Message-ID: <CAPFo5VKDsqR48OAjUSCKNZM2_28Upi0qH9f0gP5_472JBBBLPg@mail.gmail.com>
Date: Wed, 18 Dec 2024 15:46:37 -0800
From: Fabien Parent <fabien.parent@...aro.org>
To: Danilo Krummrich <dakr@...nel.org>
Cc: gregkh@...uxfoundation.org, rafael@...nel.org, bhelgaas@...gle.com, 
	ojeda@...nel.org, alex.gaynor@...il.com, boqun.feng@...il.com, 
	gary@...yguo.net, bjorn3_gh@...tonmail.com, benno.lossin@...ton.me, 
	tmgross@...ch.edu, a.hindborg@...sung.com, aliceryhl@...gle.com, 
	airlied@...il.com, fujita.tomonori@...il.com, lina@...hilina.net, 
	pstanner@...hat.com, ajanulgu@...hat.com, lyude@...hat.com, robh@...nel.org, 
	daniel.almeida@...labora.com, saravanak@...gle.com, dirk.behme@...bosch.com, 
	j@...nau.net, chrisi.schrefl@...il.com, paulmck@...nel.org, 
	rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-pci@...r.kernel.org, devicetree@...r.kernel.org, rcu@...r.kernel.org
Subject: Re: [PATCH v6 00/16] Device / Driver PCI / Platform Rust abstractions

On Thu, Dec 12, 2024 at 8:34 AM Danilo Krummrich <dakr@...nel.org> wrote:
>
> This patch series implements the necessary Rust abstractions to implement
> device drivers in Rust.
>
> This includes some basic generalizations for driver registration, handling of ID
> tables, MMIO operations and device resource handling.
>
> Those generalizations are used to implement device driver support for two
> busses, the PCI and platform bus (with OF IDs) in order to provide some evidence
> that the generalizations work as intended.
>
> The patch series also includes two patches adding two driver samples, one PCI
> driver and one platform driver.
>
> The PCI bits are motivated by the Nova driver project [1], but are used by at
> least one more OOT driver (rnvme [2]).
>
> The platform bits, besides adding some more evidence to the base abstractions,
> are required by a few more OOT drivers aiming at going upstream, i.e. rvkms [3],
> cpufreq-dt [4], asahi [5] and the i2c work from Fabien [6].
>
> The patches of this series can also be [7], [8] and [9].
>
> Changes in v6:
> ==============
> - Module:
>   - remove patch to pass the module name in `Module::init`
>   - add a patch adding the `ModuleMetadata` trait to retreive the module name
>
> - Driver:
>   - generate module structure within `module_driver!`, such that we get a unique
>     module type for which `ModuleMetadata` can be implemented to retreive the
>     module name
>   - let `Adapter::of_id_table` return `Option<of::IdTable<Self::IdInfo>>`
>
> - Platform:
>   - change type of `platform::Driver::OF_ID_TABLE` to `Option<of::IdTable>`
>
> - RCU:
>   - add RCU abstraction to MAINTAINERS file
>
> - MISC:
>   - pick up a couple of RBs
>
> Changes in v5:
> ==============
> - Opaque:
>   - add `Opaque::pin_init`
>
> - Revocable:
>   - use const generic instead of bool in `revoke_internal`
>   - don't open code things with `Opaque::try_ffi_init`, use
>     `Opaque::pin_init` instead
>
> - Driver:
>   - fix `DriverOps` -> `RegistrationOps` in commit message
>   - fix signature of `register` and `unregister` to take an
>     `Opaque<T::RegType>` instead of a mutable reference
>   - implement generic `driver::Adapter`
>
> - ID table:
>   - fix `module_device_table!` macro, according to commit 054a9cd395a7
>    (modpost: rename alias symbol for MODULE_DEVICE_TABLE())
>
> - PCI:
>   - remove `pci::DeviceId` argument from probe()
>   - provide `vendor_id` and `device_id` accessor functions
>   - use `addr_of_mut!` for the device in probe()
>
> - OF:
>   - move OF `IdTable` type alias from platform.rs to of.rs
>
> - Platform:
>   - use `addr_of_mut!` for the device in probe()
>   - move generic OF code to `driver::Adapter`
>
> - MISC:
>   - rebase onto latest rust-next (-rc2)
>
> Changes in v4:
> ==============
> - Revocable
>   - convert `Revocable::data` to `Opaque`
>   - introduce `revoke_nosync`, which does not wait for an RCU grace period
>   - fix minor typo
>
