/*
* mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx 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
* Copyright (c) 2008 MontaVista Software, Inc.
* Anton Vorontsov <avorontsov@ru.mvista.com>
*
* 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/timer.h>
#include <linux/miscdevice.h>
#include <linux/of_platform.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <sysdev/fsl_soc.h>
struct mpc8xxx_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];
};
struct mpc8xxx_wdt_type {
int prescaler;
bool hw_enabled;
};
static struct mpc8xxx_wdt __iomem *wd_base;
static int mpc8xxx_wdt_init_late(void);
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");
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
/*
* 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 DEFINE_SPINLOCK(wdt_spinlock);
static void mpc8xxx_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 void mpc8xxx_wdt_timer_ping(unsigned long arg);
static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
static void mpc8xxx_wdt_timer_ping(unsigned long arg)
{
mpc8xxx_wdt_keepalive();
/* We're pinging it twice faster than needed, just to be sure. */
mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
}
static void mpc8xxx_wdt_pr_warn(const char *msg)
{
pr_crit("mpc8xxx_wdt: %s, expect the %s soon!\n", msg,
reset ? "reset" : "machine check exception");
}
static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
if (count)
mpc8xxx_wdt_keepalive();
return count;
}
static int mpc8xxx_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 */
if (nowayout)
__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);
del_timer_sync(&wdt_timer);
return nonseekable_open(inode, file);
}
static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
{
if (!nowayout)
mpc8xxx_wdt_timer_ping(0);
else
mpc8xxx_wdt_pr_warn("watchdog closed");
clear_bit(0, &wdt_is_open);
return 0;
}
static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
static const struct watchdog_info ident = {
.options = WDIOF_KEEPALIVEPING,
.firmware_version = 1,
.identity = "MPC8xxx",
};
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p);
case WDIOC_KEEPALIVE:
mpc8xxx_wdt_keepalive();
return 0;
case WDIOC_GETTIMEOUT:
return put_user(timeout_sec, p);
default:
return -ENOTTY;
}
}
static const struct file_operations mpc8xxx_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = mpc8xxx_wdt_write,
.unlocked_ioctl = mpc8xxx_wdt_ioctl,
.open = mpc8xxx_wdt_open,
.release = mpc8xxx_wdt_release,
};
static struct miscdevice mpc8xxx_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &mpc8xxx_wdt_fops,
};
static int __devinit mpc8xxx_wdt_probe(struct of_device *ofdev,
const struct of_device_id *match)
{
int ret;
struct device_node *np = ofdev->dev.of_node;
struct mpc8xxx_wdt_type *wdt_type = match->data;
u32 freq = fsl_get_sys_freq();
bool enabled;
if (!freq || freq == -1)
return -EINVAL;
wd_base = of_iomap(np, 0);
if (!wd_base)
return -ENOMEM;
enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
if (!enabled && wdt_type->hw_enabled) {
pr_info("mpc8xxx_wdt: could not be enabled in software\n");
ret = -ENOSYS;
goto err_unmap;
}
/* Calculate the timeout in seconds */
if (prescale)
timeout_sec = (timeout * wdt_type->prescaler) / freq;
else
timeout_sec = timeout / freq;
#ifdef MODULE
ret = mpc8xxx_wdt_init_late();
if (ret)
goto err_unmap;
#endif
pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d "
"(%d seconds)\n", reset ? "reset" : "interrupt", timeout,
timeout_sec);
/*
* If the watchdog was previously enabled or we're running on
* MPC8xxx, we should ping the wdt from the kernel until the
* userspace handles it.
*/
if (enabled)
mpc8xxx_wdt_timer_ping(0);
return 0;
err_unmap:
iounmap(wd_base);
wd_base = NULL;
return ret;
}
static int __devexit mpc8xxx_wdt_remove(struct of_device *ofdev)
{
mpc8xxx_wdt_pr_warn("watchdog removed");
del_timer_sync(&wdt_timer);
misc_deregister(&mpc8xxx_wdt_miscdev);
iounmap(wd_base);
return 0;
}
static const struct of_device_id mpc8xxx_wdt_match[] = {
{
.compatible = "mpc83xx_wdt",
.data = &(struct mpc8xxx_wdt_type) {
.prescaler = 0x10000,
},
},
{
.compatible = "fsl,mpc8610-wdt",
.data = &(struct mpc8xxx_wdt_type) {
.prescaler = 0x10000,
.hw_enabled = true,
},
},
{
.compatible = "fsl,mpc823-wdt",
.data = &(struct mpc8xxx_wdt_type) {
.prescaler = 0x800,
},
},
{},
};
MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
static struct of_platform_driver mpc8xxx_wdt_driver = {
.probe = mpc8xxx_wdt_probe,
.remove = __devexit_p(mpc8xxx_wdt_remove),
.driver = {
.name = "mpc8xxx_wdt",
.owner = THIS_MODULE,
.of_match_table = mpc8xxx_wdt_match,
},
};
/*
* We do wdt initialization in two steps: arch_initcall probes the wdt
* very early to start pinging the watchdog (misc devices are not yet
* available), and later module_init() just registers the misc device.
*/
static int mpc8xxx_wdt_init_late(void)
{
int ret;
if (!wd_base)
return -ENODEV;
ret = misc_register(&mpc8xxx_wdt_miscdev);
if (ret) {
pr_err("cannot register miscdev on minor=%d (err=%d)\n",
WATCHDOG_MINOR, ret);
return ret;
}
return 0;
}
#ifndef MODULE
module_init(mpc8xxx_wdt_init_late);
#endif
static int __init mpc8xxx_wdt_init(void)
{
return of_register_platform_driver(&mpc8xxx_wdt_driver);
}
arch_initcall(mpc8xxx_wdt_init);
static void __exit mpc8xxx_wdt_exit(void)
{
of_unregister_platform_driver(&mpc8xxx_wdt_driver);
}
module_exit(mpc8xxx_wdt_exit);
MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
"uProcessors");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
