hwmon: Driver for Texas Instruments INA209

Add support for the TI / Burr-Brown INA209 voltage / current / power
monitor.

Cc: Paul Hays <haysp@magma.net>
Cc: Ira W. Snyder <iws@ovro.caltech.edu>
Tested-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 636 insertions, 0 deletions

diff --git a/drivers/hwmon/ina209.c b/drivers/hwmon/ina209.c
new file mode 100644
index 000000000000..c6fdd5bd395e
--- /dev/null
+++ b/drivers/hwmon/ina209.c
@@ -0,0 +1,636 @@
+/*
+ * Driver for the Texas Instruments / Burr Brown INA209
+ * Bidirectional Current/Power Monitor
+ *
+ * Copyright (C) 2012 Guenter Roeck <linux@roeck-us.net>
+ *
+ * Derived from Ira W. Snyder's original driver submission
+ *	Copyright (C) 2008 Paul Hays <Paul.Hays@cattail.ca>
+ *	Copyright (C) 2008-2009 Ira W. Snyder <iws@ovro.caltech.edu>
+ *
+ * Aligned with ina2xx driver
+ *	Copyright (C) 2012 Lothar Felten <l-felten@ti.com>
+ *	Thanks to Jan Volkering
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * Datasheet:
+ * http://www.ti.com/lit/gpn/ina209
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/bug.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+
+#include <linux/platform_data/ina2xx.h>
+
+/* register definitions */
+#define INA209_CONFIGURATION		0x00
+#define INA209_STATUS			0x01
+#define INA209_STATUS_MASK		0x02
+#define INA209_SHUNT_VOLTAGE		0x03
+#define INA209_BUS_VOLTAGE		0x04
+#define INA209_POWER			0x05
+#define INA209_CURRENT			0x06
+#define INA209_SHUNT_VOLTAGE_POS_PEAK	0x07
+#define INA209_SHUNT_VOLTAGE_NEG_PEAK	0x08
+#define INA209_BUS_VOLTAGE_MAX_PEAK	0x09
+#define INA209_BUS_VOLTAGE_MIN_PEAK	0x0a
+#define INA209_POWER_PEAK		0x0b
+#define INA209_SHUNT_VOLTAGE_POS_WARN	0x0c
+#define INA209_SHUNT_VOLTAGE_NEG_WARN	0x0d
+#define INA209_POWER_WARN		0x0e
+#define INA209_BUS_VOLTAGE_OVER_WARN	0x0f
+#define INA209_BUS_VOLTAGE_UNDER_WARN	0x10
+#define INA209_POWER_OVER_LIMIT		0x11
+#define INA209_BUS_VOLTAGE_OVER_LIMIT	0x12
+#define INA209_BUS_VOLTAGE_UNDER_LIMIT	0x13
+#define INA209_CRITICAL_DAC_POS		0x14
+#define INA209_CRITICAL_DAC_NEG		0x15
+#define INA209_CALIBRATION		0x16
+
+#define INA209_REGISTERS		0x17
+
+#define INA209_CONFIG_DEFAULT		0x3c47	/* PGA=8, full range */
+#define INA209_SHUNT_DEFAULT		10000	/* uOhm */
+
+struct ina209_data {
+	struct device *hwmon_dev;
+
+	struct mutex update_lock;
+	bool valid;
+	unsigned long last_updated;	/* in jiffies */
+
+	u16 regs[INA209_REGISTERS];	/* All chip registers */
+
+	u16 config_orig;		/* Original configuration */
+	u16 calibration_orig;		/* Original calibration */
+	u16 update_interval;
+};
+
+static struct ina209_data *ina209_update_device(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ina209_data *data = i2c_get_clientdata(client);
+	struct ina209_data *ret = data;
+	s32 val;
+	int i;
+
+	mutex_lock(&data->update_lock);
+
+	if (!data->valid ||
