/*
* mpc83xx_wdt.c - MPC83xx watchdog userspace interface
*
* Authors: Dave Updegraff <dave@cray.org>
* Kumar Gala <galak@kernel.crashing.org>
* Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
* ..and from sc520_wdt
*
* Note: it appears that you can only actually ENABLE or DISABLE the thing
* once after POR. Once enabled, you cannot disable, and vice versa.
*
* 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.
*/
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <asm/io.h>
#include <asm/uaccess.h>
struct mpc83xx_wdt {
__be32 res0;
__be32 swcrr; /* System watchdog control register */
#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
__be32 swcnr; /* System watchdog count register */
u8 res1[2];
__be16 swsrr; /* System watchdog service register */
u8 res2[0xF0];
};
static struct mpc83xx_wdt __iomem *wd_base;
static u16 timeout = 0xffff;
module_param(timeout, ushort, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in ticks. (0<timeout<65536, default=65535");
static int reset = 1;
module_param(reset, bool, 0);
MODULE_PARM_DESC(reset, "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
/*
* We always prescale, but if someone really doesn't want to they can set this
* to 0
*/
static int prescale = 1;
static unsigned int timeout_sec;
static unsigned long wdt_is_open;
static spinlock_t wdt_spinlock;
static void mpc83xx_wdt_keepalive(void)
{
/* Ping the WDT */
spin_lock(&wdt_spinlock);
out_be16(&wd_base->swsrr, 0x556c);
out_be16(&wd_base->swsrr, 0xaa39);
spin_unlock(&wdt_spinlock);
}
static ssize_t mpc83xx_wdt_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
if (count)
mpc83xx_wdt_keepalive();
return count;
}
static int mpc83xx_wdt_open(struct inode *inode, struct file *file)
{
u32 tmp = SWCRR_SWEN;
if (test_and_set_bit(0, &wdt_is_open))
return -EBUSY;
/* Once we start the watchdog we can't stop it */
__module_get(THIS_MODULE);
/* Good, fire up the show */
if (prescale)
tmp |= SWCRR_SWPR;
if (reset)
tmp |= SWCRR_SWRI;
tmp |= timeout << 16;
out_be32(&wd_base->swcrr, tmp);
return nonseekable_open(inode, file);
}
static int mpc83xx_wdt_release(struct inode *inode, struct file *file)
{
printk(KERN_CRIT "Unexpected close, not stopping watchdog!\n");
mpc83xx_wdt_keepalive();
clear_bit(0, &wdt_is_open);
return 0;
}
static int mpc83xx_wdt_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
static struct watchdog_info ident = {
.options = WDIOF_KEEPALIVEPING,
.firmware_version = 1,
.identity = "MPC83xx",
};
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
case WDIOC_KEEPALIVE:
mpc83xx_wdt_keepalive();
return 0;
case WDIOC_GETTIMEOUT:
return put_user(timeout_sec, p);
default:
return -ENOTTY;
}
}
static const struct file_operations mpc83xx_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = mpc83xx_wdt_write,
.ioctl = mpc83xx_wdt_ioctl,
.open = mpc83xx_wdt_open,
.release = mpc83xx_wdt_release,
};
static struct miscdevice mpc83xx_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &mpc83xx_wdt_fops,
};
static int __devinit mpc83xx_wdt_probe(struct platform_device *dev)
{
struct resource *r;
int ret;
unsigned int *freq = dev->dev.platform_data;
/* get a pointer to the register memory */
r = platform_get_resource(dev, IORESOURCE_MEM, 0);
if (!r) {
ret = -ENODEV;
goto err_out;
}
wd_base = ioremap(r->start, sizeof (struct mpc83xx_wdt));
if (wd_base == NULL) {
ret = -ENOMEM;
goto err_out;
}
ret = misc_register(&mpc83xx_wdt_miscdev);
if (ret) {
printk(KERN_ERR "cannot register miscdev on minor=%d "
"(err=%d)\n",
WATCHDOG_MINOR, ret);
goto err_unmap;
}
/* Calculate the timeout in seconds */
if (prescale)
timeout_sec = (timeout * 0x10000) / (*freq);
else
timeout_sec = timeout / (*freq);
printk(KERN_INFO "WDT driver for MPC83xx initialized. "
"mode:%s timeout=%d (%d seconds)\n",
reset ? "reset":"interrupt", timeout, timeout_sec);
spin_lock_init(&wdt_spinlock);
return 0;
err_unmap:
iounmap(wd_base);
err_out:
return ret;
}
static int __devexit mpc83xx_wdt_remove(struct platform_device *dev)
{
misc_deregister(&mpc83xx_wdt_miscdev);
iounmap(wd_base);
return 0;
}
static struct platform_driver mpc83xx_wdt_driver = {
.probe = mpc83xx_wdt_probe,
.remove = __devexit_p(mpc83xx_wdt_remove),
.driver = {
.name = "mpc83xx_wdt",
},
};
static int __init mpc83xx_wdt_init(void)
{
return platform_driver_register(&mpc83xx_wdt_driver);
}
static void __exit mpc83xx_wdt_exit(void)
{
platform_driver_unregister(&mpc83xx_wdt_driver);
}
module_init(mpc83xx_wdt_init);
module_exit(mpc83xx_wdt_exit);
MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
MODULE_DESCRIPTION("Driver for watchdog timer in MPC83xx uProcessor");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
