From nobody Tue Dec 16 14:20:34 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 92A2927C867; Thu, 6 Mar 2025 22:23:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741299839; cv=none; b=QCjSndDFmxn66bQIA4AwPX6Gy56CCtwBpW2WwzxI1s6kextZJTsqRAMPqLHAWK+QHXUBMjZoIA3YojbL4NAOLs1AoTEF3Zp1ZiVYCg+jlX8/kdT9KWAKWsSvGLdhhDiMNeOozBmnvrkvS3bd337Q4kBbW+LXgwaq0ukW+UkdbgY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741299839; c=relaxed/simple; bh=ILGJjKKo5nQZHxzXgwewCMckflvSqIeS3xmxKI0k4uM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EI3POJgmeIfj3YF6fTAnP3CU6S3/VrISBOHuxK8QGFEXpENPLCL8UFGgY8hD9uelu9GaFk9YBcLc/OSP2M6KCW5Se6rII5agz5rcSIT5lgjH48fGS/Sh6hYRLM7Hzu8mCV+zInJxtH+QQu1d0ZlUdyrBKiSpcqXGv7cfj0dwofw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MbcKDMn+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MbcKDMn+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7D4AC4CEEB; Thu, 6 Mar 2025 22:23:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741299839; bh=ILGJjKKo5nQZHxzXgwewCMckflvSqIeS3xmxKI0k4uM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MbcKDMn+v17Jlhx7k1of1maIC3wGlRZRcgexU9K896QzxSROQEhd5YkuHiPaEKPfp YNd15lAFxZ5nEXsQtXTWFtQX4EbhZRYBZhw4UxQwHF4sDXrUGs18SHeJP5xTLZGQNn hAEOFNMyQWxy7wX7mBDL5FfHqozrd1QbipglcV6Xi0TafZxC01zX/71bJxfdXTe0E9 VUbQpWfSuyDow21BWdgx9ZScYZEgK9d7+ePkGYbHau+R6kL1vlhVoLkfEvIjJ1/Yka EhZNKq8Q6eaXv42yK9oZILxlBrXGKMonB+Gsk8TC1yKwd51UvPs6zN3kGcJGdysJan 59FwoY6ItGEkg== From: Danilo Krummrich To: airlied@gmail.com, simona@ffwll.ch, corbet@lwn.net, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, ajanulgu@redhat.com, lyude@redhat.com, pstanner@redhat.com, zhiw@nvidia.com, cjia@nvidia.com, jhubbard@nvidia.com, bskeggs@nvidia.com, acurrid@nvidia.com Cc: ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu, gregkh@linuxfoundation.org, mcgrof@kernel.org, russ.weight@linux.dev, dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, nouveau@lists.freedesktop.org, rust-for-linux@vger.kernel.org, Danilo Krummrich Subject: [PATCH v6 2/5] rust: firmware: introduce `firmware::ModInfoBuilder` Date: Thu, 6 Mar 2025 23:23:28 +0100 Message-ID: <20250306222336.23482-3-dakr@kernel.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250306222336.23482-1-dakr@kernel.org> References: <20250306222336.23482-1-dakr@kernel.org> 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" The `firmware` field of the `module!` only accepts literal strings, which is due to the fact that it is implemented as a proc macro. Some drivers require a lot of firmware files (such as nova-core) and hence benefit from more flexibility composing firmware path strings. The `firmware::ModInfoBuilder` is a helper component to flexibly compose firmware path strings for the .modinfo section in const context. It is meant to be used in combination with `kernel::module_firmware!`. Co-developed-by: Alice Ryhl Signed-off-by: Alice Ryhl Signed-off-by: Danilo Krummrich --- rust/kernel/firmware.rs | 127 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 127 insertions(+) diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs index c5162fdc95ff..6008b62f2de8 100644 --- a/rust/kernel/firmware.rs +++ b/rust/kernel/firmware.rs @@ -115,3 +115,130 @@ unsafe impl Send for Firmware {} // SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, refer= ences to which are safe to // be used from any thread. unsafe impl Sync for Firmware {} + +/// Builder for firmware module info. +/// +/// [`ModInfoBuilder`] is a helper component to flexibly compose firmware = paths strings for the +/// .modinfo section in const context. +/// +/// Therefore the [`ModInfoBuilder`] provides the methods [`ModInfoBuilder= ::new_entry`] and +/// [`ModInfoBuilder::push`], where the latter is used to push path compon= ents and the former to +/// mark the beginning of a new path string. +/// +/// [`ModInfoBuilder`] is meant to be used in combination with `kernel::mo= dule_firmware!`. +/// +/// The const generic `N` as well as the `module_name` parameter of [`ModI= nfoBuilder::new`] is an +/// internal implementation detail and supplied through the above macro. +pub struct ModInfoBuilder { + buf: [u8; N], + n: usize, + module_name: &'static CStr, +} + +impl ModInfoBuilder { + /// Create an empty builder instance. + pub const fn new(module_name: &'static CStr) -> Self { + Self { + buf: [0; N], + n: 0, + module_name, + } + } + + const fn push_internal(mut self, bytes: &[u8]) -> Self { + let mut j =3D 0; + + if N =3D=3D 0 { + self.n +=3D bytes.len(); + return self; + } + + while j < bytes.len() { + if self.n < N { + self.buf[self.n] =3D bytes[j]; + } + self.n +=3D 1; + j +=3D 1; + } + self + } + + /// Push an additional path component. + /// + /// Append path components to the [`ModInfoBuilder`] instance. Paths n= eed to be separated + /// with [`ModInfoBuilder::new_entry`]. + /// + /// # Example + /// + /// ``` + /// use kernel::firmware::ModInfoBuilder; + /// + /// # const DIR: &str =3D "vendor/chip/"; + /// # const fn no_run(builder: ModInfoBuilder) { + /// let builder =3D builder.new_entry() + /// .push(DIR) + /// .push("foo.bin") + /// .new_entry() + /// .push(DIR) + /// .push("bar.bin"); + /// # } + /// ``` + pub const fn push(self, s: &str) -> Self { + // Check whether there has been an initial call to `next_entry()`. + if N !=3D 0 && self.n =3D=3D 0 { + crate::build_error!("Must call next_entry() before push()."); + } + + self.push_internal(s.as_bytes()) + } + + const fn push_module_name(self) -> Self { + let mut this =3D self; + let module_name =3D this.module_name; + + if !this.module_name.is_empty() { + this =3D this.push_internal(module_name.as_bytes_with_nul()); + + if N !=3D 0 { + // Re-use the space taken by the NULL terminator and swap = it with the '.' separator. + this.buf[this.n - 1] =3D b'.'; + } + } + + this + } + + /// Prepare the [`ModInfoBuilder`] for the next entry. + /// + /// This method acts as a separator between module firmware path entri= es. + /// + /// Must be called before constructing a new entry with subsequent cal= ls to + /// [`ModInfoBuilder::push`]. + /// + /// See [`ModInfoBuilder::push`] for an example. + pub const fn new_entry(self) -> Self { + self.push_internal(b"\0") + .push_module_name() + .push_internal(b"firmware=3D") + } + + /// Build the byte array. + pub const fn build(self) -> [u8; N] { + // Add the final NULL terminator. + let this =3D self.push_internal(b"\0"); + + if this.n =3D=3D N { + this.buf + } else { + crate::build_error!("Length mismatch."); + } + } +} + +impl ModInfoBuilder<0> { + /// Return the length of the byte array to build. + pub const fn build_length(self) -> usize { + // Compensate for the NULL terminator added by `build`. + self.n + 1 + } +} --=20 2.48.1