ds2760_battery.c

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/*
 * Driver for batteries with DS2760 chips inside.
 *
 * Copyright © 2007 Anton Vorontsov
 *         2004-2007 Matt Reimer
 *         2004 Szabolcs Gyurko
 *
 * Use consistent with the GNU GPL is permitted,
 * provided that this copyright notice is
 * preserved in its entirety in all copies and derived works.
 *
 * Author:  Anton Vorontsov <[email protected]>
 *      February 2007
 *
 *      Matt Reimer <[email protected]>
 *      April 2004, 2005, 2007
 *
 *      Szabolcs Gyurko <[email protected]>
 *      September 2004
 */

#include <linux/module.h>
#include <linux/param.h>
#include <linux/jiffies.h>
#include <linux/workqueue.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>

#include "../w1/w1.h"
#include "../w1/slaves/w1_ds2760.h"

struct ds2760_device_info {
    struct device *dev;

    /* DS2760 data, valid after calling ds2760_battery_read_status() */
    unsigned long update_time;  /* jiffies when data read */
    char raw[DS2760_DATA_SIZE]; /* raw DS2760 data */
    int voltage_raw;        /* units of 4.88 mV */
    int voltage_uV;         /* units of µV */
    int current_raw;        /* units of 0.625 mA */
    int current_uA;         /* units of µA */
    int accum_current_raw;      /* units of 0.25 mAh */
    int accum_current_uAh;      /* units of µAh */
    int temp_raw;           /* units of 0.125 °C */
    int temp_C;         /* units of 0.1 °C */
    int rated_capacity;     /* units of µAh */
    int rem_capacity;       /* percentage */
    int full_active_uAh;        /* units of µAh */
    int empty_uAh;          /* units of µAh */
    int life_sec;           /* units of seconds */
    int charge_status;      /* POWER_SUPPLY_STATUS_* */

    int full_counter;
    struct power_supply bat;
    struct device *w1_dev;
    struct workqueue_struct *monitor_wqueue;
    struct delayed_work monitor_work;
    struct delayed_work set_charged_work;
};

static unsigned int cache_time = 1000;
module_param(cache_time, uint, 0644);
MODULE_PARM_DESC(cache_time, "cache time in milliseconds");

static bool pmod_enabled;
module_param(pmod_enabled, bool, 0644);
MODULE_PARM_DESC(pmod_enabled, "PMOD enable bit");

static unsigned int rated_capacity;
module_param(rated_capacity, uint, 0644);
MODULE_PARM_DESC(rated_capacity, "rated battery capacity, 10*mAh or index");

static unsigned int current_accum;
module_param(current_accum, uint, 0644);
MODULE_PARM_DESC(current_accum, "current accumulator value");

/* Some batteries have their rated capacity stored a N * 10 mAh, while
 * others use an index into this table. */
static int rated_capacities[] = {
    0,
    920,    /* Samsung */
    920,    /* BYD */
    920,    /* Lishen */
    920,    /* NEC */
    1440,   /* Samsung */
    1440,   /* BYD */
#ifdef CONFIG_MACH_H4700
    1800,   /* HP iPAQ hx4700 3.7V 1800mAh (359113-001) */
#else
    1440,   /* Lishen */
#endif
    1440,   /* NEC */
    2880,   /* Samsung */
    2880,   /* BYD */
    2880,   /* Lishen */
    2880,   /* NEC */
#ifdef CONFIG_MACH_H4700
    0,
    3600,   /* HP iPAQ hx4700 3.7V 3600mAh (359114-001) */
#endif
};

/* array is level at temps 0°C, 10°C, 20°C, 30°C, 40°C
 * temp is in Celsius */
static int battery_interpolate(int array[], int temp)
{
    int index, dt;

    if (temp <= 0)
        return array[0];
    if (temp >= 40)
        return array[4];

    index = temp / 10;
    dt    = temp % 10;

    return array[index] + (((array[index + 1] - array[index]) * dt) / 10);
}

static int ds2760_battery_read_status(struct ds2760_device_info *di)
{
    int ret, i, start, count, scale[5];

    if (di->update_time && time_before(jiffies, di->update_time +
                       msecs_to_jiffies(cache_time)))
        return 0;

