z2_battery.c

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/*
 * Battery measurement code for Zipit Z2
 *
 * Copyright (C) 2009 Peter Edwards <[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/module.h>
#include <linux/gpio.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/power_supply.h>
#include <linux/slab.h>
#include <linux/z2_battery.h>

#define Z2_DEFAULT_NAME "Z2"

struct z2_charger {
    struct z2_battery_info  *info;
    int         bat_status;
    struct i2c_client   *client;
    struct power_supply batt_ps;
    struct mutex        work_lock;
    struct work_struct  bat_work;
};

static unsigned long z2_read_bat(struct z2_charger *charger)
{
    int data;
    data = i2c_smbus_read_byte_data(charger->client,
                    charger->info->batt_I2C_reg);
    if (data < 0)
        return 0;

    return data * charger->info->batt_mult / charger->info->batt_div;
}

static int z2_batt_get_property(struct power_supply *batt_ps,
                enum power_supply_property psp,
                union power_supply_propval *val)
{
    struct z2_charger *charger = container_of(batt_ps, struct z2_charger,
                        batt_ps);
    struct z2_battery_info *info = charger->info;

    switch (psp) {
    case POWER_SUPPLY_PROP_STATUS:
        val->intval = charger->bat_status;
        break;
    case POWER_SUPPLY_PROP_TECHNOLOGY:
        val->intval = info->batt_tech;
        break;
    case POWER_SUPPLY_PROP_VOLTAGE_NOW:
        if (info->batt_I2C_reg >= 0)
            val->intval = z2_read_bat(charger);
        else
            return -EINVAL;
        break;
    case POWER_SUPPLY_PROP_VOLTAGE_MAX:
        if (info->max_voltage >= 0)
            val->intval = info->max_voltage;
        else
            return -EINVAL;
        break;
    case POWER_SUPPLY_PROP_VOLTAGE_MIN:
        if (info->min_voltage >= 0)
            val->intval = info->min_voltage;
        else
            return -EINVAL;
        break;
    case POWER_SUPPLY_PROP_PRESENT:
        val->intval = 1;
        break;
    default:
        return -EINVAL;
    }

    return 0;
}

static void z2_batt_ext_power_changed(struct power_supply *batt_ps)
{
    struct z2_charger *charger = container_of(batt_ps, struct z2_charger,
                        batt_ps);
    schedule_work(&charger->bat_work);
}

static void z2_batt_update(struct z2_charger *charger)
{
    int old_status = charger->bat_status;
    struct z2_battery_info *info;

    info = charger->info;

    mutex_lock(&charger->work_lock);

    charger->bat_status = (info->charge_gpio >= 0) ?
        (gpio_get_value(info->charge_gpio) ?
        POWER_SUPPLY_STATUS_CHARGING :
        POWER_SUPPLY_STATUS_DISCHARGING) :
        POWER_SUPPLY_STATUS_UNKNOWN;

    if (old_status != charger->bat_status) {
        pr_debug("%s: %i -> %i\n", charger->batt_ps.name, old_status,
            charger->bat_status);
        power_supply_changed(&charger->batt_ps);
    }

    mutex_unlock(&charger->work_lock);
}

static void z2_batt_work(struct work_struct *work)
{
    struct z2_charger *charger;
    charger = container_of(work, struct z2_charger, bat_work);
    z2_batt_update(charger);
}

static irqreturn_t z2_charge_switch_irq(int irq, void *devid)
{
    struct z2_charger *charger = devid;
    schedule_work(&charger->bat_work);
    return IRQ_HANDLED;
}

static int z2_batt_ps_init(struct z2_charger *charger, int props)
{
    int i = 0;
    enum power_supply_property *prop;
    struct z2_battery_info *info = charger->info;

    if (info->charge_gpio >= 0)
        props++;    /* POWER_SUPPLY_PROP_STATUS */
    if (info->batt_tech >= 0)
        props++;    /* POWER_SUPPLY_PROP_TECHNOLOGY */
    if (info->batt_I2C_reg >= 0)
        props++;    /* POWER_SUPPLY_PROP_VOLTAGE_NOW */
    if (info->max_voltage >= 0)
        props++;    /* POWER_SUPPLY_PROP_VOLTAGE_MAX */
    if (info->min_voltage >= 0)
        props++;    /* POWER_SUPPLY_PROP_VOLTAGE_MIN */

    prop = kzalloc(props * sizeof(*prop), GFP_KERNEL);
    if (!prop)
        return -ENOMEM;

    prop[i++] = POWER_SUPPLY_PROP_PRESENT;
    if (info->charge_gpio >= 0)
        prop[i++] = POWER_SUPPLY_PROP_STATUS;
    if (info->batt_tech >= 0)
        prop[i++] = POWER_SUPPLY_PROP_TECHNOLOGY;
    if (info->batt_I2C_reg >= 0)
        prop[i++] = POWER_SUPPLY_PROP_VOLTAGE_NOW;
    if (info->max_voltage >= 0)
        prop[i++] = POWER_SUPPLY_PROP_VOLTAGE_MAX;
    if (info->min_voltage >= 0)
        prop[i++] = POWER_SUPPLY_PROP_VOLTAGE_MIN;