+	    time_after(jiffies, data->last_updated + data->update_interval)) {
+		for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
+			val = i2c_smbus_read_word_swapped(client, i);
+			if (val < 0) {
+				ret = ERR_PTR(val);
+				goto abort;
+			}
+			data->regs[i] = val;
+		}
+		data->last_updated = jiffies;
+		data->valid = true;
+	}
+abort:
+	mutex_unlock(&data->update_lock);
+	return ret;
+}
+
+/*
+ * Read a value from a device register and convert it to the
+ * appropriate sysfs units
+ */
+static long ina209_from_reg(const u8 reg, const u16 val)
+{
+	switch (reg) {
+	case INA209_SHUNT_VOLTAGE:
+	case INA209_SHUNT_VOLTAGE_POS_PEAK:
+	case INA209_SHUNT_VOLTAGE_NEG_PEAK:
+	case INA209_SHUNT_VOLTAGE_POS_WARN:
+	case INA209_SHUNT_VOLTAGE_NEG_WARN:
+		/* LSB=10 uV. Convert to mV. */
+		return DIV_ROUND_CLOSEST(val, 100);
+
+	case INA209_BUS_VOLTAGE:
+	case INA209_BUS_VOLTAGE_MAX_PEAK:
+	case INA209_BUS_VOLTAGE_MIN_PEAK:
+	case INA209_BUS_VOLTAGE_OVER_WARN:
+	case INA209_BUS_VOLTAGE_UNDER_WARN:
+	case INA209_BUS_VOLTAGE_OVER_LIMIT:
+	case INA209_BUS_VOLTAGE_UNDER_LIMIT:
+		/* LSB=4 mV, last 3 bits unused */
+		return (val >> 3) * 4;
+
+	case INA209_CRITICAL_DAC_POS:
+		/* LSB=1 mV, in the upper 8 bits */
+		return val >> 8;
+
+	case INA209_CRITICAL_DAC_NEG:
+		/* LSB=1 mV, in the upper 8 bits */
+		return -1 * (val >> 8);
+
+	case INA209_POWER:
+	case INA209_POWER_PEAK:
+	case INA209_POWER_WARN:
+	case INA209_POWER_OVER_LIMIT:
+		/* LSB=20 mW. Convert to uW */
+		return val * 20 * 1000L;
+
+	case INA209_CURRENT:
+		/* LSB=1 mA (selected). Is in mA */
+		return val;
+	}
+
+	/* programmer goofed */
+	WARN_ON_ONCE(1);
+	return 0;
+}
+
+/*
+ * Take a value and convert it to register format, clamping the value
+ * to the appropriate range.
+ */
+static int ina209_to_reg(u8 reg, u16 old, long val)
+{
+	switch (reg) {
+	case INA209_SHUNT_VOLTAGE_POS_WARN:
+	case INA209_SHUNT_VOLTAGE_NEG_WARN:
+		/* Limit to +- 320 mV, 10 uV LSB */
+		return clamp_val(val, -320, 320) * 100;
+
+	case INA209_BUS_VOLTAGE_OVER_WARN:
+	case INA209_BUS_VOLTAGE_UNDER_WARN:
+	case INA209_BUS_VOLTAGE_OVER_LIMIT:
+	case INA209_BUS_VOLTAGE_UNDER_LIMIT:
+		/*
+		 * Limit to 0-32000 mV, 4 mV LSB
+		 *
+		 * The last three bits aren't part of the value, but we'll
+		 * preserve them in their original state.
+		 */
+		return (DIV_ROUND_CLOSEST(clamp_val(val, 0, 32000), 4) << 3)
+		  | (old & 0x7);
+
+	case INA209_CRITICAL_DAC_NEG:
+		/*
+		 * Limit to -255-0 mV, 1 mV LSB
+		 * Convert the value to a positive value for the register
+		 *
+		 * The value lives in the top 8 bits only, be careful
+		 * and keep original value of other bits.
+		 */
+		return (clamp_val(-val, 0, 255) << 8) | (old & 0xff);
+
+	case INA209_CRITICAL_DAC_POS:
+		/*
+		 * Limit to 0-255 mV, 1 mV LSB
+		 *
+		 * The value lives in the top 8 bits only, be careful
+		 * and keep original value of other bits.
