/*
* Watchdog driver for SiByte SB1 SoCs
*
* Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <[email protected]>
*
* This driver is intended to make the second of two hardware watchdogs
* on the Sibyte 12XX and 11XX SoCs available to the user. There are two
* such devices available on the SoC, but it seems that there isn't an
* enumeration class for watchdogs in Linux like there is for RTCs.
* The second is used rather than the first because it uses IRQ 1,
* thereby avoiding all that IRQ 0 problematic nonsense.
*
* I have not tried this driver on a 1480 processor; it might work
* just well enough to really screw things up.
*
* It is a simple timer, and there is an interrupt that is raised the
* first time the timer expires. The second time it expires, the chip
* is reset and there is no way to redirect that NMI. Which could
* be problematic in some cases where this chip is sitting on the HT
* bus and has just taken responsibility for providing a cache block.
* Since the reset can't be redirected to the external reset pin, it is
* possible that other HT connected processors might hang and not reset.
* For Linux, a soft reset would probably be even worse than a hard reset.
* There you have it.
*
* The timer takes 23 bits of a 64 bit register (?) as a count value,
* and decrements the count every microsecond, for a max value of
* 0x7fffff usec or about 8.3ish seconds.
*
* This watchdog borrows some user semantics from the softdog driver,
* in that if you close the fd, it leaves the watchdog running, unless
* you previously wrote a 'V' to the fd, in which case it disables
* the watchdog when you close the fd like some other drivers.
*
* Based on various other watchdog drivers, which are probably all
* loosely based on something Alan Cox wrote years ago.
*
* (c) Copyright 1996 Alan Cox <[email protected]>,
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 1 or 2 as published by the Free Software Foundation.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/fs.h>
#include <linux/reboot.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/interrupt.h>
#include <asm/sibyte/sb1250.h>
#include <asm/sibyte/sb1250_regs.h>
#include <asm/sibyte/sb1250_int.h>
#include <asm/sibyte/sb1250_scd.h>
static DEFINE_SPINLOCK(sbwd_lock);
/*
* set the initial count value of a timer
*
* wdog is the iomem address of the cfg register
*/
static void sbwdog_set(char __iomem *wdog, unsigned long t)
{
spin_lock(&sbwd_lock);
__raw_writeb(0, wdog);
__raw_writeq(t & 0x7fffffUL, wdog - 0x10);
spin_unlock(&sbwd_lock);
}
/*
* cause the timer to [re]load it's initial count and start counting
* all over again
*
* wdog is the iomem address of the cfg register
*/
static void sbwdog_pet(char __iomem *wdog)
{
spin_lock(&sbwd_lock);
__raw_writeb(__raw_readb(wdog) | 1, wdog);
spin_unlock(&sbwd_lock);
}
static unsigned long sbwdog_gate; /* keeps it to one thread only */
static char __iomem *kern_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_0));
static char __iomem *user_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_1));
static unsigned long timeout = 0x7fffffUL; /* useconds: 8.3ish secs. */
static int expect_close;
static const struct watchdog_info ident = {
.options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT |
WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
.identity = "SiByte Watchdog",
};
/*
* Allow only a single thread to walk the dog
*/
static int sbwdog_open(struct inode *inode, struct file *file)
{
stream_open(inode, file);
if (test_and_set_bit(0, &sbwdog_gate))
return -EBUSY;
__module_get(THIS_MODULE);
/*
* Activate the timer
*/
sbwdog_set(user_dog, timeout);
__raw_writeb(1, user_dog);
return 0;
}
/*
* Put the dog back in the kennel.
