[WATCHDOG] hpwdt: Add NMI priority option

 not be updated in a timely fashion and a hardware system reset (also known as

 an Automatic Server Recovery (ASR)) event will occur.

 The hpwdt driver also has three (3) module parameters. They are the following:

 The hpwdt driver also has four (4) module parameters. They are the following:

 soft_margin - allows the user to set the watchdog timer value

 allow_kdump - allows the user to save off a kernel dump image after an NMI

 nowayout    - basic watchdog parameter that does not allow the timer to

               be restarted or an impending ASR to be escaped.

 priority    - determines whether or not the hpwdt driver is first on the

               die_notify list to handle NMIs or last. The default value

               for this module parameter is 0 or LAST. If the user wants to

               enable NMI sourcing then reload the hpwdt driver with

               priority=1 (and boot with nmi_watchdog=0).

 NOTE: More information about watchdog drivers in general, including the ioctl

       interface to /dev/watchdog can be found in

       Documentation/watchdog/watchdog-api.txt and Documentation/IPMI.txt.

 The NMI sourcing capability is disabled when the driver discovers that the

 nmi_watchdog is turned on (nmi_watchdog = 1). This is due to the inability to

 The priority parameter was introduced due to other kernel software that relied

 on handling NMIs (like oprofile). Keeping hpwdt's priority at 0 (or LAST)

 enables the users of NMIs for non critical events to be work as expected.

 The NMI sourcing capability is disabled by default due to the inability to

 distinguish between "NMI Watchdog Ticks" and "HW generated NMI events" in the

 Linux kernel. What this means is that the hpwdt nmi handler code is called

 each time the NMI signal fires off. This could amount to several thousands of

 NMIs in a matter of seconds. If a user sees the Linux kernel's "dazed and

 confused" message in the logs or if the system gets into a hung state, then

 the user should reboot with nmi_watchdog=0.

 the hpwdt driver can be reloaded with the "priority" module parameter set

 (priority=1).

 1. If the kernel has not been booted with nmi_watchdog turned off then

    edit /boot/grub/menu.lst and place the nmi_watchdog=0 at the end of the

    currently booting kernel line.

 2. reboot the sever

 3. Once the system comes up perform a rmmod hpwdt

 4. insmod /lib/modules/`uname -r`/kernel/drivers/char/watchdog/hpwdt.ko priority=1

 Now, the hpwdt can successfully receive and source the NMI and provide a log

 message that details the reason for the NMI (as determined by the HP BIOS).

static char expect_release;

static unsigned long hpwdt_is_open;

static unsigned int allow_kdump;

static int hpwdt_nmi_sourcing;

static unsigned int hpwdt_nmi_sourcing;

static unsigned int priority;		/* hpwdt at end of die_notify list */

static void __iomem *pci_mem_addr;		/* the PCI-memory address */

static unsigned long __iomem *hpwdt_timer_reg;

static struct notifier_block die_notifier = {

	.notifier_call = hpwdt_pretimeout,

	.priority = 0x7FFFFFFF,

	.priority = 0,

};

/*

		hpwdt_nmi_sourcing = 1;

	else

		dev_warn(&dev->dev, "NMI sourcing is disabled. To enable this "

			"functionality you must reboot with nmi_watchdog=0.\n");

			"functionality you must reboot with nmi_watchdog=0 "

			"and load the hpwdt driver with priority=1.\n");

}

#else

static void __devinit hpwdt_check_nmi_sourcing(struct pci_dev *dev)

	cmn_regs.u1.rah = 0x0D;

	cmn_regs.u1.ral = 0x02;

	/*

	 * If the priority is set to 1, then we will be put first on the

	 * die notify list to handle a critical NMI. The default is to

	 * be last so other users of the NMI signal can function.

	 */

	if (priority)

		die_notifier.priority = 0x7FFFFFFF;

	retval = register_die_notifier(&die_notifier);

	if (retval != 0) {

		dev_warn(&dev->dev,

	printk(KERN_INFO

		"hp Watchdog Timer Driver: %s"

		", timer margin: %d seconds (nowayout=%d)"

		", allow kernel dump: %s (default = 0/OFF).\n",

		", allow kernel dump: %s (default = 0/OFF)"

		", priority: %s (default = 0/LAST).\n",

		HPWDT_VERSION, soft_margin, nowayout,

		(allow_kdump == 0) ? "OFF" : "ON");

		(allow_kdump == 0) ? "OFF" : "ON",

		(priority == 0) ? "LAST" : "FIRST");

	return 0;

MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="

		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

module_param(priority, int, 0);

MODULE_PARM_DESC(priority, "The hpwdt driver handles NMIs first or last"

		" (default = 0/Last)\n");

module_init(hpwdt_init);

module_exit(hpwdt_cleanup);