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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/watchdog
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'Documentation/watchdog')
-rw-r--r--Documentation/watchdog/pcwd-watchdog.txt135
-rw-r--r--Documentation/watchdog/watchdog-api.txt399
-rw-r--r--Documentation/watchdog/watchdog.txt115
3 files changed, 649 insertions, 0 deletions
diff --git a/Documentation/watchdog/pcwd-watchdog.txt b/Documentation/watchdog/pcwd-watchdog.txt
new file mode 100644
index 000000000000..12187a33e310
--- /dev/null
+++ b/Documentation/watchdog/pcwd-watchdog.txt
@@ -0,0 +1,135 @@
1 Berkshire Products PC Watchdog Card
2 Support for ISA Cards Revision A and C
3 Documentation and Driver by Ken Hollis <kenji@bitgate.com>
4
5 The PC Watchdog is a card that offers the same type of functionality that
6 the WDT card does, only it doesn't require an IRQ to run. Furthermore,
7 the Revision C card allows you to monitor any IO Port to automatically
8 trigger the card into being reset. This way you can make the card
9 monitor hard drive status, or anything else you need.
10
11 The Watchdog Driver has one basic role: to talk to the card and send
12 signals to it so it doesn't reset your computer ... at least during
13 normal operation.
14
15 The Watchdog Driver will automatically find your watchdog card, and will
16 attach a running driver for use with that card. After the watchdog
17 drivers have initialized, you can then talk to the card using the PC
18 Watchdog program, available from http://ftp.bitgate.com/pcwd/.
19
20 I suggest putting a "watchdog -d" before the beginning of an fsck, and
21 a "watchdog -e -t 1" immediately after the end of an fsck. (Remember
22 to run the program with an "&" to run it in the background!)
23
24 If you want to write a program to be compatible with the PC Watchdog
25 driver, simply do the following:
26
27-- Snippet of code --
28/*
29 * Watchdog Driver Test Program
30 */
31
32#include <stdio.h>
33#include <stdlib.h>
34#include <string.h>
35#include <unistd.h>
36#include <fcntl.h>
37#include <sys/ioctl.h>
38#include <linux/types.h>
39#include <linux/watchdog.h>
40
41int fd;
42
43/*
44 * This function simply sends an IOCTL to the driver, which in turn ticks
45 * the PC Watchdog card to reset its internal timer so it doesn't trigger
46 * a computer reset.
47 */
48void keep_alive(void)
49{
50 int dummy;
51
52 ioctl(fd, WDIOC_KEEPALIVE, &dummy);
53}
54
55/*
56 * The main program. Run the program with "-d" to disable the card,
57 * or "-e" to enable the card.
58 */
59int main(int argc, char *argv[])
60{
61 fd = open("/dev/watchdog", O_WRONLY);
62
63 if (fd == -1) {
64 fprintf(stderr, "Watchdog device not enabled.\n");
65 fflush(stderr);
66 exit(-1);
67 }
68
69 if (argc > 1) {
70 if (!strncasecmp(argv[1], "-d", 2)) {
71 ioctl(fd, WDIOC_SETOPTIONS, WDIOS_DISABLECARD);
72 fprintf(stderr, "Watchdog card disabled.\n");
73 fflush(stderr);
74 exit(0);
75 } else if (!strncasecmp(argv[1], "-e", 2)) {
76 ioctl(fd, WDIOC_SETOPTIONS, WDIOS_ENABLECARD);
77 fprintf(stderr, "Watchdog card enabled.\n");
78 fflush(stderr);
79 exit(0);
80 } else {
81 fprintf(stderr, "-d to disable, -e to enable.\n");
82 fprintf(stderr, "run by itself to tick the card.\n");
83 fflush(stderr);
84 exit(0);
85 }
86 } else {
87 fprintf(stderr, "Watchdog Ticking Away!\n");
88 fflush(stderr);
89 }
90
91 while(1) {
92 keep_alive();
93 sleep(1);
94 }
95}
96-- End snippet --
97
98 Other IOCTL functions include:
99
100 WDIOC_GETSUPPORT
101 This returns the support of the card itself. This
102 returns in structure "PCWDS" which returns:
103 options = WDIOS_TEMPPANIC
104 (This card supports temperature)
105 firmware_version = xxxx
106 (Firmware version of the card)
107
108 WDIOC_GETSTATUS
109 This returns the status of the card, with the bits of
110 WDIOF_* bitwise-anded into the value. (The comments
111 are in linux/pcwd.h)
112
113 WDIOC_GETBOOTSTATUS
114 This returns the status of the card that was reported
115 at bootup.