*/
static int sbwdog_release(struct inode *inode, struct file *file)
{
if (expect_close == 42) {
__raw_writeb(0, user_dog);
module_put(THIS_MODULE);
} else {
pr_crit("%s: Unexpected close, not stopping watchdog!\n",
ident.identity);
sbwdog_pet(user_dog);
}
clear_bit(0, &sbwdog_gate);
expect_close = 0;
return 0;
}
/*
* 42 - the answer
*/
static ssize_t sbwdog_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
int i;
if (len) {
/*
* restart the timer
*/
expect_close = 0;
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
expect_close = 42;
}
sbwdog_pet(user_dog);
}
return len;
}
static long sbwdog_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int ret = -ENOTTY;
unsigned long time;
void __user *argp = (void __user *)arg;
int __user *p = argp;
switch (cmd) {
case WDIOC_GETSUPPORT:
ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
break;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
ret = put_user(0, p);
break;
case WDIOC_KEEPALIVE:
sbwdog_pet(user_dog);
ret = 0;
break;
case WDIOC_SETTIMEOUT:
ret = get_user(time, p);
if (ret)
break;
time *= 1000000;
if (time > 0x7fffffUL) {
ret = -EINVAL;
break;
}
timeout = time;
sbwdog_set(user_dog, timeout);
sbwdog_pet(user_dog);
fallthrough;
case WDIOC_GETTIMEOUT:
/*
* get the remaining count from the ... count register
* which is 1*8 before the config register
*/
ret = put_user((u32)__raw_readq(user_dog - 8) / 1000000, p);
break;
}
return ret;
}
/*
* Notifier for system down
*/
static int sbwdog_notify_sys(struct notifier_block *this, unsigned long code,
void *erf)
{
if (code == SYS_DOWN || code == SYS_HALT) {
/*
* sit and sit
*/
__raw_writeb(0, user_dog);
__raw_writeb(0, kern_dog);
}
return NOTIFY_DONE;
}
static const struct file_operations sbwdog_fops = {
.owner = THIS_MODULE,
.write = sbwdog_write,
.unlocked_ioctl = sbwdog_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.open = sbwdog_open,
.release = sbwdog_release,
};
static struct miscdevice sbwdog_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &sbwdog_fops,
};
static struct notifier_block sbwdog_notifier = {
.notifier_call = sbwdog_notify_sys,
};
/*
* interrupt handler
*
* doesn't do a whole lot for user, but oh so cleverly written so kernel
* code can use it to re-up the watchdog, thereby saving the kernel from
* having to create and maintain a timer, just to tickle another timer,
* which is just so wrong.
*/
irqreturn_t sbwdog_interrupt(int irq, void *addr)
{
unsigned long wd_init;
char *wd_cfg_reg = (char *)addr;
u8 cfg;
cfg = __raw_readb(wd_cfg_reg);
wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff;
/*
* if it's the second watchdog timer, it's for those users
*/
if (wd_cfg_reg == user_dog)
pr_crit("%s in danger of initiating system reset "
"in %ld.%01ld seconds\n",
ident.identity,
wd_init / 1000000, (wd_init / 100000) % 10);
else
cfg |= 1;
__raw_writeb(cfg, wd_cfg_reg);
return IRQ_HANDLED;
}
static int __init sbwdog_init(void)
{
int ret;
/*
* register a reboot notifier
*/
ret = register_reboot_notifier(&sbwdog_notifier);
if (ret) {
pr_err("%s: cannot register reboot notifier (err=%d)\n",
ident.identity, ret);
return ret;
}
/*
* get the resources
*/
ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED,
ident.identity, (void *)user_dog);
if (ret) {
pr_err("%s: failed to request irq 1 - %d\n",
ident.identity, ret);
goto out;
}
ret = misc_register(&sbwdog_miscdev);
if (ret == 0) {
pr_info("%s: timeout is %ld.%ld secs\n",
ident.identity,
timeout / 1000000, (timeout / 100000) % 10);
return 0;
}
free_irq(1, (void *)user_dog);
out:
unregister_reboot_notifier(&sbwdog_notifier);
return ret;
}
static void __exit sbwdog_exit(void)
{
misc_deregister(&sbwdog_miscdev);
free_irq(1, (void *)user_dog);
unregister_reboot_notifier(&sbwdog_notifier);
}
module_init(sbwdog_init);
module_exit(sbwdog_exit);
MODULE_AUTHOR("Andrew Sharp <[email protected]>");
MODULE_DESCRIPTION("SiByte Watchdog");
module_param(timeout, ulong, 0);
MODULE_PARM_DESC(timeout,
"Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)");
MODULE_LICENSE("GPL");
/*
* example code that can be put in a platform code area to utilize the
* first watchdog timer for the kernels own purpose.
void platform_wd_setup(void)
{
int ret;
ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED,
"Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
if (ret) {
pr_crit("Watchdog IRQ zero(0) failed to be requested - %d\n", ret);
}
}
*/
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