On Mon, Nov 18, 2019 at 12:45 PM Mark Brown <broonie@xxxxxxxxxx> wrote:
>
> So this is one device that has two separate modes? This sounds like you
> need a property specifying how the device is wired up, or possibly just
> different compatibles at the root of the device though that's not quite
> idiomatic. Splitting this up with different devices is a bit of a Linux
> specific implementation detail.
Yes, that does make sense and sounds elegant. However, bear with me:
This mfd chip can be wired up as one of the following:
- gpio only
- gpio + regulator
- gpio + led
- gpio + flash
So I need a way to indicate this in the dt.
Imagine I do this with a text/value property, like this:
i2c0 {
tps61052@33 {
compatible = "ti,tps61050";
reg = <0x33>;
mode = "regulator"; // or
mode = <TPS6105X_REGULATOR_MODE>;
};
};
in this case, there is no elegant way to specify the regulator properties in
the devicetree. Except by grabbing a reference to a subnode perhaps. And then
I'd have to somehow make sure that the sub driver's device->of_node points
at this subnode, which the mfd core doesn't do automatically.
Now imagine I use a reference property:
i2c0 {
tps61052@33 {
compatible = "ti,tps61050";
reg = <0x33>;
mode = <&tps_reg>;
tps_reg: regulator {
regulator-min-microvolt = <5000000>;
regulator-max-microvolt = <5000000>;
regulator-always-on;
};
};
};
However for this to work, I need to make sure the regulator subdriver gets a
valid dev->of_node, which the mfd core doesn't do automatically. So I'd have
to follow the 'mode' node, check that its compatible is correct, and then
manually assign the of_node to the mfd child driver (not sure how to even
do that).
So I arrived at the following:
i2c0 {
tps61052@33 {
compatible = "ti,tps61050";
reg = <0x33>;
regulator {
compatible = "ti,tps6105x-regulator";
regulator-min-microvolt = <5000000>;
regulator-max-microvolt = <5000000>;
regulator-always-on;
};
};
};
In this case, I only need to verify that there is at most one single subnode.
And when I specify of_compatible = "ti,tps6105x-regulator" in the mfd cell,
the mfd core will automatically assign the child driver's of_node. Nice 'n
elegant?
Would you be able to suggest a way forward?
