Fixed MTP to work with TWRP

Documentation/watchdog/Makefile

@@ -0,0 +1 @@
+subdir-y := src

Documentation/watchdog/convert_drivers_to_kernel_api.txt

@@ -0,0 +1,218 @@
+Converting old watchdog drivers to the watchdog framework
+by Wolfram Sang <w.sang@pengutronix.de>
+=========================================================
+
+Before the watchdog framework came into the kernel, every driver had to
+implement the API on its own. Now, as the framework factored out the common
+components, those drivers can be lightened making it a user of the framework.
+This document shall guide you for this task. The necessary steps are described
+as well as things to look out for.
+
+
+Remove the file_operations struct
+---------------------------------
+
+Old drivers define their own file_operations for actions like open(), write(),
+etc... These are now handled by the framework and just call the driver when
+needed. So, in general, the 'file_operations' struct and assorted functions can
+go. Only very few driver-specific details have to be moved to other functions.
+Here is a overview of the functions and probably needed actions:
+
+- open: Everything dealing with resource management (file-open checks, magic
+  close preparations) can simply go. Device specific stuff needs to go to the
+  driver specific start-function. Note that for some drivers, the start-function
+  also serves as the ping-function. If that is the case and you need start/stop
+  to be balanced (clocks!), you are better off refactoring a separate start-function.
+
+- close: Same hints as for open apply.
+
+- write: Can simply go, all defined behaviour is taken care of by the framework,
+  i.e. ping on write and magic char ('V') handling.
+
+- ioctl: While the driver is allowed to have extensions to the IOCTL interface,
+  the most common ones are handled by the framework, supported by some assistance
+  from the driver:
+
+	WDIOC_GETSUPPORT:
+		Returns the mandatory watchdog_info struct from the driver
+
+	WDIOC_GETSTATUS:
+		Needs the status-callback defined, otherwise returns 0
+
+	WDIOC_GETBOOTSTATUS:
+		Needs the bootstatus member properly set. Make sure it is 0 if you
+		don't have further support!
+
+	WDIOC_SETOPTIONS:
+		No preparations needed
+
+	WDIOC_KEEPALIVE:
+		If wanted, options in watchdog_info need to have WDIOF_KEEPALIVEPING
+		set
+
+	WDIOC_SETTIMEOUT:
+		Options in watchdog_info need to have WDIOF_SETTIMEOUT set
+		and a set_timeout-callback has to be defined. The core will also
+		do limit-checking, if min_timeout and max_timeout in the watchdog
+		device are set. All is optional.
+
+	WDIOC_GETTIMEOUT:
+		No preparations needed
+
+	WDIOC_GETTIMELEFT:
+		It needs get_timeleft() callback to be defined. Otherwise it
+		will return EOPNOTSUPP
+
+  Other IOCTLs can be served using the ioctl-callback. Note that this is mainly
+  intended for porting old drivers; new drivers should not invent private IOCTLs.
+  Private IOCTLs are processed first. When the callback returns with
+  -ENOIOCTLCMD, the IOCTLs of the framework will be tried, too. Any other error
+  is directly given to the user.
+
+Example conversion:
+
+-static const struct file_operations s3c2410wdt_fops = {
+-       .owner          = THIS_MODULE,
+-       .llseek         = no_llseek,
+-       .write          = s3c2410wdt_write,
+-       .unlocked_ioctl = s3c2410wdt_ioctl,
+-       .open           = s3c2410wdt_open,
+-       .release        = s3c2410wdt_release,
+-};
+
+Check the functions for device-specific stuff and keep it for later
+refactoring. The rest can go.
+
+
+Remove the miscdevice
+---------------------
+
+Since the file_operations are gone now, you can also remove the 'struct
+miscdevice'. The framework will create it on watchdog_dev_register() called by
+watchdog_register_device().
+
+-static struct miscdevice s3c2410wdt_miscdev = {
+-       .minor          = WATCHDOG_MINOR,
+-       .name           = "watchdog",
+-       .fops           = &s3c2410wdt_fops,
+-};
+
+
+Remove obsolete includes and defines
+------------------------------------
+
+Because of the simplifications, a few defines are probably unused now. Remove
+them. Includes can be removed, too. For example:
+
+- #include <linux/fs.h>
+- #include <linux/miscdevice.h> (if MODULE_ALIAS_MISCDEV is not used)
+- #include <linux/uaccess.h> (if no custom IOCTLs are used)
+
+
+Add the watchdog operations
+---------------------------
+
+All possible callbacks are defined in 'struct watchdog_ops'. You can find it
+explained in 'watchdog-kernel-api.txt' in this directory. start(), stop() and
+owner must be set, the rest are optional. You will easily find corresponding
+functions in the old driver. Note that you will now get a pointer to the
+watchdog_device as a parameter to these functions, so you probably have to
+change the function header. Other changes are most likely not needed, because
+here simply happens the direct hardware access. If you have device-specific
+code left from the above steps, it should be refactored into these callbacks.
+
+Here is a simple example:
+
++static struct watchdog_ops s3c2410wdt_ops = {
++       .owner = THIS_MODULE,
++       .start = s3c2410wdt_start,
++       .stop = s3c2410wdt_stop,
++       .ping = s3c2410wdt_keepalive,
++       .set_timeout = s3c2410wdt_set_heartbeat,
++};
+
+A typical function-header change looks like:
+
+-static void s3c2410wdt_keepalive(void)
++static int s3c2410wdt_keepalive(struct watchdog_device *wdd)
+ {
+...
++
++       return 0;
+ }
+
+...
+
+-       s3c2410wdt_keepalive();
++       s3c2410wdt_keepalive(&s3c2410_wdd);
+
+
+Add the watchdog device
+-----------------------
+
+Now we need to create a 'struct watchdog_device' and populate it with the
+necessary information for the framework. The struct is also explained in detail
+in 'watchdog-kernel-api.txt' in this directory. We pass it the mandatory
+watchdog_info struct and the newly created watchdog_ops. Often, old drivers
+have their own record-keeping for things like bootstatus and timeout using
+static variables. Those have to be converted to use the members in
+watchdog_device. Note that the timeout values are unsigned int. Some drivers
+use signed int, so this has to be converted, too.
+
+Here is a simple example for a watchdog device:
+
++static struct watchdog_device s3c2410_wdd = {
++       .info = &s3c2410_wdt_ident,
++       .ops = &s3c2410wdt_ops,
++};
+
+
+Handle the 'nowayout' feature
+-----------------------------
+
+A few drivers use nowayout statically, i.e. there is no module parameter for it
+and only CONFIG_WATCHDOG_NOWAYOUT determines if the feature is going to be
+used. This needs to be converted by initializing the status variable of the
+watchdog_device like this:
+
+        .status = WATCHDOG_NOWAYOUT_INIT_STATUS,
+
+Most drivers, however, also allow runtime configuration of nowayout, usually
+by adding a module parameter. The conversion for this would be something like:
+
+	watchdog_set_nowayout(&s3c2410_wdd, nowayout);
+
+The module parameter itself needs to stay, everything else related to nowayout
+can go, though. This will likely be some code in open(), close() or write().
+
+
+Register the watchdog device
+----------------------------
+
+Replace misc_register(&miscdev) with watchdog_register_device(&watchdog_dev).
+Make sure the return value gets checked and the error message, if present,
+still fits. Also convert the unregister case.
+
+-       ret = misc_register(&s3c2410wdt_miscdev);
++       ret = watchdog_register_device(&s3c2410_wdd);
+
+...
+
+-       misc_deregister(&s3c2410wdt_miscdev);
++       watchdog_unregister_device(&s3c2410_wdd);
+
+
+Update the Kconfig-entry
+------------------------
+
+The entry for the driver now needs to select WATCHDOG_CORE:
+
++       select WATCHDOG_CORE
+
+
+Create a patch and send it to upstream
+--------------------------------------
+
+Make sure you understood Documentation/SubmittingPatches and send your patch to
+linux-watchdog@vger.kernel.org. We are looking forward to it :)
+

