Am 2022-04-21 16:23, schrieb Rob Herring:
What's needed here is a connector node (and driver) for the mikrobus
socket. The connector node's purpose is to decouple the host DT from
add-on board overlay DT. Something like this:
Funny I had a similar idea to have a connector with all the
properties, but I failed to see how that would be of any help.
Do you mind an example of such an overlay? Judging by the spi
and i2c subnode, I guess it will amend the connector node and
fill in it's devices?
And all the child device properties will reference the connector,
correct?
connector {
// And a more specific compatible if pins can have alt funcs?
// Spec version needed?
compatible = "mikrobus-socket";
// Will need regulators defined if child devices expect
// regulators
vcc-33-supply = <®33>;
vcc-5-supply = <®5v>;
i2c-parent = <&i2c1>; // Already a defined property
spi-parent = <&spi0>; // New
uart/serial needed too?
// RST pin
reset-gpios = <&gpio 4 0>;
// remap 'INT' (index 0) to host interrupt
#interrupt-cells = <2>;
#address-cells = <0>;
interrupt-map = <0 0 &gpio 3 0>;
spi {
For example:
my-device@0 {
reg = <0>; // really needed? there is only one SPI CS line
compatible = "my-device";
reset-gpios = // may be left unset if it's optional, but what
// what if it is a required property and in hardware
// its connected to the RST pin of the module?
other-gpios = <&connector 2>;
vdd-supply = // what comes here? <&connector VCC_33>?
interrupts-extended = <&connector 0 ..>;
}
-michael
//devices
};
i2c {
};
};
The DT spec defines 'foo-map' properties extending interrupt-map.
Currently only GPIO is defined. We might want to do the same thing for
PWM. Or we make the connector node both a PWM consumer and provider.
Rob
