linux/drivers/s390/char/vmwatchdog.c
Heiko Carstens a53c8fab3f s390/comments: unify copyright messages and remove file names
Remove the file name from the comment at top of many files. In most
cases the file name was wrong anyway, so it's rather pointless.

Also unify the IBM copyright statement. We did have a lot of sightly
different statements and wanted to change them one after another
whenever a file gets touched. However that never happened. Instead
people start to take the old/"wrong" statements to use as a template
for new files.
So unify all of them in one go.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2012-07-20 11:15:04 +02:00

338 lines
8.1 KiB
C

/*
* Watchdog implementation based on z/VM Watchdog Timer API
*
* Copyright IBM Corp. 2004, 2009
*
* The user space watchdog daemon can use this driver as
* /dev/vmwatchdog to have z/VM execute the specified CP
* command when the timeout expires. The default command is
* "IPL", which which cause an immediate reboot.
*/
#define KMSG_COMPONENT "vmwatchdog"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/suspend.h>
#include <linux/watchdog.h>
#include <asm/ebcdic.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#define MAX_CMDLEN 240
#define MIN_INTERVAL 15
static char vmwdt_cmd[MAX_CMDLEN] = "IPL";
static bool vmwdt_conceal;
static bool vmwdt_nowayout = WATCHDOG_NOWAYOUT;
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
MODULE_DESCRIPTION("z/VM Watchdog Timer");
module_param_string(cmd, vmwdt_cmd, MAX_CMDLEN, 0644);
MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers");
module_param_named(conceal, vmwdt_conceal, bool, 0644);
MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog "
" is active");
module_param_named(nowayout, vmwdt_nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"
" (default=CONFIG_WATCHDOG_NOWAYOUT)");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
static unsigned int vmwdt_interval = 60;
static unsigned long vmwdt_is_open;
static int vmwdt_expect_close;
static DEFINE_MUTEX(vmwdt_mutex);
#define VMWDT_OPEN 0 /* devnode is open or suspend in progress */
#define VMWDT_RUNNING 1 /* The watchdog is armed */
enum vmwdt_func {
/* function codes */
wdt_init = 0,
wdt_change = 1,
wdt_cancel = 2,
/* flags */
wdt_conceal = 0x80000000,
};
static int __diag288(enum vmwdt_func func, unsigned int timeout,
char *cmd, size_t len)
{
register unsigned long __func asm("2") = func;
register unsigned long __timeout asm("3") = timeout;
register unsigned long __cmdp asm("4") = virt_to_phys(cmd);
register unsigned long __cmdl asm("5") = len;
int err;
err = -EINVAL;
asm volatile(
" diag %1,%3,0x288\n"
"0: la %0,0\n"
"1:\n"
EX_TABLE(0b,1b)
: "+d" (err) : "d"(__func), "d"(__timeout),
"d"(__cmdp), "d"(__cmdl) : "1", "cc");
return err;
}
static int vmwdt_keepalive(void)
{
/* we allocate new memory every time to avoid having
* to track the state. static allocation is not an
* option since that might not be contiguous in real
* storage in case of a modular build */
static char *ebc_cmd;
size_t len;
int ret;
unsigned int func;
ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
if (!ebc_cmd)
return -ENOMEM;
len = strlcpy(ebc_cmd, vmwdt_cmd, MAX_CMDLEN);
ASCEBC(ebc_cmd, MAX_CMDLEN);
EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
func = vmwdt_conceal ? (wdt_init | wdt_conceal) : wdt_init;
set_bit(VMWDT_RUNNING, &vmwdt_is_open);
ret = __diag288(func, vmwdt_interval, ebc_cmd, len);
WARN_ON(ret != 0);
kfree(ebc_cmd);
return ret;
}
static int vmwdt_disable(void)
{
int ret = __diag288(wdt_cancel, 0, "", 0);
WARN_ON(ret != 0);
clear_bit(VMWDT_RUNNING, &vmwdt_is_open);
return ret;
}
static int __init vmwdt_probe(void)
{
/* there is no real way to see if the watchdog is supported,
* so we try initializing it with a NOP command ("BEGIN")
* that won't cause any harm even if the following disable
* fails for some reason */
static char __initdata ebc_begin[] = {
194, 197, 199, 201, 213
};
if (__diag288(wdt_init, 15, ebc_begin, sizeof(ebc_begin)) != 0)
return -EINVAL;
return vmwdt_disable();
}
static int vmwdt_open(struct inode *i, struct file *f)
{
int ret;
if (test_and_set_bit(VMWDT_OPEN, &vmwdt_is_open))