> - Device ID
>   - fix ID table export name to always be unique
>   - remove `#![allow(stable_features)]`
>   - move `#![allow(const_refs_to_cell)]` to the "stable in 1.83" list
>
> - I/O
>   - split `Io<SIZE>` in `IoRaw<SIZE>` and `Io<SIZE>`
>   - add rust helper for ioremap() and iounmap() (needed by doctests)
>
> - Devres
>   - optimze `drop` by using `revoke_nosync` (we're guaranteed there are no more
>     concurrent users, hence no need to wait for a full grace period)
>
> - OF
>   - rename "Open Firmware" -> "Device Tree / Open Firmware" (Rob)
>   - remove unused C header reference
>   - add TODO comment to loop in `DeviceId::new`
>   - remove `DeviceId::compatible`; was only used in sample code
>   - add missing `#[repr(transparent)]`
>   - use #[cfg(CONFIG_OF)] for the relevant functions
>
> - PCI
>   - let Rust helper for pci_resource_len() return resource_size_t
>
> - PCI Sample
>   - remove unnecessary `from_le`
>
> - Platform
>   - fix example compatible string
>   - add example for `platform::Driver`
>   - rename `ID_TABLE` to `OF_ID_TABLE`
>   - don't allow public use of `of_match_table`; convert to `of_id_info` to
>     retrieve the `of::DeviceId` to gather the corresponding `IdInfo`
>   - remove wrong example reference in the documentation of `platform::Driver`
>   - remove `as_dev`, as we already implement `AsRef` for `platform::Device`
>
> - Platform Sample
>   - fix compatible string; add corresponding entry to drivers/of/unittest-data/tests-platform.dtsi
>   - remove usage of `of_match_table`
>
> - MISC
>   - fix a few spelling mistakes
>   - rebase onto rust-next (v6.13-rc1)
>
> Changes in v3:
> ==============
> - add commits for `Opaque::try_ffi_init` and `InPlaceModule`
> - rename `DriverOps` to `RegistrationOps`
> - rework device ID abstractions to get rid of almost all macro magic (thanks to
>   Gary Guo for working this out!)
>   - this is possible due to recently stabilized language features
> - add modpost alias generation for device ID tables
>   - unfortunately, this is the part that still requires some macro magic in the
>     device ID abstractions
> - PCI
>   - represent the driver private data with the driver specific `Driver` instance
>     and bind it's lifetime to the time of the driver being bound to a device
>     - this allows us to handle class / subsystem registrations in a cleaner way
>   - get rid of `Driver::remove`
>     - Rust drivers should bind cleanup code to the `Drop` implementation of the
>       corresponding structure instead and put it into their driver structure for
>       automatic cleanup
>   - add a sample PCI driver
> - add abstractions for `struct of_device_id`
> - add abstractions for the platform bus, including a sample driver
> - update the MAINTAINERS file accordingly
>   - currently this turns out a bit messy, but it should become better once the
>     build system supports a treewide distribution of the kernel crate
>   - I didn't add myself as maintainer, but (if requested) I'm willing to do so
>     and help with maintenance
>
> Changes in v2:
> ==============
> - statically initialize driver structures (Greg)
> - move base device ID abstractions to a separate source file (Greg)
> - remove `DeviceRemoval` trait in favor of using a `Devres` callback to
>   unregister drivers
> - remove `device::Data`, we don't need this abstraction anymore now that we
>   `Devres` to revoke resources and registrations
> - pass the module name to `Module::init` and `InPlaceModule::init` in a separate
>   patch
> - rework of `Io` including compile time boundary checks (Miguel, Wedson)
> - adjust PCI abstractions accordingly and implement a `module_pci_driver!` macro
> - rework `pci::Bar` to support a const SIZE
> - increase the total amount of Documentation, rephrase some safety comments and
>   commit messages for less ambiguity
> - fix compilation issues with some documentation examples
>