+		 */
+		return (clamp_val(val, 0, 255) << 8) | (old & 0xff);
+
+	case INA209_POWER_WARN:
+	case INA209_POWER_OVER_LIMIT:
+		/* 20 mW LSB */
+		return DIV_ROUND_CLOSEST(val, 20 * 1000);
+	}
+
+	/* Other registers are read-only, return access error */
+	return -EACCES;
+}
+
+static int ina209_interval_from_reg(u16 reg)
+{
+	return 68 >> (15 - ((reg >> 3) & 0x0f));
+}
+
+static u16 ina209_reg_from_interval(u16 config, long interval)
+{
+	int i, adc;
+
+	if (interval <= 0) {
+		adc = 8;
+	} else {
+		adc = 15;
+		for (i = 34 + 34 / 2; i; i >>= 1) {
+			if (i < interval)
+				break;
+			adc--;
+		}
+	}
+	return (config & 0xf807) | (adc << 3) | (adc << 7);
+}
+
+static ssize_t ina209_set_interval(struct device *dev,
+				   struct device_attribute *da,
+				   const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ina209_data *data = ina209_update_device(dev);
+	long val;
+	u16 regval;
+	int ret;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	ret = kstrtol(buf, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&data->update_lock);
+	regval = ina209_reg_from_interval(data->regs[INA209_CONFIGURATION],
+					  val);
+	i2c_smbus_write_word_swapped(client, INA209_CONFIGURATION, regval);
+	data->regs[INA209_CONFIGURATION] = regval;
+	data->update_interval = ina209_interval_from_reg(regval);
+	mutex_unlock(&data->update_lock);
+	return count;
+}
+
+static ssize_t ina209_show_interval(struct device *dev,
+				    struct device_attribute *da, char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ina209_data *data = i2c_get_clientdata(client);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", data->update_interval);
+}
+
+/*
+ * History is reset by writing 1 into bit 0 of the respective peak register.
+ * Since more than one peak register may be affected by the scope of a
+ * reset_history attribute write, use a bit mask in attr->index to identify
+ * which registers are affected.
+ */
+static u16 ina209_reset_history_regs[] = {
+	INA209_SHUNT_VOLTAGE_POS_PEAK,
+	INA209_SHUNT_VOLTAGE_NEG_PEAK,
+	INA209_BUS_VOLTAGE_MAX_PEAK,
+	INA209_BUS_VOLTAGE_MIN_PEAK,
+	INA209_POWER_PEAK
+};
+
+static ssize_t ina209_reset_history(struct device *dev,
+				    struct device_attribute *da,
+				    const char *buf,
+				    size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ina209_data *data = i2c_get_clientdata(client);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	u32 mask = attr->index;
+	long val;
+	int i, ret;
+
+	ret = kstrtol(buf, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&data->update_lock);
+	for (i = 0; i < ARRAY_SIZE(ina209_reset_history_regs); i++) {
+		if (mask & (1 << i))
+			i2c_smbus_write_word_swapped(client,
+					ina209_reset_history_regs[i], 1);
+	}
+	data->valid = false;
+	mutex_unlock(&data->update_lock);
+	return count;
+}
+
+static ssize_t ina209_set_value(struct device *dev,
+				struct device_attribute *da,
+				const char *buf,
+				size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ina209_data *data = ina209_update_device(dev);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	int reg = attr->index;
+	long val;
+	int ret;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	ret = kstrtol(buf, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&data->update_lock);
+	ret = ina209_to_reg(reg, data->regs[reg], val);
+	if (ret < 0) {
+		count = ret;
