Re: [PATCH 08/10] rust: property: Add property_get_reference_args

Danilo Krummrich
2025-03-27T14:32:42Z

On Wed, Mar 26, 2025 at 06:13:47PM +0100, Remo Senekowitsch wrote:
> Signed-off-by: Remo Senekowitsch <remo@buenzli.dev>
> ---
> rust/kernel/property.rs | 63 +++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 63 insertions(+)
>
> diff --git a/rust/kernel/property.rs b/rust/kernel/property.rs
> index dc927ad93..f1d0a33ba 100644
> --- a/rust/kernel/property.rs
> +++ b/rust/kernel/property.rs
> @@ -8,6 +8,7 @@
>
> use crate::{
> alloc::KVec,
> + arrayvec::ArrayVec,
> bindings,
> device::Device,
> error::{to_result, Result},
> @@ -64,6 +65,20 @@ pub fn get_child_by_name(&self, name: &CStr) -> Option<ARef<FwNode>> {
> pub fn children<'a>(&'a self) -> impl Iterator<Item = ARef<FwNode>> + 'a {
> self.fwnode().children()
> }
> +
> + /// Finds a reference with arguments.
> + pub fn property_get_reference_args(
> + &self,
> + prop: &CStr,
> + nargs: NArgs<'_>,
> + index: u32,
> + ) -> Result<(
> + ARef<FwNode>,
> + ArrayVec<{ bindings::NR_FWNODE_REFERENCE_ARGS as usize }, u64>,
> + )> {
> + self.fwnode()
> + .property_get_reference_args(prop, nargs, index)
> + }
> }
>
> /// A reference-counted fwnode_handle.
> @@ -226,6 +241,45 @@ pub fn children<'a>(&'a self) -> impl Iterator<Item = ARef<FwNode>> + 'a {
> Some(next)
> })
> }
> +
> + /// Finds a reference with arguments.
> + pub fn property_get_reference_args(
> + &self,
> + prop: &CStr,
> + nargs: NArgs<'_>,
> + index: u32,
> + ) -> Result<(
> + ARef<Self>,
> + ArrayVec<{ bindings::NR_FWNODE_REFERENCE_ARGS as usize }, u64>,
> + )> {
> + let mut out_args = bindings::fwnode_reference_args::default();
> +
> + let (nargs_prop, nargs) = match nargs {
> + NArgs::Prop(nargs_prop) => (nargs_prop.as_char_ptr(), 0),
> + NArgs::N(nargs) => (ptr::null(), nargs),
> + };
> +
> + let ret = unsafe {
> + bindings::fwnode_property_get_reference_args(
> + self.0.get(),
> + prop.as_char_ptr(),
> + nargs_prop,
> + nargs,
> + index,
> + &mut out_args,
> + )
> + };
> + to_result(ret)?;
> +
> + let node = unsafe { FwNode::from_raw(out_args.fwnode) };
> + let mut args = ArrayVec::default();
> +
> + for i in 0..out_args.nargs {
> + args.push(out_args.args[i as usize]);
> + }

Why the copy? Can't you just write an abstraction for struct
fwnode_reference_args and just return an instance of that?