    /* The first time we read the entire contents of SRAM/EEPROM,
     * but after that we just read the interesting bits that change. */
    if (di->update_time == 0) {
        start = 0;
        count = DS2760_DATA_SIZE;
    } else {
        start = DS2760_VOLTAGE_MSB;
        count = DS2760_TEMP_LSB - start + 1;
    }

    ret = w1_ds2760_read(di->w1_dev, di->raw + start, start, count);
    if (ret != count) {
        dev_warn(di->dev, "call to w1_ds2760_read failed (0x%p)\n",
             di->w1_dev);
        return 1;
    }

    di->update_time = jiffies;

    /* DS2760 reports voltage in units of 4.88mV, but the battery class
     * reports in units of uV, so convert by multiplying by 4880. */
    di->voltage_raw = (di->raw[DS2760_VOLTAGE_MSB] << 3) |
              (di->raw[DS2760_VOLTAGE_LSB] >> 5);
    di->voltage_uV = di->voltage_raw * 4880;

    /* DS2760 reports current in signed units of 0.625mA, but the battery
     * class reports in units of µA, so convert by multiplying by 625. */
    di->current_raw =
        (((signed char)di->raw[DS2760_CURRENT_MSB]) << 5) |
              (di->raw[DS2760_CURRENT_LSB] >> 3);
    di->current_uA = di->current_raw * 625;

    /* DS2760 reports accumulated current in signed units of 0.25mAh. */
    di->accum_current_raw =
        (((signed char)di->raw[DS2760_CURRENT_ACCUM_MSB]) << 8) |
               di->raw[DS2760_CURRENT_ACCUM_LSB];
    di->accum_current_uAh = di->accum_current_raw * 250;

    /* DS2760 reports temperature in signed units of 0.125°C, but the
     * battery class reports in units of 1/10 °C, so we convert by
     * multiplying by .125 * 10 = 1.25. */
    di->temp_raw = (((signed char)di->raw[DS2760_TEMP_MSB]) << 3) |
                     (di->raw[DS2760_TEMP_LSB] >> 5);
    di->temp_C = di->temp_raw + (di->temp_raw / 4);

    /* At least some battery monitors (e.g. HP iPAQ) store the battery's
     * maximum rated capacity. */
    if (di->raw[DS2760_RATED_CAPACITY] < ARRAY_SIZE(rated_capacities))
        di->rated_capacity = rated_capacities[
            (unsigned int)di->raw[DS2760_RATED_CAPACITY]];
    else
        di->rated_capacity = di->raw[DS2760_RATED_CAPACITY] * 10;

    di->rated_capacity *= 1000; /* convert to µAh */

    /* Calculate the full level at the present temperature. */
    di->full_active_uAh = di->raw[DS2760_ACTIVE_FULL] << 8 |
                  di->raw[DS2760_ACTIVE_FULL + 1];

    /* If the full_active_uAh value is not given, fall back to the rated
     * capacity. This is likely to happen when chips are not part of the
     * battery pack and is therefore not bootstrapped. */
    if (di->full_active_uAh == 0)
        di->full_active_uAh = di->rated_capacity / 1000L;

    scale[0] = di->full_active_uAh;
    for (i = 1; i < 5; i++)
        scale[i] = scale[i - 1] + di->raw[DS2760_ACTIVE_FULL + 1 + i];

    di->full_active_uAh = battery_interpolate(scale, di->temp_C / 10);
    di->full_active_uAh *= 1000; /* convert to µAh */

    /* Calculate the empty level at the present temperature. */
    scale[4] = di->raw[DS2760_ACTIVE_EMPTY + 4];
    for (i = 3; i >= 0; i--)
        scale[i] = scale[i + 1] + di->raw[DS2760_ACTIVE_EMPTY + i];

    di->empty_uAh = battery_interpolate(scale, di->temp_C / 10);
    di->empty_uAh *= 1000; /* convert to µAh */

    if (di->full_active_uAh == di->empty_uAh)
        di->rem_capacity = 0;
    else
        /* From Maxim Application Note 131: remaining capacity =
         * ((ICA - Empty Value) / (Full Value - Empty Value)) x 100% */
        di->rem_capacity = ((di->accum_current_uAh - di->empty_uAh) * 100L) /
                    (di->full_active_uAh - di->empty_uAh);

    if (di->rem_capacity < 0)
        di->rem_capacity = 0;
    if (di->rem_capacity > 100)
        di->rem_capacity = 100;

    if (di->current_uA < -100L)
        di->life_sec = -((di->accum_current_uAh - di->empty_uAh) * 36L)
                    / (di->current_uA / 100L);
    else
        di->life_sec = 0;

    return 0;
}

static void ds2760_battery_set_current_accum(struct ds2760_device_info *di,
                         unsigned int acr_val)
{
    unsigned char acr[2];

