staging: iio: adc: new driver for AD7291 devices

Signed-off-by: Sonic Zhang <sonic.zhang@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>

drivers/staging/iio/adc/Kconfig

@@ -41,6 +41,13 @@ config AD7152
 	  Say yes here to build support for Analog Devices capacitive sensors.
 	  (ad7152, ad7153) Provides direct access via sysfs.
 
+config AD7291
+	tristate "Analog Devices AD7291 temperature sensor driver"
+	depends on I2C
+	help
+	  Say yes here to build support for Analog Devices AD7291
+	  temperature sensors.
+
 config AD799X
 	tristate "Analog Devices AD799x ADC driver"
 	depends on I2C

drivers/staging/iio/adc/Makefile

@@ -17,3 +17,4 @@ obj-$(CONFIG_AD7476) += ad7476.o
 
 obj-$(CONFIG_AD7150) += ad7150.o
 obj-$(CONFIG_AD7152) += ad7152.o
+obj-$(CONFIG_AD7291) += ad7291.o

drivers/staging/iio/adc/ad7291.c

+/*
+ * AD7291 digital temperature sensor driver supporting AD7291
+ *
+ * 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"
+
+/*
+ * AD7291 registers definition
+ */
+#define AD7291_COMMAND			0
+#define AD7291_VOLTAGE			1
+#define AD7291_T_SENSE			2
+#define AD7291_T_AVERAGE		3
+#define AD7291_VOLTAGE_LIMIT_BASE	4
+#define AD7291_VOLTAGE_LIMIT_COUNT	8
+#define AD7291_T_SENSE_HIGH		0x1c
+#define AD7291_T_SENSE_LOW		0x1d
+#define AD7291_T_SENSE_HYST		0x1e
+#define AD7291_VOLTAGE_ALERT_STATUS	0x1f
+#define AD7291_T_ALERT_STATUS		0x20
+
+/*
+ * AD7291 command
+ */
+#define AD7291_AUTOCYCLE		0x1
+#define AD7291_RESET			0x2
+#define AD7291_ALART_CLEAR		0x4
+#define AD7291_ALART_POLARITY		0x8
+#define AD7291_EXT_REF			0x10
+#define AD7291_NOISE_DELAY		0x20
+#define AD7291_T_SENSE_MASK		0x40
+#define AD7291_VOLTAGE_MASK		0xff00
+#define AD7291_VOLTAGE_OFFSET		0x8
+
+/*
+ * AD7291 value masks
+ */
+#define AD7291_CHANNEL_MASK		0xf000
+#define AD7291_VALUE_MASK		0xfff
+#define AD7291_T_VALUE_SIGN		0x400
+#define AD7291_T_VALUE_FLOAT_OFFSET	2
+#define AD7291_T_VALUE_FLOAT_MASK	0x2
+
+/*
+ * struct ad7291_chip_info - chip specifc information
+ */
+
+struct ad7291_chip_info {
+	const char *name;
+	struct i2c_client *client;
+	struct iio_dev *indio_dev;
+	struct work_struct thresh_work;
+	s64 last_timestamp;
+	u16 command;
+	u8  channels;	/* Active voltage channels */
+};
+
+/*
+ * struct ad7291_chip_info - chip specifc information
+ */
+
+struct ad7291_limit_regs {
+	u16	data_high;
+	u16	data_low;
+	u16	hysteresis;
+};
+
+/*
+ * ad7291 register access by I2C
+ */
+static int ad7291_i2c_read(struct ad7291_chip_info *chip, u8 reg, u16 *data)
+{
+	struct i2c_client *client = chip->client;
+	int ret = 0;
+
+	ret = i2c_smbus_read_word_data(client, reg);
+	if (ret < 0) {
+		dev_err(&client->dev, "I2C read error\n");
+		return ret;
+	}
+
+	*data = swab16((u16)ret);
+
+	return 0;
+}
+
+static int ad7291_i2c_write(struct ad7291_chip_info *chip, u8 reg, u16 data)
+{
+	struct i2c_client *client = chip->client;
+	int ret = 0;
+
+	ret = i2c_smbus_write_word_data(client, reg, swab16(data));
+	if (ret < 0)
+		dev_err(&client->dev, "I2C write error\n");
+
+	return ret;
+}
+