+		goto abort;
+	}
+	i2c_smbus_write_word_swapped(client, reg, ret);
+	data->regs[reg] = ret;
+abort:
+	mutex_unlock(&data->update_lock);
+	return count;
+}
+
+static ssize_t ina209_show_value(struct device *dev,
+				 struct device_attribute *da,
+				 char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct ina209_data *data = ina209_update_device(dev);
+	long val;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	val = ina209_from_reg(attr->index, data->regs[attr->index]);
+	return snprintf(buf, PAGE_SIZE, "%ld\n", val);
+}
+
+static ssize_t ina209_show_alarm(struct device *dev,
+				 struct device_attribute *da,
+				 char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct ina209_data *data = ina209_update_device(dev);
+	const unsigned int mask = attr->index;
+	u16 status;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	status = data->regs[INA209_STATUS];
+
+	/*
+	 * All alarms are in the INA209_STATUS register. To avoid a long
+	 * switch statement, the mask is passed in attr->index
+	 */
+	return snprintf(buf, PAGE_SIZE, "%u\n", !!(status & mask));
+}
+
+/* Shunt voltage, history, limits, alarms */
+static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ina209_show_value, NULL,
+			  INA209_SHUNT_VOLTAGE);
+static SENSOR_DEVICE_ATTR(in0_input_highest, S_IRUGO, ina209_show_value, NULL,
+			  INA209_SHUNT_VOLTAGE_POS_PEAK);
+static SENSOR_DEVICE_ATTR(in0_input_lowest, S_IRUGO, ina209_show_value, NULL,
+			  INA209_SHUNT_VOLTAGE_NEG_PEAK);
+static SENSOR_DEVICE_ATTR(in0_reset_history, S_IWUSR, NULL,
+			  ina209_reset_history, (1 << 0) | (1 << 1));
+static SENSOR_DEVICE_ATTR(in0_max, S_IRUGO | S_IWUSR, ina209_show_value,
+			  ina209_set_value, INA209_SHUNT_VOLTAGE_POS_WARN);
+static SENSOR_DEVICE_ATTR(in0_min, S_IRUGO | S_IWUSR, ina209_show_value,
+			  ina209_set_value, INA209_SHUNT_VOLTAGE_NEG_WARN);
+static SENSOR_DEVICE_ATTR(in0_crit_max, S_IRUGO | S_IWUSR, ina209_show_value,
+			  ina209_set_value, INA209_CRITICAL_DAC_POS);
+static SENSOR_DEVICE_ATTR(in0_crit_min, S_IRUGO | S_IWUSR, ina209_show_value,
+			  ina209_set_value, INA209_CRITICAL_DAC_NEG);
+
+static SENSOR_DEVICE_ATTR(in0_min_alarm,  S_IRUGO, ina209_show_alarm, NULL,
+			  1 << 11);
+static SENSOR_DEVICE_ATTR(in0_max_alarm, S_IRUGO, ina209_show_alarm, NULL,
+			  1 << 12);
+static SENSOR_DEVICE_ATTR(in0_crit_min_alarm, S_IRUGO, ina209_show_alarm, NULL,
+			  1 << 6);
+static SENSOR_DEVICE_ATTR(in0_crit_max_alarm, S_IRUGO, ina209_show_alarm, NULL,
+			  1 << 7);
+
+/* Bus voltage, history, limits, alarms */
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ina209_show_value, NULL,
+			  INA209_BUS_VOLTAGE);
+static SENSOR_DEVICE_ATTR(in1_input_highest, S_IRUGO, ina209_show_value, NULL,
+			  INA209_BUS_VOLTAGE_MAX_PEAK);
+static SENSOR_DEVICE_ATTR(in1_input_lowest, S_IRUGO, ina209_show_value, NULL,
+			  INA209_BUS_VOLTAGE_MIN_PEAK);
+static SENSOR_DEVICE_ATTR(in1_reset_history, S_IWUSR, NULL,
+			  ina209_reset_history, (1 << 2) | (1 << 3));
+static SENSOR_DEVICE_ATTR(in1_max, S_IRUGO | S_IWUSR, ina209_show_value,
+			  ina209_set_value, INA209_BUS_VOLTAGE_OVER_WARN);
+static SENSOR_DEVICE_ATTR(in1_min, S_IRUGO | S_IWUSR, ina209_show_value,
+			  ina209_set_value, INA209_BUS_VOLTAGE_UNDER_WARN);
+static SENSOR_DEVICE_ATTR(in1_crit_max, S_IRUGO | S_IWUSR, ina209_show_value,
