From mboxrd@z Thu Jan 1 00:00:00 1970 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 BDC4217BB35; Tue, 11 Jun 2024 13:44:48 +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=1718113488; cv=none; b=sd9nNaSoqcKkXXhHF2aM202lgXCW0Ayop5oF3CGGNbI4XJX0qi1Xt6NOTQJBvPiEVoqmbCZvJ54+qahvKfRA4NNgCMyaxXQkFO8QMTpTbmrBZ+31WTKBi77Ek1d0dVhAzPALE3OKgUL75+XzJsZdVftD8DXykOAETJEidkFbB0Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718113488; c=relaxed/simple; bh=7ngSoxLZaufS4dE9eWtSM/KyLBIsiZkn3hKOd64rBsY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gsdEkl/8kFU7BoBP0VOmxcGjIwWlRyfMidJ47cm4t8UsipJ4lBGXv3XayaJA1rhWWj10JiQkFf4skJfol806uEyhjKW/G/+VHxzbv5ZLg21K5C97ou3sw7sZlTO/x9/AfbvXQL0Z3iDwwNj4tTIu4JnS4Y4QDY5iidJy6zv7Oso= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Rb8aj9Cy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Rb8aj9Cy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4888C2BD10; Tue, 11 Jun 2024 13:44:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1718113488; bh=7ngSoxLZaufS4dE9eWtSM/KyLBIsiZkn3hKOd64rBsY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Rb8aj9CyHMjOQ3rsLMLqJh+C7UCJ+9/ozIMU+dTjJLkT60dTrnj+naKKqcZH11eL5 nq9Ug0U+Uea/MyxBXsF/RYzG+VzVWF8MrER+AMd7m+RBOYCXu4ZsVa8+cIZOsVzaAL VZRhDY1T/gMhYDhsjzPvhisFWq7HrPuwTxnTC2OI= Date: Tue, 11 Jun 2024 15:44:45 +0200 From: Greg KH To: Danilo Krummrich Cc: rafael@kernel.org, mcgrof@kernel.org, russell.h.weight@intel.com, ojeda@kernel.org, alex.gaynor@gmail.com, wedsonaf@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, a.hindborg@samsung.com, aliceryhl@google.com, airlied@gmail.com, fujita.tomonori@gmail.com, pstanner@redhat.com, ajanulgu@redhat.com, lyude@redhat.com, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] rust: add firmware abstractions Message-ID: <2024061126-clang-relax-7875@gregkh> References: <20240610180318.72152-1-dakr@redhat.com> <20240610180318.72152-3-dakr@redhat.com> <2024061128-provolone-coyness-1d3c@gregkh> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Jun 11, 2024 at 03:34:22PM +0200, Danilo Krummrich wrote: > On Tue, Jun 11, 2024 at 08:31:46AM +0200, Greg KH wrote: > > On Mon, Jun 10, 2024 at 08:02:28PM +0200, Danilo Krummrich wrote: > > > Add an abstraction around the kernels firmware API to request firmware > > > images. The abstraction provides functions to access the firmware's size > > > and backing buffer. > > > > > > The firmware is released once the abstraction instance is dropped. > > > > > > Signed-off-by: Danilo Krummrich > > > --- > > > rust/bindings/bindings_helper.h | 1 + > > > rust/kernel/firmware.rs | 107 ++++++++++++++++++++++++++++++++ > > > rust/kernel/lib.rs | 1 + > > > 3 files changed, 109 insertions(+) > > > create mode 100644 rust/kernel/firmware.rs > > > > > > diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h > > > index ddb5644d4fd9..18a3f05115cb 100644 > > > --- a/rust/bindings/bindings_helper.h > > > +++ b/rust/bindings/bindings_helper.h > > > @@ -9,6 +9,7 @@ > > > #include > > > #include > > > #include > > > +#include > > > #include > > > #include > > > #include > > > diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs > > > new file mode 100644 > > > index 000000000000..7ff4c325f670 > > > --- /dev/null > > > +++ b/rust/kernel/firmware.rs > > > @@ -0,0 +1,107 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > + > > > +//! Firmware abstraction > > > +//! > > > +//! C header: [`include/linux/firmware.h`](srctree/include/linux/firmware.h") > > > + > > > +use crate::{bindings, device::Device, error::Error, error::Result, str::CStr}; > > > +use core::ptr::NonNull; > > > + > > > +// One of the following: `bindings::request_firmware`, `bindings::firmware_request_nowarn`, > > > +// `firmware_request_platform`, `bindings::request_firmware_direct` > > > +type FwFunc = > > > + unsafe extern "C" fn(*mut *const bindings::firmware, *const i8, *mut bindings::device) -> i32; > > > + > > > +/// Abstraction around a C `struct firmware`. > > > +/// > > > +/// This is a simple abstraction around the C firmware API. Just like with the C API, firmware can > > > +/// be requested. Once requested the abstraction provides direct access to the firmware buffer as > > > +/// `&[u8]`. The firmware is released once [`Firmware`] is dropped. > > > +/// > > > +/// # Invariants > > > +/// > > > +/// The pointer is valid, and has ownership over the instance of `struct firmware`. > > > +/// > > > +/// # Examples > > > +/// > > > +/// ``` > > > +/// use kernel::firmware::Firmware; > > > +/// > > > +/// let fw = Firmware::request("path/to/firmware.bin", dev.as_ref())?; > > > +/// driver_load_firmware(fw.data()); > > > +/// ``` > > > +pub struct Firmware(NonNull); > > > + > > > +impl Firmware { > > > + fn request_internal(name: &CStr, dev: &Device, func: FwFunc) -> Result { > > > + let mut fw: *mut bindings::firmware = core::ptr::null_mut(); > > > + let pfw: *mut *mut bindings::firmware = &mut fw; > > > + > > > + // SAFETY: `pfw` is a valid pointer to a NULL initialized `bindings::firmware` pointer. > > > + // `name` and `dev` are valid as by their type invariants. > > > + let ret = unsafe { func(pfw as _, name.as_char_ptr(), dev.as_raw()) }; > > > + if ret != 0 { > > > + return Err(Error::from_errno(ret)); > > > + } > > > + > > > + // SAFETY: `func` not bailing out with a non-zero error code, guarantees that `fw` is a > > > + // valid pointer to `bindings::firmware`. > > > + Ok(Firmware(unsafe { NonNull::new_unchecked(fw) })) > > > + } > > > + > > > + /// Send a firmware request and wait for it. See also `bindings::request_firmware`. > > > + pub fn request(name: &CStr, dev: &Device) -> Result { > > > + Self::request_internal(name, dev, bindings::request_firmware) > > > + } > > > > How does this handle when CONFIG_FW_LOADER is not enabled? Why are you > > building these bindings if that option is not checked? > > Good catch, gonna fix it. > > > > > > + > > > + /// Send a request for an optional firmware module. See also > > > + /// `bindings::firmware_request_nowarn`. > > > + pub fn request_nowarn(name: &CStr, dev: &Device) -> Result { > > > + Self::request_internal(name, dev, bindings::firmware_request_nowarn) > > > + } > > > + > > > + /// Send a request for a firmware with platform-fw fallback. See also > > > + /// `bindings::firmware_request_platform`. > > > + pub fn request_platform(name: &CStr, dev: &Device) -> Result { > > > + Self::request_internal(name, dev, bindings::firmware_request_platform) > > > + } > > > + > > > + /// Send a request for a firmware directly without usermode helper. See also > > > + /// `bindings::request_firmware_direct`. > > > + pub fn request_direct(name: &CStr, dev: &Device) -> Result { > > > + Self::request_internal(name, dev, bindings::request_firmware_direct) > > > + } > > > > Why just these variants? Why not just add the ones that people actually > > need instead of a random assortment like you choose here :) > > Indeed seems a bit random, not entirely though. I chose `request_firmware` and > `firmware_request_nowarn` since those are the ones we need in Nova, maybe we can > switch some calls to `request_firmware_into_buf` in the future, once we got the > allocator API in place. > > I added `firmware_request_platform` and `request_firmware_direct` as well, since > they share the same function signature as the ones mentioned above and hence all > four of them share the same implementation through `Firmware::request_internal`, > just passing a different function pointer. > > If you prefer I can drop the latter for now though. Yes, please only add bindings that you "know" will be used. We can always add new ones later. thanks, greg k-h