+/* Returns negative errno, or else the number of words read. */
+static int ad7291_i2c_read_data(struct ad7291_chip_info *chip, u8 reg, u16 *data)
+{
+	struct i2c_client *client = chip->client;
+	u8 commands[4];
+	int ret = 0;
+	int i, count;
+
+	if (reg == AD7291_T_SENSE || reg == AD7291_T_AVERAGE)
+		count = 2;
+	else if (reg == AD7291_VOLTAGE) {
+		if (!chip->channels) {
+			dev_err(&client->dev, "No voltage channel is selected.\n");
+			return -EINVAL;
+		}
+		count = 2 + chip->channels * 2;
+	} else {
+		dev_err(&client->dev, "I2C wrong data register\n");
+		return -EINVAL;
+	}
+
+	commands[0] = 0;
+	commands[1] = (chip->command >> 8) & 0xff;
+	commands[2] = chip->command & 0xff;
+	commands[3] = reg;
+
+	ret = i2c_master_send(client, commands, 4);
+	if (ret < 0) {
+		dev_err(&client->dev, "I2C master send error\n");
+		return ret;
+	}
+
+	ret = i2c_master_recv(client, (u8 *)data, count);
+	if (ret < 0) {
+		dev_err(&client->dev, "I2C master receive error\n");
+		return ret;
+	}
+	ret >>= 2;
+
+	for (i = 0; i < ret; i++)
+		data[i] = swab16(data[i]);
+
+	return ret;
+}
+
+static ssize_t ad7291_show_mode(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+
+	if (chip->command & AD7291_AUTOCYCLE)
+		return sprintf(buf, "autocycle\n");
+	else
+		return sprintf(buf, "command\n");
+}
+
+static ssize_t ad7291_store_mode(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	u16 command;
+	int ret;
+
+	command = chip->command & (~AD7291_AUTOCYCLE);
+	if (strcmp(buf, "autocycle"))
+		command |= AD7291_AUTOCYCLE;
+
+	ret = ad7291_i2c_write(chip, AD7291_COMMAND, command);
+	if (ret)
+		return -EIO;
+
+	chip->command = command;
+
+	return ret;
+}
+
+static IIO_DEVICE_ATTR(mode, S_IRUGO | S_IWUSR,
+		ad7291_show_mode,
+		ad7291_store_mode,
+		0);
+
+static ssize_t ad7291_show_available_modes(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	return sprintf(buf, "command\nautocycle\n");
+}
+
+static IIO_DEVICE_ATTR(available_modes, S_IRUGO, ad7291_show_available_modes, NULL, 0);
+
+static ssize_t ad7291_store_reset(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	u16 command;
+	int ret;
+
+	command = chip->command | AD7291_RESET;
+
+	ret = ad7291_i2c_write(chip, AD7291_COMMAND, command);
+	if (ret)
+		return -EIO;
+
+	return ret;
+}
+
+static IIO_DEVICE_ATTR(reset, S_IWUSR,
+		NULL,
+		ad7291_store_reset,
+		0);
+
+static ssize_t ad7291_show_ext_ref(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+
+	return sprintf(buf, "%d\n", !!(chip->command & AD7291_EXT_REF));
+}
+
+static ssize_t ad7291_store_ext_ref(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	u16 command;
+	int ret;
+
+	command = chip->command & (~AD7291_EXT_REF);
+	if (strcmp(buf, "1"))
+		command |= AD7291_EXT_REF;
+
+	ret = ad7291_i2c_write(chip, AD7291_COMMAND, command);
+	if (ret)
+		return -EIO;
+
+	chip->command = command;
+
+	return ret;
+}
+
+static IIO_DEVICE_ATTR(ext_ref, S_IRUGO | S_IWUSR,
+		ad7291_show_ext_ref,
+		ad7291_store_ext_ref,
+		0);
+
