Messages in this thread | | | Date | Thu, 21 Feb 2002 15:53:48 +0000 | From | Joel Becker <> | Subject | Re: [DRIVER][RFC] SC1200 Watchdog driver |
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On Thu, Feb 21, 2002 at 01:57:43PM +0100, Christer Weinigel wrote: > I'm not even sure if single-open sematics are neccesary at all, but I > copied most of the interface from wdt285.c so I copied this too. The > watchdog API seems to be a rather ad hoc thing. For example I just > noticed that the WDIOC_SETTIMEOUT call probably takes a parameter > which seems to be minutes, not seconds. "Someone (tm)" ought to write > a more formal API specification.
WDIOC_SETTIMEOUT is defined as being in seconds. This is commented in linux/watchdog.h against the WDIOF_SETTIMOUT flag. Where you see funky math against the passed parameter is where a watchdog card takes strange values on its hardware and the driver is computing the proper strange value for the given amount of seconds. Also note that WDIOC_SETTIMEOUT rounds up to the nearest second interval the watchdog can handle if the watchdog cannot support the passed interval. For this reason, it always returns the actual timeout set in the passed int*. This is usually done with the fall-through to the WDIOC_GETTIMEOUT code. You don't see WDIOC_SETTIMEOUT in 2.4.17 because it was added in 2.4.18pre.
Joel
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