116
117 WDIOC_GETTEMP
118 This returns the temperature of the card. (You can also
119 read /dev/watchdog, which gives a temperature update
120 every second.)
121
122 WDIOC_SETOPTIONS
123 This lets you set the options of the card. You can either
124 enable or disable the card this way.
125
126 WDIOC_KEEPALIVE
127 This pings the card to tell it not to reset your computer.
128
129 And that's all she wrote!
130
131 -- Ken Hollis
132 (kenji@bitgate.com)
133
134(This documentation may be out of date. Check
135 http://ftp.bitgate.com/pcwd/ for the absolute latest additions.)
diff --git a/Documentation/watchdog/watchdog-api.txt b/Documentation/watchdog/watchdog-api.txt
new file mode 100644
index 000000000000..28388aa700c6
--- /dev/null
+++ b/Documentation/watchdog/watchdog-api.txt
@@ -0,0 +1,399 @@
1The Linux Watchdog driver API.
2
3Copyright 2002 Christer Weingel <wingel@nano-system.com>
4
5Some parts of this document are copied verbatim from the sbc60xxwdt
6driver which is (c) Copyright 2000 Jakob Oestergaard <jakob@ostenfeld.dk>
7
8This document describes the state of the Linux 2.4.18 kernel.
9
10Introduction:
11
12A Watchdog Timer (WDT) is a hardware circuit that can reset the
13computer system in case of a software fault. You probably knew that
14already.
15
16Usually a userspace daemon will notify the kernel watchdog driver via the
17/dev/watchdog special device file that userspace is still alive, at
18regular intervals. When such a notification occurs, the driver will
19usually tell the hardware watchdog that everything is in order, and
20that the watchdog should wait for yet another little while to reset
21the system. If userspace fails (RAM error, kernel bug, whatever), the
22notifications cease to occur, and the hardware watchdog will reset the
23system (causing a reboot) after the timeout occurs.
24
25The Linux watchdog API is a rather AD hoc construction and different
26drivers implement different, and sometimes incompatible, parts of it.
27This file is an attempt to document the existing usage and allow
28future driver writers to use it as a reference.
29
30The simplest API:
31
32All drivers support the basic mode of operation, where the watchdog
33activates as soon as /dev/watchdog is opened and will reboot unless
34the watchdog is pinged within a certain time, this time is called the
35timeout or margin. The simplest way to ping the watchdog is to write
36some data to the device. So a very simple watchdog daemon would look
37like this:
38
39int main(int argc, const char *argv[]) {
40 int fd=open("/dev/watchdog",O_WRONLY);
41 if (fd==-1) {
42 perror("watchdog");
43 exit(1);
44 }
45 while(1) {
46 write(fd, "\0", 1);
47 sleep(10);
48 }
49}
50
51A more advanced driver could for example check that a HTTP server is
52still responding before doing the write call to ping the watchdog.
53
54When the device is closed, the watchdog is disabled. This is not
55always such a good idea, since if there is a bug in the watchdog
56daemon and it crashes the system will not reboot. Because of this,
57some of the drivers support the configuration option "Disable watchdog
58shutdown on close", CONFIG_WATCHDOG_NOWAYOUT. If it is set to Y when
59compiling the kernel, there is no way of disabling the watchdog once
60it has been started. So, if the watchdog dameon crashes, the system
61will reboot after the timeout has passed.
62
63Some other drivers will not disable the watchdog, unless a specific
64magic character 'V' has been sent /dev/watchdog just before closing
65the file. If the userspace daemon closes the file without sending
66this special character, the driver will assume that the daemon (and
67userspace in general) died, and will stop pinging the watchdog without
68disabling it first. This will then cause a reboot.
