From patchwork Tue Oct 22 21:31:52 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Danilo Krummrich X-Patchwork-Id: 13846183 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 DC1CC1CCECA; Tue, 22 Oct 2024 21:33:55 +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=1729632836; cv=none; b=X3Pj2fvi658B9JrlaEa0MNymQkWZXekAVdxif7nnKLlwFKbbRrAPdcjdNnfXTFE7xjrmIw0FaG23YUFG+0uw3DjLyuW8mlds75HgxvgJ3vhOrYWnEZwxpAzsraXMX1LCdgPdsXMsdKCSHHIZ8hqZ9UNfRy+mIvcRMeG48BnYGBM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729632836; c=relaxed/simple; bh=I99bItPUGGImSDmgGsci4gBQnJK7yi7CqarWLCTyKN4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XEuVSdsVCHcW7y4gxwtfPXX/XqTo97WtVeGsR6+KmoDXfvFXXmqRh4B7UrFTgBcwDGted8pU5WF82oLGeGdNVpApl27qVeZPytFaWGK1Ha1oWVP1db8Q9RSGGiRI9qvVn4Rq+MAx3/jBJRgk1xUL8LuvM1qIseGLC6LIFvxuKD0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ifJpBmMC; 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="ifJpBmMC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61774C4CEE6; Tue, 22 Oct 2024 21:33:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729632835; bh=I99bItPUGGImSDmgGsci4gBQnJK7yi7CqarWLCTyKN4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ifJpBmMC34RJoPDWNMaaGZVmYJaezRiEsY/Ed8u7gjsJRtstuREBufmQRI4LMzxm0 1Eo72sH3Fo53t6qgBbqvAbpJrDh0Ifa7c6CqKo0vCiHiqVfKp5aYSEToEOImPZu/G/ 0DOW+L0L3Ox3uXYANdAPZwHBOwtwlU4ODSQH8fQEXHNXsoNBIJca5MjnJQPBdYIZMT RpvJ3jYLRNnHMrKgja1ip257Ws0g/lnGF/b42uzpyV6MNB8Y3mEtfQMivfwSExBxeW +zk1N6pFFfwVkFe/H50CtUN5+jj/Iz5TXs05YDZz+9jdmWjrvk9RDRLyR4Nuo03dGw zQomzAGFpnXSw== From: Danilo Krummrich To: gregkh@linuxfoundation.org, rafael@kernel.org, bhelgaas@google.com, ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, tmgross@umich.edu, a.hindborg@samsung.com, aliceryhl@google.com, airlied@gmail.com, fujita.tomonori@gmail.com, lina@asahilina.net, pstanner@redhat.com, ajanulgu@redhat.com, lyude@redhat.com, robh@kernel.org, daniel.almeida@collabora.com, saravanak@google.com Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, Danilo Krummrich Subject: [PATCH v3 15/16] rust: platform: add basic platform device / driver abstractions Date: Tue, 22 Oct 2024 23:31:52 +0200 Message-ID: <20241022213221.2383-16-dakr@kernel.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241022213221.2383-1-dakr@kernel.org> References: <20241022213221.2383-1-dakr@kernel.org> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Implement the basic platform bus abstractions required to write a basic platform driver. This includes the following data structures: The `platform::Driver` trait represents the interface to the driver and provides `pci::Driver::probe` for the driver to implement. The `platform::Device` abstraction represents a `struct platform_device`. In order to provide the platform bus specific parts to a generic `driver::Registration` the `driver::RegistrationOps` trait is implemented by `platform::Adapter`. Signed-off-by: Danilo Krummrich --- MAINTAINERS | 1 + rust/bindings/bindings_helper.h | 1 + rust/helpers/helpers.c | 1 + rust/helpers/platform.c | 13 ++ rust/kernel/lib.rs | 1 + rust/kernel/platform.rs | 217 ++++++++++++++++++++++++++++++++ 6 files changed, 234 insertions(+) create mode 100644 rust/helpers/platform.c create mode 100644 rust/kernel/platform.rs diff --git a/MAINTAINERS b/MAINTAINERS index 87eb9a7869eb..173540375863 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6985,6 +6985,7 @@ F: rust/kernel/device.rs F: rust/kernel/device_id.rs F: rust/kernel/devres.rs F: rust/kernel/driver.rs +F: rust/kernel/platform.rs DRIVERS FOR OMAP ADAPTIVE VOLTAGE SCALING (AVS) M: Nishanth Menon diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 312f03cbdce9..217c776615b9 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 8bc6e9735589..663cdc2a45e0 