[WATCHDOG] hpwdt: Add NMI sourcing

Add NMI sourcing functionality (Can only be active if nmi_watchdog is
inactive).
Signed-off-by: Thomas Mingarelli <thomas.mingarelli@hp.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

Documentation/watchdog/hpwdt.txt

+Last reviewed: 06/02/2009
+
+                     HP iLO2 NMI Watchdog Driver
+              NMI sourcing for iLO2 based ProLiant Servers
+                     Documentation and Driver by
+              Thomas Mingarelli <thomas.mingarelli@hp.com>
+
+ The HP iLO2 NMI Watchdog driver is a kernel module that provides basic
+ watchdog functionality and the added benefit of NMI sourcing. Both the
+ watchdog functionality and the NMI sourcing capability need to be enabled
+ by the user. Remember that the two modes are not dependant on one another.
+ A user can have the NMI sourcing without the watchdog timer and vice-versa.
+
+ Watchdog functionality is enabled like any other common watchdog driver. That
+ is, an application needs to be started that kicks off the watchdog timer. A
+ basic application exists in the Documentation/watchdog/src directory called
+ watchdog-test.c. Simply compile the C file and kick it off. If the system
+ gets into a bad state and hangs, the HP ProLiant iLO 2 timer register will
+ 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:
+
+ 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.
+
+ 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
+ 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.
+
+ 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
+
+ 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).
+
+ Below is a list of NMIs the HP BIOS understands along with the associated
+ code (reason):
+
+	No source found                00h
+
+	Uncorrectable Memory Error     01h
+
+	ASR NMI                        1Bh
+
+	PCI Parity Error               20h
+
+	NMI Button Press               27h
+
+	SB_BUS_NMI                     28h
+
+	ILO Doorbell NMI               29h
+
+	ILO IOP NMI                    2Ah
+
+	ILO Watchdog NMI               2Bh
+
+	Proc Throt NMI                 2Ch
+
+	Front Side Bus NMI             2Dh
+
+	PCI Express Error              2Fh
+
+	DMA controller NMI             30h
+
+	Hypertransport/CSI Error       31h
+
+
+
+ -- Tom Mingarelli
+    (thomas.mingarelli@hp.com)

drivers/watchdog/hpwdt.c

@@ -19,6 +19,7 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/irq.h>
+#include <linux/nmi.h>
 #include <linux/kernel.h>
 #include <linux/miscdevice.h>
 #include <linux/mm.h>
@@ -47,7 +48,7 @@
 #define PCI_BIOS32_PARAGRAPH_LEN	16
 #define PCI_ROM_BASE1			0x000F0000
 #define ROM_SIZE			0x10000
-#define HPWDT_VERSION			"1.01"
+#define HPWDT_VERSION			"1.1.1"
 
 struct bios32_service_dir {
 	u32 signature;
@@ -119,6 +120,7 @@ static int nowayout = WATCHDOG_NOWAYOUT;
 static char expect_release;
 static unsigned long hpwdt_is_open;
 static unsigned int allow_kdump;
+static int hpwdt_nmi_sourcing;
 
 static void __iomem *pci_mem_addr;		/* the PCI-memory address */
 static unsigned long __iomem *hpwdt_timer_reg;
@@ -468,21 +470,22 @@ static int hpwdt_pretimeout(struct notifier_block *nb, unsigned long ulReason,
 	if (ulReason != DIE_NMI && ulReason != DIE_NMI_IPI)
 		return NOTIFY_OK;
 
-	spin_lock_irqsave(&rom_lock, rom_pl);
-	if (!die_nmi_called)
-		asminline_call(&cmn_regs, cru_rom_addr);
-	die_nmi_called = 1;
-	spin_unlock_irqrestore(&rom_lock, rom_pl);
-	if (cmn_regs.u1.ral == 0) {
-		printk(KERN_WARNING "hpwdt: An NMI occurred, "
-			"but unable to determine source.\n");
-	} else {
-		if (allow_kdump)
-			hpwdt_stop();
-		panic("An NMI occurred, please see the Integrated "
-			"Management Log for details.\n");
+	if (hpwdt_nmi_sourcing) {
+		spin_lock_irqsave(&rom_lock, rom_pl);
+		if (!die_nmi_called)
+			asminline_call(&cmn_regs, cru_rom_addr);
+		die_nmi_called = 1;
+		spin_unlock_irqrestore(&rom_lock, rom_pl);
+		if (cmn_regs.u1.ral == 0) {
+			printk(KERN_WARNING "hpwdt: An NMI occurred, "
+				"but unable to determine source.\n");
+		} else {
+			if (allow_kdump)
+				hpwdt_stop();
+			panic("An NMI occurred, please see the Integrated "
+				"Management Log for details.\n");
+		}
 	}
-
 	return NOTIFY_OK;
 }
 
@@ -627,11 +630,37 @@ static struct notifier_block die_notifier = {
  *	Init & Exit
  */
 
+#ifdef ARCH_HAS_NMI_WATCHDOG
+static void __devinit hpwdt_check_nmi_sourcing(struct pci_dev *dev)
+{
+	/*
+	 * If nmi_watchdog is turned off then we can turn on
+	 * our nmi sourcing capability.
+	 */
+	if (!nmi_watchdog_active())
+		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");
+}
+#else
+static void __devinit hpwdt_check_nmi_sourcing(struct pci_dev *dev)
+{
+	dev_warn(&dev->dev, "NMI sourcing is disabled. "
+		"Your kernel does not support a NMI Watchdog.\n");
+}
+#endif
+
 static int __devinit hpwdt_init_one(struct pci_dev *dev,
 					const struct pci_device_id *ent)
 {
 	int retval;
 
+	/*
+	 * Check if we can do NMI sourcing or not
+	 */
+	hpwdt_check_nmi_sourcing(dev);
+
 	/*
 	 * First let's find out if we are on an iLO2 server. We will
 	 * not run on a legacy ASM box.