aspeed2500 SPI1 control at run-time with OpenBMC

[Oskar Senft]

> I can
> switch SPI1 control to master through pinmux-select:
> [...]
>
> However, I cannot access the device. '/dev/mtd6' doesn't exist, and I
> cannot bind it:
> $  echo 1e630000.spi >/sys/bus/platform/drivers/aspeed-smc/bind
> -sh: echo: write error: No such file or directory

Is there an existing interaction (in the code) between the Aspeed SPI
driver and pinmux? I guess ideally we'd want the SPI driver to talk
with pinmux to tell it "I'd like to bind the device, can you please
configure the pins properly" as well as "I just unbound the device.
pinmux, please release the pins".

With that, I wonder if we somewhat have that already and "pinctrl-0 =
<&pinctrl_spi1passthru_default>" ends up "confusing" the link between
the pinmux and the spi driver (since it's actually the opposite of
what we want)? How is that _supposed_ to work? Maybe there's just a
bug?

Also, I'm wondering: Is it possible to have "&spi1" defined, but not
bound initially? I guess that's what we want by default?

Oskar.