On 15.03.21 12:46, Rasmus Villemoes wrote:
Hi,
So how is one supposed to get the kernel to set and maintain a value for
a gpio, without having to keep a dummy process around? Also, with the
sysfs interface, another process can later change the gpio value; I
don't think that's possible with a dummy process hanging onto it.
I've got a few remaining legacy systems in the field, where I still use
the classic sysfs interface for exactly that reason: separate
short-running programs (shell scripts) do certain things on the gpio and
then
exit.
For newer applications, I don't use raw gpios anymore (except for rare
things like generic PLCs, where I have no influence on the actual
workloads)
So, for example, one init script we have first configures a temperature
sensor with a high-temp alert threshold, and after that value has been
written, sets a gpio that will make such an alert trigger a reset of the
board.
Bind a proper driver to it. Either IIO or hwmon (depending on what that
sensor is actually for).
--mtx
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Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
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