+static ssize_t ad7291_show_noise_delay(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+
+	return sprintf(buf, "%d\n", !!(chip->command & AD7291_NOISE_DELAY));
+}
+
+static ssize_t ad7291_store_noise_delay(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	u16 command;
+	int ret;
+
+	command = chip->command & (~AD7291_NOISE_DELAY);
+	if (strcmp(buf, "1"))
+		command |= AD7291_NOISE_DELAY;
+
+	ret = ad7291_i2c_write(chip, AD7291_COMMAND, command);
+	if (ret)
+		return -EIO;
+
+	chip->command = command;
+
+	return ret;
+}
+
+static IIO_DEVICE_ATTR(noise_delay, S_IRUGO | S_IWUSR,
+		ad7291_show_noise_delay,
+		ad7291_store_noise_delay,
+		0);
+
+static ssize_t ad7291_show_t_sense(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	u16 data;
+	char sign = ' ';
+	int ret;
+
+	ret = ad7291_i2c_read_data(chip, AD7291_T_SENSE, &data);
+	if (ret)
+		return -EIO;
+
+	if (data & AD7291_T_VALUE_SIGN) {
+		/* convert supplement to positive value */
+		data = (AD7291_T_VALUE_SIGN << 1) - data;
+		sign = '-';
+	}
+
+	return sprintf(buf, "%c%d.%.2d\n", sign,
+		(data >> AD7291_T_VALUE_FLOAT_OFFSET),
+		(data & AD7291_T_VALUE_FLOAT_MASK) * 25);
+}
+
+static IIO_DEVICE_ATTR(t_sense, S_IRUGO, ad7291_show_t_sense, NULL, 0);
+
+static ssize_t ad7291_show_t_average(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	u16 data;
+	char sign = ' ';
+	int ret;
+
+	ret = ad7291_i2c_read_data(chip, AD7291_T_AVERAGE, &data);
+	if (ret)
+		return -EIO;
+
+	if (data & AD7291_T_VALUE_SIGN) {
+		/* convert supplement to positive value */
+		data = (AD7291_T_VALUE_SIGN << 1) - data;
+		sign = '-';
+	}
+
+	return sprintf(buf, "%c%d.%.2d\n", sign,
+		(data >> AD7291_T_VALUE_FLOAT_OFFSET),
+		(data & AD7291_T_VALUE_FLOAT_MASK) * 25);
+}
+
+static IIO_DEVICE_ATTR(t_average, S_IRUGO, ad7291_show_t_average, NULL, 0);
+
+static ssize_t ad7291_show_voltage(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	u16 data[AD7291_VOLTAGE_LIMIT_COUNT];
+	int i, size, ret;
+
+	ret = ad7291_i2c_read_data(chip, AD7291_VOLTAGE, data);
+	if (ret)
+		return -EIO;
+
+	for (i = 0; i < AD7291_VOLTAGE_LIMIT_COUNT; i++) {
+		if (chip->command & (AD7291_T_SENSE_MASK << i)) {
+			ret = sprintf(buf, "channel[%d]=%d\n", i,
+					data[i] & AD7291_VALUE_MASK);
+			if (ret < 0)
+				break;
+			buf += ret;
+			size += ret;
+		}
+	}
+
+	return size;
+}
+
+static IIO_DEVICE_ATTR(voltage, S_IRUGO, ad7291_show_voltage, NULL, 0);
+
+static ssize_t ad7291_show_channel_mask(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+
+	return sprintf(buf, "0x%x\n", (chip->command & AD7291_VOLTAGE_MASK) >>
+			AD7291_VOLTAGE_OFFSET);
+}
+
+static ssize_t ad7291_store_channel_mask(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	u16 command;
+	unsigned long data;
+	int i, ret;
+
+	ret = strict_strtoul(buf, 16, &data);
+	if (ret || data > 0xff)
+		return -EINVAL;
+
+	command = chip->command & (~AD7291_VOLTAGE_MASK);
+	command |= data << AD7291_VOLTAGE_OFFSET;
+
+	ret = ad7291_i2c_write(chip, AD7291_COMMAND, command);
+	if (ret)
+		return -EIO;
+
+	chip->command = command;
+