+			  ina209_set_value, INA209_BUS_VOLTAGE_OVER_LIMIT);
+static SENSOR_DEVICE_ATTR(in1_crit_min, S_IRUGO | S_IWUSR, ina209_show_value,
+			  ina209_set_value, INA209_BUS_VOLTAGE_UNDER_LIMIT);
+
+static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ina209_show_alarm, NULL,
+			  1 << 14);
+static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ina209_show_alarm, NULL,
+			  1 << 15);
+static SENSOR_DEVICE_ATTR(in1_crit_min_alarm, S_IRUGO, ina209_show_alarm, NULL,
+			  1 << 9);
+static SENSOR_DEVICE_ATTR(in1_crit_max_alarm, S_IRUGO, ina209_show_alarm, NULL,
+			  1 << 10);
+
+/* Power */
+static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ina209_show_value, NULL,
+			  INA209_POWER);
+static SENSOR_DEVICE_ATTR(power1_input_highest, S_IRUGO, ina209_show_value,
+			  NULL, INA209_POWER_PEAK);
+static SENSOR_DEVICE_ATTR(power1_reset_history, S_IWUSR, NULL,
+			  ina209_reset_history, 1 << 4);
+static SENSOR_DEVICE_ATTR(power1_max, S_IRUGO | S_IWUSR, ina209_show_value,
+			  ina209_set_value, INA209_POWER_WARN);
+static SENSOR_DEVICE_ATTR(power1_crit, S_IRUGO | S_IWUSR, ina209_show_value,
+			  ina209_set_value, INA209_POWER_OVER_LIMIT);
+
+static SENSOR_DEVICE_ATTR(power1_max_alarm, S_IRUGO, ina209_show_alarm, NULL,
+			  1 << 13);
+static SENSOR_DEVICE_ATTR(power1_crit_alarm, S_IRUGO, ina209_show_alarm, NULL,
+			  1 << 8);
+
+/* Current */
+static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ina209_show_value, NULL,
+			  INA209_CURRENT);
+
+static SENSOR_DEVICE_ATTR(update_interval, S_IRUGO | S_IWUSR,
+			  ina209_show_interval, ina209_set_interval, 0);
+
+/*
+ * Finally, construct an array of pointers to members of the above objects,
+ * as required for sysfs_create_group()
+ */
+static struct attribute *ina209_attributes[] = {
+	&sensor_dev_attr_in0_input.dev_attr.attr,
+	&sensor_dev_attr_in0_input_highest.dev_attr.attr,
+	&sensor_dev_attr_in0_input_lowest.dev_attr.attr,
+	&sensor_dev_attr_in0_reset_history.dev_attr.attr,
+	&sensor_dev_attr_in0_max.dev_attr.attr,
+	&sensor_dev_attr_in0_min.dev_attr.attr,
+	&sensor_dev_attr_in0_crit_max.dev_attr.attr,
+	&sensor_dev_attr_in0_crit_min.dev_attr.attr,
+	&sensor_dev_attr_in0_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_in0_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_in0_crit_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_in0_crit_min_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_in1_input.dev_attr.attr,
+	&sensor_dev_attr_in1_input_highest.dev_attr.attr,
+	&sensor_dev_attr_in1_input_lowest.dev_attr.attr,
+	&sensor_dev_attr_in1_reset_history.dev_attr.attr,
+	&sensor_dev_attr_in1_max.dev_attr.attr,
+	&sensor_dev_attr_in1_min.dev_attr.attr,
+	&sensor_dev_attr_in1_crit_max.dev_attr.attr,
+	&sensor_dev_attr_in1_crit_min.dev_attr.attr,
+	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_in1_crit_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_in1_crit_min_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_power1_input.dev_attr.attr,
+	&sensor_dev_attr_power1_input_highest.dev_attr.attr,
+	&sensor_dev_attr_power1_reset_history.dev_attr.attr,
+	&sensor_dev_attr_power1_max.dev_attr.attr,
+	&sensor_dev_attr_power1_crit.dev_attr.attr,
+	&sensor_dev_attr_power1_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_power1_crit_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_curr1_input.dev_attr.attr,
