Am 2020-09-26 14:44, schrieb Tom Rini:
[..]
If we want to have a hardware based watchdog in the UEFI context, we
need a U-Boot internal API by which we can enable and disable a
hardware
watchdog with an arbitrary duration (>> 5 min) with 1 second
resolution.
Then our implementation of SetWatchdogTimer() could call into this
API.
Thanks for excerpting from the UEFI spec where it talks about a
"watchdog" at all. It's clear from these excerpts that the spec simply
does not talk about a hardware watchdog at all and is using the term in
one of its other meanings. Which means that we need to figure out and
document something nominally sane so at least it's not a surprise to
the
user.
Michael, what driver under drivers/watchdog/ is your platform using
exactly? Thanks!
In its current form (i.e. basic BSP support) it uses the sp805_wdt.c;
which is a nice to have, but the real watchdog is an external device.
There is no support in U-Boot for it yet, but I'm planning to add it
and thus I need the CONFIG_WDT ;)
Currently this external watchdog is disabled (there are non-volatile
configuration bits on the board and one bit is for disabling this
watchdog at startup). Otherwise it would always activate the board's
failsafe mode because it isn't triggered by U-Boot.
And yes, this watchdog also have a lock bit, once set, you cannot
deactivate it anymore (although you can change the timeout period
in a given range).
Because at the moment there is no driver for this watchdog yet (it
is a custom one), my newest version of my "basic board support for
Kontron sl28" has the CONFIG_WDT deactivated. I prefer having a
usable bootefi to have support for the SoC internal watchdog.
-michael
