/*
 * 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 <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/jiffies.h>
#include <linux/of.h>
#include <linux/delay.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
#define INA2XX_MAX_DELAY                69 /* worst case delay in ms */

#define INA2XX_RSHUNT_DEFAULT           10000

/* bit mask for reading the averaging setting in the configuration register */
#define INA226_AVG_RD_MASK              0x0E00

#define INA226_READ_AVG(reg)            (((reg) & INA226_AVG_RD_MASK) >> 9)
#define INA226_SHIFT_AVG(val)           ((val) << 9)

/* common attrs, ina226 attrs and NULL */
#define INA2XX_MAX_ATTRIBUTE_GROUPS     3

/*
 * Both bus voltage and shunt voltage conversion times for ina226 are set
 * to 0b0100 on POR, which translates to 2200 microseconds in total.
 */
#define INA226_TOTAL_CONV_TIME_DEFAULT  2200

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 i2c_client *client;
        const struct ina2xx_config *config;

        long rshunt;
        u16 curr_config;

        struct mutex update_lock;
        bool valid;
        unsigned long last_updated;
        int update_interval; /* in jiffies */

        int kind;
        const struct attribute_group *groups[INA2XX_MAX_ATTRIBUTE_GROUPS];
        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,
        },
};

/*
 * Available averaging rates for ina226. The indices correspond with
 * the bit values expected by the chip (according to the ina226 datasheet,
 * table 3 AVG bit settings, found at
 * http://www.ti.com/lit/ds/symlink/ina226.pdf.
 */
static const int ina226_avg_tab[] = { 1, 4, 16, 64, 128, 256, 512, 1024 };

static int ina226_avg_bits(int avg)
{
        int i;

        /* Get the closest average from the tab. */
        for (i = 0; i < ARRAY_SIZE(ina226_avg_tab) - 1; i++) {
                if (avg <= (ina226_avg_tab[i] + ina226_avg_tab[i + 1]) / 2)
                        break;
        }

        return i; /* Return 0b0111 for values greater than 1024. */
}

static int ina226_reg_to_interval(u16 config)
{
        int avg = ina226_avg_tab[INA226_READ_AVG(config)];

        /*
         * Multiply the total conversion time by the number of averages.
         * Return the result in milliseconds.
         */
        return DIV_ROUND_CLOSEST(avg * INA226_TOTAL_CONV_TIME_DEFAULT, 1000);
}

static u16 ina226_interval_to_reg(int interval, u16 config)
{
        int avg, avg_bits;

        avg = DIV_ROUND_CLOSEST(interval * 1000,
                                INA226_TOTAL_CONV_TIME_DEFAULT);
        avg_bits = ina226_avg_bits(avg);

        return (config & ~INA226_AVG_RD_MASK) | INA226_SHIFT_AVG(avg_bits);
}

static void ina226_set_update_interval(struct ina2xx_data *data)
{
        int ms;

        ms = ina226_reg_to_interval(data->curr_config);
        data->update_interval = msecs_to_jiffies(ms);
}

static int ina2xx_calibrate(struct ina2xx_data *data)
{
        u16 val = DIV_ROUND_CLOSEST(data->config->calibration_factor,
                                    data->rshunt);

        return i2c_smbus_write_word_swapped(data->client,
                                            INA2XX_CALIBRATION, val);
}

/*
 * Initialize the configuration and calibration registers.
 */
static int ina2xx_init(struct ina2xx_data *data)
{
        struct i2c_client *client = data->client;
        int ret;

        /* device configuration */
        ret = i2c_smbus_write_word_swapped(client, INA2XX_CONFIG,
                                           data->curr_config);
        if (ret < 0)
                return ret;

        /*
         * Set current LSB to 1mA, shunt is in uOhms
         * (equation 13 in datasheet).
         */
        return ina2xx_calibrate(data);
}

static int ina2xx_do_update(struct device *dev)
{
        struct ina2xx_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        int i, rv, retry;

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

        for (retry = 5; retry; retry--) {
                /* Read all registers */
                for (i = 0; i < data->config->registers; i++) {
                        rv = i2c_smbus_read_word_swapped(client, i);
                        if (rv < 0)
                                return rv;
                        data->regs[i] = rv;
                }

                /*
                 * If the current value in the calibration register is 0, the
                 * power and current registers will also remain at 0. In case
                 * the chip has been reset let's check the calibration
                 * register and reinitialize if needed.
                 */
                if (data->regs[INA2XX_CALIBRATION] == 0) {
                        dev_warn(dev, "chip not calibrated, reinitializing\n");

                        rv = ina2xx_init(data);
                        if (rv < 0)
                                return rv;

                        /*
                         * Let's make sure the power and current registers
                         * have been updated before trying again.
                         */
                        msleep(INA2XX_MAX_DELAY);
                        continue;
                }

                data->last_updated = jiffies;
                data->valid = 1;

                return 0;
        }

        /*
         * If we're here then although all write operations succeeded, the
         * chip still returns 0 in the calibration register. Nothing more we
         * can do here.
         */
        dev_err(dev, "unable to reinitialize the chip\n");
        return -ENODEV;
}

static struct ina2xx_data *ina2xx_update_device(struct device *dev)
{
        struct ina2xx_data *data = dev_get_drvdata(dev);
        struct ina2xx_data *ret = data;
        unsigned long after;
        int rv;

        mutex_lock(&data->update_lock);

        after = data->last_updated + data->update_interval;
        if (time_after(jiffies, after) || !data->valid) {
                rv = ina2xx_do_update(dev);
                if (rv < 0)
                        ret = ERR_PTR(rv);
        }

