Re: iTCO multiple /dev entries

Re: iTCO multiple /dev entries

[Wim Van Sebroeck]

Hi Fabio,

> Hi, on some machines I'm trying to setup iTCO wdt (ivybridge/panther
> point), but I'm perplexed about the presence of three devices:
> 
> 
> kefk dev # ls -la wat*
> crw------- 1 root root  10, 130  4 ago 22.21 watchdog
> crw------- 1 root root 251,   0  4 ago 22.21 watchdog0
> crw------- 1 root root 251,   1  4 ago 22.21 watchdog1
> 
> 
> I was expecting only one, so I'm a bit confused about the difference
> between the devices and how to use it. I googled a bit without big
> success... maybe you could point me to some documentation?
> I checked also sources and kernel Documentation/, still no clues :)

with the introduction of the watchdog generic framework we allowed more
then 1 watchdog device. So you have watchdog0 till watchdog... .
In your case you have 2 devices that were detected: watchdog0 and watchdog1.
(for instance a iTCO device and a Super-I/O watchdog device).
for compatibility /dev/watchdog0 is the same as /dev/watchdog.

We indeed have real documentation about it, but the ideas are in
Documentation/watchdog/watchdog-kernel-api.txt (See the part:
	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.

Kind regards,
Wim.