Commit 4e5c79da authored by Wim Van Sebroeck's avatar Wim Van Sebroeck

[WATCHDOG] sbc60xxwdt.c patch

general cleanup of trailing spaces and comments
fix possible wdt_is_open race
add KERN_* to printk's
changed watchdog_info to correctly reflect what the driver offers
added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
made timeout (the emulated heartbeat) a module_param
made the keepalive ping an internal subroutine
added MODULE_AUTHOR and MODULE_DESCRIPTION info
parent ca377000
......@@ -12,46 +12,33 @@
* any of this software. This material is provided "AS-IS" in
* the hope that it may be useful for others.
*
* (c) Copyright 2000 Jakob Oestergaard <jakob@ostenfeld.dk>
* (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net>
*
* 12/4 - 2000 [Initial revision]
* 25/4 - 2000 Added /dev/watchdog support
* 09/5 - 2001 [smj@oro.net] fixed fop_write to "return 1" on success
* 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read
* fix possible wdt_is_open race
* add CONFIG_WATCHDOG_NOWAYOUT support
* remove lock_kernel/unlock_kernel pairs
* added KERN_* to printk's
* got rid of extraneous comments
* changed watchdog_info to correctly reflect what the driver offers
* added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, WDIOC_SETTIMEOUT,
* WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
* 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces
* use module_param
* made timeout (the emulated heartbeat) a module_param
* made the keepalive ping an internal subroutine
* added MODULE_AUTHOR and MODULE_DESCRIPTION info
*
*
* Theory of operation:
* A Watchdog Timer (WDT) is a hardware circuit that can
* reset the computer system in case of a software fault.
* You probably knew that already.
*
* Usually a userspace daemon will notify the kernel WDT driver
* via the /proc/watchdog special device file that userspace is
* still alive, at regular intervals. When such a notification
* occurs, the driver will usually tell the hardware watchdog
* that everything is in order, and that the watchdog should wait
* for yet another little while to reset the system.
* If userspace fails (RAM error, kernel bug, whatever), the
* notifications cease to occur, and the hardware watchdog will
* reset the system (causing a reboot) after the timeout occurs.
*
* This WDT driver is different from the other Linux WDT
* drivers in several ways:
* drivers in the following ways:
* *) The driver will ping the watchdog by itself, because this
* particular WDT has a very short timeout (one second) and it
* would be insane to count on any userspace daemon always
* getting scheduled within that time frame.
* *) This driver expects the userspace daemon to send a specific
* character code ('V') to /dev/watchdog before closing the
* /dev/watchdog file. If the userspace daemon closes the file
* without sending this special character, the driver will assume
* that the daemon (and userspace in general) died, and will
* stop pinging the WDT without disabling it first. This will
* cause a reboot.
*
* Why `V' ? Well, `V' is the character in ASCII for the value 86,
* and we all know that 86 is _the_ most random number in the universe.
* Therefore it is the letter that has the slightest chance of occurring
* by chance, when the system becomes corrupted.
*
*/
......@@ -73,6 +60,7 @@
#include <asm/system.h>
#define OUR_NAME "sbc60xxwdt"
#define PFX OUR_NAME ": "
/*
* You must set these - The driver cannot probe for the settings
......@@ -92,19 +80,16 @@
/*
* We must not require too good response from the userspace daemon.
* Here we require the userspace daemon to send us a heartbeat
* char to /dev/watchdog every 10 seconds.
* If the daemon pulses us every 5 seconds, we can still afford
* char to /dev/watchdog every 30 seconds.
* If the daemon pulses us every 25 seconds, we can still afford
* a 5 second scheduling delay on the (high priority) daemon. That
* should be sufficient for a box under any load.
