twl4030_wdt.c

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/*
 * Copyright (C) Nokia Corporation
 *
 * Written by Timo Kokkonen <timo.t.kokkonen at nokia.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/miscdevice.h>
#include <linux/uaccess.h>
#include <linux/i2c/twl.h>

#define TWL4030_WATCHDOG_CFG_REG_OFFS   0x3

#define TWL4030_WDT_STATE_OPEN      0x1
#define TWL4030_WDT_STATE_ACTIVE    0x8

static struct platform_device *twl4030_wdt_dev;

struct twl4030_wdt {
    struct miscdevice   miscdev;
    int         timer_margin;
    unsigned long       state;
};

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
    "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

static int twl4030_wdt_write(unsigned char val)
{
    return twl_i2c_write_u8(TWL4030_MODULE_PM_RECEIVER, val,
                    TWL4030_WATCHDOG_CFG_REG_OFFS);
}

static int twl4030_wdt_enable(struct twl4030_wdt *wdt)
{
    return twl4030_wdt_write(wdt->timer_margin + 1);
}

static int twl4030_wdt_disable(struct twl4030_wdt *wdt)
{
    return twl4030_wdt_write(0);
}

static int twl4030_wdt_set_timeout(struct twl4030_wdt *wdt, int timeout)
{
    if (timeout < 0 || timeout > 30) {
        dev_warn(wdt->miscdev.parent,
            "Timeout can only be in the range [0-30] seconds");
        return -EINVAL;
    }
    wdt->timer_margin = timeout;
    return twl4030_wdt_enable(wdt);
}

static ssize_t twl4030_wdt_write_fop(struct file *file,
        const char __user *data, size_t len, loff_t *ppos)
{
    struct twl4030_wdt *wdt = file->private_data;

    if (len)
        twl4030_wdt_enable(wdt);

    return len;
}

static long twl4030_wdt_ioctl(struct file *file,
        unsigned int cmd, unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    int new_margin;
    struct twl4030_wdt *wdt = file->private_data;

    static const struct watchdog_info twl4030_wd_ident = {
        .identity = "TWL4030 Watchdog",
        .options = WDIOF_SETTIMEOUT,
        .firmware_version = 0,
    };

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        return copy_to_user(argp, &twl4030_wd_ident,
                sizeof(twl4030_wd_ident)) ? -EFAULT : 0;

    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, p);

    case WDIOC_KEEPALIVE:
        twl4030_wdt_enable(wdt);
        break;

    case WDIOC_SETTIMEOUT:
        if (get_user(new_margin, p))
            return -EFAULT;
        if (twl4030_wdt_set_timeout(wdt, new_margin))
            return -EINVAL;
        return put_user(wdt->timer_margin, p);

    case WDIOC_GETTIMEOUT:
        return put_user(wdt->timer_margin, p);

    default:
        return -ENOTTY;
    }

    return 0;
}

static int twl4030_wdt_open(struct inode *inode, struct file *file)
{
    struct twl4030_wdt *wdt = platform_get_drvdata(twl4030_wdt_dev);

    /* /dev/watchdog can only be opened once */
    if (test_and_set_bit(0, &wdt->state))
        return -EBUSY;

    wdt->state |= TWL4030_WDT_STATE_ACTIVE;
    file->private_data = (void *) wdt;

    twl4030_wdt_enable(wdt);
    return nonseekable_open(inode, file);
}

static int twl4030_wdt_release(struct inode *inode, struct file *file)
{
    struct twl4030_wdt *wdt = file->private_data;
    if (nowayout) {
        dev_alert(wdt->miscdev.parent,
               "Unexpected close, watchdog still running!\n");
        twl4030_wdt_enable(wdt);
    } else {
        if (twl4030_wdt_disable(wdt))
            return -EFAULT;
        wdt->state &= ~TWL4030_WDT_STATE_ACTIVE;
    }

    clear_bit(0, &wdt->state);
    return 0;
}

static const struct file_operations twl4030_wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .open       = twl4030_wdt_open,
    .release    = twl4030_wdt_release,
    .unlocked_ioctl = twl4030_wdt_ioctl,
    .write      = twl4030_wdt_write_fop,
};

static int __devinit twl4030_wdt_probe(struct platform_device *pdev)
{
    int ret = 0;
    struct twl4030_wdt *wdt;

    wdt = kzalloc(sizeof(struct twl4030_wdt), GFP_KERNEL);
    if (!wdt)
        return -ENOMEM;

    wdt->state      = 0;
    wdt->timer_margin   = 30;
    wdt->miscdev.parent = &pdev->dev;
    wdt->miscdev.fops   = &twl4030_wdt_fops;
    wdt->miscdev.minor  = WATCHDOG_MINOR;
    wdt->miscdev.name   = "watchdog";

    platform_set_drvdata(pdev, wdt);

    twl4030_wdt_dev = pdev;

    twl4030_wdt_disable(wdt);

    ret = misc_register(&wdt->miscdev);
    if (ret) {
        dev_err(wdt->miscdev.parent,
            "Failed to register misc device\n");
        platform_set_drvdata(pdev, NULL);
        kfree(wdt);
        twl4030_wdt_dev = NULL;
        return ret;
    }
    return 0;
}

static int __devexit twl4030_wdt_remove(struct platform_device *pdev)
{
    struct twl4030_wdt *wdt = platform_get_drvdata(pdev);

    if (wdt->state & TWL4030_WDT_STATE_ACTIVE)
        if (twl4030_wdt_disable(wdt))
            return -EFAULT;

    wdt->state &= ~TWL4030_WDT_STATE_ACTIVE;
    misc_deregister(&wdt->miscdev);

    platform_set_drvdata(pdev, NULL);
    kfree(wdt);
    twl4030_wdt_dev = NULL;

    return 0;
}

#ifdef CONFIG_PM
static int twl4030_wdt_suspend(struct platform_device *pdev, pm_message_t state)
{
    struct twl4030_wdt *wdt = platform_get_drvdata(pdev);
    if (wdt->state & TWL4030_WDT_STATE_ACTIVE)
        return twl4030_wdt_disable(wdt);

    return 0;
}

static int twl4030_wdt_resume(struct platform_device *pdev)
{
    struct twl4030_wdt *wdt = platform_get_drvdata(pdev);
    if (wdt->state & TWL4030_WDT_STATE_ACTIVE)
        return twl4030_wdt_enable(wdt);

    return 0;
}
#else
#define twl4030_wdt_suspend        NULL
#define twl4030_wdt_resume         NULL
#endif

static struct platform_driver twl4030_wdt_driver = {
    .probe      = twl4030_wdt_probe,
    .remove     = __devexit_p(twl4030_wdt_remove),
    .suspend    = twl4030_wdt_suspend,
    .resume     = twl4030_wdt_resume,
    .driver     = {
        .owner  = THIS_MODULE,
        .name   = "twl4030_wdt",
    },
};

module_platform_driver(twl4030_wdt_driver);

MODULE_AUTHOR("Nokia Corporation");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:twl4030_wdt");