69
70The ioctl API:
71
72All conforming drivers also support an ioctl API.
73
74Pinging the watchdog using an ioctl:
75
76All drivers that have an ioctl interface support at least one ioctl,
77KEEPALIVE. This ioctl does exactly the same thing as a write to the
78watchdog device, so the main loop in the above program could be
79replaced with:
80
81 while (1) {
82 ioctl(fd, WDIOC_KEEPALIVE, 0);
83 sleep(10);
84 }
85
86the argument to the ioctl is ignored.
87
88Setting and getting the timeout:
89
90For some drivers it is possible to modify the watchdog timeout on the
91fly with the SETTIMEOUT ioctl, those drivers have the WDIOF_SETTIMEOUT
92flag set in their option field. The argument is an integer
93representing the timeout in seconds. The driver returns the real
94timeout used in the same variable, and this timeout might differ from
95the requested one due to limitation of the hardware.
96
97 int timeout = 45;
98 ioctl(fd, WDIOC_SETTIMEOUT, &timeout);
99 printf("The timeout was set to %d seconds\n", timeout);
100
101This example might actually print "The timeout was set to 60 seconds"
102if the device has a granularity of minutes for its timeout.
103
104Starting with the Linux 2.4.18 kernel, it is possible to query the
105current timeout using the GETTIMEOUT ioctl.
106
107 ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
108 printf("The timeout was is %d seconds\n", timeout);
109
110Envinronmental monitoring:
111
112All watchdog drivers are required return more information about the system,
113some do temperature, fan and power level monitoring, some can tell you
114the reason for the last reboot of the system. The GETSUPPORT ioctl is
115available to ask what the device can do:
116
117 struct watchdog_info ident;
118 ioctl(fd, WDIOC_GETSUPPORT, &ident);
119
120the fields returned in the ident struct are:
121
122 identity a string identifying the watchdog driver
123 firmware_version the firmware version of the card if available
124 options a flags describing what the device supports
125
126the options field can have the following bits set, and describes what
127kind of information that the GET_STATUS and GET_BOOT_STATUS ioctls can
128return. [FIXME -- Is this correct?]
129
130 WDIOF_OVERHEAT Reset due to CPU overheat
131
132The machine was last rebooted by the watchdog because the thermal limit was
133exceeded
134
135 WDIOF_FANFAULT Fan failed
136
137A system fan monitored by the watchdog card has failed
138
139 WDIOF_EXTERN1 External relay 1
140
141External monitoring relay/source 1 was triggered. Controllers intended for
142real world applications include external monitoring pins that will trigger
143a reset.
144
145 WDIOF_EXTERN2 External relay 2
146
147External monitoring relay/source 2 was triggered
148
149 WDIOF_POWERUNDER Power bad/power fault
150
151The machine is showing an undervoltage status
152
153 WDIOF_CARDRESET Card previously reset the CPU
154
155The last reboot was caused by the watchdog card
156
157 WDIOF_POWEROVER Power over voltage
158
159The machine is showing an overvoltage status. Note that if one level is
160under and one over both bits will be set - this may seem odd but makes
161sense.
162
163 WDIOF_KEEPALIVEPING Keep alive ping reply
164
165The watchdog saw a keepalive ping since it was last queried.
166
167 WDIOF_SETTIMEOUT Can set/get the timeout
168
169
170For those drivers that return any bits set in the option field, the
171GETSTATUS and GETBOOTSTATUS ioctls can be used to ask for the current
172status, and the status at the last reboot, respectively.
173
174 int flags;
175 ioctl(fd, WDIOC_GETSTATUS, &flags);
176
177 or
178
179 ioctl(fd, WDIOC_GETBOOTSTATUS, &flags);
180
181Note that not all devices support these two calls, and some only
182support the GETBOOTSTATUS call.
183
184Some drivers can measure the temperature using the GETTEMP ioctl. The
185returned value is the temperature in degrees farenheit.
