info->dev_data;
+
+	chip->last_timestamp = timestamp;
+	schedule_work(&chip->thresh_work);
+
+	return 0;
+}
+
+IIO_EVENT_SH(data_rdy, &ad774x_interrupt_handler_th);
+
+static ssize_t ad774x_query_out_mode(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	/*
+	 * AD774X provides one /RDY pin, which can be used as interrupt
+	 * but the pin is not configurable
+	 */
+	return sprintf(buf, "1\n");
+}
+
+static ssize_t ad774x_set_out_mode(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	return len;
+}
+
+IIO_EVENT_ATTR_CAP_RDY_SH(iio_event_data_rdy, ad774x_query_out_mode, ad774x_set_out_mode, 0);
+IIO_EVENT_ATTR_VT_RDY_SH(iio_event_data_rdy, ad774x_query_out_mode, ad774x_set_out_mode, 0);
+
+static struct attribute *ad774x_event_attributes[] = {
+	&iio_event_attr_cap_rdy.dev_attr.attr,
+	&iio_event_attr_vt_rdy.dev_attr.attr,
+	NULL,
+};
+
+static struct attribute_group ad774x_event_attribute_group = {
+	.attrs = ad774x_event_attributes,
+};
+
+/*
+ * device probe and remove
+ */
+
+static int __devinit ad774x_probe(struct i2c_client *client,
+		const struct i2c_device_id *id)
+{
+	int ret = 0, regdone = 0;
+	struct ad774x_chip_info *chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+	if (chip == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+
+	/* this is only used for device removal purposes */
+	i2c_set_clientdata(client, chip);
+
+	chip->client = client;
+	chip->name = id->name;
+
+	chip->indio_dev = iio_allocate_device();
+	if (chip->indio_dev == NULL) {
+		ret = -ENOMEM;
+		goto error_free_chip;
+	}
+
+	/* Establish that the iio_dev is a child of the i2c device */
+	chip->indio_dev->dev.parent = &client->dev;
+	chip->indio_dev->attrs = &ad774x_attribute_group;
+	chip->indio_dev->event_attrs = &ad774x_event_attribute_group;
+	chip->indio_dev->dev_data = (void *)(chip);
+	chip->indio_dev->driver_module = THIS_MODULE;
+	chip->indio_dev->num_interrupt_lines = 1;
+	chip->indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = iio_device_register(chip->indio_dev);
+	if (ret)
+		goto error_free_dev;
+	regdone = 1;
+
+	if (client->irq) {
+		ret = iio_register_interrupt_line(client->irq,
+				chip->indio_dev,
+				0,
+				IRQF_TRIGGER_FALLING,
+				"ad774x");
+		if (ret)
+			goto error_free_dev;
+
+		iio_add_event_to_list(iio_event_attr_cap_rdy.listel,
+				&chip->indio_dev->interrupts[0]->ev_list);
+
+		INIT_WORK(&chip->thresh_work, ad774x_interrupt_handler_bh);
+	}
+
+	dev_err(&client->dev, "%s capacitive sensor registered, irq: %d\n", id->name, client->irq);
+
+	return 0;
+
+error_free_dev:
+	if (regdone)
+		iio_device_unregister(chip->indio_dev);
+	else
+		iio_free_device(chip->indio_dev);
+error_free_chip:
+	kfree(chip);
+error_ret:
+	return ret;
+}
+
+static int __devexit ad774x_remove(struct i2c_client *client)
+{
+	struct ad774x_chip_info *chip = i2c_get_clientdata(client);
+	struct iio_dev *indio_dev = chip->indio_dev;
+
+	if (client->irq)
+		iio_unregister_interrupt_line(indio_dev, 0);
+	iio_device_unregister(indio_dev);
+	kfree(chip);
+
+	return 0;
+}
+
+static const struct i2c_device_id ad774x_id[] = {
+	{ "ad7745", 0 },
+	{ "ad7746", 0 },
+	{ "ad7747", 0 },
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, ad774x_id);
+
+static struct i2c_driver ad774x_driver = {
+	.driver = {
+		.name = "ad774x",
+	},
+	.probe = ad774x_probe,
+	.remove = __devexit_p(ad774x_remove),
+	.id_table = ad774x_id,
+};
+
+static __init int ad774x_init(void)
+{
+	return i2c_add_driver(&ad774x_driver);
+}
+
+static __exit void ad774x_exit(void)
+{
+	i2c_del_driver(&ad774x_driver);
+}
+
+MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>");
+MODULE_DESCRIPTION("Analog Devices ad7745/6/7 capacitive sensor driver");
+MODULE_LICENSE("GPL v2");
+
+module_init(ad774x_init);
+module_exit(ad774x_exit);