ds2782_battery.c

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/*
 * I2C client/driver for the Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC
 *
 * Copyright (C) 2009 Bluewater Systems Ltd
 *
 * Author: Ryan Mallon
 *
 * DS2786 added by Yulia Vilensky <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/swab.h>
#include <linux/i2c.h>
#include <linux/idr.h>
#include <linux/power_supply.h>
#include <linux/slab.h>
#include <linux/ds2782_battery.h>

#define DS2782_REG_RARC     0x06    /* Remaining active relative capacity */

#define DS278x_REG_VOLT_MSB 0x0c
#define DS278x_REG_TEMP_MSB 0x0a
#define DS278x_REG_CURRENT_MSB  0x0e

/* EEPROM Block */
#define DS2782_REG_RSNSP    0x69    /* Sense resistor value */

/* Current unit measurement in uA for a 1 milli-ohm sense resistor */
#define DS2782_CURRENT_UNITS    1563

#define DS2786_REG_RARC     0x02    /* Remaining active relative capacity */

#define DS2786_CURRENT_UNITS    25

struct ds278x_info;

struct ds278x_battery_ops {
    int (*get_battery_current)(struct ds278x_info *info, int *current_uA);
    int (*get_battery_voltage)(struct ds278x_info *info, int *voltage_uV);
    int (*get_battery_capacity)(struct ds278x_info *info, int *capacity);
};

#define to_ds278x_info(x) container_of(x, struct ds278x_info, battery)

struct ds278x_info {
    struct i2c_client   *client;
    struct power_supply battery;
    struct ds278x_battery_ops  *ops;
    int         id;
    int                     rsns;
};

static DEFINE_IDR(battery_id);
static DEFINE_MUTEX(battery_lock);

static inline int ds278x_read_reg(struct ds278x_info *info, int reg, u8 *val)
{
    int ret;

    ret = i2c_smbus_read_byte_data(info->client, reg);
    if (ret < 0) {
        dev_err(&info->client->dev, "register read failed\n");
        return ret;
    }

    *val = ret;
    return 0;
}

static inline int ds278x_read_reg16(struct ds278x_info *info, int reg_msb,
                    s16 *val)
{
    int ret;

    ret = swab16(i2c_smbus_read_word_data(info->client, reg_msb));
    if (ret < 0) {
        dev_err(&info->client->dev, "register read failed\n");
        return ret;
    }

    *val = ret;
    return 0;
}

static int ds278x_get_temp(struct ds278x_info *info, int *temp)
{
    s16 raw;
    int err;

    /*
     * Temperature is measured in units of 0.125 degrees celcius, the
     * power_supply class measures temperature in tenths of degrees
     * celsius. The temperature value is stored as a 10 bit number, plus
     * sign in the upper bits of a 16 bit register.
     */
    err = ds278x_read_reg16(info, DS278x_REG_TEMP_MSB, &raw);
    if (err)
        return err;
    *temp = ((raw / 32) * 125) / 100;
    return 0;
}

static int ds2782_get_current(struct ds278x_info *info, int *current_uA)
{
    int sense_res;
    int err;
    u8 sense_res_raw;
    s16 raw;

    /*
     * The units of measurement for current are dependent on the value of
     * the sense resistor.
     */
    err = ds278x_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
    if (err)
        return err;
    if (sense_res_raw == 0) {
        dev_err(&info->client->dev, "sense resistor value is 0\n");
        return -ENXIO;
    }
    sense_res = 1000 / sense_res_raw;

    dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
        sense_res);
    err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
    if (err)
        return err;
    *current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
    return 0;
}

static int ds2782_get_voltage(struct ds278x_info *info, int *voltage_uV)
{
    s16 raw;
    int err;

    /*
     * Voltage is measured in units of 4.88mV. The voltage is stored as
     * a 10-bit number plus sign, in the upper bits of a 16-bit register
     */
    err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
    if (err)
        return err;
    *voltage_uV = (raw / 32) * 4800;
    return 0;
}

static int ds2782_get_capacity(struct ds278x_info *info, int *capacity)
{
    int err;
    u8 raw;

    err = ds278x_read_reg(info, DS2782_REG_RARC, &raw);
    if (err)
        return err;
    *capacity = raw;
    return 0;
}

static int ds2786_get_current(struct ds278x_info *info, int *current_uA)
{
    int err;
    s16 raw;

    err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
    if (err)
        return err;
    *current_uA = (raw / 16) * (DS2786_CURRENT_UNITS / info->rsns);
    return 0;
}

static int ds2786_get_voltage(struct ds278x_info *info, int *voltage_uV)
{
    s16 raw;
    int err;

    /*
     * Voltage is measured in units of 1.22mV. The voltage is stored as
     * a 10-bit number plus sign, in the upper bits of a 16-bit register
     */
    err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
    if (err)
        return err;
    *voltage_uV = (raw / 8) * 1220;
    return 0;
}

static int ds2786_get_capacity(struct ds278x_info *info, int *capacity)
{
    int err;
    u8 raw;

    err = ds278x_read_reg(info, DS2786_REG_RARC, &raw);
    if (err)
        return err;
    /* Relative capacity is displayed with resolution 0.5 % */
    *capacity = raw/2 ;
    return 0;
}

static int ds278x_get_status(struct ds278x_info *info, int *status)
{
    int err;
    int current_uA;
    int capacity;

    err = info->ops->get_battery_current(info, &current_uA);
    if (err)
        return err;

    err = info->ops->get_battery_capacity(info, &capacity);
    if (err)
        return err;