186
187 int temperature;
188 ioctl(fd, WDIOC_GETTEMP, &temperature);
189
190Finally the SETOPTIONS ioctl can be used to control some aspects of
191the cards operation; right now the pcwd driver is the only one
192supporting thiss ioctl.
193
194 int options = 0;
195 ioctl(fd, WDIOC_SETOPTIONS, options);
196
197The following options are available:
198
199 WDIOS_DISABLECARD Turn off the watchdog timer
200 WDIOS_ENABLECARD Turn on the watchdog timer
201 WDIOS_TEMPPANIC Kernel panic on temperature trip
202
203[FIXME -- better explanations]
204
205Implementations in the current drivers in the kernel tree:
206
207Here I have tried to summarize what the different drivers support and
208where they do strange things compared to the other drivers.
209
210acquirewdt.c -- Acquire Single Board Computer
211
212 This driver has a hardcoded timeout of 1 minute
213
214 Supports CONFIG_WATCHDOG_NOWAYOUT
215
216 GETSUPPORT returns KEEPALIVEPING. GETSTATUS will return 1 if
217 the device is open, 0 if not. [FIXME -- isn't this rather
218 silly? To be able to use the ioctl, the device must be open
219 and so GETSTATUS will always return 1].
220
221advantechwdt.c -- Advantech Single Board Computer
222
223 Timeout that defaults to 60 seconds, supports SETTIMEOUT.
224
225 Supports CONFIG_WATCHDOG_NOWAYOUT
226
227 GETSUPPORT returns WDIOF_KEEPALIVEPING and WDIOF_SETTIMEOUT.
228 The GETSTATUS call returns if the device is open or not.
229 [FIXME -- silliness again?]
230
231eurotechwdt.c -- Eurotech CPU-1220/1410
232
233 The timeout can be set using the SETTIMEOUT ioctl and defaults
234 to 60 seconds.
235
236 Also has a module parameter "ev", event type which controls
237 what should happen on a timeout, the string "int" or anything
238 else that causes a reboot. [FIXME -- better description]
239
240 Supports CONFIG_WATCHDOG_NOWAYOUT
241
242 GETSUPPORT returns CARDRESET and WDIOF_SETTIMEOUT but
243 GETSTATUS is not supported and GETBOOTSTATUS just returns 0.
244
245i810-tco.c -- Intel 810 chipset
246
247 Also has support for a lot of other i8x0 stuff, but the
248 watchdog is one of the things.
249
250 The timeout is set using the module parameter "i810_margin",
251 which is in steps of 0.6 seconds where 2<i810_margin<64. The
252 driver supports the SETTIMEOUT ioctl.
253
254 Supports CONFIG_WATCHDOG_NOWAYOUT.
255
256 GETSUPPORT returns WDIOF_SETTIMEOUT. The GETSTATUS call
257 returns some kind of timer value which ist not compatible with
258 the other drivers. GETBOOT status returns some kind of
259 hardware specific boot status. [FIXME -- describe this]
260
261ib700wdt.c -- IB700 Single Board Computer
262
263 Default timeout of 30 seconds and the timeout is settable
264 using the SETTIMEOUT ioctl. Note that only a few timeout
265 values are supported.
266
267 Supports CONFIG_WATCHDOG_NOWAYOUT
268
269 GETSUPPORT returns WDIOF_KEEPALIVEPING and WDIOF_SETTIMEOUT.
270 The GETSTATUS call returns if the device is open or not.
271 [FIXME -- silliness again?]
272
273machzwd.c -- MachZ ZF-Logic
274
275 Hardcoded timeout of 10 seconds
276
277 Has a module parameter "action" that controls what happens
278 when the timeout runs out which can be 0 = RESET (default),
279 1 = SMI, 2 = NMI, 3 = SCI.
280
281 Supports CONFIG_WATCHDOG_NOWAYOUT and the magic character
282 'V' close handling.
283
284 GETSUPPORT returns WDIOF_KEEPALIVEPING, and the GETSTATUS call
285 returns if the device is open or not. [FIXME -- silliness
286 again?]
