rdc321x_wdt.c

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/*
 * RDC321x watchdog driver
 *
 * Copyright (C) 2007-2010 Florian Fainelli <[email protected]>
 *
 * This driver is highly inspired from the cpu5_wdt driver
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/timer.h>
#include <linux/completion.h>
#include <linux/jiffies.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/mfd/rdc321x.h>

#define RDC_WDT_MASK    0x80000000 /* Mask */
#define RDC_WDT_EN  0x00800000 /* Enable bit */
#define RDC_WDT_WTI 0x00200000 /* Generate CPU reset/NMI/WDT on timeout */
#define RDC_WDT_RST 0x00100000 /* Reset bit */
#define RDC_WDT_WIF 0x00040000 /* WDT IRQ Flag */
#define RDC_WDT_IRT 0x00000100 /* IRQ Routing table */
#define RDC_WDT_CNT 0x00000001 /* WDT count */

#define RDC_CLS_TMR 0x80003844 /* Clear timer */

#define RDC_WDT_INTERVAL    (HZ/10+1)

static int ticks = 1000;

/* some device data */

static struct {
    struct completion stop;
    int running;
    struct timer_list timer;
    int queue;
    int default_ticks;
    unsigned long inuse;
    spinlock_t lock;
    struct pci_dev *sb_pdev;
    int base_reg;
} rdc321x_wdt_device;

/* generic helper functions */

static void rdc321x_wdt_trigger(unsigned long unused)
{
    unsigned long flags;
    u32 val;

    if (rdc321x_wdt_device.running)
        ticks--;

    /* keep watchdog alive */
    spin_lock_irqsave(&rdc321x_wdt_device.lock, flags);
    pci_read_config_dword(rdc321x_wdt_device.sb_pdev,
                    rdc321x_wdt_device.base_reg, &val);
    val |= RDC_WDT_EN;
    pci_write_config_dword(rdc321x_wdt_device.sb_pdev,
                    rdc321x_wdt_device.base_reg, val);
    spin_unlock_irqrestore(&rdc321x_wdt_device.lock, flags);

    /* requeue?? */
    if (rdc321x_wdt_device.queue && ticks)
        mod_timer(&rdc321x_wdt_device.timer,
                jiffies + RDC_WDT_INTERVAL);
    else {
        /* ticks doesn't matter anyway */
        complete(&rdc321x_wdt_device.stop);
    }

}

static void rdc321x_wdt_reset(void)
{
    ticks = rdc321x_wdt_device.default_ticks;
}

static void rdc321x_wdt_start(void)
{
    unsigned long flags;

    if (!rdc321x_wdt_device.queue) {
        rdc321x_wdt_device.queue = 1;

        /* Clear the timer */
        spin_lock_irqsave(&rdc321x_wdt_device.lock, flags);
        pci_write_config_dword(rdc321x_wdt_device.sb_pdev,
                rdc321x_wdt_device.base_reg, RDC_CLS_TMR);

        /* Enable watchdog and set the timeout to 81.92 us */
        pci_write_config_dword(rdc321x_wdt_device.sb_pdev,
                    rdc321x_wdt_device.base_reg,
                    RDC_WDT_EN | RDC_WDT_CNT);
        spin_unlock_irqrestore(&rdc321x_wdt_device.lock, flags);

        mod_timer(&rdc321x_wdt_device.timer,
                jiffies + RDC_WDT_INTERVAL);
    }

    /* if process dies, counter is not decremented */
    rdc321x_wdt_device.running++;
}

static int rdc321x_wdt_stop(void)
{
    if (rdc321x_wdt_device.running)
        rdc321x_wdt_device.running = 0;

    ticks = rdc321x_wdt_device.default_ticks;

    return -EIO;
}

/* filesystem operations */
static int rdc321x_wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(0, &rdc321x_wdt_device.inuse))
        return -EBUSY;

    return nonseekable_open(inode, file);
}

static int rdc321x_wdt_release(struct inode *inode, struct file *file)
{
    clear_bit(0, &rdc321x_wdt_device.inuse);
    return 0;
}

static long rdc321x_wdt_ioctl(struct file *file, unsigned int cmd,
                unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    u32 value;
    static const struct watchdog_info ident = {
        .options = WDIOF_CARDRESET,
        .identity = "RDC321x WDT",
    };
    unsigned long flags;

