ina2xx.c

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/*
 * Driver for Texas Instruments INA219, INA226 power monitor chips
 *
 * INA219:
 * Zero Drift Bi-Directional Current/Power Monitor with I2C Interface
 * Datasheet: http://www.ti.com/product/ina219
 *
 * INA220:
 * Bi-Directional Current/Power Monitor with I2C Interface
 * Datasheet: http://www.ti.com/product/ina220
 *
 * INA226:
 * Bi-Directional Current/Power Monitor with I2C Interface
 * Datasheet: http://www.ti.com/product/ina226
 *
 * INA230:
 * Bi-directional Current/Power Monitor with I2C Interface
 * Datasheet: http://www.ti.com/product/ina230
 *
 * Copyright (C) 2012 Lothar Felten <[email protected]>
 * 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.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>

#include <linux/platform_data/ina2xx.h>

/* common register definitions */
#define INA2XX_CONFIG           0x00
#define INA2XX_SHUNT_VOLTAGE        0x01 /* readonly */
#define INA2XX_BUS_VOLTAGE      0x02 /* readonly */
#define INA2XX_POWER            0x03 /* readonly */
#define INA2XX_CURRENT          0x04 /* readonly */
#define INA2XX_CALIBRATION      0x05

/* INA226 register definitions */
#define INA226_MASK_ENABLE      0x06
#define INA226_ALERT_LIMIT      0x07
#define INA226_DIE_ID           0xFF


/* register count */
#define INA219_REGISTERS        6
#define INA226_REGISTERS        8

#define INA2XX_MAX_REGISTERS        8

/* settings - depend on use case */
#define INA219_CONFIG_DEFAULT       0x399F  /* PGA=8 */
#define INA226_CONFIG_DEFAULT       0x4527  /* averages=16 */

/* worst case is 68.10 ms (~14.6Hz, ina219) */
#define INA2XX_CONVERSION_RATE      15

enum ina2xx_ids { ina219, ina226 };

struct ina2xx_config {
    u16 config_default;
    int calibration_factor;
    int registers;
    int shunt_div;
    int bus_voltage_shift;
    int bus_voltage_lsb;    /* uV */
    int power_lsb;      /* uW */
};

struct ina2xx_data {
    struct device *hwmon_dev;
    const struct ina2xx_config *config;

    struct mutex update_lock;
    bool valid;
    unsigned long last_updated;

    int kind;
    u16 regs[INA2XX_MAX_REGISTERS];
};

static const struct ina2xx_config ina2xx_config[] = {
    [ina219] = {
        .config_default = INA219_CONFIG_DEFAULT,
        .calibration_factor = 40960000,
        .registers = INA219_REGISTERS,
        .shunt_div = 100,
        .bus_voltage_shift = 3,
        .bus_voltage_lsb = 4000,
        .power_lsb = 20000,
    },
    [ina226] = {
        .config_default = INA226_CONFIG_DEFAULT,
        .calibration_factor = 5120000,
        .registers = INA226_REGISTERS,
        .shunt_div = 400,
        .bus_voltage_shift = 0,
        .bus_voltage_lsb = 1250,
        .power_lsb = 25000,
    },
};

static struct ina2xx_data *ina2xx_update_device(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct ina2xx_data *data = i2c_get_clientdata(client);
    struct ina2xx_data *ret = data;

    mutex_lock(&data->update_lock);

    if (time_after(jiffies, data->last_updated +
               HZ / INA2XX_CONVERSION_RATE) || !data->valid) {

        int i;

        dev_dbg(&client->dev, "Starting ina2xx update\n");

        /* Read all registers */
        for (i = 0; i < data->config->registers; i++) {
            int rv = i2c_smbus_read_word_swapped(client, i);
            if (rv < 0) {
                ret = ERR_PTR(rv);
                goto abort;
            }
            data->regs[i] = rv;
        }
        data->last_updated = jiffies;
        data->valid = 1;
    }
abort:
    mutex_unlock(&data->update_lock);
    return ret;
}

static int ina2xx_get_value(struct ina2xx_data *data, u8 reg)
{
    int val;

    switch (reg) {
    case INA2XX_SHUNT_VOLTAGE:
        val = DIV_ROUND_CLOSEST(data->regs[reg],
                    data->config->shunt_div);
        break;
    case INA2XX_BUS_VOLTAGE:
        val = (data->regs[reg] >> data->config->bus_voltage_shift)
          * data->config->bus_voltage_lsb;
        val = DIV_ROUND_CLOSEST(val, 1000);
        break;
    case INA2XX_POWER:
        val = data->regs[reg] * data->config->power_lsb;
        break;
    case INA2XX_CURRENT:
        /* LSB=1mA (selected). Is in mA */
        val = data->regs[reg];
        break;
    default:
        /* programmer goofed */
        WARN_ON_ONCE(1);
        val = 0;
        break;
    }