287
288mixcomwd.c -- MixCom Watchdog
289
290 [FIXME -- I'm unable to tell what the timeout is]
291
292 Supports CONFIG_WATCHDOG_NOWAYOUT
293
294 GETSUPPORT returns WDIOF_KEEPALIVEPING, GETSTATUS returns if
295 the device is opened or not [FIXME -- I'm not really sure how
296 this works, there seems to be some magic connected to
297 CONFIG_WATCHDOG_NOWAYOUT]
298
299pcwd.c -- Berkshire PC Watchdog
300
301 Hardcoded timeout of 1.5 seconds
302
303 Supports CONFIG_WATCHDOG_NOWAYOUT
304
305 GETSUPPORT returns WDIOF_OVERHEAT|WDIOF_CARDRESET and both
306 GETSTATUS and GETBOOTSTATUS return something useful.
307
308 The SETOPTIONS call can be used to enable and disable the card
309 and to ask the driver to call panic if the system overheats.
310
311sbc60xxwdt.c -- 60xx Single Board Computer
312
313 Hardcoded timeout of 10 seconds
314
315 Does not support CONFIG_WATCHDOG_NOWAYOUT, but has the magic
316 character 'V' close handling.
317
318 No bits set in GETSUPPORT
319
320scx200.c -- National SCx200 CPUs
321
322 Not in the kernel yet.
323
324 The timeout is set using a module parameter "margin" which
325 defaults to 60 seconds. The timeout can also be set using
326 SETTIMEOUT and read using GETTIMEOUT.
327
328 Supports a module parameter "nowayout" that is initialized
329 with the value of CONFIG_WATCHDOG_NOWAYOUT. Also supports the
330 magic character 'V' handling.
331
332shwdt.c -- SuperH 3/4 processors
333
334 [FIXME -- I'm unable to tell what the timeout is]
335
336 Supports CONFIG_WATCHDOG_NOWAYOUT
337
338 GETSUPPORT returns WDIOF_KEEPALIVEPING, and the GETSTATUS call
339 returns if the device is open or not. [FIXME -- silliness
340 again?]
341
342softdog.c -- Software watchdog
343
344 The timeout is set with the module parameter "soft_margin"
345 which defaults to 60 seconds, the timeout is also settable
346 using the SETTIMEOUT ioctl.
347
348 Supports CONFIG_WATCHDOG_NOWAYOUT
349
350 WDIOF_SETTIMEOUT bit set in GETSUPPORT
351
352w83877f_wdt.c -- W83877F Computer
353
354 Hardcoded timeout of 30 seconds
355
356 Does not support CONFIG_WATCHDOG_NOWAYOUT, but has the magic
357 character 'V' close handling.
358
359 No bits set in GETSUPPORT
360
361w83627hf_wdt.c -- w83627hf watchdog
362
363 Timeout that defaults to 60 seconds, supports SETTIMEOUT.
364
365 Supports CONFIG_WATCHDOG_NOWAYOUT
366
367 GETSUPPORT returns WDIOF_KEEPALIVEPING and WDIOF_SETTIMEOUT.
368 The GETSTATUS call returns if the device is open or not.
369
370wdt.c -- ICS WDT500/501 ISA and
371wdt_pci.c -- ICS WDT500/501 PCI
372
373 Default timeout of 60 seconds. The timeout is also settable
374 using the SETTIMEOUT ioctl.
375
376 Supports CONFIG_WATCHDOG_NOWAYOUT
377
378 GETSUPPORT returns with bits set depending on the actual
379 card. The WDT501 supports a lot of external monitoring, the
380 WDT500 much less.
381
382wdt285.c -- Footbridge watchdog
383
384 The timeout is set with the module parameter "soft_margin"
385 which defaults to 60 seconds. The timeout is also settable
386 using the SETTIMEOUT ioctl.