    switch (cmd) {
    case WDIOC_KEEPALIVE:
        rdc321x_wdt_reset();
        break;
    case WDIOC_GETSTATUS:
        /* Read the value from the DATA register */
        spin_lock_irqsave(&rdc321x_wdt_device.lock, flags);
        pci_read_config_dword(rdc321x_wdt_device.sb_pdev,
                    rdc321x_wdt_device.base_reg, &value);
        spin_unlock_irqrestore(&rdc321x_wdt_device.lock, flags);
        if (copy_to_user(argp, &value, sizeof(u32)))
            return -EFAULT;
        break;
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &ident, sizeof(ident)))
            return -EFAULT;
        break;
    case WDIOC_SETOPTIONS:
        if (copy_from_user(&value, argp, sizeof(int)))
            return -EFAULT;
        switch (value) {
        case WDIOS_ENABLECARD:
            rdc321x_wdt_start();
            break;
        case WDIOS_DISABLECARD:
            return rdc321x_wdt_stop();
        default:
            return -EINVAL;
        }
        break;
    default:
        return -ENOTTY;
    }
    return 0;
}

static ssize_t rdc321x_wdt_write(struct file *file, const char __user *buf,
                size_t count, loff_t *ppos)
{
    if (!count)
        return -EIO;

    rdc321x_wdt_reset();

    return count;
}

static const struct file_operations rdc321x_wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .unlocked_ioctl = rdc321x_wdt_ioctl,
    .open       = rdc321x_wdt_open,
    .write      = rdc321x_wdt_write,
    .release    = rdc321x_wdt_release,
};

static struct miscdevice rdc321x_wdt_misc = {
    .minor  = WATCHDOG_MINOR,
    .name   = "watchdog",
    .fops   = &rdc321x_wdt_fops,
};

static int __devinit rdc321x_wdt_probe(struct platform_device *pdev)
{
    int err;
    struct resource *r;
    struct rdc321x_wdt_pdata *pdata;

    pdata = pdev->dev.platform_data;
    if (!pdata) {
        dev_err(&pdev->dev, "no platform data supplied\n");
        return -ENODEV;
    }

    r = platform_get_resource_byname(pdev, IORESOURCE_IO, "wdt-reg");
    if (!r) {
        dev_err(&pdev->dev, "failed to get wdt-reg resource\n");
        return -ENODEV;
    }

    rdc321x_wdt_device.sb_pdev = pdata->sb_pdev;
    rdc321x_wdt_device.base_reg = r->start;

    err = misc_register(&rdc321x_wdt_misc);
    if (err < 0) {
        dev_err(&pdev->dev, "misc_register failed\n");
        return err;
    }

    spin_lock_init(&rdc321x_wdt_device.lock);

    /* Reset the watchdog */
    pci_write_config_dword(rdc321x_wdt_device.sb_pdev,
                rdc321x_wdt_device.base_reg, RDC_WDT_RST);

    init_completion(&rdc321x_wdt_device.stop);
    rdc321x_wdt_device.queue = 0;

    clear_bit(0, &rdc321x_wdt_device.inuse);

    setup_timer(&rdc321x_wdt_device.timer, rdc321x_wdt_trigger, 0);

    rdc321x_wdt_device.default_ticks = ticks;

    dev_info(&pdev->dev, "watchdog init success\n");

    return 0;
}

static int __devexit rdc321x_wdt_remove(struct platform_device *pdev)
{
    if (rdc321x_wdt_device.queue) {
        rdc321x_wdt_device.queue = 0;
        wait_for_completion(&rdc321x_wdt_device.stop);
    }

    misc_deregister(&rdc321x_wdt_misc);

    return 0;
}

static struct platform_driver rdc321x_wdt_driver = {
    .probe = rdc321x_wdt_probe,
    .remove = __devexit_p(rdc321x_wdt_remove),
    .driver = {
        .owner = THIS_MODULE,
        .name = "rdc321x-wdt",
    },
};

module_platform_driver(rdc321x_wdt_driver);

MODULE_AUTHOR("Florian Fainelli <[email protected]>");
MODULE_DESCRIPTION("RDC321x watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);