Documentation/watchdog/hpwdt.txt

@@ -0,0 +1,95 @@
+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 dependent 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 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 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 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).
+
+ 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)

Documentation/watchdog/pcwd-watchdog.txt

@@ -0,0 +1,66 @@
+Last reviewed: 10/05/2007
+
+                     Berkshire Products PC Watchdog Card
+                   Support for ISA Cards  Revision A and C
+           Documentation and Driver by Ken Hollis <kenji@bitgate.com>
+
+ The PC Watchdog is a card that offers the same type of functionality that
+ the WDT card does, only it doesn't require an IRQ to run.  Furthermore,
+ the Revision C card allows you to monitor any IO Port to automatically
+ trigger the card into being reset.  This way you can make the card
+ monitor hard drive status, or anything else you need.
+
+ The Watchdog Driver has one basic role: to talk to the card and send
+ signals to it so it doesn't reset your computer ... at least during
+ normal operation.
+
+ The Watchdog Driver will automatically find your watchdog card, and will
+ attach a running driver for use with that card.  After the watchdog
+ drivers have initialized, you can then talk to the card using a PC
+ Watchdog program.
+
+ I suggest putting a "watchdog -d" before the beginning of an fsck, and
+ a "watchdog -e -t 1" immediately after the end of an fsck.  (Remember
+ to run the program with an "&" to run it in the background!)
+
+ If you want to write a program to be compatible with the PC Watchdog
+ driver, simply use of modify the watchdog test program:
+ Documentation/watchdog/src/watchdog-test.c
+
+
+ Other IOCTL functions include:
+
+	WDIOC_GETSUPPORT
+		This returns the support of the card itself.  This
+		returns in structure "PCWDS" which returns:
+			options = WDIOS_TEMPPANIC
+				  (This card supports temperature)
+			firmware_version = xxxx
+				  (Firmware version of the card)
+
+	WDIOC_GETSTATUS
+		This returns the status of the card, with the bits of
+		WDIOF_* bitwise-anded into the value.  (The comments
+		are in linux/pcwd.h)
+
+	WDIOC_GETBOOTSTATUS
+		This returns the status of the card that was reported
+		at bootup.
+
+	WDIOC_GETTEMP
+		This returns the temperature of the card.  (You can also
+		read /dev/watchdog, which gives a temperature update
+		every second.)
+
+	WDIOC_SETOPTIONS
+		This lets you set the options of the card.  You can either
+		enable or disable the card this way.
+
+	WDIOC_KEEPALIVE
+		This pings the card to tell it not to reset your computer.
+
+ And that's all she wrote!
+
+ -- Ken Hollis
+    (kenji@bitgate.com)
+

Documentation/watchdog/src/Makefile

@@ -0,0 +1,5 @@
+# List of programs to build
+hostprogs-y := watchdog-simple watchdog-test
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)

Documentation/watchdog/src/watchdog-simple.c

@@ -0,0 +1,24 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+int main(void)
+{
+	int fd = open("/dev/watchdog", O_WRONLY);
+	int ret = 0;
+	if (fd == -1) {
+		perror("watchdog");
+		exit(EXIT_FAILURE);
+	}
+	while (1) {
+		ret = write(fd, "\0", 1);
+		if (ret != 1) {
+			ret = -1;
+			break;
+		}
+		sleep(10);
+	}
+	close(fd);
+	return ret;
+}

