On Thu, 27 May 2021 at 16:00, Rasmus Villemoes <rasmus.villem...@prevas.dk> wrote: > > A rather common kind of external watchdog circuit is one that is kept > alive by toggling a gpio. Add a driver for handling such a watchdog. > > The corresponding linux driver apparently has support for some > watchdog circuits which can be disabled by tri-stating the gpio, but I > have never actually encountered such a chip in the wild; the whole > point of adding an external watchdog is usually that it is not in any > way under software control. For forward-compatibility, and to make DT > describe the hardware, the current driver only supports devices that > have the always-running property. I went a little back and forth on > whether I should fail ->probe or only ->start, and ended up deciding > ->start was the right place. > > The compatible string is probably a little odd as it has nothing to do > with linux per se - however, I chose that to make .dts snippets > reusable between device trees used with U-Boot and linux, and this is > the (only) compatible string that linux' corresponding driver and DT > binding accepts. I have asked whether one should/could add "wdt-gpio" > to that binding, but the answer was no: > > > https://lore.kernel.org/lkml/CAL_JsqKEGaFpiFV_oAtE+S_bnHkg4qry+bhx2EDs=nsbvf_...@mail.gmail.com/ > > If someone feels strongly about this, I can certainly remove the > "linux," part from the string - it probably wouldn't the only place where > one can't reuse a DT snippet as-is between linux and U-Boot. > > Signed-off-by: Rasmus Villemoes <rasmus.villem...@prevas.dk> > --- > .../watchdog/gpio-wdt.txt | 19 +++++ > drivers/watchdog/Kconfig | 9 +++ > drivers/watchdog/Makefile | 1 + > drivers/watchdog/gpio_wdt.c | 69 +++++++++++++++++++ > 4 files changed, 98 insertions(+) > create mode 100644 doc/device-tree-bindings/watchdog/gpio-wdt.txt > create mode 100644 drivers/watchdog/gpio_wdt.c >
Reviewed-by: Simon Glass <s...@chromium.org>