+	for (i = 0, chip->channels = 0; i < AD7291_VOLTAGE_LIMIT_COUNT; i++) {
+		if (chip->command & (AD7291_T_SENSE_MASK << i))
+			chip->channels++;
+	}
+
+	return ret;
+}
+
+static IIO_DEVICE_ATTR(channel_mask, S_IRUGO | S_IWUSR,
+		ad7291_show_channel_mask,
+		ad7291_store_channel_mask,
+		0);
+
+static ssize_t ad7291_show_name(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	return sprintf(buf, "%s\n", chip->name);
+}
+
+static IIO_DEVICE_ATTR(name, S_IRUGO, ad7291_show_name, NULL, 0);
+
+static struct attribute *ad7291_attributes[] = {
+	&iio_dev_attr_available_modes.dev_attr.attr,
+	&iio_dev_attr_mode.dev_attr.attr,
+	&iio_dev_attr_reset.dev_attr.attr,
+	&iio_dev_attr_ext_ref.dev_attr.attr,
+	&iio_dev_attr_noise_delay.dev_attr.attr,
+	&iio_dev_attr_t_sense.dev_attr.attr,
+	&iio_dev_attr_t_average.dev_attr.attr,
+	&iio_dev_attr_voltage.dev_attr.attr,
+	&iio_dev_attr_channel_mask.dev_attr.attr,
+	&iio_dev_attr_name.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ad7291_attribute_group = {
+	.attrs = ad7291_attributes,
+};
+
+/*
+ * temperature bound events
+ */
+
+#define IIO_EVENT_CODE_AD7291_T_SENSE_HIGH  IIO_BUFFER_EVENT_CODE(0)
+#define IIO_EVENT_CODE_AD7291_T_SENSE_LOW   IIO_BUFFER_EVENT_CODE(1)
+#define IIO_EVENT_CODE_AD7291_T_AVG_HIGH    IIO_BUFFER_EVENT_CODE(2)
+#define IIO_EVENT_CODE_AD7291_T_AVG_LOW     IIO_BUFFER_EVENT_CODE(3)
+#define IIO_EVENT_CODE_AD7291_VOLTAGE_BASE  IIO_BUFFER_EVENT_CODE(4)
+
+static void ad7291_interrupt_bh(struct work_struct *work_s)
+{
+	struct ad7291_chip_info *chip =
+		container_of(work_s, struct ad7291_chip_info, thresh_work);
+	u16 t_status, v_status;
+	u16 command;
+	int i;
+
+	if (ad7291_i2c_read(chip, AD7291_T_ALERT_STATUS, &t_status))
+		return;
+
+	if (ad7291_i2c_read(chip, AD7291_VOLTAGE_ALERT_STATUS, &v_status))
+		return;
+
+	if (!(t_status || v_status))
+		return;
+
+	command = chip->command | AD7291_ALART_CLEAR;
+	ad7291_i2c_write(chip, AD7291_COMMAND, command);
+
+	command = chip->command & ~AD7291_ALART_CLEAR;
+	ad7291_i2c_write(chip, AD7291_COMMAND, command);
+
+	enable_irq(chip->client->irq);
+
+	for (i = 0; i < 4; i++) {
+		if (t_status & (1 << i))
+			iio_push_event(chip->indio_dev, 0,
+				IIO_EVENT_CODE_AD7291_T_SENSE_HIGH + i,
+				chip->last_timestamp);
+	}
+
+	for (i = 0; i < AD7291_VOLTAGE_LIMIT_COUNT*2; i++) {
+		if (v_status & (1 << i))
+			iio_push_event(chip->indio_dev, 0,
+				IIO_EVENT_CODE_AD7291_VOLTAGE_BASE + i,
+				chip->last_timestamp);
+	}
+}
+
+static int ad7291_interrupt(struct iio_dev *dev_info,
+		int index,
+		s64 timestamp,
+		int no_test)
+{
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+
+	chip->last_timestamp = timestamp;
+	schedule_work(&chip->thresh_work);
+
+	return 0;
+}
+
+IIO_EVENT_SH(ad7291, &ad7291_interrupt);
+
+static inline ssize_t ad7291_show_t_bound(struct device *dev,
+		struct device_attribute *attr,
+		u8 bound_reg,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	u16 data;
+	char sign = ' ';
+	int ret;
+
+	ret = ad7291_i2c_read(chip, bound_reg, &data);