Documentation/watchdog/src/watchdog-test.c

@@ -0,0 +1,86 @@
+/*
+ * Watchdog Driver Test Program
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/ioctl.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+int fd;
+
+/*
+ * This function simply sends an IOCTL to the driver, which in turn ticks
+ * the PC Watchdog card to reset its internal timer so it doesn't trigger
+ * a computer reset.
+ */
+static void keep_alive(void)
+{
+    int dummy;
+
+    ioctl(fd, WDIOC_KEEPALIVE, &dummy);
+}
+
+/*
+ * The main program.  Run the program with "-d" to disable the card,
+ * or "-e" to enable the card.
+ */
+
+static void term(int sig)
+{
+    close(fd);
+    fprintf(stderr, "Stopping watchdog ticks...\n");
+    exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+    int flags;
+
+    fd = open("/dev/watchdog", O_WRONLY);
+
+    if (fd == -1) {
+	fprintf(stderr, "Watchdog device not enabled.\n");
+	fflush(stderr);
+	exit(-1);
+    }
+
+    if (argc > 1) {
+	if (!strncasecmp(argv[1], "-d", 2)) {
+	    flags = WDIOS_DISABLECARD;
+	    ioctl(fd, WDIOC_SETOPTIONS, &flags);
+	    fprintf(stderr, "Watchdog card disabled.\n");
+	    fflush(stderr);
+	    goto end;
+	} else if (!strncasecmp(argv[1], "-e", 2)) {
+	    flags = WDIOS_ENABLECARD;
+	    ioctl(fd, WDIOC_SETOPTIONS, &flags);
+	    fprintf(stderr, "Watchdog card enabled.\n");
+	    fflush(stderr);
+	    goto end;
+	} else {
+	    fprintf(stderr, "-d to disable, -e to enable.\n");
+	    fprintf(stderr, "run by itself to tick the card.\n");
+	    fflush(stderr);
+	    goto end;
+	}
+    } else {
+	fprintf(stderr, "Watchdog Ticking Away!\n");
+	fflush(stderr);
+    }
+
+    signal(SIGINT, term);
+
+    while(1) {
+	keep_alive();
+	sleep(1);
+    }
+end:
+    close(fd);
+    return 0;
+}

