drivers: regulator: regulator_shell: create command to print regulators

[bdesterBE]

The regulator shell commands require that you provide the name of the regulator node to be able to interact with them (e.g. regulator enable myRegulator). It can be inconvenient to have to go to Devicetree files to find the name of the regulator to change.

Fixes: #83073

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[gmarull]

this doesn't make sense, you're documenting "Print regulator names", but only regulator-fixed is considered.

[bdesterBE]

this doesn't make sense, you're documenting "Print regulator names", but only regulator-fixed is considered.

Thanks for the reply. I originally implemented this as any node with status okay that has the regulator-name property. Does that solution satisfy this?

[gmarull]

this doesn't make sense, you're documenting "Print regulator names", but only regulator-fixed is considered.

Thanks for the reply. I originally implemented this as any node with status okay that has the regulator-name property. Does that solution satisfy this?

First, name should be stored on each regulator, then, you can iterate over all regulators and retrieve their name.

[gmarull]

I still fail to see the utility of this. List may be incomplete to start with, and you can't obtain a regulator device handle from its 'regulator-name'. It's now possible to list all devices from a particular class, so better use that.

[bdesterBE]

The intended utility is to be able to easily get the names of regulator nodes without needing to reference devicetree files or guess from tab completion. The node names are needed in order to do anything with regulators from the shell.

I pushed the change to use the device class, thanks for the suggestion as it's definitely a better solution. Please let me know if it's preferred to use DEVICE_API_IS() directly rather than device_is_regulator() so that the command functions remain organized together. Alternatively, could declare device_is_regulator() prototype at the top of the file.

[gmarull]

this is pasting tons of if (device_is_regulator(device_get_binding(DT_NODE_FULL_NAME(node_id)))), ie, runtime checks, when regulator devices are known at compile time now. Why is this useful when tab autocompletes regulators only?