    if (!info->batt_name) {
        dev_info(&charger->client->dev,
                "Please consider setting proper battery "
                "name in platform definition file, falling "
                "back to name \" Z2_DEFAULT_NAME \"\n");
        charger->batt_ps.name = Z2_DEFAULT_NAME;
    } else
        charger->batt_ps.name = info->batt_name;

    charger->batt_ps.properties     = prop;
    charger->batt_ps.num_properties     = props;
    charger->batt_ps.type           = POWER_SUPPLY_TYPE_BATTERY;
    charger->batt_ps.get_property       = z2_batt_get_property;
    charger->batt_ps.external_power_changed = z2_batt_ext_power_changed;
    charger->batt_ps.use_for_apm        = 1;

    return 0;
}

static int __devinit z2_batt_probe(struct i2c_client *client,
                const struct i2c_device_id *id)
{
    int ret = 0;
    int props = 1;  /* POWER_SUPPLY_PROP_PRESENT */
    struct z2_charger *charger;
    struct z2_battery_info *info = client->dev.platform_data;

    if (info == NULL) {
        dev_err(&client->dev,
            "Please set platform device platform_data"
            " to a valid z2_battery_info pointer!\n");
        return -EINVAL;
    }

    charger = kzalloc(sizeof(*charger), GFP_KERNEL);
    if (charger == NULL)
        return -ENOMEM;

    charger->bat_status = POWER_SUPPLY_STATUS_UNKNOWN;
    charger->info = info;
    charger->client = client;
    i2c_set_clientdata(client, charger);

    mutex_init(&charger->work_lock);

    if (info->charge_gpio >= 0 && gpio_is_valid(info->charge_gpio)) {
        ret = gpio_request(info->charge_gpio, "BATT CHRG");
        if (ret)
            goto err;

        ret = gpio_direction_input(info->charge_gpio);
        if (ret)
            goto err2;

        irq_set_irq_type(gpio_to_irq(info->charge_gpio),
                 IRQ_TYPE_EDGE_BOTH);
        ret = request_irq(gpio_to_irq(info->charge_gpio),
                z2_charge_switch_irq, 0,
                "AC Detect", charger);
        if (ret)
            goto err3;
    }

    ret = z2_batt_ps_init(charger, props);
    if (ret)
        goto err3;

    INIT_WORK(&charger->bat_work, z2_batt_work);

    ret = power_supply_register(&client->dev, &charger->batt_ps);
    if (ret)
        goto err4;

    schedule_work(&charger->bat_work);

    return 0;

err4:
    kfree(charger->batt_ps.properties);
err3:
    if (info->charge_gpio >= 0 && gpio_is_valid(info->charge_gpio))
        free_irq(gpio_to_irq(info->charge_gpio), charger);
err2:
    if (info->charge_gpio >= 0 && gpio_is_valid(info->charge_gpio))
        gpio_free(info->charge_gpio);
err:
    kfree(charger);
    return ret;
}

static int __devexit z2_batt_remove(struct i2c_client *client)
{
    struct z2_charger *charger = i2c_get_clientdata(client);
    struct z2_battery_info *info = charger->info;

    cancel_work_sync(&charger->bat_work);
    power_supply_unregister(&charger->batt_ps);

    kfree(charger->batt_ps.properties);
    if (info->charge_gpio >= 0 && gpio_is_valid(info->charge_gpio)) {
        free_irq(gpio_to_irq(info->charge_gpio), charger);
        gpio_free(info->charge_gpio);
    }

    kfree(charger);

    return 0;
}

#ifdef CONFIG_PM
static int z2_batt_suspend(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct z2_charger *charger = i2c_get_clientdata(client);

    flush_work(&charger->bat_work);
    return 0;
}

static int z2_batt_resume(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct z2_charger *charger = i2c_get_clientdata(client);

    schedule_work(&charger->bat_work);
    return 0;
}

static const struct dev_pm_ops z2_battery_pm_ops = {
    .suspend    = z2_batt_suspend,
    .resume     = z2_batt_resume,
};

#define Z2_BATTERY_PM_OPS   (&z2_battery_pm_ops)

#else
#define Z2_BATTERY_PM_OPS   (NULL)
#endif

static const struct i2c_device_id z2_batt_id[] = {
    { "aer915", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, z2_batt_id);

static struct i2c_driver z2_batt_driver = {
    .driver = {
        .name   = "z2-battery",
        .owner  = THIS_MODULE,
        .pm = Z2_BATTERY_PM_OPS
    },
    .probe      = z2_batt_probe,
    .remove     = __devexit_p(z2_batt_remove),
    .id_table   = z2_batt_id,
};
module_i2c_driver(z2_batt_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Peter Edwards <[email protected]>");
MODULE_DESCRIPTION("Zipit Z2 battery driver");