Documentation/watchdog/watchdog-api.txt

@@ -0,0 +1,237 @@
+Last reviewed: 10/05/2007
+
+
+The Linux Watchdog driver API.
+
+Copyright 2002 Christer Weingel <wingel@nano-system.com>
+
+Some parts of this document are copied verbatim from the sbc60xxwdt
+driver which is (c) Copyright 2000 Jakob Oestergaard <jakob@ostenfeld.dk>
+
+This document describes the state of the Linux 2.4.18 kernel.
+
+Introduction:
+
+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 watchdog driver via the
+/dev/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.
+
+The Linux watchdog API is a rather ad-hoc construction and different
+drivers implement different, and sometimes incompatible, parts of it.
+This file is an attempt to document the existing usage and allow
+future driver writers to use it as a reference.
+
+The simplest API:
+
+All drivers support the basic mode of operation, where the watchdog
+activates as soon as /dev/watchdog is opened and will reboot unless
+the watchdog is pinged within a certain time, this time is called the
+timeout or margin.  The simplest way to ping the watchdog is to write
+some data to the device.  So a very simple watchdog daemon would look
+like this source file:  see Documentation/watchdog/src/watchdog-simple.c
+
+A more advanced driver could for example check that a HTTP server is
+still responding before doing the write call to ping the watchdog.
+
+When the device is closed, the watchdog is disabled, unless the "Magic
+Close" feature is supported (see below).  This is not always such a
+good idea, since if there is a bug in the watchdog daemon and it
+crashes the system will not reboot.  Because of this, some of the
+drivers support the configuration option "Disable watchdog shutdown on
+close", CONFIG_WATCHDOG_NOWAYOUT.  If it is set to Y when compiling
+the kernel, there is no way of disabling the watchdog once it has been
+started.  So, if the watchdog daemon crashes, the system will reboot
+after the timeout has passed. Watchdog devices also usually support
+the nowayout module parameter so that this option can be controlled at
+runtime.
+
+Magic Close feature:
+
+If a driver supports "Magic Close", the driver will not disable the
+watchdog unless a specific magic character 'V' has been sent to
+/dev/watchdog just before closing the 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 watchdog without disabling it first.  This will then
+cause a reboot if the watchdog is not re-opened in sufficient time.
+
+The ioctl API:
+
+All conforming drivers also support an ioctl API.
+
+Pinging the watchdog using an ioctl:
+
+All drivers that have an ioctl interface support at least one ioctl,
+KEEPALIVE.  This ioctl does exactly the same thing as a write to the
+watchdog device, so the main loop in the above program could be
+replaced with:
+
+	while (1) {
+		ioctl(fd, WDIOC_KEEPALIVE, 0);
+		sleep(10);
+	}
+
+the argument to the ioctl is ignored.
+
+Setting and getting the timeout:
+
+For some drivers it is possible to modify the watchdog timeout on the
+fly with the SETTIMEOUT ioctl, those drivers have the WDIOF_SETTIMEOUT
+flag set in their option field.  The argument is an integer
+representing the timeout in seconds.  The driver returns the real
+timeout used in the same variable, and this timeout might differ from
+the requested one due to limitation of the hardware.
+
+    int timeout = 45;
+    ioctl(fd, WDIOC_SETTIMEOUT, &timeout);
+    printf("The timeout was set to %d seconds\n", timeout);
+
+This example might actually print "The timeout was set to 60 seconds"
+if the device has a granularity of minutes for its timeout.
+
+Starting with the Linux 2.4.18 kernel, it is possible to query the
+current timeout using the GETTIMEOUT ioctl.
+
+    ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
+    printf("The timeout was is %d seconds\n", timeout);
+
+Pretimeouts:
+
+Some watchdog timers can be set to have a trigger go off before the
+actual time they will reset the system.  This can be done with an NMI,
+interrupt, or other mechanism.  This allows Linux to record useful
+information (like panic information and kernel coredumps) before it
+resets.
+
+    pretimeout = 10;
+    ioctl(fd, WDIOC_SETPRETIMEOUT, &pretimeout);
+
+Note that the pretimeout is the number of seconds before the time
+when the timeout will go off.  It is not the number of seconds until
+the pretimeout.  So, for instance, if you set the timeout to 60 seconds
+and the pretimeout to 10 seconds, the pretimeout will go off in 50
+seconds.  Setting a pretimeout to zero disables it.
+
+There is also a get function for getting the pretimeout:
+
+    ioctl(fd, WDIOC_GETPRETIMEOUT, &timeout);
+    printf("The pretimeout was is %d seconds\n", timeout);
+
+Not all watchdog drivers will support a pretimeout.
+
+Get the number of seconds before reboot:
+
+Some watchdog drivers have the ability to report the remaining time
+before the system will reboot. The WDIOC_GETTIMELEFT is the ioctl
+that returns the number of seconds before reboot.
+
+    ioctl(fd, WDIOC_GETTIMELEFT, &timeleft);
+    printf("The timeout was is %d seconds\n", timeleft);
+
+Environmental monitoring:
+
+All watchdog drivers are required return more information about the system,
+some do temperature, fan and power level monitoring, some can tell you
+the reason for the last reboot of the system.  The GETSUPPORT ioctl is
+available to ask what the device can do:
+
+	struct watchdog_info ident;
+	ioctl(fd, WDIOC_GETSUPPORT, &ident);
+
+the fields returned in the ident struct are:
+
+        identity		a string identifying the watchdog driver
+	firmware_version	the firmware version of the card if available
+	options			a flags describing what the device supports
+
+the options field can have the following bits set, and describes what
+kind of information that the GET_STATUS and GET_BOOT_STATUS ioctls can
+return.   [FIXME -- Is this correct?]
+
+	WDIOF_OVERHEAT		Reset due to CPU overheat
+
+The machine was last rebooted by the watchdog because the thermal limit was
+exceeded
+
+	WDIOF_FANFAULT		Fan failed
+
+A system fan monitored by the watchdog card has failed
+
+	WDIOF_EXTERN1		External relay 1
+
+External monitoring relay/source 1 was triggered. Controllers intended for
+real world applications include external monitoring pins that will trigger
+a reset.
+
+	WDIOF_EXTERN2		External relay 2
+
+External monitoring relay/source 2 was triggered
+
+	WDIOF_POWERUNDER	Power bad/power fault
+
+The machine is showing an undervoltage status
+
+	WDIOF_CARDRESET		Card previously reset the CPU
+
+The last reboot was caused by the watchdog card
+
+	WDIOF_POWEROVER		Power over voltage
+
+The machine is showing an overvoltage status. Note that if one level is
+under and one over both bits will be set - this may seem odd but makes
+sense.
+
+	WDIOF_KEEPALIVEPING	Keep alive ping reply
+
+The watchdog saw a keepalive ping since it was last queried.
+
+	WDIOF_SETTIMEOUT	Can set/get the timeout
+
+The watchdog can do pretimeouts.
+
+	WDIOF_PRETIMEOUT	Pretimeout (in seconds), get/set
+
+
+For those drivers that return any bits set in the option field, the
+GETSTATUS and GETBOOTSTATUS ioctls can be used to ask for the current
+status, and the status at the last reboot, respectively.  
+
+    int flags;
+    ioctl(fd, WDIOC_GETSTATUS, &flags);
+
+    or
+
+    ioctl(fd, WDIOC_GETBOOTSTATUS, &flags);
+
+Note that not all devices support these two calls, and some only
+support the GETBOOTSTATUS call.
+
+Some drivers can measure the temperature using the GETTEMP ioctl.  The
+returned value is the temperature in degrees fahrenheit.
+
+    int temperature;
+    ioctl(fd, WDIOC_GETTEMP, &temperature);
+
+Finally the SETOPTIONS ioctl can be used to control some aspects of
+the cards operation.
+
+    int options = 0;
+    ioctl(fd, WDIOC_SETOPTIONS, &options);
+
+The following options are available:
+
+	WDIOS_DISABLECARD	Turn off the watchdog timer
+	WDIOS_ENABLECARD	Turn on the watchdog timer
+	WDIOS_TEMPPANIC		Kernel panic on temperature trip
+
+[FIXME -- better explanations]
+