+
+	&sensor_dev_attr_update_interval.dev_attr.attr,
+
+	NULL,
+};
+
+static const struct attribute_group ina209_group = {
+	.attrs = ina209_attributes,
+};
+
+static void ina209_restore_conf(struct i2c_client *client,
+				struct ina209_data *data)
+{
+	/* Restore initial configuration */
+	i2c_smbus_write_word_swapped(client, INA209_CONFIGURATION,
+				     data->config_orig);
+	i2c_smbus_write_word_swapped(client, INA209_CALIBRATION,
+				     data->calibration_orig);
+}
+
+static int ina209_init_client(struct i2c_client *client,
+			      struct ina209_data *data)
+{
+	struct ina2xx_platform_data *pdata = dev_get_platdata(&client->dev);
+	u32 shunt;
+	int reg;
+
+	reg = i2c_smbus_read_word_swapped(client, INA209_CALIBRATION);
+	if (reg < 0)
+		return reg;
+	data->calibration_orig = reg;
+
+	reg = i2c_smbus_read_word_swapped(client, INA209_CONFIGURATION);
+	if (reg < 0)
+		return reg;
+	data->config_orig = reg;
+
+	if (pdata) {
+		if (pdata->shunt_uohms <= 0)
+			return -EINVAL;
+		shunt = pdata->shunt_uohms;
+	} else if (!of_property_read_u32(client->dev.of_node, "shunt-resistor",
+					 &shunt)) {
+		if (shunt == 0)
+			return -EINVAL;
+	} else {
+		shunt = data->calibration_orig ?
+		  40960000 / data->calibration_orig : INA209_SHUNT_DEFAULT;
+	}
+
+	i2c_smbus_write_word_swapped(client, INA209_CONFIGURATION,
+				     INA209_CONFIG_DEFAULT);
+	data->update_interval = ina209_interval_from_reg(INA209_CONFIG_DEFAULT);
+
+	/*
+	 * Calibrate current LSB to 1mA. Shunt is in uOhms.
+	 * See equation 13 in datasheet.
+	 */
+	i2c_smbus_write_word_swapped(client, INA209_CALIBRATION,
+				     clamp_val(40960000 / shunt, 1, 65535));
+
+	/* Clear status register */
+	i2c_smbus_read_word_swapped(client, INA209_STATUS);
+
+	return 0;
+}
+
+static int ina209_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct ina209_data *data;
+	int ret;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, data);
+	mutex_init(&data->update_lock);
+
+	ret = ina209_init_client(client, data);
+	if (ret)
+		return ret;
+
+	/* Register sysfs hooks */
+	ret = sysfs_create_group(&client->dev.kobj, &ina209_group);
+	if (ret)
+		goto out_restore_conf;
+
+	data->hwmon_dev = hwmon_device_register(&client->dev);
+	if (IS_ERR(data->hwmon_dev)) {
+		ret = PTR_ERR(data->hwmon_dev);
+		goto out_hwmon_device_register;
+	}
+
+	return 0;
+
+out_hwmon_device_register:
+	sysfs_remove_group(&client->dev.kobj, &ina209_group);
+out_restore_conf:
+	ina209_restore_conf(client, data);
+	return ret;
+}
+
+static int ina209_remove(struct i2c_client *client)
+{
+	struct ina209_data *data = i2c_get_clientdata(client);
+
+	hwmon_device_unregister(data->hwmon_dev);
+	sysfs_remove_group(&client->dev.kobj, &ina209_group);
+	ina209_restore_conf(client, data);
+
+	return 0;
+}
+
+static const struct i2c_device_id ina209_id[] = {
+	{ "ina209", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ina209_id);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver ina209_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "ina209",
+	},
+	.probe		= ina209_probe,
+	.remove		= ina209_remove,
+	.id_table	= ina209_id,
+};
+
+module_i2c_driver(ina209_driver);
+
+MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>, Paul Hays <Paul.Hays@cattail.ca>, Guenter Roeck <linux@roeck-us.net>");
+MODULE_DESCRIPTION("INA209 driver");
+MODULE_LICENSE("GPL");