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -17,6 +17,7 @@ #include "kunit.c" #include "mutex.c" #include "page.c" +#include "platform.c" #include "pci.c" #include "rbtree.c" #include "rcu.c" diff --git a/rust/helpers/platform.c b/rust/helpers/platform.c new file mode 100644 index 000000000000..ab9b9f317301 --- /dev/null +++ b/rust/helpers/platform.c @@ -0,0 +1,13 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +void *rust_helper_platform_get_drvdata(const struct platform_device *pdev) +{ + return platform_get_drvdata(pdev); +} + +void rust_helper_platform_set_drvdata(struct platform_device *pdev, void *data) +{ + platform_set_drvdata(pdev, data); +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 5946f59f1688..9e8dcd6d7c01 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -53,6 +53,7 @@ pub mod net; pub mod of; pub mod page; +pub mod platform; pub mod prelude; pub mod print; pub mod rbtree; diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs new file mode 100644 index 000000000000..addf5356f44f --- /dev/null +++ b/rust/kernel/platform.rs @@ -0,0 +1,217 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Abstractions for the platform bus. +//! +//! C header: [`include/linux/platform_device.h`](srctree/include/linux/platform_device.h) + +use crate::{ + bindings, container_of, device, + device_id::RawDeviceId, + driver, + error::{to_result, Result}, + of, + prelude::*, + str::CStr, + types::{ARef, ForeignOwnable}, + ThisModule, +}; + +/// An adapter for the registration of platform drivers. +pub struct Adapter(T); + +impl driver::RegistrationOps for Adapter { + type RegType = bindings::platform_driver; + + fn register( + pdrv: &mut Self::RegType, + name: &'static CStr, + module: &'static ThisModule, + ) -> Result { + pdrv.driver.name = name.as_char_ptr(); + pdrv.probe = Some(Self::probe_callback); + + // Both members of this union are identical in data layout and semantics. + pdrv.__bindgen_anon_1.remove = Some(Self::remove_callback); + pdrv.driver.of_match_table = T::ID_TABLE.as_ptr(); + + // SAFETY: `pdrv` is guaranteed to be a valid `RegType`. + to_result(unsafe { bindings::__platform_driver_register(pdrv, module.0) }) + } + + fn unregister(pdrv: &mut Self::RegType) { + // SAFETY: `pdrv` is guaranteed to be a valid `RegType`. + unsafe { bindings::platform_driver_unregister(pdrv) }; + } +} + +impl Adapter { + fn id_info(pdev: &Device) -> Option<&'static T::IdInfo> { + let table = T::ID_TABLE; + let id = T::of_match_device(pdev)?; + + Some(table.info(id.index())) + } + + extern "C" fn probe_callback(pdev: *mut bindings::platform_device) -> core::ffi::c_int { + // SAFETY: The platform bus only ever calls the probe callback with a valid `pdev`. + let dev = unsafe { device::Device::from_raw(&mut (*pdev).dev) }; + // SAFETY: `dev` is guaranteed to be embedded in a valid `struct platform_device` by the + // call above. + let mut pdev = unsafe { Device::from_dev(dev) }; + + let info = Self::id_info(&pdev); + match T::probe(&mut pdev, info) { + Ok(data) => { + // Let the `struct platform_device` own a reference of the driver's private data. + // SAFETY: By the type invariant `pdev.as_raw` returns a valid pointer to a + // `struct platform_device`. + unsafe { bindings::platform_set_drvdata(pdev.as_raw(), data.into_foreign() as _) }; + } + Err(err) => return Error::to_errno(err), + } + + 0 + } + + extern "C" fn remove_callback(pdev: *mut bindings::platform_device) { + // SAFETY: `pdev` is a valid pointer to a `struct platform_device`. + let ptr = unsafe { bindings::platform_get_drvdata(pdev) }; + + // SAFETY: `remove_callback` is only ever called after a successful call to + // `probe_callback`, hence it's guaranteed that `ptr` points to a valid and initialized + // `KBox` pointer created through `KBox::into_foreign`. + let _ = unsafe { KBox::::from_foreign(ptr) }; + } +} + +/// Declares a kernel module that exposes a single platform driver. +/// +/// # Examples +/// +/// ```ignore +/// kernel::module_platform_driver! { +/// type: MyDriver, +/// name: "Module name", +/// author: "Author name", +/// description: "Description", +/// license: "GPL v2", +/// } +/// ``` +#[macro_export] +macro_rules! module_platform_driver { + ($($f:tt)*) => { + $crate::module_driver!