    if (capacity == 100)
        *status = POWER_SUPPLY_STATUS_FULL;
    else if (current_uA == 0)
        *status = POWER_SUPPLY_STATUS_NOT_CHARGING;
    else if (current_uA < 0)
        *status = POWER_SUPPLY_STATUS_DISCHARGING;
    else
        *status = POWER_SUPPLY_STATUS_CHARGING;

    return 0;
}

static int ds278x_battery_get_property(struct power_supply *psy,
                       enum power_supply_property prop,
                       union power_supply_propval *val)
{
    struct ds278x_info *info = to_ds278x_info(psy);
    int ret;

    switch (prop) {
    case POWER_SUPPLY_PROP_STATUS:
        ret = ds278x_get_status(info, &val->intval);
        break;

    case POWER_SUPPLY_PROP_CAPACITY:
        ret = info->ops->get_battery_capacity(info, &val->intval);
        break;

    case POWER_SUPPLY_PROP_VOLTAGE_NOW:
        ret = info->ops->get_battery_voltage(info, &val->intval);
        break;

    case POWER_SUPPLY_PROP_CURRENT_NOW:
        ret = info->ops->get_battery_current(info, &val->intval);
        break;

    case POWER_SUPPLY_PROP_TEMP:
        ret = ds278x_get_temp(info, &val->intval);
        break;

    default:
        ret = -EINVAL;
    }

    return ret;
}

static enum power_supply_property ds278x_battery_props[] = {
    POWER_SUPPLY_PROP_STATUS,
    POWER_SUPPLY_PROP_CAPACITY,
    POWER_SUPPLY_PROP_VOLTAGE_NOW,
    POWER_SUPPLY_PROP_CURRENT_NOW,
    POWER_SUPPLY_PROP_TEMP,
};

static void ds278x_power_supply_init(struct power_supply *battery)
{
    battery->type           = POWER_SUPPLY_TYPE_BATTERY;
    battery->properties     = ds278x_battery_props;
    battery->num_properties     = ARRAY_SIZE(ds278x_battery_props);
    battery->get_property       = ds278x_battery_get_property;
    battery->external_power_changed = NULL;
}

static int ds278x_battery_remove(struct i2c_client *client)
{
    struct ds278x_info *info = i2c_get_clientdata(client);

    power_supply_unregister(&info->battery);
    kfree(info->battery.name);

    mutex_lock(&battery_lock);
    idr_remove(&battery_id, info->id);
    mutex_unlock(&battery_lock);

    kfree(info);
    return 0;
}

enum ds278x_num_id {
    DS2782 = 0,
    DS2786,
};

static struct ds278x_battery_ops ds278x_ops[] = {
    [DS2782] = {
        .get_battery_current  = ds2782_get_current,
        .get_battery_voltage  = ds2782_get_voltage,
        .get_battery_capacity = ds2782_get_capacity,
    },
    [DS2786] = {
        .get_battery_current  = ds2786_get_current,
        .get_battery_voltage  = ds2786_get_voltage,
        .get_battery_capacity = ds2786_get_capacity,
    }
};

static int ds278x_battery_probe(struct i2c_client *client,
                const struct i2c_device_id *id)
{
    struct ds278x_platform_data *pdata = client->dev.platform_data;
    struct ds278x_info *info;
    int ret;
    int num;

    /*
     * ds2786 should have the sense resistor value set
     * in the platform data
     */
    if (id->driver_data == DS2786 && !pdata) {
        dev_err(&client->dev, "missing platform data for ds2786\n");
        return -EINVAL;
    }

    /* Get an ID for this battery */
    ret = idr_pre_get(&battery_id, GFP_KERNEL);
    if (ret == 0) {
        ret = -ENOMEM;
        goto fail_id;
    }

    mutex_lock(&battery_lock);
    ret = idr_get_new(&battery_id, client, &num);
    mutex_unlock(&battery_lock);
    if (ret < 0)
        goto fail_id;

    info = kzalloc(sizeof(*info), GFP_KERNEL);
    if (!info) {
        ret = -ENOMEM;
        goto fail_info;
    }

    info->battery.name = kasprintf(GFP_KERNEL, "%s-%d", client->name, num);
    if (!info->battery.name) {
        ret = -ENOMEM;
        goto fail_name;
    }

    if (id->driver_data == DS2786)
        info->rsns = pdata->rsns;

    i2c_set_clientdata(client, info);
    info->client = client;
    info->id = num;
    info->ops  = &ds278x_ops[id->driver_data];
    ds278x_power_supply_init(&info->battery);

    ret = power_supply_register(&client->dev, &info->battery);
    if (ret) {
        dev_err(&client->dev, "failed to register battery\n");
        goto fail_register;
    }

    return 0;

fail_register:
    kfree(info->battery.name);
fail_name:
    kfree(info);
fail_info:
    mutex_lock(&battery_lock);
    idr_remove(&battery_id, num);
    mutex_unlock(&battery_lock);
fail_id:
    return ret;
}

static const struct i2c_device_id ds278x_id[] = {
    {"ds2782", DS2782},
    {"ds2786", DS2786},
    {},
};
MODULE_DEVICE_TABLE(i2c, ds278x_id);

static struct i2c_driver ds278x_battery_driver = {
    .driver     = {
        .name   = "ds2782-battery",
    },
    .probe      = ds278x_battery_probe,
    .remove     = ds278x_battery_remove,
    .id_table   = ds278x_id,
};
module_i2c_driver(ds278x_battery_driver);

MODULE_AUTHOR("Ryan Mallon");
MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver");
MODULE_LICENSE("GPL");