2024-05-02 at 15:49, Peter Rosin wrote:
> Since you appear to need to change both the gpio pin and the io-channel, the
> mux isn't a perfect fit. The closest you can get with the current code is to
> create a gpio mux, I think. You would then use that mux twice to fan out both
> io-channels, but only expose the "left leg" on the first fan-out and only the
> "right leg" on the other. Something like this (untested, probably riddled with
> errors, use salt etc etc):
>
> rcs: raw-current-sense {
> compatible = "current-sense-shunt";
> io-channels = <&adc 0>;
> io-channel-name = "raw-current";
> #io-channel-cells = <1>;
>
> shunt-resistor-micro-ohms = <3300000>;
> };
>
> rvs: raw-voltage-sense {
> compatible = "voltage-divider";
> io-channels = <&adc 1>;
> io-channel-name = "raw-voltage";
> #io-channel-cells = <1>;
>
> output-ohms = <22>;
> full-ohms = <222>;
> };
>
> mux: gpio-mux {
> compatible = "gpio-mux";
> #mux-control-cells = <0>;
>
> gpios-mux = <&main_gpio0 29 GPIO_ACTIVE_HIGH>;
> };
>
> current-sense {
> compatible = "io-channel-mux";
> io-channels = <&rcs 0>;
> io-channel-names = "parent";
>
> mux-controls = <&mux>;
>
> channels = "current", "";
> };
>
> voltage-sense {
> compatible = "io-channel-mux";
> io-channels = <&rvs 0>;
> io-channel-names = "parent";
>
> mux-controls = <&mux>;
>
> channels = "", "voltage";
> };
>
> What the mux solves is exclusion, so that the gpio pin is locked while
> measurement is made on either current-sense or voltage-sense.
>
> However, the channels from the raw-{current,voltage}-sense nodes are exposed
> to user space, and it will be possible to make "raw" measurements without
> regard to how the gpio pin is set. That will of course not yield the desired
> results, but is also a user error and might not be a big problem?
I just realized that it's also possible to do this "the other way around". Maybe
that makes more sense?
Cheers,
Peter
mux: gpio-mux {
compatible = "gpio-mux";
#mux-control-cells = <0>;
gpios-mux = <&main_gpio0 29 GPIO_ACTIVE_HIGH>;
};
rcs: raw-current-sense {
compatible = "io-channel-mux";
io-channels = <&adc 0>;
io-channel-names = "parent";
#io-channel-cells = <1>;
mux-controls = <&mux>;
channels = "raw-current", "";
};
rvs: raw-voltage-sense {
compatible = "io-channel-mux";
io-channels = <&adc 1>;
io-channel-names = "parent";
#io-channel-cells = <1>;
mux-controls = <&mux>;
channels = "", "raw-voltage";
};
current-sense {
compatible = "current-sense-shunt";
io-channels = <&rcs 0>;
io-channel-name = "current";
shunt-resistor-micro-ohms = <3300000>;
};
voltage-sense {
compatible = "voltage-divider";
io-channels = <&rvs 1>;
io-channel-name = "voltage";
output-ohms = <22>;
full-ohms = <222>;
};
Cheers,
Peter