    /* acr is in units of 0.25 mAh */
    acr_val *= 4L;
    acr_val /= 1000;

    acr[0] = acr_val >> 8;
    acr[1] = acr_val & 0xff;

    if (w1_ds2760_write(di->w1_dev, acr, DS2760_CURRENT_ACCUM_MSB, 2) < 2)
        dev_warn(di->dev, "ACR write failed\n");
}

static void ds2760_battery_update_status(struct ds2760_device_info *di)
{
    int old_charge_status = di->charge_status;

    ds2760_battery_read_status(di);

    if (di->charge_status == POWER_SUPPLY_STATUS_UNKNOWN)
        di->full_counter = 0;

    if (power_supply_am_i_supplied(&di->bat)) {
        if (di->current_uA > 10000) {
            di->charge_status = POWER_SUPPLY_STATUS_CHARGING;
            di->full_counter = 0;
        } else if (di->current_uA < -5000) {
            if (di->charge_status != POWER_SUPPLY_STATUS_NOT_CHARGING)
                dev_notice(di->dev, "not enough power to "
                       "charge\n");
            di->charge_status = POWER_SUPPLY_STATUS_NOT_CHARGING;
            di->full_counter = 0;
        } else if (di->current_uA < 10000 &&
                di->charge_status != POWER_SUPPLY_STATUS_FULL) {

            /* Don't consider the battery to be full unless
             * we've seen the current < 10 mA at least two
             * consecutive times. */

            di->full_counter++;

            if (di->full_counter < 2) {
                di->charge_status = POWER_SUPPLY_STATUS_CHARGING;
            } else {
                di->charge_status = POWER_SUPPLY_STATUS_FULL;
                ds2760_battery_set_current_accum(di,
                        di->full_active_uAh);
            }
        }
    } else {
        di->charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
        di->full_counter = 0;
    }

    if (di->charge_status != old_charge_status)
        power_supply_changed(&di->bat);
}

static void ds2760_battery_write_status(struct ds2760_device_info *di,
                    char status)
{
    if (status == di->raw[DS2760_STATUS_REG])
        return;

    w1_ds2760_write(di->w1_dev, &status, DS2760_STATUS_WRITE_REG, 1);
    w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
    w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
}

static void ds2760_battery_write_rated_capacity(struct ds2760_device_info *di,
                        unsigned char rated_capacity)
{
    if (rated_capacity == di->raw[DS2760_RATED_CAPACITY])
        return;

    w1_ds2760_write(di->w1_dev, &rated_capacity, DS2760_RATED_CAPACITY, 1);
    w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
    w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
}

static void ds2760_battery_write_active_full(struct ds2760_device_info *di,
                         int active_full)
{
    unsigned char tmp[2] = {
        active_full >> 8,
        active_full & 0xff
    };

    if (tmp[0] == di->raw[DS2760_ACTIVE_FULL] &&
        tmp[1] == di->raw[DS2760_ACTIVE_FULL + 1])
        return;

    w1_ds2760_write(di->w1_dev, tmp, DS2760_ACTIVE_FULL, sizeof(tmp));
    w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK0);
    w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK0);

    /* Write to the di->raw[] buffer directly - the DS2760_ACTIVE_FULL
     * values won't be read back by ds2760_battery_read_status() */
    di->raw[DS2760_ACTIVE_FULL] = tmp[0];
    di->raw[DS2760_ACTIVE_FULL + 1] = tmp[1];
}

static void ds2760_battery_work(struct work_struct *work)
{
    struct ds2760_device_info *di = container_of(work,
        struct ds2760_device_info, monitor_work.work);
    const int interval = HZ * 60;

    dev_dbg(di->dev, "%s\n", __func__);

    ds2760_battery_update_status(di);
    queue_delayed_work(di->monitor_wqueue, &di->monitor_work, interval);
}

#define to_ds2760_device_info(x) container_of((x), struct ds2760_device_info, \
                          bat);

static void ds2760_battery_external_power_changed(struct power_supply *psy)
{
    struct ds2760_device_info *di = to_ds2760_device_info(psy);

    dev_dbg(di->dev, "%s\n", __func__);

    mod_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ/10);
}


static void ds2760_battery_set_charged_work(struct work_struct *work)
{
    char bias;
    struct ds2760_device_info *di = container_of(work,
        struct ds2760_device_info, set_charged_work.work);

    dev_dbg(di->dev, "%s\n", __func__);

    ds2760_battery_read_status(di);