> [1] https://gitlab.freedesktop.org/drm/nova/-/tree/nova-next
> [2] https://github.com/metaspace/linux/tree/rnvme
> [3] https://lore.kernel.org/all/20240930233257.1189730-1-lyude@redhat.com/
> [4] https://git.kernel.org/pub/scm/linux/kernel/git/vireshk/linux.git/log/?h=rust/cpufreq-dt
> [5] https://github.com/AsahiLinux/linux
> [6] https://github.com/Fabo/linux/tree/fparent/rust-i2c
> [7] https://github.com/Rust-for-Linux/linux/tree/staging/rust-device
> [8] https://github.com/Rust-for-Linux/linux/tree/staging/rust-pci
> [9] https://github.com/Rust-for-Linux/linux/tree/staging/dev
>
> Danilo Krummrich (14):
>   rust: module: add trait `ModuleMetadata`
>   rust: implement generic driver registration
>   rust: implement `IdArray`, `IdTable` and `RawDeviceId`
>   rust: types: add `Opaque::pin_init`
>   rust: add `io::{Io, IoRaw}` base types
>   rust: add devres abstraction
>   rust: pci: add basic PCI device / driver abstractions
>   rust: pci: implement I/O mappable `pci::Bar`
>   samples: rust: add Rust PCI sample driver
>   rust: of: add `of::DeviceId` abstraction
>   rust: driver: implement `Adapter`
>   rust: platform: add basic platform device / driver abstractions
>   samples: rust: add Rust platform sample driver
>   MAINTAINERS: add Danilo to DRIVER CORE
>
> Wedson Almeida Filho (2):
>   rust: add rcu abstraction
>   rust: add `Revocable` type
>
>  MAINTAINERS                                  |  10 +
>  drivers/of/unittest-data/tests-platform.dtsi |   5 +
>  rust/bindings/bindings_helper.h              |   3 +
>  rust/helpers/device.c                        |  10 +
>  rust/helpers/helpers.c                       |   5 +
>  rust/helpers/io.c                            | 101 +++++
>  rust/helpers/pci.c                           |  18 +
>  rust/helpers/platform.c                      |  13 +
>  rust/helpers/rcu.c                           |  13 +
>  rust/kernel/device_id.rs                     | 165 +++++++
>  rust/kernel/devres.rs                        | 179 ++++++++
>  rust/kernel/driver.rs                        | 174 ++++++++
>  rust/kernel/io.rs                            | 260 +++++++++++
>  rust/kernel/lib.rs                           |  20 +
>  rust/kernel/of.rs                            |  60 +++
>  rust/kernel/pci.rs                           | 438 +++++++++++++++++++
>  rust/kernel/platform.rs                      | 198 +++++++++
>  rust/kernel/revocable.rs                     | 223 ++++++++++
>  rust/kernel/sync.rs                          |   1 +
>  rust/kernel/sync/rcu.rs                      |  47 ++
>  rust/kernel/types.rs                         |  11 +
>  rust/macros/module.rs                        |   4 +
>  samples/rust/Kconfig                         |  21 +
>  samples/rust/Makefile                        |   2 +
>  samples/rust/rust_driver_pci.rs              | 110 +++++
>  samples/rust/rust_driver_platform.rs         |  49 +++
>  26 files changed, 2140 insertions(+)
>  create mode 100644 rust/helpers/device.c
>  create mode 100644 rust/helpers/io.c
>  create mode 100644 rust/helpers/pci.c
>  create mode 100644 rust/helpers/platform.c
>  create mode 100644 rust/helpers/rcu.c
>  create mode 100644 rust/kernel/device_id.rs
>  create mode 100644 rust/kernel/devres.rs
>  create mode 100644 rust/kernel/driver.rs
>  create mode 100644 rust/kernel/io.rs
>  create mode 100644 rust/kernel/of.rs
>  create mode 100644 rust/kernel/pci.rs
>  create mode 100644 rust/kernel/platform.rs
>  create mode 100644 rust/kernel/revocable.rs
>  create mode 100644 rust/kernel/sync/rcu.rs
>  create mode 100644 samples/rust/rust_driver_pci.rs
>  create mode 100644 samples/rust/rust_driver_platform.rs
>
>
> base-commit: fac04efc5c793dccbd07e2d59af9f90b7fc0dca4
> --
> 2.47.1
>

Tested on arm64 as dependency for my own series:
https://lkml.org/lkml/2024/12/18/1358

Tested-by: Fabien Parent <fabien.parent@...aro.org>

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