*/
#define WDT_HEARTBEAT (HZ * 10)
static void wdt_timer_ping(unsigned long);
static struct timer_list timer;
static unsigned long next_heartbeat;
static int wdt_is_open;
static int wdt_expect_close;
#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=WATCHDOG_TIMEOUT)");
#ifdef CONFIG_WATCHDOG_NOWAYOUT
static int nowayout = 1;
......@@ -115,6 +100,12 @@ static int nowayout = 0;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
static void wdt_timer_ping(unsigned long);
static struct timer_list timer;
static unsigned long next_heartbeat;
static unsigned long wdt_is_open;
static char wdt_expect_close;
/*
* Whack the dog
*/
......@@ -132,7 +123,7 @@ static void wdt_timer_ping(unsigned long data)
timer.expires = jiffies + WDT_INTERVAL;
add_timer(&timer);
} else {
printk(OUR_NAME ": Heartbeat lost! Will not ping the watchdog\n");
printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
}
}
......@@ -142,12 +133,12 @@ static void wdt_timer_ping(unsigned long data)
static void wdt_startup(void)
{
next_heartbeat = jiffies + WDT_HEARTBEAT;
next_heartbeat = jiffies + (timeout * HZ);
/* Start the timer */
timer.expires = jiffies + WDT_INTERVAL;
add_timer(&timer);
printk(OUR_NAME ": Watchdog timer is now enabled.\n");
printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
}
static void wdt_turnoff(void)
......@@ -155,9 +146,14 @@ static void wdt_turnoff(void)
/* Stop the timer */
del_timer(&timer);
inb_p(WDT_STOP);
printk(OUR_NAME ": Watchdog timer is now disabled...\n");
printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
}
static void wdt_keepalive(void)
{
/* user land ping */
next_heartbeat = jiffies + (timeout * HZ);
}
/*
* /dev/watchdog handling
......@@ -169,8 +165,10 @@ static ssize_t fop_write(struct file * file, const char * buf, size_t count, lof
if(ppos != &file->f_pos)
return -ESPIPE;
/* See if we got the magic character */
/* See if we got the magic character 'V' and reload the timer */
if(count)
{
if (!nowayout)
{
size_t ofs;
......@@ -178,54 +176,47 @@ static ssize_t fop_write(struct file * file, const char * buf, size_t count, lof
* five months ago... */
wdt_expect_close = 0;
/* now scan */
/* scan to see wether or not we got the magic character */
for(ofs = 0; ofs != count; ofs++)
{
char c;
if(get_user(c, buf+ofs))
return -EFAULT;
if(c == 'V')
wdt_expect_close = 1;
wdt_expect_close = 42;
}
}
/* Well, anyhow someone wrote to us, we should return that favour */
next_heartbeat = jiffies + WDT_HEARTBEAT;
return 1;
wdt_keepalive();
}
return 0;
return count;
}
static int fop_open(struct inode * inode, struct file * file)
{
switch(minor(inode->i_rdev))
{
case WATCHDOG_MINOR:
/* Just in case we're already talking to someone... */
if(wdt_is_open)
if(test_and_set_bit(0, &wdt_is_open))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
/* Good, fire up the show */
wdt_is_open = 1;
wdt_startup();
return 0;
default:
return -ENODEV;
}
}
static int fop_close(struct inode * inode, struct file * file)
{
if(minor(inode->i_rdev) == WATCHDOG_MINOR)
{
if(wdt_expect_close && !nowayout)
if(wdt_expect_close == 42)
wdt_turnoff();
else {
del_timer(&timer);
printk(OUR_NAME ": device file closed unexpectedly. Will not stop the WDT!\n");
}
printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
}
wdt_is_open = 0;
clear_bit(0, &wdt_is_open);
wdt_expect_close = 0;
return 0;
}
......@@ -234,9 +225,9 @@ static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
{
static struct watchdog_info ident=
{
.options = WDIOF_MAGICCLOSE,
.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
.firmware_version = 1,
.identity = "SB60xx"
.identity = "SBC60xx",
};
switch(cmd)
......@@ -245,9 +236,47 @@ static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
return -ENOTTY;
case WDIOC_GETSUPPORT:
return copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident))?-EFAULT:0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, (int *)arg);
case WDIOC_KEEPALIVE:
next_heartbeat = jiffies + WDT_HEARTBEAT;
wdt_keepalive();
return 0;
case WDIOC_SETOPTIONS:
{
int new_options, retval = -EINVAL;
if(get_user(new_options, (int *)arg))
return -EFAULT;
if(new_options & WDIOS_DISABLECARD) {
wdt_turnoff();
retval = 0;
}
if(new_options & WDIOS_ENABLECARD) {
wdt_startup();
retval = 0;
}
return retval;
}
case WDIOC_SETTIMEOUT:
{
int new_timeout;
if(get_user(new_timeout, (int *)arg))
return -EFAULT;
if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
return -EINVAL;
timeout = new_timeout;
wdt_keepalive();
/* Fall through */
}
case WDIOC_GETTIMEOUT:
return put_user(timeout, (int *)arg);
}
}
......@@ -257,13 +286,13 @@ static struct file_operations wdt_fops = {
.write = fop_write,
.open = fop_open,
.release = fop_close,
.ioctl = fop_ioctl
.ioctl = fop_ioctl,
};
static struct miscdevice wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &wdt_fops
.fops = &wdt_fops,
};
/*
......@@ -287,7 +316,7 @@ static struct notifier_block wdt_notifier=
{
.notifier_call = wdt_notify_sys,
.next = NULL,
.priority = 0
.priority = 0,
};
static void __exit sbc60xxwdt_unload(void)
......@@ -312,6 +341,13 @@ static int __init sbc60xxwdt_init(void)
if (!request_region(WDT_START, 1, "SBC 60XX WDT"))
goto err_out_region1;
if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
{
timeout = WATCHDOG_TIMEOUT;
printk (KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
timeout);
}
init_timer(&timer);
timer.function = wdt_timer_ping;
timer.data = 0;
......@@ -324,7 +360,7 @@ static int __init sbc60xxwdt_init(void)
if (rc)
goto err_out_miscdev;
printk(KERN_INFO OUR_NAME ": WDT driver for 60XX single board computer initialised.\n");
printk(KERN_INFO PFX "WDT driver for 60XX single board computer initialised.\n");
return 0;
......@@ -341,4 +377,6 @@ static int __init sbc60xxwdt_init(void)
module_init(sbc60xxwdt_init);
module_exit(sbc60xxwdt_unload);
MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
MODULE_LICENSE("GPL");
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