/*
 * 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 <cbou@mail.ru>
 *          February 2007
 *
 *          Matt Reimer <mreimer@vpop.net>
 *          April 2004, 2005, 2007
 *
 *          Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
 *          September 2004
 */

#include <linux/module.h>
#include <linux/param.h>
#include <linux/jiffies.h>
#include <linux/workqueue.h>
#include <linux/pm.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;
};

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

/* 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 */
        1440,   /* Lishen */
        1440,   /* NEC */
        2880,   /* Samsung */
        2880,   /* BYD */
        2880,   /* Lishen */
        2880    /* NEC */
};

/* 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];

        scale[0] = di->raw[DS2760_ACTIVE_FULL] << 8 |
                   di->raw[DS2760_ACTIVE_FULL + 1];
        for (i = 1; i < 5; i++)
                scale[i] = scale[i - 1] + di->raw[DS2760_ACTIVE_FULL + 2 + 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)
                di->life_sec = -((di->accum_current_uAh - di->empty_uAh) *
                                 3600L) / di->current_uA;
        else
                di->life_sec = 0;

        return 0;
}

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 {
                                unsigned char acr[2];
                                int acr_val;

                                /* acr is in units of 0.25 mAh */
                                acr_val = di->full_active_uAh * 4L / 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 reset failed\n");

                                di->charge_status = POWER_SUPPLY_STATUS_FULL;
                        }
                }
        } 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_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__);

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

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;
        default:
                return -EINVAL;
        }

        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,
};

static int ds2760_battery_probe(struct platform_device *pdev)
{
        int retval = 0;
        struct ds2760_device_info *di;
        struct ds2760_platform_data *pdata;

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

        platform_set_drvdata(pdev, di);

        pdata = pdev->dev.platform_data;
        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.external_power_changed =
                                  ds2760_battery_external_power_changed;

        di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;

        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);
        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_rearming_delayed_workqueue(di->monitor_wqueue,
                                          &di->monitor_work);
        destroy_workqueue(di->monitor_wqueue);
        power_supply_unregister(&di->bat);

        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);

        cancel_delayed_work(&di->monitor_work);
        queue_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,
};

static int __init ds2760_battery_init(void)
{
        return platform_driver_register(&ds2760_battery_driver);
}

static void __exit ds2760_battery_exit(void)
{
        platform_driver_unregister(&ds2760_battery_driver);
}

module_init(ds2760_battery_init);
module_exit(ds2760_battery_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>, "
              "Matt Reimer <mreimer@vpop.net>, "
              "Anton Vorontsov <cbou@mail.ru>");
MODULE_DESCRIPTION("ds2760 battery driver");