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>

3 files changed, 647 insertions, 0 deletions

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 3588b2a0915c..5e77cef09ca6 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1157,6 +1157,16 @@ config SENSORS_AMC6821
           This driver can also be build as a module.  If so, the module
           will be called amc6821.
 
+config SENSORS_INA209
+        tristate "TI / Burr Brown INA209"
+        depends on I2C
+        help
+          If you say yes here you get support for the TI / Burr Brown INA209
+          voltage / current / power monitor I2C interface.
+
+          This driver can also be built as a module. If so, the module will
+          be called ina209.
+
 config SENSORS_INA2XX
         tristate "Texas Instruments INA219 and compatibles"
         depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index a37a82c64da2..8d6d97ea7c1e 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -65,6 +65,7 @@ obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
 obj-$(CONFIG_SENSORS_I5K_AMB)   += i5k_amb.o
 obj-$(CONFIG_SENSORS_IBMAEM)    += ibmaem.o
 obj-$(CONFIG_SENSORS_IBMPEX)    += ibmpex.o
+obj-$(CONFIG_SENSORS_INA209)    += ina209.o
 obj-$(CONFIG_SENSORS_INA2XX)    += ina2xx.o
 obj-$(CONFIG_SENSORS_IT87)      += it87.o
 obj-$(CONFIG_SENSORS_JC42)      += jc42.o
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");