387
388 Does not support CONFIG_WATCHDOG_NOWAYOUT
389
390 WDIOF_SETTIMEOUT bit set in GETSUPPORT
391
392wdt977.c -- Netwinder W83977AF chip
393
394 Hardcoded timeout of 3 minutes
395
396 Supports CONFIG_WATCHDOG_NOWAYOUT
397
398 Does not support any ioctls at all.
399
diff --git a/Documentation/watchdog/watchdog.txt b/Documentation/watchdog/watchdog.txt
new file mode 100644
index 000000000000..dffda29c8799
--- /dev/null
+++ b/Documentation/watchdog/watchdog.txt
@@ -0,0 +1,115 @@
1 Watchdog Timer Interfaces For The Linux Operating System
2
3 Alan Cox <alan@lxorguk.ukuu.org.uk>
4
5 Custom Linux Driver And Program Development
6
7
8The following watchdog drivers are currently implemented:
9
10 ICS WDT501-P
11 ICS WDT501-P (no fan tachometer)
12 ICS WDT500-P
13 Software Only
14 SA1100 Internal Watchdog
15 Berkshire Products PC Watchdog Revision A & C (by Ken Hollis)
16
17
18All six interfaces provide /dev/watchdog, which when open must be written
19to within a timeout or the machine will reboot. Each write delays the reboot
20time another timeout. In the case of the software watchdog the ability to
21reboot will depend on the state of the machines and interrupts. The hardware
22boards physically pull the machine down off their own onboard timers and
23will reboot from almost anything.
24
25A second temperature monitoring interface is available on the WDT501P cards
26and some Berkshire cards. This provides /dev/temperature. This is the machine
27internal temperature in degrees Fahrenheit. Each read returns a single byte
28giving the temperature.
29
30The third interface logs kernel messages on additional alert events.
31
32Both software and hardware watchdog drivers are available in the standard
33kernel. If you are using the software watchdog, you probably also want
34to use "panic=60" as a boot argument as well.
35
36The wdt card cannot be safely probed for. Instead you need to pass
37wdt=ioaddr,irq as a boot parameter - eg "wdt=0x240,11".
38
39The SA1100 watchdog module can be configured with the "sa1100_margin"
40commandline argument which specifies timeout value in seconds.
41
42The i810 TCO watchdog modules can be configured with the "i810_margin"
43commandline argument which specifies the counter initial value. The counter
44is decremented every 0.6 seconds and default to 50 (30 seconds). Values can
45range between 3 and 63.
46
47The i810 TCO watchdog driver also implements the WDIOC_GETSTATUS and
48WDIOC_GETBOOTSTATUS ioctl()s. WDIOC_GETSTATUS returns the actual counter value
49and WDIOC_GETBOOTSTATUS returns the value of TCO2 Status Register (see Intel's
50documentation for the 82801AA and 82801AB datasheet).
51
52Features
53--------
54 WDT501P WDT500P Software Berkshire i810 TCO SA1100WD
55Reboot Timer X X X X X X
56External Reboot X X o o o X
57I/O Port Monitor o o o X o o
58Temperature X o o X o o
59Fan Speed X o o o o o
60Power Under X o o o o o
61Power Over X o o o o o
62Overheat X o o o o o
63
64The external event interfaces on the WDT boards are not currently supported.
65Minor numbers are however allocated for it.
66
67
68Example Watchdog Driver
69-----------------------
70
71#include <stdio.h>
72#include <unistd.h>
73#include <fcntl.h>
74
75int main(int argc, const char *argv[])
76{
77 int fd=open("/dev/watchdog",O_WRONLY);
78 if(fd==-1)
79 {
80 perror("watchdog");
81 exit(1);
82 }
83 while(1)
84 {
85 write(fd,"\0",1);
86 fsync(fd);
87 sleep(10);
88 }
89}
90
91
92Contact Information
93
94People keep asking about the WDT watchdog timer hardware: The phone contacts
95for Industrial Computer Source are:
96
97Industrial Computer Source
98http://www.indcompsrc.com
99ICS Advent, San Diego
1006260 Sequence Dr.
101San Diego, CA 92121-4371
102Phone (858) 677-0877
103FAX: (858) 677-0895
104>
105ICS Advent Europe, UK
106Oving Road
107Chichester,
108West Sussex,
109PO19 4ET, UK
110Phone: 00.44.1243.533900
111
112
113and please mention Linux when enquiring.
114
115For full information about the PCWD cards see the pcwd-watchdog.txt document.