+	if (ret)
+		return -EIO;
+
+	data &= AD7291_VALUE_MASK;
+	if (data & AD7291_T_VALUE_SIGN) {
+		/* convert supplement to positive value */
+		data = (AD7291_T_VALUE_SIGN << 1) - data;
+		sign = '-';
+	}
+
+	return sprintf(buf, "%c%d.%.2d\n", sign,
+			data >> AD7291_T_VALUE_FLOAT_OFFSET,
+			(data & AD7291_T_VALUE_FLOAT_MASK) * 25);
+}
+
+static inline ssize_t ad7291_set_t_bound(struct device *dev,
+		struct device_attribute *attr,
+		u8 bound_reg,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	long tmp1, tmp2;
+	u16 data;
+	char *pos;
+	int ret;
+
+	pos = strchr(buf, '.');
+
+	ret = strict_strtol(buf, 10, &tmp1);
+
+	if (ret || tmp1 > 127 || tmp1 < -128)
+		return -EINVAL;
+
+	if (pos) {
+		len = strlen(pos);
+		if (len > AD7291_T_VALUE_FLOAT_OFFSET)
+			len = AD7291_T_VALUE_FLOAT_OFFSET;
+		pos[len] = 0;
+		ret = strict_strtol(pos, 10, &tmp2);
+
+		if (!ret)
+			tmp2 = (tmp2 / 25) * 25;
+	}
+
+	if (tmp1 < 0)
+		data = (u16)(-tmp1);
+	else
+		data = (u16)tmp1;
+	data = (data << AD7291_T_VALUE_FLOAT_OFFSET) |
+		(tmp2 & AD7291_T_VALUE_FLOAT_MASK);
+	if (tmp1 < 0)
+		/* convert positive value to supplyment */
+		data = (AD7291_T_VALUE_SIGN << 1) - data;
+
+	ret = ad7291_i2c_write(chip, bound_reg, data);
+	if (ret)
+		return -EIO;
+
+	return ret;
+}
+
+static ssize_t ad7291_show_t_sense_high(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	return ad7291_show_t_bound(dev, attr,
+			AD7291_T_SENSE_HIGH, buf);
+}
+
+static inline ssize_t ad7291_set_t_sense_high(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	return ad7291_set_t_bound(dev, attr,
+			AD7291_T_SENSE_HIGH, buf, len);
+}
+
+static ssize_t ad7291_show_t_sense_low(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	return ad7291_show_t_bound(dev, attr,
+			AD7291_T_SENSE_LOW, buf);
+}
+
+static inline ssize_t ad7291_set_t_sense_low(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	return ad7291_set_t_bound(dev, attr,
+			AD7291_T_SENSE_LOW, buf, len);
+}
+
+static ssize_t ad7291_show_t_sense_hyst(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	return ad7291_show_t_bound(dev, attr,
+			AD7291_T_SENSE_HYST, buf);
+}
+
+static inline ssize_t ad7291_set_t_sense_hyst(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	return ad7291_set_t_bound(dev, attr,
+			AD7291_T_SENSE_HYST, buf, len);
+}
+
+static inline ssize_t ad7291_show_v_bound(struct device *dev,
+		struct device_attribute *attr,
+		u8 bound_reg,
+		char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	u16 data;
+	int ret;
+
+	if (bound_reg < AD7291_VOLTAGE_LIMIT_BASE ||
+		bound_reg >= AD7291_VOLTAGE_LIMIT_BASE +
+		AD7291_VOLTAGE_LIMIT_COUNT)
+		return -EINVAL;
+
+	ret = ad7291_i2c_read(chip, bound_reg, &data);
+	if (ret)
+		return -EIO;
+
+	data &= AD7291_VALUE_MASK;
+
+	return sprintf(buf, "%d\n", data);
+}
+
+static inline ssize_t ad7291_set_v_bound(struct device *dev,
+		struct device_attribute *attr,
+		u8 bound_reg,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad7291_chip_info *chip = dev_info->dev_data;