        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:
                /* signed register */
                val = DIV_ROUND_CLOSEST((s16)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:
                /* signed register, LSB=1mA (selected), in mA */
                val = (s16)data->regs[reg];
                break;
        case INA2XX_CALIBRATION:
                val = DIV_ROUND_CLOSEST(data->config->calibration_factor,
                                        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));
}

static ssize_t ina2xx_set_shunt(struct device *dev,
                                struct device_attribute *da,
                                const char *buf, size_t count)
{
        struct ina2xx_data *data = ina2xx_update_device(dev);
        unsigned long val;
        int status;

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

        status = kstrtoul(buf, 10, &val);
        if (status < 0)
                return status;

        if (val == 0 ||
            /* Values greater than the calibration factor make no sense. */
            val > data->config->calibration_factor)
                return -EINVAL;

        mutex_lock(&data->update_lock);
        data->rshunt = val;
        status = ina2xx_calibrate(data);
        mutex_unlock(&data->update_lock);
        if (status < 0)
                return status;

        return count;
}

static ssize_t ina226_set_interval(struct device *dev,
                                   struct device_attribute *da,
                                   const char *buf, size_t count)
{
        struct ina2xx_data *data = dev_get_drvdata(dev);
        unsigned long val;
        int status;

        status = kstrtoul(buf, 10, &val);
        if (status < 0)
                return status;

        if (val > INT_MAX || val == 0)
                return -EINVAL;

        mutex_lock(&data->update_lock);
        data->curr_config = ina226_interval_to_reg(val,
                                                   data->regs[INA2XX_CONFIG]);
        status = i2c_smbus_write_word_swapped(data->client,
                                              INA2XX_CONFIG,
                                              data->curr_config);

        ina226_set_update_interval(data);
        /* Make sure the next access re-reads all registers. */
        data->valid = 0;
        mutex_unlock(&data->update_lock);
        if (status < 0)
                return status;

        return count;
}

static ssize_t ina226_show_interval(struct device *dev,
                                    struct device_attribute *da, char *buf)
{
        struct ina2xx_data *data = ina2xx_update_device(dev);

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

        /*
         * We don't use data->update_interval here as we want to display
         * the actual interval used by the chip and jiffies_to_msecs()
         * doesn't seem to be accurate enough.
         */
        return snprintf(buf, PAGE_SIZE, "%d\n",
                        ina226_reg_to_interval(data->regs[INA2XX_CONFIG]));
}

/* 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);

/* shunt resistance */
static SENSOR_DEVICE_ATTR(shunt_resistor, S_IRUGO | S_IWUSR,
                          ina2xx_show_value, ina2xx_set_shunt,
                          INA2XX_CALIBRATION);

/* update interval (ina226 only) */
static SENSOR_DEVICE_ATTR(update_interval, S_IRUGO | S_IWUSR,
                          ina226_show_interval, ina226_set_interval, 0);

/* pointers to created device attributes */
static struct attribute *ina2xx_attrs[] = {
        &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,
        &sensor_dev_attr_shunt_resistor.dev_attr.attr,
        NULL,
};

static const struct attribute_group ina2xx_group = {
        .attrs = ina2xx_attrs,
};

static struct attribute *ina226_attrs[] = {
        &sensor_dev_attr_update_interval.dev_attr.attr,
        NULL,
};

static const struct attribute_group ina226_group = {
        .attrs = ina226_attrs,
};

static int ina2xx_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
{
        struct i2c_adapter *adapter = client->adapter;
        struct ina2xx_platform_data *pdata;
        struct device *dev = &client->dev;
        struct ina2xx_data *data;
        struct device *hwmon_dev;
        u32 val;
        int ret, group = 0;

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA))
                return -ENODEV;

        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        if (dev_get_platdata(dev)) {
                pdata = dev_get_platdata(dev);
                data->rshunt = pdata->shunt_uohms;
        } else if (!of_property_read_u32(dev->of_node,
                                         "shunt-resistor", &val)) {
                data->rshunt = val;
        } else {
                data->rshunt = INA2XX_RSHUNT_DEFAULT;
        }

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

        /*
         * Ina226 has a variable update_interval. For ina219 we
         * use a constant value.
         */
        if (data->kind == ina226)
                ina226_set_update_interval(data);
        else
                data->update_interval = HZ / INA2XX_CONVERSION_RATE;

        if (data->rshunt <= 0 ||
            data->rshunt > data->config->calibration_factor)
                return -ENODEV;

        ret = ina2xx_init(data);
        if (ret < 0) {
                dev_err(dev, "error configuring the device: %d\n", ret);
                return -ENODEV;
        }

        mutex_init(&data->update_lock);

        data->groups[group++] = &ina2xx_group;
        if (data->kind == ina226)
                data->groups[group++] = &ina226_group;

        hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
                                                           data, data->groups);
        if (IS_ERR(hwmon_dev))
                return PTR_ERR(hwmon_dev);

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

        return 0;
}

static const struct i2c_device_id ina2xx_id[] = {
        { "ina219", ina219 },
        { "ina220", ina219 },
        { "ina226", ina226 },
        { "ina230", ina226 },
        { "ina231", ina226 },
        { }
};
MODULE_DEVICE_TABLE(i2c, ina2xx_id);

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

module_i2c_driver(ina2xx_driver);

MODULE_AUTHOR("Lothar Felten <l-felten@ti.com>");
MODULE_DESCRIPTION("ina2xx driver");
MODULE_LICENSE("GPL");