From nobody Sat Oct 11 08:30:51 2025 Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [80.241.56.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4BD6426A081; Wed, 11 Jun 2025 10:30:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749637803; cv=none; b=aYE80ceISjgYjXzGj9WtxLN5l5/5vCjBGjerYTmN21dfwdgtfRdUqH9MZ9eS5oonmMhKDLDd//5InyKDOa4QDYWW7wD4qGLK8F2mTnvKjLJ5DrAt9km6AeT7BoyllJs3HDa3hnVZwdvuD6bOHkY1jw8nt1FSf3VVhEUG+QLqN9Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749637803; c=relaxed/simple; bh=HZo7sWs6Rd/8ppVZwK1eaOO/YcXTMZfvUnndHC7pUEc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BKzkRd0pOcUp5K7tXchyV9YoPA1085teEwLA3Sg9sjmCb/I2Vr2pyEyQS/I7liHL2P1HEsEPJ86kFGfeObhtEUj/wuNIpbRCe0Q0Mu0GdiO1+75bJlQOPNxllJFpebSPZb1B9pK4oSf7cTONOKNeWsS9C7sZ/9/NhBZvDncaNY4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=buenzli.dev; spf=pass smtp.mailfrom=buenzli.dev; arc=none smtp.client-ip=80.241.56.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=buenzli.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=buenzli.dev Received: from smtp202.mailbox.org (smtp202.mailbox.org [10.196.197.202]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-202.mailbox.org (Postfix) with ESMTPS id 4bHMNj5XdJz9tQ8; Wed, 11 Jun 2025 12:29:57 +0200 (CEST) From: Remo Senekowitsch To: Rob Herring , Saravana Kannan , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Greg Kroah-Hartman , "Rafael J. Wysocki" , Dirk Behme , Remo Senekowitsch Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, rust-for-linux@vger.kernel.org Subject: [PATCH v8 8/9] rust: device: Add property_get_reference_args Date: Wed, 11 Jun 2025 12:29:07 +0200 Message-ID: <20250611102908.212514-9-remo@buenzli.dev> In-Reply-To: <20250611102908.212514-1-remo@buenzli.dev> References: <20250611102908.212514-1-remo@buenzli.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Allow Rust code to read reference args from device properties. The wrapper type `FwNodeReferenceArgs` allows callers to access the buffer of read args safely. Tested-by: Dirk Behme Signed-off-by: Remo Senekowitsch --- rust/kernel/device/property.rs | 67 ++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) diff --git a/rust/kernel/device/property.rs b/rust/kernel/device/property.rs index cd640adf18ca5..28d9848ea5fb1 100644 --- a/rust/kernel/device/property.rs +++ b/rust/kernel/device/property.rs @@ -246,6 +246,64 @@ pub fn children<'a>(&'a self) -> impl Iterator> + 'a { Some(next) }) } + + /// Finds a reference with arguments. + pub fn property_get_reference_args( + &self, + prop: &CStr, + nargs: NArgs<'_>, + index: u32, + ) -> Result { + let mut out_args =3D FwNodeReferenceArgs::default(); + + let (nargs_prop, nargs) =3D match nargs { + NArgs::Prop(nargs_prop) =3D> (nargs_prop.as_char_ptr(), 0), + NArgs::N(nargs) =3D> (ptr::null(), nargs), + }; + + // SAFETY: + // - `self.0.get()` is valid. + // - `prop.as_char_ptr()` is valid and zero-terminated. + // - `nargs_prop` is valid and zero-terminated if `nargs` + // is zero, otherwise it is allowed to be a null-pointer. + let ret =3D unsafe { + bindings::fwnode_property_get_reference_args( + self.0.get(), + prop.as_char_ptr(), + nargs_prop, + nargs, + index, + &mut out_args.0, + ) + }; + to_result(ret)?; + + Ok(out_args) + } +} + +/// The return value of [`FwNode::property_get_reference_args`]. +#[repr(transparent)] +#[derive(Copy, Clone, Default)] +pub struct FwNodeReferenceArgs(bindings::fwnode_reference_args); + +impl FwNodeReferenceArgs { + /// Returns the slice of reference arguments. + pub fn as_slice(&self) -> &[u64] { + // SAFETY: As per the safety invariant of `FwNodeReferenceArgs`, `= nargs` + // is the number of elements in `args` that is valid. + unsafe { core::slice::from_raw_parts(self.0.args.as_ptr(), self.0.= nargs as usize) } + } + + /// Returns the number of reference arguments. + pub fn len(&self) -> usize { + self.0.nargs as usize + } + + /// Returns `true` if there are no reference arguments. + pub fn is_empty(&self) -> bool { + self.0.nargs =3D=3D 0 + } } =20 // SAFETY: Instances of `FwNode` are always reference-counted. @@ -412,6 +470,15 @@ fn read_from_fwnode_property(fwnode: &FwNode, name: &C= Str) -> Result { i64: fwnode_property_read_u64_array, } =20 +/// The number of arguments of a reference. +pub enum NArgs<'a> { + /// The name of the property of the reference indicating the number of + /// arguments. + Prop(&'a CStr), + /// The known number of arguments. + N(u32), +} + /// A helper for reading device properties. /// /// Use [`Self::required_by`] if a missing property is considered a bug and --=20 2.49.0