+	unsigned long value;
+	u16 data;
+	int ret;
+
+	if (bound_reg < AD7291_VOLTAGE_LIMIT_BASE ||
+		bound_reg >= AD7291_VOLTAGE_LIMIT_BASE +
+		AD7291_VOLTAGE_LIMIT_COUNT)
+		return -EINVAL;
+
+	ret = strict_strtoul(buf, 10, &value);
+
+	if (ret || value >= 4096)
+		return -EINVAL;
+
+	data = (u16)value;
+	ret = ad7291_i2c_write(chip, bound_reg, data);
+	if (ret)
+		return -EIO;
+
+	return ret;
+}
+
+static int ad7291_get_voltage_limit_regs(const char *channel)
+{
+	int index;
+
+	if (strlen(channel) < 3 && channel[0] != 'v')
+		return -EINVAL;
+
+	index = channel[1] - '0';
+	if (index >= AD7291_VOLTAGE_LIMIT_COUNT)
+		return -EINVAL;
+
+	return index;
+}
+
+static ssize_t ad7291_show_voltage_high(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	int regs;
+
+	regs = ad7291_get_voltage_limit_regs(attr->attr.name);
+
+	if (regs < 0)
+		return regs;
+
+	return ad7291_show_t_bound(dev, attr, regs, buf);
+}
+
+static inline ssize_t ad7291_set_voltage_high(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	int regs;
+
+	regs = ad7291_get_voltage_limit_regs(attr->attr.name);
+
+	if (regs < 0)
+		return regs;
+
+	return ad7291_set_t_bound(dev, attr, regs, buf, len);
+}
+
+static ssize_t ad7291_show_voltage_low(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	int regs;
+
+	regs = ad7291_get_voltage_limit_regs(attr->attr.name);
+
+	if (regs < 0)
+		return regs;
+
+	return ad7291_show_t_bound(dev, attr, regs+1, buf);
+}
+
+static inline ssize_t ad7291_set_voltage_low(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	int regs;
+
+	regs = ad7291_get_voltage_limit_regs(attr->attr.name);
+
+	if (regs < 0)
+		return regs;
+
+	return ad7291_set_t_bound(dev, attr, regs+1, buf, len);
+}
+
+static ssize_t ad7291_show_voltage_hyst(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	int regs;
+
+	regs = ad7291_get_voltage_limit_regs(attr->attr.name);
+
+	if (regs < 0)
+		return regs;
+
+	return ad7291_show_t_bound(dev, attr, regs+2, buf);
+}
+
+static inline ssize_t ad7291_set_voltage_hyst(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	int regs;
+
+	regs = ad7291_get_voltage_limit_regs(attr->attr.name);
+
+	if (regs < 0)
+		return regs;
+
+	return ad7291_set_t_bound(dev, attr, regs+2, buf, len);
+}
+
+IIO_EVENT_ATTR_SH(t_sense_high, iio_event_ad7291,
+		ad7291_show_t_sense_high, ad7291_set_t_sense_high, 0);
+IIO_EVENT_ATTR_SH(t_sense_low, iio_event_ad7291,
+		ad7291_show_t_sense_low, ad7291_set_t_sense_low, 0);
+IIO_EVENT_ATTR_SH(t_sense_hyst, iio_event_ad7291,
+		ad7291_show_t_sense_hyst, ad7291_set_t_sense_hyst, 0);
+
+IIO_EVENT_ATTR_SH(v0_high, iio_event_ad7291,
+		ad7291_show_voltage_high, ad7291_set_voltage_high, 0);
+IIO_EVENT_ATTR_SH(v0_low, iio_event_ad7291,
+		ad7291_show_voltage_low, ad7291_set_voltage_low, 0);
+IIO_EVENT_ATTR_SH(v0_hyst, iio_event_ad7291,
+		ad7291_show_voltage_hyst, ad7291_set_voltage_hyst, 0);
+IIO_EVENT_ATTR_SH(v1_high, iio_event_ad7291,
+		ad7291_show_voltage_high, ad7291_set_voltage_high, 0);
+IIO_EVENT_ATTR_SH(v1_low, iio_event_ad7291,