    return val;
}

static ssize_t ina2xx_show_value(struct device *dev,
                 struct device_attribute *da, char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
    struct ina2xx_data *data = ina2xx_update_device(dev);

    if (IS_ERR(data))
        return PTR_ERR(data);

    return snprintf(buf, PAGE_SIZE, "%d\n",
            ina2xx_get_value(data, attr->index));
}

/* shunt voltage */
static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, \
    ina2xx_show_value, NULL, INA2XX_SHUNT_VOLTAGE);

/* bus voltage */
static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, \
    ina2xx_show_value, NULL, INA2XX_BUS_VOLTAGE);

/* calculated current */
static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, \
    ina2xx_show_value, NULL, INA2XX_CURRENT);

/* calculated power */
static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, \
    ina2xx_show_value, NULL, INA2XX_POWER);

/* pointers to created device attributes */
static struct attribute *ina2xx_attributes[] = {
    &sensor_dev_attr_in0_input.dev_attr.attr,
    &sensor_dev_attr_in1_input.dev_attr.attr,
    &sensor_dev_attr_curr1_input.dev_attr.attr,
    &sensor_dev_attr_power1_input.dev_attr.attr,
    NULL,
};

static const struct attribute_group ina2xx_group = {
    .attrs = ina2xx_attributes,
};

static int ina2xx_probe(struct i2c_client *client,
            const struct i2c_device_id *id)
{
    struct i2c_adapter *adapter = client->adapter;
    struct ina2xx_data *data;
    struct ina2xx_platform_data *pdata;
    int ret;
    long shunt = 10000; /* default shunt value 10mOhms */

    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;

    if (client->dev.platform_data) {
        pdata =
          (struct ina2xx_platform_data *)client->dev.platform_data;
        shunt = pdata->shunt_uohms;
    }

    if (shunt <= 0)
        return -ENODEV;

    /* set the device type */
    data->kind = id->driver_data;
    data->config = &ina2xx_config[data->kind];

    /* device configuration */
    i2c_smbus_write_word_swapped(client, INA2XX_CONFIG,
                     data->config->config_default);
    /* set current LSB to 1mA, shunt is in uOhms */
    /* (equation 13 in datasheet) */
    i2c_smbus_write_word_swapped(client, INA2XX_CALIBRATION,
                     data->config->calibration_factor / shunt);

    i2c_set_clientdata(client, data);
    mutex_init(&data->update_lock);

    ret = sysfs_create_group(&client->dev.kobj, &ina2xx_group);
    if (ret)
        return ret;

    data->hwmon_dev = hwmon_device_register(&client->dev);
    if (IS_ERR(data->hwmon_dev)) {
        ret = PTR_ERR(data->hwmon_dev);
        goto out_err_hwmon;
    }

    dev_info(&client->dev, "power monitor %s (Rshunt = %li uOhm)\n",
         id->name, shunt);

    return 0;

out_err_hwmon:
    sysfs_remove_group(&client->dev.kobj, &ina2xx_group);
    return ret;
}

static int ina2xx_remove(struct i2c_client *client)
{
    struct ina2xx_data *data = i2c_get_clientdata(client);

    hwmon_device_unregister(data->hwmon_dev);
    sysfs_remove_group(&client->dev.kobj, &ina2xx_group);

    return 0;
}

static const struct i2c_device_id ina2xx_id[] = {
    { "ina219", ina219 },
    { "ina220", ina219 },
    { "ina226", ina226 },
    { "ina230", ina226 },
    { }
};
MODULE_DEVICE_TABLE(i2c, ina2xx_id);

static struct i2c_driver ina2xx_driver = {
    .driver = {
        .name   = "ina2xx",
    },
    .probe      = ina2xx_probe,
    .remove     = ina2xx_remove,
    .id_table   = ina2xx_id,
};

static int __init ina2xx_init(void)
{
    return i2c_add_driver(&ina2xx_driver);
}

static void __exit ina2xx_exit(void)
{
    i2c_del_driver(&ina2xx_driver);
}

MODULE_AUTHOR("Lothar Felten <[email protected]>");
MODULE_DESCRIPTION("ina2xx driver");
MODULE_LICENSE("GPL");

module_init(ina2xx_init);
module_exit(ina2xx_exit);