Documentation/watchdog/watchdog-kernel-api.txt

@@ -0,0 +1,226 @@
+The Linux WatchDog Timer Driver Core kernel API.
+===============================================
+Last reviewed: 12-Feb-2013
+
+Wim Van Sebroeck <wim@iguana.be>
+
+Introduction
+------------
+This document does not describe what a WatchDog Timer (WDT) Driver or Device is.
+It also does not describe the API which can be used by user space to communicate
+with a WatchDog Timer. If you want to know this then please read the following
+file: Documentation/watchdog/watchdog-api.txt .
+
+So what does this document describe? It describes the API that can be used by
+WatchDog Timer Drivers that want to use the WatchDog Timer Driver Core
+Framework. This framework provides all interfacing towards user space so that
+the same code does not have to be reproduced each time. This also means that
+a watchdog timer driver then only needs to provide the different routines
+(operations) that control the watchdog timer (WDT).
+
+The API
+-------
+Each watchdog timer driver that wants to use the WatchDog Timer Driver Core
+must #include <linux/watchdog.h> (you would have to do this anyway when
+writing a watchdog device driver). This include file contains following
+register/unregister routines:
+
+extern int watchdog_register_device(struct watchdog_device *);
+extern void watchdog_unregister_device(struct watchdog_device *);
+
+The watchdog_register_device routine registers a watchdog timer device.
+The parameter of this routine is a pointer to a watchdog_device structure.
+This routine returns zero on success and a negative errno code for failure.
+
+The watchdog_unregister_device routine deregisters a registered watchdog timer
+device. The parameter of this routine is the pointer to the registered
+watchdog_device structure.
+
+The watchdog device structure looks like this:
+
+struct watchdog_device {
+	int id;
+	struct cdev cdev;
+	struct device *dev;
+	struct device *parent;
+	const struct watchdog_info *info;
+	const struct watchdog_ops *ops;
+	unsigned int bootstatus;
+	unsigned int timeout;
+	unsigned int min_timeout;
+	unsigned int max_timeout;
+	void *driver_data;
+	struct mutex lock;
+	unsigned long status;
+};
+
+It contains following fields:
+* id: set by watchdog_register_device, id 0 is special. It has both a
+  /dev/watchdog0 cdev (dynamic major, minor 0) as well as the old
+  /dev/watchdog miscdev. The id is set automatically when calling
+  watchdog_register_device.
+* cdev: cdev for the dynamic /dev/watchdog<id> device nodes. This
+  field is also populated by watchdog_register_device.
+* dev: device under the watchdog class (created by watchdog_register_device).
+* parent: set this to the parent device (or NULL) before calling
+  watchdog_register_device.
+* info: a pointer to a watchdog_info structure. This structure gives some
+  additional information about the watchdog timer itself. (Like it's unique name)
+* ops: a pointer to the list of watchdog operations that the watchdog supports.
+* timeout: the watchdog timer's timeout value (in seconds).
+* min_timeout: the watchdog timer's minimum timeout value (in seconds).
+* max_timeout: the watchdog timer's maximum timeout value (in seconds).
+* bootstatus: status of the device after booting (reported with watchdog
+  WDIOF_* status bits).
+* driver_data: a pointer to the drivers private data of a watchdog device.
+  This data should only be accessed via the watchdog_set_drvdata and
+  watchdog_get_drvdata routines.
+* lock: Mutex for WatchDog Timer Driver Core internal use only.
+* status: this field contains a number of status bits that give extra
+  information about the status of the device (Like: is the watchdog timer
+  running/active, is the nowayout bit set, is the device opened via
+  the /dev/watchdog interface or not, ...).
+
+The list of watchdog operations is defined as:
+
+struct watchdog_ops {
+	struct module *owner;
+	/* mandatory operations */
+	int (*start)(struct watchdog_device *);
+	int (*stop)(struct watchdog_device *);
+	/* optional operations */
+	int (*ping)(struct watchdog_device *);
+	unsigned int (*status)(struct watchdog_device *);
+	int (*set_timeout)(struct watchdog_device *, unsigned int);
+	unsigned int (*get_timeleft)(struct watchdog_device *);
+	void (*ref)(struct watchdog_device *);
+	void (*unref)(struct watchdog_device *);
+	long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
+};
+
+It is important that you first define the module owner of the watchdog timer
+driver's operations. This module owner will be used to lock the module when
+the watchdog is active. (This to avoid a system crash when you unload the
+module and /dev/watchdog is still open).
+
+If the watchdog_device struct is dynamically allocated, just locking the module
+is not enough and a driver also needs to define the ref and unref operations to
+ensure the structure holding the watchdog_device does not go away.
+
+The simplest (and usually sufficient) implementation of this is to:
+1) Add a kref struct to the same structure which is holding the watchdog_device
+2) Define a release callback for the kref which frees the struct holding both
+3) Call kref_init on this kref *before* calling watchdog_register_device()
+4) Define a ref operation calling kref_get on this kref
+5) Define a unref operation calling kref_put on this kref
+6) When it is time to cleanup:
+ * Do not kfree() the struct holding both, the last kref_put will do this!
+ * *After* calling watchdog_unregister_device() call kref_put on the kref
+
+Some operations are mandatory and some are optional. The mandatory operations
+are:
+* start: this is a pointer to the routine that starts the watchdog timer
+  device.
+  The routine needs a pointer to the watchdog timer device structure as a
+  parameter. It returns zero on success or a negative errno code for failure.
+* stop: with this routine the watchdog timer device is being stopped.
+  The routine needs a pointer to the watchdog timer device structure as a
+  parameter. It returns zero on success or a negative errno code for failure.
+  Some watchdog timer hardware can only be started and not be stopped. The
+  driver supporting this hardware needs to make sure that a start and stop
+  routine is being provided. This can be done by using a timer in the driver
+  that regularly sends a keepalive ping to the watchdog timer hardware.
+
+Not all watchdog timer hardware supports the same functionality. That's why
+all other routines/operations are optional. They only need to be provided if
+they are supported. These optional routines/operations are:
+* ping: this is the routine that sends a keepalive ping to the watchdog timer
+  hardware.
+  The routine needs a pointer to the watchdog timer device structure as a
+  parameter. It returns zero on success or a negative errno code for failure.
+  Most hardware that does not support this as a separate function uses the
+  start function to restart the watchdog timer hardware. And that's also what
+  the watchdog timer driver core does: to send a keepalive ping to the watchdog
+  timer hardware it will either use the ping operation (when available) or the
+  start operation (when the ping operation is not available).
+  (Note: the WDIOC_KEEPALIVE ioctl call will only be active when the
+  WDIOF_KEEPALIVEPING bit has been set in the option field on the watchdog's
+  info structure).
+* status: this routine checks the status of the watchdog timer device. The
+  status of the device is reported with watchdog WDIOF_* status flags/bits.
+* set_timeout: this routine checks and changes the timeout of the watchdog
+  timer device. It returns 0 on success, -EINVAL for "parameter out of range"
+  and -EIO for "could not write value to the watchdog". On success this
+  routine should set the timeout value of the watchdog_device to the
+  achieved timeout value (which may be different from the requested one
+  because the watchdog does not necessarily has a 1 second resolution).
+  (Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
+  watchdog's info structure).
+* get_timeleft: this routines returns the time that's left before a reset.
+* ref: the operation that calls kref_get on the kref of a dynamically
+  allocated watchdog_device struct.
+* unref: the operation that calls kref_put on the kref of a dynamically
+  allocated watchdog_device struct.
+* ioctl: if this routine is present then it will be called first before we do
+  our own internal ioctl call handling. This routine should return -ENOIOCTLCMD
+  if a command is not supported. The parameters that are passed to the ioctl
+  call are: watchdog_device, cmd and arg.
+
+The status bits should (preferably) be set with the set_bit and clear_bit alike
+bit-operations. The status bits that are defined are:
+* WDOG_ACTIVE: this status bit indicates whether or not a watchdog timer device
+  is active or not. When the watchdog is active after booting, then you should
+  set this status bit (Note: when you register the watchdog timer device with
+  this bit set, then opening /dev/watchdog will skip the start operation)
+* WDOG_DEV_OPEN: this status bit shows whether or not the watchdog device
+  was opened via /dev/watchdog.
+  (This bit should only be used by the WatchDog Timer Driver Core).
+* WDOG_ALLOW_RELEASE: this bit stores whether or not the magic close character
+  has been sent (so that we can support the magic close feature).
+  (This bit should only be used by the WatchDog Timer Driver Core).
+* WDOG_NO_WAY_OUT: this bit stores the nowayout setting for the watchdog.
+  If this bit is set then the watchdog timer will not be able to stop.
+* WDOG_UNREGISTERED: this bit gets set by the WatchDog Timer Driver Core
+  after calling watchdog_unregister_device, and then checked before calling
+  any watchdog_ops, so that you can be sure that no operations (other then
+  unref) will get called after unregister, even if userspace still holds a
+  reference to /dev/watchdog
+
+  To set the WDOG_NO_WAY_OUT status bit (before registering your watchdog
+  timer device) you can either:
+  * set it statically in your watchdog_device struct with
+	.status = WATCHDOG_NOWAYOUT_INIT_STATUS,
+    (this will set the value the same as CONFIG_WATCHDOG_NOWAYOUT) or
+  * use the following helper function:
+  static inline void watchdog_set_nowayout(struct watchdog_device *wdd, int nowayout)
+
+Note: The WatchDog Timer Driver Core supports the magic close feature and
+the nowayout feature. To use the magic close feature you must set the
+WDIOF_MAGICCLOSE bit in the options field of the watchdog's info structure.
+The nowayout feature will overrule the magic close feature.
+
+To get or set driver specific data the following two helper functions should be
+used:
+
+static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data)
+static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
+
+The watchdog_set_drvdata function allows you to add driver specific data. The
+arguments of this function are the watchdog device where you want to add the
+driver specific data to and a pointer to the data itself.
+
+The watchdog_get_drvdata function allows you to retrieve driver specific data.
+The argument of this function is the watchdog device where you want to retrieve
+data from. The function returns the pointer to the driver specific data.
+
+To initialize the timeout field, the following function can be used:
+
+extern int watchdog_init_timeout(struct watchdog_device *wdd,
+                                  unsigned int timeout_parm, struct device *dev);
+
+The watchdog_init_timeout function allows you to initialize the timeout field
+using the module timeout parameter or by retrieving the timeout-sec property from
+the device tree (if the module timeout parameter is invalid). Best practice is
+to set the default timeout value as timeout value in the watchdog_device and
+then use this function to set the user "preferred" timeout value.
+This routine returns zero on success and a negative errno code for failure.