    /* When we get notified by external circuitry that the battery is
     * considered fully charged now, we know that there is no current
     * flow any more. However, the ds2760's internal current meter is
     * too inaccurate to rely on - spec say something ~15% failure.
     * Hence, we use the current offset bias register to compensate
     * that error.
     */

    if (!power_supply_am_i_supplied(&di->bat))
        return;

    bias = (signed char) di->current_raw +
        (signed char) di->raw[DS2760_CURRENT_OFFSET_BIAS];

    dev_dbg(di->dev, "%s: bias = %d\n", __func__, bias);

    w1_ds2760_write(di->w1_dev, &bias, DS2760_CURRENT_OFFSET_BIAS, 1);
    w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
    w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);

    /* Write to the di->raw[] buffer directly - the CURRENT_OFFSET_BIAS
     * value won't be read back by ds2760_battery_read_status() */
    di->raw[DS2760_CURRENT_OFFSET_BIAS] = bias;
}

static void ds2760_battery_set_charged(struct power_supply *psy)
{
    struct ds2760_device_info *di = to_ds2760_device_info(psy);

    /* postpone the actual work by 20 secs. This is for debouncing GPIO
     * signals and to let the current value settle. See AN4188. */
    mod_delayed_work(di->monitor_wqueue, &di->set_charged_work, HZ * 20);
}

static int ds2760_battery_get_property(struct power_supply *psy,
                       enum power_supply_property psp,
                       union power_supply_propval *val)
{
    struct ds2760_device_info *di = to_ds2760_device_info(psy);

    switch (psp) {
    case POWER_SUPPLY_PROP_STATUS:
        val->intval = di->charge_status;
        return 0;
    default:
        break;
    }

    ds2760_battery_read_status(di);

    switch (psp) {
    case POWER_SUPPLY_PROP_VOLTAGE_NOW:
        val->intval = di->voltage_uV;
        break;
    case POWER_SUPPLY_PROP_CURRENT_NOW:
        val->intval = di->current_uA;
        break;
    case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
        val->intval = di->rated_capacity;
        break;
    case POWER_SUPPLY_PROP_CHARGE_FULL:
        val->intval = di->full_active_uAh;
        break;
    case POWER_SUPPLY_PROP_CHARGE_EMPTY:
        val->intval = di->empty_uAh;
        break;
    case POWER_SUPPLY_PROP_CHARGE_NOW:
        val->intval = di->accum_current_uAh;
        break;
    case POWER_SUPPLY_PROP_TEMP:
        val->intval = di->temp_C;
        break;
    case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
        val->intval = di->life_sec;
        break;
    case POWER_SUPPLY_PROP_CAPACITY:
        val->intval = di->rem_capacity;
        break;
    default:
        return -EINVAL;
    }

    return 0;
}

static int ds2760_battery_set_property(struct power_supply *psy,
                       enum power_supply_property psp,
                       const union power_supply_propval *val)
{
    struct ds2760_device_info *di = to_ds2760_device_info(psy);

    switch (psp) {
    case POWER_SUPPLY_PROP_CHARGE_FULL:
        /* the interface counts in uAh, convert the value */
        ds2760_battery_write_active_full(di, val->intval / 1000L);
        break;

    case POWER_SUPPLY_PROP_CHARGE_NOW:
        /* ds2760_battery_set_current_accum() does the conversion */
        ds2760_battery_set_current_accum(di, val->intval);
        break;

    default:
        return -EPERM;
    }

    return 0;
}

static int ds2760_battery_property_is_writeable(struct power_supply *psy,
                        enum power_supply_property psp)
{
    switch (psp) {
    case POWER_SUPPLY_PROP_CHARGE_FULL:
    case POWER_SUPPLY_PROP_CHARGE_NOW:
        return 1;

    default:
        break;
    }

    return 0;
}

static enum power_supply_property ds2760_battery_props[] = {
    POWER_SUPPLY_PROP_STATUS,
    POWER_SUPPLY_PROP_VOLTAGE_NOW,
    POWER_SUPPLY_PROP_CURRENT_NOW,
    POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
    POWER_SUPPLY_PROP_CHARGE_FULL,
    POWER_SUPPLY_PROP_CHARGE_EMPTY,
    POWER_SUPPLY_PROP_CHARGE_NOW,
    POWER_SUPPLY_PROP_TEMP,
    POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW,
    POWER_SUPPLY_PROP_CAPACITY,
};

