From patchwork Wed Feb 26 17:55:45 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Danilo Krummrich X-Patchwork-Id: 13992872 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 46194C021B8 for ; Wed, 26 Feb 2025 17:56:24 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B782910E992; Wed, 26 Feb 2025 17:56:23 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="MqJfmxWQ"; dkim-atps=neutral Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9D20010E992; Wed, 26 Feb 2025 17:56:22 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 35C506151D; Wed, 26 Feb 2025 17:56:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90BE1C4CEE9; Wed, 26 Feb 2025 17:56:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740592581; bh=BQ8xHMKrltZRFNzxJKwFtK1VAIQkorDo50VJfIqedqI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MqJfmxWQBjJ7tvEUfd6uYf1PEpWYAv09MkXWzee9bKtMvDe1brA+59hTUTi7Itawj lICX7awqJbiC+u/jdk9ZwjwPp45oSKWBUeiurrmsrtWyeM5XP2akF5TdAPLomd9N/u FmfocWK7R9CApGtVfmggHmJ+PvpXT1J7nIWr7+Rx9Qfu2A2pr5KM94E5jE1hUyqrwV 5WUTyQ0Tqn57A5QoAEAwZRNw8sEhGYcR0BcFXqlPZXJLFBqpcBYkxUKDcHKCN/xpyU tC1vFxRDndUTHptxeO9xXM1rVEKE725QtUB2sJ6cPkfOV66qrxBIy+sQL2jIo4r05l L0D8hs9UQ8+sQ== 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, 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 v4 3/6] rust: firmware: introduce `firmware::ModInfoBuilder` Date: Wed, 26 Feb 2025 18:55:45 +0100 Message-ID: <20250226175552.29381-4-dakr@kernel.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250226175552.29381-1-dakr@kernel.org> References: <20250226175552.29381-1-dakr@kernel.org> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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!`, which is introduced in a subsequent patch. Co-developed-by: Alice Ryhl Signed-off-by: Alice Ryhl Signed-off-by: Danilo Krummrich --- rust/kernel/firmware.rs | 98 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs index c5162fdc95ff..0f27dc212d6e 100644 --- a/rust/kernel/firmware.rs +++ b/rust/kernel/firmware.rs @@ -115,3 +115,101 @@ unsafe impl Send for Firmware {} // SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, references 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. +/// +/// It is meant to be used in combination with [`kernel::module_firmware!`]. +/// +/// For more details and an example, see [`kernel::module_firmware!`]. +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 = 0; + + if N == 0 { + self.n += bytes.len(); + return self; + } + + while j < bytes.len() { + if self.n < N { + self.buf[self.n] = bytes[j]; + } + self.n += 1; + j += 1; + } + self + } + + /// Push an additional path component. + /// + /// After a new [`ModInfoBuilder`] instance has been created, [`ModInfoBuilder::prepare`] must + /// be called before adding path components. + pub const fn push(self, bytes: &[u8]) -> Self { + if N != 0 && self.n == 0 { + crate::build_error!("Must call prepare() before push()."); + } + + self.push_internal(bytes) + } + + const fn prepare_module_name(self) -> Self { + let mut this = self; + let module_name = this.module_name; + + if !this.module_name.is_empty() { + this = this.push_internal(module_name.as_bytes_with_nul()); + + if N != 0 { + // Re-use the space taken by the NULL terminator and swap it with the '.' separator. + this.buf[this.n - 1] = b'.'; + } + } + + this.push_internal(b"firmware=") + } + + /// Prepare for the next module info entry. + /// + /// Must be called before [`ModInfoBuilder::push`] can be called. + pub const fn prepare(self) -> Self { + self.push_internal(b"\0").prepare_module_name() + } + + /// Build the byte array. + pub const fn build(self) -> [u8; N] { + // Add the final NULL terminator. + let this = self.push_internal(b"\0"); + + if this.n == 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 + } +}