Documentation/watchdog/watchdog-parameters.txt

@@ -0,0 +1,399 @@
+This file provides information on the module parameters of many of
+the Linux watchdog drivers.  Watchdog driver parameter specs should
+be listed here unless the driver has its own driver-specific information
+file.
+
+
+See Documentation/kernel-parameters.txt for information on
+providing kernel parameters for builtin drivers versus loadable
+modules.
+
+
+-------------------------------------------------
+acquirewdt:
+wdt_stop: Acquire WDT 'stop' io port (default 0x43)
+wdt_start: Acquire WDT 'start' io port (default 0x443)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+advantechwdt:
+wdt_stop: Advantech WDT 'stop' io port (default 0x443)
+wdt_start: Advantech WDT 'start' io port (default 0x443)
+timeout: Watchdog timeout in seconds. 1<= timeout <=63, default=60.
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+alim1535_wdt:
+timeout: Watchdog timeout in seconds. (0 < timeout < 18000, default=60
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+alim7101_wdt:
+timeout: Watchdog timeout in seconds. (1<=timeout<=3600, default=30
+use_gpio: Use the gpio watchdog (required by old cobalt boards).
+	default=0/off/no
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+ar7_wdt:
+margin: Watchdog margin in seconds (default=60)
+nowayout: Disable watchdog shutdown on close
+	(default=kernel config parameter)
+-------------------------------------------------
+at32ap700x_wdt:
+timeout: Timeout value. Limited to be 1 or 2 seconds. (default=2)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+at91rm9200_wdt:
+wdt_time: Watchdog time in seconds. (default=5)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+at91sam9_wdt:
+heartbeat: Watchdog heartbeats in seconds. (default = 15)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+bcm47xx_wdt:
+wdt_time: Watchdog time in seconds. (default=30)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+bfin_wdt:
+timeout: Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default=20)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+coh901327_wdt:
+margin: Watchdog margin in seconds (default 60s)
+-------------------------------------------------
+cpu5wdt:
+port: base address of watchdog card, default is 0x91
+verbose: be verbose, default is 0 (no)
+ticks: count down ticks, default is 10000
+-------------------------------------------------
+cpwd:
+wd0_timeout: Default watchdog0 timeout in 1/10secs
+wd1_timeout: Default watchdog1 timeout in 1/10secs
+wd2_timeout: Default watchdog2 timeout in 1/10secs
+-------------------------------------------------
+da9052wdt:
+timeout: Watchdog timeout in seconds. 2<= timeout <=131, default=2.048s
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+davinci_wdt:
+heartbeat: Watchdog heartbeat period in seconds from 1 to 600, default 60
+-------------------------------------------------
+ep93xx_wdt:
+nowayout: Watchdog cannot be stopped once started
+timeout: Watchdog timeout in seconds. (1<=timeout<=3600, default=TBD)
+-------------------------------------------------
+eurotechwdt:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+io: Eurotech WDT io port (default=0x3f0)
+irq: Eurotech WDT irq (default=10)
+ev: Eurotech WDT event type (default is `int')
+-------------------------------------------------
+gef_wdt:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+geodewdt:
+timeout: Watchdog timeout in seconds. 1<= timeout <=131, default=60.
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+i6300esb:
+heartbeat: Watchdog heartbeat in seconds. (1<heartbeat<2046, default=30)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+iTCO_wdt:
+heartbeat: Watchdog heartbeat in seconds.
+	(2<heartbeat<39 (TCO v1) or 613 (TCO v2), default=30)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+iTCO_vendor_support:
+vendorsupport: iTCO vendor specific support mode, default=0 (none),
+	1=SuperMicro Pent3, 2=SuperMicro Pent4+, 911=Broken SMI BIOS
+-------------------------------------------------
+ib700wdt:
+timeout: Watchdog timeout in seconds. 0<= timeout <=30, default=30.
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+ibmasr:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+imx2_wdt:
+timeout: Watchdog timeout in seconds (default 60 s)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+indydog:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+iop_wdt:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+it8712f_wdt:
+margin: Watchdog margin in seconds (default 60)
+nowayout: Disable watchdog shutdown on close
+	(default=kernel config parameter)
+-------------------------------------------------
+it87_wdt:
+nogameport: Forbid the activation of game port, default=0
+nocir: Forbid the use of CIR (workaround for some buggy setups); set to 1 if
+system resets despite watchdog daemon running, default=0
+exclusive: Watchdog exclusive device open, default=1
+timeout: Watchdog timeout in seconds, default=60
+testmode: Watchdog test mode (1 = no reboot), default=0
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+ixp2000_wdt:
+heartbeat: Watchdog heartbeat in seconds (default 60s)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+ixp4xx_wdt:
+heartbeat: Watchdog heartbeat in seconds (default 60s)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+ks8695_wdt:
+wdt_time: Watchdog time in seconds. (default=5)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+machzwd:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+action: after watchdog resets, generate:
+	0 = RESET(*)  1 = SMI  2 = NMI  3 = SCI
+-------------------------------------------------
+max63xx_wdt:
+heartbeat: Watchdog heartbeat period in seconds from 1 to 60, default 60
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+nodelay: Force selection of a timeout setting without initial delay
+	(max6373/74 only, default=0)
+-------------------------------------------------
+mixcomwd:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+mpc8xxx_wdt:
+timeout: Watchdog timeout in ticks. (0<timeout<65536, default=65535)
+reset: Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+mv64x60_wdt:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+nuc900_wdt:
+heartbeat: Watchdog heartbeats in seconds.