+		ad7291_show_voltage_low, ad7291_set_voltage_low, 0);
+IIO_EVENT_ATTR_SH(v1_hyst, iio_event_ad7291,
+		ad7291_show_voltage_hyst, ad7291_set_voltage_hyst, 0);
+IIO_EVENT_ATTR_SH(v2_high, iio_event_ad7291,
+		ad7291_show_voltage_high, ad7291_set_voltage_high, 0);
+IIO_EVENT_ATTR_SH(v2_low, iio_event_ad7291,
+		ad7291_show_voltage_low, ad7291_set_voltage_low, 0);
+IIO_EVENT_ATTR_SH(v2_hyst, iio_event_ad7291,
+		ad7291_show_voltage_hyst, ad7291_set_voltage_hyst, 0);
+IIO_EVENT_ATTR_SH(v3_high, iio_event_ad7291,
+		ad7291_show_voltage_high, ad7291_set_voltage_high, 0);
+IIO_EVENT_ATTR_SH(v3_low, iio_event_ad7291,
+		ad7291_show_voltage_low, ad7291_set_voltage_low, 0);
+IIO_EVENT_ATTR_SH(v3_hyst, iio_event_ad7291,
+		ad7291_show_voltage_hyst, ad7291_set_voltage_hyst, 0);
+IIO_EVENT_ATTR_SH(v4_high, iio_event_ad7291,
+		ad7291_show_voltage_high, ad7291_set_voltage_high, 0);
+IIO_EVENT_ATTR_SH(v4_low, iio_event_ad7291,
+		ad7291_show_voltage_low, ad7291_set_voltage_low, 0);
+IIO_EVENT_ATTR_SH(v4_hyst, iio_event_ad7291,
+		ad7291_show_voltage_hyst, ad7291_set_voltage_hyst, 0);
+IIO_EVENT_ATTR_SH(v5_high, iio_event_ad7291,
+		ad7291_show_voltage_high, ad7291_set_voltage_high, 0);
+IIO_EVENT_ATTR_SH(v5_low, iio_event_ad7291,
+		ad7291_show_voltage_low, ad7291_set_voltage_low, 0);
+IIO_EVENT_ATTR_SH(v5_hyst, iio_event_ad7291,
+		ad7291_show_voltage_hyst, ad7291_set_voltage_hyst, 0);
+IIO_EVENT_ATTR_SH(v6_high, iio_event_ad7291,
+		ad7291_show_voltage_high, ad7291_set_voltage_high, 0);
+IIO_EVENT_ATTR_SH(v6_low, iio_event_ad7291,
+		ad7291_show_voltage_low, ad7291_set_voltage_low, 0);
+IIO_EVENT_ATTR_SH(v6_hyst, iio_event_ad7291,
+		ad7291_show_voltage_hyst, ad7291_set_voltage_hyst, 0);
+IIO_EVENT_ATTR_SH(v7_high, iio_event_ad7291,
+		ad7291_show_voltage_high, ad7291_set_voltage_high, 0);
+IIO_EVENT_ATTR_SH(v7_low, iio_event_ad7291,
+		ad7291_show_voltage_low, ad7291_set_voltage_low, 0);
+IIO_EVENT_ATTR_SH(v7_hyst, iio_event_ad7291,
+		ad7291_show_voltage_hyst, ad7291_set_voltage_hyst, 0);
+
+static struct attribute *ad7291_event_attributes[] = {
+	&iio_event_attr_t_sense_high.dev_attr.attr,
+	&iio_event_attr_t_sense_low.dev_attr.attr,
+	&iio_event_attr_t_sense_hyst.dev_attr.attr,
+	&iio_event_attr_v0_high.dev_attr.attr,
+	&iio_event_attr_v0_low.dev_attr.attr,
+	&iio_event_attr_v0_hyst.dev_attr.attr,
+	&iio_event_attr_v1_high.dev_attr.attr,
+	&iio_event_attr_v1_low.dev_attr.attr,
+	&iio_event_attr_v1_hyst.dev_attr.attr,
+	&iio_event_attr_v2_high.dev_attr.attr,
+	&iio_event_attr_v2_low.dev_attr.attr,
+	&iio_event_attr_v2_hyst.dev_attr.attr,
+	&iio_event_attr_v3_high.dev_attr.attr,
+	&iio_event_attr_v3_low.dev_attr.attr,
+	&iio_event_attr_v3_hyst.dev_attr.attr,
+	&iio_event_attr_v4_high.dev_attr.attr,
+	&iio_event_attr_v4_low.dev_attr.attr,
+	&iio_event_attr_v4_hyst.dev_attr.attr,
+	&iio_event_attr_v5_high.dev_attr.attr,
+	&iio_event_attr_v5_low.dev_attr.attr,
+	&iio_event_attr_v5_hyst.dev_attr.attr,
+	&iio_event_attr_v6_high.dev_attr.attr,
+	&iio_event_attr_v6_low.dev_attr.attr,