(, $crate::platform::Adapter, { $($f)* }); + }; +} + +/// IdTable type for platform drivers. +pub type IdTable = &'static dyn kernel::device_id::IdTable; + +/// The platform driver trait. +/// +/// # Example +/// +///``` +/// # use kernel::{bindings, c_str, of, platform}; +/// +/// struct MyDriver; +/// +/// kernel::of_device_table!( +/// OF_TABLE, +/// MODULE_OF_TABLE, +/// ::IdInfo, +/// [ +/// (of::DeviceId::new(c_str!("redhat,my-device")), ()) +/// ] +/// ); +/// +/// impl platform::Driver for MyDriver { +/// type IdInfo = (); +/// const ID_TABLE: platform::IdTable = &OF_TABLE; +/// +/// fn probe( +/// _pdev: &mut platform::Device, +/// _id_info: Option<&Self::IdInfo>, +/// ) -> Result>> { +/// Err(ENODEV) +/// } +/// } +///``` +/// Drivers must implement this trait in order to get a platform driver registered. Please refer to +/// the `Adapter` documentation for an example. +pub trait Driver { + /// The type holding information about each device id supported by the driver. + /// + /// TODO: Use associated_type_defaults once stabilized: + /// + /// type IdInfo: 'static = (); + type IdInfo: 'static; + + /// The table of device ids supported by the driver. + const ID_TABLE: IdTable; + + /// Platform driver probe. + /// + /// Called when a new platform device is added or discovered. + /// Implementers should attempt to initialize the device here. + fn probe(dev: &mut Device, id_info: Option<&Self::IdInfo>) -> Result>>; + + /// Find the [`of::DeviceId`] within [`Driver::ID_TABLE`] matching the given [`Device`], if any. + fn of_match_device(pdev: &Device) -> Option<&of::DeviceId> { + let table = Self::ID_TABLE; + + // SAFETY: + // - `table` has static lifetime, hence it's valid for read, + // - `dev` is guaranteed to be valid while it's alive, and so is + // `pdev.as_dev().as_raw()`. + let raw_id = unsafe { bindings::of_match_device(table.as_ptr(), pdev.as_dev().as_raw()) }; + + if raw_id.is_null() { + None + } else { + // SAFETY: `DeviceId` is a `#[repr(transparent)` wrapper of `struct of_device_id` and + // does not add additional invariants, so it's safe to transmute. + Some(unsafe { &*raw_id.cast::() }) + } + } +} + +/// The platform device representation. +/// +/// A platform device is based on an always reference counted `device:Device` instance. Cloning a +/// platform device, hence, also increments the base device' reference count. +/// +/// # Invariants +/// +/// `Device` holds a valid reference of `ARef` whose underlying `struct device` is a +/// member of a `struct platform_device`. +#[derive(Clone)] +pub struct Device(ARef); + +impl Device { + /// Convert a raw kernel device into a `Device` + /// + /// # Safety + /// + /// `dev` must be an `Aref` whose underlying `bindings::device` is a member of a + /// `bindings::platform_device`. + unsafe fn from_dev(dev: ARef) -> Self { + Self(dev) + } + + fn as_dev(&self) -> &device::Device { + &self.0 + } + + fn as_raw(&self) -> *mut bindings::platform_device { + // SAFETY: By the type invariant `self.0.as_raw` is a pointer to the `struct device` + // embedded in `struct platform_device`. + unsafe { container_of!(self.0.as_raw(), bindings::platform_device, dev) }.cast_mut() + } +} + +impl AsRef for Device { + fn as_ref(&self) -> &device::Device { + &self.0 + } +}