static int ds2760_battery_probe(struct platform_device *pdev)
{
    char status;
    int retval = 0;
    struct ds2760_device_info *di;

    di = kzalloc(sizeof(*di), GFP_KERNEL);
    if (!di) {
        retval = -ENOMEM;
        goto di_alloc_failed;
    }

    platform_set_drvdata(pdev, di);

    di->dev         = &pdev->dev;
    di->w1_dev      = pdev->dev.parent;
    di->bat.name        = dev_name(&pdev->dev);
    di->bat.type        = POWER_SUPPLY_TYPE_BATTERY;
    di->bat.properties  = ds2760_battery_props;
    di->bat.num_properties  = ARRAY_SIZE(ds2760_battery_props);
    di->bat.get_property    = ds2760_battery_get_property;
    di->bat.set_property    = ds2760_battery_set_property;
    di->bat.property_is_writeable =
                  ds2760_battery_property_is_writeable;
    di->bat.set_charged = ds2760_battery_set_charged;
    di->bat.external_power_changed =
                  ds2760_battery_external_power_changed;

    di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;

    /* enable sleep mode feature */
    ds2760_battery_read_status(di);
    status = di->raw[DS2760_STATUS_REG];
    if (pmod_enabled)
        status |= DS2760_STATUS_PMOD;
    else
        status &= ~DS2760_STATUS_PMOD;

    ds2760_battery_write_status(di, status);

    /* set rated capacity from module param */
    if (rated_capacity)
        ds2760_battery_write_rated_capacity(di, rated_capacity);

    /* set current accumulator if given as parameter.
     * this should only be done for bootstrapping the value */
    if (current_accum)
        ds2760_battery_set_current_accum(di, current_accum);

    retval = power_supply_register(&pdev->dev, &di->bat);
    if (retval) {
        dev_err(di->dev, "failed to register battery\n");
        goto batt_failed;
    }

    INIT_DELAYED_WORK(&di->monitor_work, ds2760_battery_work);
    INIT_DELAYED_WORK(&di->set_charged_work,
              ds2760_battery_set_charged_work);
    di->monitor_wqueue = create_singlethread_workqueue(dev_name(&pdev->dev));
    if (!di->monitor_wqueue) {
        retval = -ESRCH;
        goto workqueue_failed;
    }
    queue_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ * 1);

    goto success;

workqueue_failed:
    power_supply_unregister(&di->bat);
batt_failed:
    kfree(di);
di_alloc_failed:
success:
    return retval;
}

static int ds2760_battery_remove(struct platform_device *pdev)
{
    struct ds2760_device_info *di = platform_get_drvdata(pdev);

    cancel_delayed_work_sync(&di->monitor_work);
    cancel_delayed_work_sync(&di->set_charged_work);
    destroy_workqueue(di->monitor_wqueue);
    power_supply_unregister(&di->bat);
    kfree(di);

    return 0;
}

#ifdef CONFIG_PM

static int ds2760_battery_suspend(struct platform_device *pdev,
                  pm_message_t state)
{
    struct ds2760_device_info *di = platform_get_drvdata(pdev);

    di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;

    return 0;
}

static int ds2760_battery_resume(struct platform_device *pdev)
{
    struct ds2760_device_info *di = platform_get_drvdata(pdev);

    di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;
    power_supply_changed(&di->bat);

    mod_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ);

    return 0;
}

#else

#define ds2760_battery_suspend NULL
#define ds2760_battery_resume NULL

#endif /* CONFIG_PM */

MODULE_ALIAS("platform:ds2760-battery");

static struct platform_driver ds2760_battery_driver = {
    .driver = {
        .name = "ds2760-battery",
    },
    .probe    = ds2760_battery_probe,
    .remove   = ds2760_battery_remove,
    .suspend  = ds2760_battery_suspend,
    .resume   = ds2760_battery_resume,
};

module_platform_driver(ds2760_battery_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Szabolcs Gyurko <[email protected]>, "
          "Matt Reimer <[email protected]>, "
          "Anton Vorontsov <[email protected]>");
MODULE_DESCRIPTION("ds2760 battery driver");