+	(default = 15)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+omap_wdt:
+timer_margin: initial watchdog timeout (in seconds)
+-------------------------------------------------
+orion_wdt:
+heartbeat: Initial watchdog heartbeat in seconds
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+pc87413_wdt:
+io: pc87413 WDT I/O port (default: io).
+timeout: Watchdog timeout in minutes (default=timeout).
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+pika_wdt:
+heartbeat: Watchdog heartbeats in seconds. (default = 15)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+pnx4008_wdt:
+heartbeat: Watchdog heartbeat period in seconds from 1 to 60, default 19
+nowayout: Set to 1 to keep watchdog running after device release
+-------------------------------------------------
+pnx833x_wdt:
+timeout: Watchdog timeout in Mhz. (68Mhz clock), default=2040000000 (30 seconds)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+start_enabled: Watchdog is started on module insertion (default=1)
+-------------------------------------------------
+rc32434_wdt:
+timeout: Watchdog timeout value, in seconds (default=20)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+riowd:
+riowd_timeout: Watchdog timeout in minutes (default=1)
+-------------------------------------------------
+s3c2410_wdt:
+tmr_margin: Watchdog tmr_margin in seconds. (default=15)
+tmr_atboot: Watchdog is started at boot time if set to 1, default=0
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+soft_noboot: Watchdog action, set to 1 to ignore reboots, 0 to reboot
+debug: Watchdog debug, set to >1 for debug, (default 0)
+-------------------------------------------------
+sa1100_wdt:
+margin: Watchdog margin in seconds (default 60s)
+-------------------------------------------------
+sb_wdog:
+timeout: Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)
+-------------------------------------------------
+sbc60xxwdt:
+wdt_stop: SBC60xx WDT 'stop' io port (default 0x45)
+wdt_start: SBC60xx WDT 'start' io port (default 0x443)
+timeout: Watchdog timeout in seconds. (1<=timeout<=3600, default=30)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+sbc7240_wdt:
+timeout: Watchdog timeout in seconds. (1<=timeout<=255, default=30)
+nowayout: Disable watchdog when closing device file
+-------------------------------------------------
+sbc8360:
+timeout: Index into timeout table (0-63) (default=27 (60s))
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+sbc_epx_c3:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+sbc_fitpc2_wdt:
+margin: Watchdog margin in seconds (default 60s)
+nowayout: Watchdog cannot be stopped once started
+-------------------------------------------------
+sc1200wdt:
+isapnp: When set to 0 driver ISA PnP support will be disabled (default=1)
+io: io port
+timeout: range is 0-255 minutes, default is 1
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+sc520_wdt:
+timeout: Watchdog timeout in seconds. (1 <= timeout <= 3600, default=30)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+sch311x_wdt:
+force_id: Override the detected device ID
+therm_trip: Should a ThermTrip trigger the reset generator
+timeout: Watchdog timeout in seconds. 1<= timeout <=15300, default=60
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+scx200_wdt:
+margin: Watchdog margin in seconds
+nowayout: Disable watchdog shutdown on close
+-------------------------------------------------
+shwdt:
+clock_division_ratio: Clock division ratio. Valid ranges are from 0x5 (1.31ms)
+	to 0x7 (5.25ms). (default=7)
+heartbeat: Watchdog heartbeat in seconds. (1 <= heartbeat <= 3600, default=30
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+smsc37b787_wdt:
+timeout: range is 1-255 units, default is 60
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+softdog:
+soft_margin: Watchdog soft_margin in seconds.
+	(0 < soft_margin < 65536, default=60)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+soft_noboot: Softdog action, set to 1 to ignore reboots, 0 to reboot
+	(default=0)
+-------------------------------------------------
+stmp3xxx_wdt:
+heartbeat: Watchdog heartbeat period in seconds from 1 to 4194304, default 19
+-------------------------------------------------
+tegra_wdt:
+heartbeat: Watchdog heartbeats in seconds. (default = 120)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+ts72xx_wdt:
+timeout: Watchdog timeout in seconds. (1 <= timeout <= 8, default=8)
+nowayout: Disable watchdog shutdown on close
+-------------------------------------------------
+twl4030_wdt:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+txx9wdt:
+timeout: Watchdog timeout in seconds. (0<timeout<N, default=60)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+w83627hf_wdt:
+wdt_io: w83627hf/thf WDT io port (default 0x2E)
+timeout: Watchdog timeout in seconds. 1 <= timeout <= 255, default=60.
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+w83697hf_wdt:
+wdt_io: w83697hf/hg WDT io port (default 0x2e, 0 = autodetect)
+timeout: Watchdog timeout in seconds. 1<= timeout <=255 (default=60)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+early_disable: Watchdog gets disabled at boot time (default=1)
+-------------------------------------------------
+w83697ug_wdt:
+wdt_io: w83697ug/uf WDT io port (default 0x2e)
+timeout: Watchdog timeout in seconds. 1<= timeout <=255 (default=60)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+w83877f_wdt:
+timeout: Watchdog timeout in seconds. (1<=timeout<=3600, default=30)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+w83977f_wdt:
+timeout: Watchdog timeout in seconds (15..7635), default=45)
+testmode: Watchdog testmode (1 = no reboot), default=0
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+wafer5823wdt:
+timeout: Watchdog timeout in seconds. 1 <= timeout <= 255, default=60.
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+wdt285:
+soft_margin: Watchdog timeout in seconds (default=60)
+-------------------------------------------------
+wdt977:
+timeout: Watchdog timeout in seconds (60..15300, default=60)
+testmode: Watchdog testmode (1 = no reboot), default=0
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+wm831x_wdt:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
+wm8350_wdt:
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------