return -EBUSY;
ret = vmwdt_keepalive();
if (ret)
clear_bit(VMWDT_OPEN, &vmwdt_is_open);
return ret ? ret : nonseekable_open(i, f);
}
static int vmwdt_close(struct inode *i, struct file *f)
{
if (vmwdt_expect_close == 42)
vmwdt_disable();
vmwdt_expect_close = 0;
clear_bit(VMWDT_OPEN, &vmwdt_is_open);
return 0;
}
static struct watchdog_info vmwdt_info = {
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
.firmware_version = 0,
.identity = "z/VM Watchdog Timer",
};
static int __vmwdt_ioctl(unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case WDIOC_GETSUPPORT:
if (copy_to_user((void __user *)arg, &vmwdt_info,
sizeof(vmwdt_info)))
return -EFAULT;
return 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, (int __user *)arg);
case WDIOC_GETTEMP:
return -EINVAL;
case WDIOC_SETOPTIONS:
{
int options, ret;
if (get_user(options, (int __user *)arg))
return -EFAULT;
ret = -EINVAL;
if (options & WDIOS_DISABLECARD) {
ret = vmwdt_disable();
if (ret)
return ret;
}
if (options & WDIOS_ENABLECARD) {
ret = vmwdt_keepalive();
}
return ret;
}
case WDIOC_GETTIMEOUT:
return put_user(vmwdt_interval, (int __user *)arg);
case WDIOC_SETTIMEOUT:
{
int interval;
if (get_user(interval, (int __user *)arg))
return -EFAULT;
if (interval < MIN_INTERVAL)
return -EINVAL;
vmwdt_interval = interval;
}
return vmwdt_keepalive();
case WDIOC_KEEPALIVE:
return vmwdt_keepalive();
}
return -EINVAL;
}
static long vmwdt_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
int rc;
mutex_lock(&vmwdt_mutex);
rc = __vmwdt_ioctl(cmd, arg);
mutex_unlock(&vmwdt_mutex);
return (long) rc;
}
static ssize_t vmwdt_write(struct file *f, const char __user *buf,
size_t count, loff_t *ppos)
{
if(count) {
if (!vmwdt_nowayout) {
size_t i;
/* note: just in case someone wrote the magic character
* five months ago... */
vmwdt_expect_close = 0;
for (i = 0; i != count; i++) {
char c;
if (get_user(c, buf+i))
return -EFAULT;
if (c == 'V')
vmwdt_expect_close = 42;
}
}
/* someone wrote to us, we should restart timer */
vmwdt_keepalive();
}
return count;
}
static int vmwdt_resume(void)
{
clear_bit(VMWDT_OPEN, &vmwdt_is_open);
return NOTIFY_DONE;
}
/*
* It makes no sense to go into suspend while the watchdog is running.
* Depending on the memory size, the watchdog might trigger, while we
* are still saving the memory.
* We reuse the open flag to ensure that suspend and watchdog open are
* exclusive operations
*/
static int vmwdt_suspend(void)
{
if (test_and_set_bit(VMWDT_OPEN, &vmwdt_is_open)) {
pr_err("The system cannot be suspended while the watchdog"
" is in use\n");
return notifier_from_errno(-EBUSY);
}
if (test_bit(VMWDT_RUNNING, &vmwdt_is_open)) {
clear_bit(VMWDT_OPEN, &vmwdt_is_open);
pr_err("The system cannot be suspended while the watchdog"
" is running\n");
return notifier_from_errno(-EBUSY);
}
return NOTIFY_DONE;
}
/*
* This function is called for suspend and resume.
*/
static int vmwdt_power_event(struct notifier_block *this, unsigned long event,
void *ptr)
{
switch (event) {
case PM_POST_HIBERNATION:
case PM_POST_SUSPEND:
return vmwdt_resume();
case PM_HIBERNATION_PREPARE:
case PM_SUSPEND_PREPARE:
return vmwdt_suspend();
default:
return NOTIFY_DONE;
}
}
static struct notifier_block vmwdt_power_notifier = {
.notifier_call = vmwdt_power_event,
};
static const struct file_operations vmwdt_fops = {
.open = &vmwdt_open,
.release = &vmwdt_close,
.unlocked_ioctl = &vmwdt_ioctl,
.write = &vmwdt_write,
.owner = THIS_MODULE,
.llseek = noop_llseek,
};
static struct miscdevice vmwdt_dev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &vmwdt_fops,
};
static int __init vmwdt_init(void)
{
int ret;
ret = vmwdt_probe();
if (ret)
return ret;
ret = register_pm_notifier(&vmwdt_power_notifier);
if (ret)
return ret;
/*
* misc_register() has to be the last action in module_init(), because
* file operations will be available right after this.
*/
ret = misc_register(&vmwdt_dev);
if (ret) {
unregister_pm_notifier(&vmwdt_power_notifier);
return ret;
}
return 0;
}
module_init(vmwdt_init);
static void __exit vmwdt_exit(void)
{
unregister_pm_notifier(&vmwdt_power_notifier);
misc_deregister(&vmwdt_dev);
}
module_exit(vmwdt_exit);