wm831x_backup.c

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/*
 * Backup battery driver for Wolfson Microelectronics wm831x PMICs
 *
 * Copyright 2009 Wolfson Microelectronics PLC.
 *
 * 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/err.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>
#include <linux/slab.h>

#include <linux/mfd/wm831x/core.h>
#include <linux/mfd/wm831x/auxadc.h>
#include <linux/mfd/wm831x/pmu.h>
#include <linux/mfd/wm831x/pdata.h>

struct wm831x_backup {
    struct wm831x *wm831x;
    struct power_supply backup;
    char name[20];
};

static int wm831x_backup_read_voltage(struct wm831x *wm831x,
                     enum wm831x_auxadc src,
                     union power_supply_propval *val)
{
    int ret;

    ret = wm831x_auxadc_read_uv(wm831x, src);
    if (ret >= 0)
        val->intval = ret;

    return ret;
}

/*********************************************************************
 *      Backup supply properties
 *********************************************************************/

static void wm831x_config_backup(struct wm831x *wm831x)
{
    struct wm831x_pdata *wm831x_pdata = wm831x->dev->platform_data;
    struct wm831x_backup_pdata *pdata;
    int ret, reg;

    if (!wm831x_pdata || !wm831x_pdata->backup) {
        dev_warn(wm831x->dev,
             "No backup battery charger configuration\n");
        return;
    }

    pdata = wm831x_pdata->backup;

    reg = 0;

    if (pdata->charger_enable)
        reg |= WM831X_BKUP_CHG_ENA | WM831X_BKUP_BATT_DET_ENA;
    if (pdata->no_constant_voltage)
        reg |= WM831X_BKUP_CHG_MODE;

    switch (pdata->vlim) {
    case 2500:
        break;
    case 3100:
        reg |= WM831X_BKUP_CHG_VLIM;
        break;
    default:
        dev_err(wm831x->dev, "Invalid backup voltage limit %dmV\n",
            pdata->vlim);
    }

    switch (pdata->ilim) {
    case 100:
        break;
    case 200:
        reg |= 1;
        break;
    case 300:
        reg |= 2;
        break;
    case 400:
        reg |= 3;
        break;
    default:
        dev_err(wm831x->dev, "Invalid backup current limit %duA\n",
            pdata->ilim);
    }

    ret = wm831x_reg_unlock(wm831x);
    if (ret != 0) {
        dev_err(wm831x->dev, "Failed to unlock registers: %d\n", ret);
        return;
    }

    ret = wm831x_set_bits(wm831x, WM831X_BACKUP_CHARGER_CONTROL,
                  WM831X_BKUP_CHG_ENA_MASK |
                  WM831X_BKUP_CHG_MODE_MASK |
                  WM831X_BKUP_BATT_DET_ENA_MASK |
                  WM831X_BKUP_CHG_VLIM_MASK |
                  WM831X_BKUP_CHG_ILIM_MASK,
                  reg);
    if (ret != 0)
        dev_err(wm831x->dev,
            "Failed to set backup charger config: %d\n", ret);

    wm831x_reg_lock(wm831x);
}

static int wm831x_backup_get_prop(struct power_supply *psy,
                  enum power_supply_property psp,
                  union power_supply_propval *val)
{
    struct wm831x_backup *devdata = dev_get_drvdata(psy->dev->parent);
    struct wm831x *wm831x = devdata->wm831x;
    int ret = 0;

    ret = wm831x_reg_read(wm831x, WM831X_BACKUP_CHARGER_CONTROL);
    if (ret < 0)
        return ret;

    switch (psp) {
    case POWER_SUPPLY_PROP_STATUS:
        if (ret & WM831X_BKUP_CHG_STS)
            val->intval = POWER_SUPPLY_STATUS_CHARGING;
        else
            val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
        break;

    case POWER_SUPPLY_PROP_VOLTAGE_NOW:
        ret = wm831x_backup_read_voltage(wm831x, WM831X_AUX_BKUP_BATT,
                        val);
        break;

    case POWER_SUPPLY_PROP_PRESENT:
        if (ret & WM831X_BKUP_CHG_STS)
            val->intval = 1;
        else
            val->intval = 0;
        break;

    default:
        ret = -EINVAL;
        break;
    }

    return ret;
}

static enum power_supply_property wm831x_backup_props[] = {
    POWER_SUPPLY_PROP_STATUS,
    POWER_SUPPLY_PROP_VOLTAGE_NOW,
    POWER_SUPPLY_PROP_PRESENT,
};

/*********************************************************************
 *      Initialisation
 *********************************************************************/

static __devinit int wm831x_backup_probe(struct platform_device *pdev)
{
    struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
    struct wm831x_pdata *wm831x_pdata = wm831x->dev->platform_data;
    struct wm831x_backup *devdata;
    struct power_supply *backup;
    int ret;

    devdata = kzalloc(sizeof(struct wm831x_backup), GFP_KERNEL);
    if (devdata == NULL)
        return -ENOMEM;

    devdata->wm831x = wm831x;
    platform_set_drvdata(pdev, devdata);

    backup = &devdata->backup;

    /* We ignore configuration failures since we can still read
     * back the status without enabling the charger (which may
     * already be enabled anyway).
     */
    wm831x_config_backup(wm831x);

    if (wm831x_pdata && wm831x_pdata->wm831x_num)
        snprintf(devdata->name, sizeof(devdata->name),
             "wm831x-backup.%d", wm831x_pdata->wm831x_num);
    else
        snprintf(devdata->name, sizeof(devdata->name),
             "wm831x-backup");

    backup->name = devdata->name;
    backup->type = POWER_SUPPLY_TYPE_BATTERY;
    backup->properties = wm831x_backup_props;
    backup->num_properties = ARRAY_SIZE(wm831x_backup_props);
    backup->get_property = wm831x_backup_get_prop;
    ret = power_supply_register(&pdev->dev, backup);
    if (ret)
        goto err_kmalloc;

    return ret;

err_kmalloc:
    kfree(devdata);
    return ret;
}

static __devexit int wm831x_backup_remove(struct platform_device *pdev)
{
    struct wm831x_backup *devdata = platform_get_drvdata(pdev);

    power_supply_unregister(&devdata->backup);
    kfree(devdata->backup.name);
    kfree(devdata);

    return 0;
}

static struct platform_driver wm831x_backup_driver = {
    .probe = wm831x_backup_probe,
    .remove = __devexit_p(wm831x_backup_remove),
    .driver = {
        .name = "wm831x-backup",
    },
};

module_platform_driver(wm831x_backup_driver);

MODULE_DESCRIPTION("Backup battery charger driver for WM831x PMICs");
MODULE_AUTHOR("Mark Brown <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:wm831x-backup");