Documentation/watchdog/wdt.txt

@@ -0,0 +1,50 @@
+Last Reviewed: 10/05/2007
+
+	WDT Watchdog Timer Interfaces For The Linux Operating System
+		Alan Cox <alan@lxorguk.ukuu.org.uk>
+
+	ICS	WDT501-P
+	ICS	WDT501-P (no fan tachometer)
+	ICS	WDT500-P
+
+All the interfaces provide /dev/watchdog, which when open must be written
+to within a timeout or the machine will reboot. Each write delays the reboot
+time another timeout. In the case of the software watchdog the ability to
+reboot will depend on the state of the machines and interrupts. The hardware
+boards physically pull the machine down off their own onboard timers and
+will reboot from almost anything.
+
+A second temperature monitoring interface is available on the WDT501P cards.
+This provides /dev/temperature. This is the machine internal temperature in
+degrees Fahrenheit. Each read returns a single byte giving the temperature.
+
+The third interface logs kernel messages on additional alert events.
+
+The ICS ISA-bus wdt card cannot be safely probed for. Instead you need to
+pass IO address and IRQ boot parameters.  E.g.:
+	wdt.io=0x240 wdt.irq=11
+
+Other "wdt" driver parameters are:
+	heartbeat	Watchdog heartbeat in seconds (default 60)
+	nowayout	Watchdog cannot be stopped once started (kernel
+				build parameter)
+	tachometer	WDT501-P Fan Tachometer support (0=disable, default=0)
+	type		WDT501-P Card type (500 or 501, default=500)
+
+Features
+--------
+		WDT501P		WDT500P
+Reboot Timer	   X               X
+External Reboot	   X	           X
+I/O Port Monitor   o		   o
+Temperature	   X		   o
+Fan Speed          X		   o
+Power Under	   X               o
+Power Over         X               o
+Overheat           X               o
+
+The external event interfaces on the WDT boards are not currently supported.
+Minor numbers are however allocated for it.
+
+
+Example Watchdog Driver:  see Documentation/watchdog/src/watchdog-simple.c