+	&iio_event_attr_v6_hyst.dev_attr.attr,
+	&iio_event_attr_v7_high.dev_attr.attr,
+	&iio_event_attr_v7_low.dev_attr.attr,
+	&iio_event_attr_v7_hyst.dev_attr.attr,
+	NULL,
+};
+
+static struct attribute_group ad7291_event_attribute_group = {
+	.attrs = ad7291_event_attributes,
+};
+
+/*
+ * device probe and remove
+ */
+
+static int __devinit ad7291_probe(struct i2c_client *client,
+		const struct i2c_device_id *id)
+{
+	struct ad7291_chip_info *chip;
+	int ret = 0;
+
+	chip = kzalloc(sizeof(struct ad7291_chip_info), GFP_KERNEL);
+
+	if (chip == NULL)
+		return -ENOMEM;
+
+	/* this is only used for device removal purposes */
+	i2c_set_clientdata(client, chip);
+
+	chip->client = client;
+	chip->name = id->name;
+	chip->command = AD7291_NOISE_DELAY | AD7291_T_SENSE_MASK;
+
+	chip->indio_dev = iio_allocate_device();
+	if (chip->indio_dev == NULL) {
+		ret = -ENOMEM;
+		goto error_free_chip;
+	}
+
+	chip->indio_dev->dev.parent = &client->dev;
+	chip->indio_dev->attrs = &ad7291_attribute_group;
+	chip->indio_dev->event_attrs = &ad7291_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;
+
+	if (client->irq > 0) {
+		ret = iio_register_interrupt_line(client->irq,
+				chip->indio_dev,
+				0,
+				IRQF_TRIGGER_LOW,
+				chip->name);
+		if (ret)
+			goto error_unreg_dev;
+
+		/*
+		 * The event handler list element refer to iio_event_ad7291.
+		 * All event attributes bind to the same event handler.
+		 * So, only register event handler once.
+		 */
+		iio_add_event_to_list(&iio_event_ad7291,
+				&chip->indio_dev->interrupts[0]->ev_list);
+
+		INIT_WORK(&chip->thresh_work, ad7291_interrupt_bh);
+
+		/* set irq polarity low level */
+		chip->command |= AD7291_ALART_POLARITY;
+	}
+
+	ret = ad7291_i2c_write(chip, AD7291_COMMAND, chip->command);
+	if (ret) {
+		ret = -EIO;
+		goto error_unreg_irq;
+	}
+
+	dev_info(&client->dev, "%s temperature sensor registered.\n",
+			 id->name);
+
+	return 0;
+
+error_unreg_irq:
+	iio_unregister_interrupt_line(chip->indio_dev, 0);
+error_unreg_dev:
+	iio_device_unregister(chip->indio_dev);
+error_free_dev:
+	iio_free_device(chip->indio_dev);
+error_free_chip:
+	kfree(chip);
+
+	return ret;
+}
+
+static int __devexit ad7291_remove(struct i2c_client *client)
+{
+	struct ad7291_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);
+	iio_free_device(chip->indio_dev);
+	kfree(chip);
+
+	return 0;
+}
+
+static const struct i2c_device_id ad7291_id[] = {
+	{ "ad7291", 0 },
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, ad7291_id);
+
+static struct i2c_driver ad7291_driver = {
+	.driver = {
+		.name = "ad7291",
+	},
+	.probe = ad7291_probe,
+	.remove = __devexit_p(ad7291_remove),
+	.id_table = ad7291_id,
+};
+
+static __init int ad7291_init(void)
+{
+	return i2c_add_driver(&ad7291_driver);
+}
+
+static __exit void ad7291_exit(void)
+{
+	i2c_del_driver(&ad7291_driver);
+}
+
+MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD7291 digital"
+			" temperature sensor driver");
+MODULE_LICENSE("GPL v2");
+
+module_init(ad7291_init);
+module_exit(ad7291_exit);