/*
 * 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
 *
 * INA226:
 * Bi-Directional Current/Power Monitor with I2C Interface
 * Datasheet: http://www.ti.com/product/ina226
 *
 * 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.
 */

#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/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_data {
        struct device *hwmon_dev;

        struct mutex update_lock;
        bool valid;
        unsigned long last_updated;

        int kind;
        int registers;
        u16 regs[INA2XX_MAX_REGISTERS];
};

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->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 ina219_get_value(struct ina2xx_data *data, u8 reg)
{
        /*
         * calculate exact value for the given register
         * we assume default power-on reset settings:
         * bus voltage range 32V
         * gain = /8
         * adc 1 & 2 -> conversion time 532uS
         * mode is continuous shunt and bus
         * calibration value is INA219_CALIBRATION_VALUE
         */
        int val = data->regs[reg];

        switch (reg) {
        case INA2XX_SHUNT_VOLTAGE:
                /* LSB=10uV. Convert to mV. */
                val = DIV_ROUND_CLOSEST(val, 100);
                break;
        case INA2XX_BUS_VOLTAGE:
                /* LSB=4mV. Register is not right aligned, convert to mV. */
                val = (val >> 3) * 4;
                break;
        case INA2XX_POWER:
                /* LSB=20mW. Convert to uW */
                val = val * 20 * 1000;
                break;
        case INA2XX_CURRENT:
                /* LSB=1mA (selected). Is in mA */
                break;
        default:
                /* programmer goofed */
                WARN_ON_ONCE(1);
                val = 0;
                break;
        }

        return val;
}

static int ina226_get_value(struct ina2xx_data *data, u8 reg)
{
        /*
         * calculate exact value for the given register
         * we assume default power-on reset settings:
         * bus voltage range 32V
         * gain = /8
         * adc 1 & 2 -> conversion time 532uS
         * mode is continuous shunt and bus
         * calibration value is INA226_CALIBRATION_VALUE
         */
        int val = data->regs[reg];

        switch (reg) {
        case INA2XX_SHUNT_VOLTAGE:
                /* LSB=2.5uV. Convert to mV. */
                val = DIV_ROUND_CLOSEST(val, 400);
                break;
        case INA2XX_BUS_VOLTAGE:
                /* LSB=1.25mV. Convert to mV. */
                val = val + DIV_ROUND_CLOSEST(val, 4);
                break;
        case INA2XX_POWER:
                /* LSB=25mW. Convert to uW */
                val = val * 25 * 1000;
                break;
        case INA2XX_CURRENT:
                /* LSB=1mA (selected). Is in mA */
                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);
        int value = 0;

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

        switch (data->kind) {
        case ina219:
                value = ina219_get_value(data, attr->index);
                break;
        case ina226:
                value = ina226_get_value(data, attr->index);
                break;
        default:
                WARN_ON_ONCE(1);
                break;
        }
        return snprintf(buf, PAGE_SIZE, "%d\n", value);
}

/* 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 = 0;
        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;

        switch (data->kind) {
        case ina219:
                /* device configuration */
                i2c_smbus_write_word_swapped(client, INA2XX_CONFIG,
                                             INA219_CONFIG_DEFAULT);

                /* set current LSB to 1mA, shunt is in uOhms */
                /* (equation 13 in datasheet) */
                i2c_smbus_write_word_swapped(client, INA2XX_CALIBRATION,
                                             40960000 / shunt);
                dev_info(&client->dev,
                         "power monitor INA219 (Rshunt = %li uOhm)\n", shunt);
                data->registers = INA219_REGISTERS;
                break;
        case ina226:
                /* device configuration */
                i2c_smbus_write_word_swapped(client, INA2XX_CONFIG,
                                             INA226_CONFIG_DEFAULT);

                /* set current LSB to 1mA, shunt is in uOhms */
                /* (equation 1 in datasheet)*/
                i2c_smbus_write_word_swapped(client, INA2XX_CALIBRATION,
                                             5120000 / shunt);
                dev_info(&client->dev,
                         "power monitor INA226 (Rshunt = %li uOhm)\n", shunt);
                data->registers = INA226_REGISTERS;
                break;
        default:
                /* unknown device id */
                return -ENODEV;
        }

        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;
        }

        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 },
        { "ina226", 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 <l-felten@ti.com>");
MODULE_DESCRIPTION("ina2xx driver");
MODULE_LICENSE("GPL");

module_init(ina2xx_init);
module_exit(ina2xx_exit);