riowd.c

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/* riowd.c - driver for hw watchdog inside Super I/O of RIO
 *
 * Copyright (C) 2001, 2008 David S. Miller ([email protected])
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/slab.h>


/* RIO uses the NatSemi Super I/O power management logical device
 * as its' watchdog.
 *
 * When the watchdog triggers, it asserts a line to the BBC (Boot Bus
 * Controller) of the machine.  The BBC can only be configured to
 * trigger a power-on reset when the signal is asserted.  The BBC
 * can be configured to ignore the signal entirely as well.
 *
 * The only Super I/O device register we care about is at index
 * 0x05 (WDTO_INDEX) which is the watchdog time-out in minutes (1-255).
 * If set to zero, this disables the watchdog.  When set, the system
 * must periodically (before watchdog expires) clear (set to zero) and
 * re-set the watchdog else it will trigger.
 *
 * There are two other indexed watchdog registers inside this Super I/O
 * logical device, but they are unused.  The first, at index 0x06 is
 * the watchdog control and can be used to make the watchdog timer re-set
 * when the PS/2 mouse or serial lines show activity.  The second, at
 * index 0x07 is merely a sampling of the line from the watchdog to the
 * BBC.
 *
 * The watchdog device generates no interrupts.
 */

MODULE_AUTHOR("David S. Miller <[email protected]>");
MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
MODULE_SUPPORTED_DEVICE("watchdog");
MODULE_LICENSE("GPL");

#define DRIVER_NAME "riowd"
#define PFX     DRIVER_NAME ": "

struct riowd {
    void __iomem        *regs;
    spinlock_t      lock;
};

static struct riowd *riowd_device;

#define WDTO_INDEX  0x05

static int riowd_timeout = 1;       /* in minutes */
module_param(riowd_timeout, int, 0);
MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");

static void riowd_writereg(struct riowd *p, u8 val, int index)
{
    unsigned long flags;

    spin_lock_irqsave(&p->lock, flags);
    writeb(index, p->regs + 0);
    writeb(val, p->regs + 1);
    spin_unlock_irqrestore(&p->lock, flags);
}

static int riowd_open(struct inode *inode, struct file *filp)
{
    nonseekable_open(inode, filp);
    return 0;
}

static int riowd_release(struct inode *inode, struct file *filp)
{
    return 0;
}

static long riowd_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
    static const struct watchdog_info info = {
        .options        = WDIOF_SETTIMEOUT,
        .firmware_version   = 1,
        .identity       = DRIVER_NAME,
    };
    void __user *argp = (void __user *)arg;
    struct riowd *p = riowd_device;
    unsigned int options;
    int new_margin;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &info, sizeof(info)))
            return -EFAULT;
        break;

    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        if (put_user(0, (int __user *)argp))
            return -EFAULT;
        break;

    case WDIOC_KEEPALIVE:
        riowd_writereg(p, riowd_timeout, WDTO_INDEX);
        break;

    case WDIOC_SETOPTIONS:
        if (copy_from_user(&options, argp, sizeof(options)))
            return -EFAULT;

        if (options & WDIOS_DISABLECARD)
            riowd_writereg(p, 0, WDTO_INDEX);
        else if (options & WDIOS_ENABLECARD)
            riowd_writereg(p, riowd_timeout, WDTO_INDEX);
        else
            return -EINVAL;

        break;

    case WDIOC_SETTIMEOUT:
        if (get_user(new_margin, (int __user *)argp))
            return -EFAULT;
        if ((new_margin < 60) || (new_margin > (255 * 60)))
            return -EINVAL;
        riowd_timeout = (new_margin + 59) / 60;
        riowd_writereg(p, riowd_timeout, WDTO_INDEX);
        /* Fall */

    case WDIOC_GETTIMEOUT:
        return put_user(riowd_timeout * 60, (int __user *)argp);

    default:
        return -EINVAL;
    };

    return 0;
}

static ssize_t riowd_write(struct file *file, const char __user *buf,
                        size_t count, loff_t *ppos)
{
    struct riowd *p = riowd_device;

    if (count) {
        riowd_writereg(p, riowd_timeout, WDTO_INDEX);
        return 1;
    }

    return 0;
}

static const struct file_operations riowd_fops = {
    .owner =        THIS_MODULE,
    .llseek =       no_llseek,
    .unlocked_ioctl =   riowd_ioctl,
    .open =         riowd_open,
    .write =        riowd_write,
    .release =      riowd_release,
};

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

static int __devinit riowd_probe(struct platform_device *op)
{
    struct riowd *p;
    int err = -EINVAL;

    if (riowd_device)
        goto out;

    err = -ENOMEM;
    p = kzalloc(sizeof(*p), GFP_KERNEL);
    if (!p)
        goto out;

    spin_lock_init(&p->lock);

    p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
    if (!p->regs) {
        pr_err("Cannot map registers\n");
        goto out_free;
    }
    /* Make miscdev useable right away */
    riowd_device = p;

    err = misc_register(&riowd_miscdev);
    if (err) {
        pr_err("Cannot register watchdog misc device\n");
        goto out_iounmap;
    }

    pr_info("Hardware watchdog [%i minutes], regs at %p\n",
        riowd_timeout, p->regs);

    dev_set_drvdata(&op->dev, p);
    return 0;

out_iounmap:
    riowd_device = NULL;
    of_iounmap(&op->resource[0], p->regs, 2);

out_free:
    kfree(p);

out:
    return err;
}

static int __devexit riowd_remove(struct platform_device *op)
{
    struct riowd *p = dev_get_drvdata(&op->dev);

    misc_deregister(&riowd_miscdev);
    of_iounmap(&op->resource[0], p->regs, 2);
    kfree(p);

    return 0;
}

static const struct of_device_id riowd_match[] = {
    {
        .name = "pmc",
    },
    {},
};
MODULE_DEVICE_TABLE(of, riowd_match);

static struct platform_driver riowd_driver = {
    .driver = {
        .name = DRIVER_NAME,
        .owner = THIS_MODULE,
        .of_match_table = riowd_match,
    },
    .probe      = riowd_probe,
    .remove     = __devexit_p(riowd_remove),
};

module_platform_driver(riowd_driver);