Re: [PATCH v3 1/3] rust: Add soc_device support

["Alexandre Courbot" <acourbot@nvidia.com>]

On Sat Dec 27, 2025 at 4:26 AM JST, Matthew Maurer wrote:
> On Tue, Dec 16, 2025 at 6:31 PM Alexandre Courbot <acourbot@nvidia.com> wrote:
>>
>> On Wed Dec 17, 2025 at 4:24 AM JST, Matthew Maurer wrote:
>> > Allow SoC drivers in Rust to present metadata about their devices to
>> > userspace through /sys/devices/socX and other drivers to identify their
>> > properties through `soc_device_match`.
>> >
>> > Signed-off-by: Matthew Maurer <mmaurer@google.com>
>> > ---
>> >  MAINTAINERS                     |   1 +
>> >  rust/bindings/bindings_helper.h |   1 +
>> >  rust/kernel/lib.rs              |   2 +
>> >  rust/kernel/soc.rs              | 135 ++++++++++++++++++++++++++++++++++++++++
>> >  4 files changed, 139 insertions(+)
>> >
>> > diff --git a/MAINTAINERS b/MAINTAINERS
>> > index c5a7cda26c600e49c7ab0d547306d3281333f672..4ff01fb0f1bda27002094113c0bf9d074d28fdb6 100644
>> > --- a/MAINTAINERS
>> > +++ b/MAINTAINERS
>> > @@ -7700,6 +7700,7 @@ F:      rust/kernel/devres.rs
>> >  F:   rust/kernel/driver.rs
>> >  F:   rust/kernel/faux.rs
>> >  F:   rust/kernel/platform.rs
>> > +F:   rust/kernel/soc.rs
>> >  F:   samples/rust/rust_debugfs.rs
>> >  F:   samples/rust/rust_debugfs_scoped.rs
>> >  F:   samples/rust/rust_driver_platform.rs
>> > diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
>> > index a067038b4b422b4256f4a2b75fe644d47e6e82c8..9fdf76ca630e00715503e2a3a809bedc895697fd 100644
>> > --- a/rust/bindings/bindings_helper.h
>> > +++ b/rust/bindings/bindings_helper.h
>> > @@ -80,6 +80,7 @@
>> >  #include <linux/sched.h>
>> >  #include <linux/security.h>
>> >  #include <linux/slab.h>
>> > +#include <linux/sys_soc.h>
>> >  #include <linux/task_work.h>
>> >  #include <linux/tracepoint.h>
>> >  #include <linux/usb.h>
>> > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
>> > index f812cf12004286962985a068665443dc22c389a2..6d637e2fed1b605e2dfc2e7b2247179439a90ba9 100644
>> > --- a/rust/kernel/lib.rs
>> > +++ b/rust/kernel/lib.rs
>> > @@ -138,6 +138,8 @@
>> >  pub mod seq_file;
>> >  pub mod sizes;
>> >  pub mod slice;
>> > +#[cfg(CONFIG_SOC_BUS)]
>> > +pub mod soc;
>> >  mod static_assert;
>> >  #[doc(hidden)]
>> >  pub mod std_vendor;
>> > diff --git a/rust/kernel/soc.rs b/rust/kernel/soc.rs
>> > new file mode 100644
>> > index 0000000000000000000000000000000000000000..0d6a36c83cb67ef20dc1e3d3995752f36e25ac9f
>> > --- /dev/null
>> > +++ b/rust/kernel/soc.rs
>> > @@ -0,0 +1,135 @@
>> > +// SPDX-License-Identifier: GPL-2.0
>> > +
>> > +// Copyright (C) 2025 Google LLC.
>> > +
>> > +//! SoC Driver Abstraction.
>> > +//!
>> > +//! C header: [`include/linux/sys_soc.h`](srctree/include/linux/sys_soc.h)
>> > +
>> > +use crate::{
>> > +    bindings,
>> > +    error,
>> > +    prelude::*,
>> > +    str::CString,
>> > +    types::Opaque, //
>> > +};
>> > +use core::ptr::NonNull;
>> > +
>> > +/// Attributes for a SoC device.
>> > +///
>> > +/// These are both exported to userspace under /sys/devices/socX and provided to other drivers to
>> > +/// match against via `soc_device_match` (not yet available in Rust) to enable quirks or
>> > +/// device-specific support where necessary.
>> > +///
>> > +/// All fields are freeform - they have no specific formatting, just defined meanings.
>> > +/// For example, the [`machine`](`Attributes::machine`) field could be "DB8500" or
>> > +/// "Qualcomm Technologies, Inc. SM8560 HDK", but regardless it should identify a board or product.
>> > +pub struct Attributes {
>> > +    /// Should generally be a board ID or product ID. Examples
>> > +    /// include DB8500 (ST-Ericsson) or "Qualcomm Technologies, inc. SM8560 HDK".
>> > +    ///
>> > +    /// If this field is not populated, the SoC infrastructure will try to populate it from
>> > +    /// `/model` in the device tree.
>> > +    pub machine: Option<CString>,
>> > +    /// The broader class this SoC belongs to. Examples include ux500
>> > +    /// (for DB8500) or Snapdragon (for SM8650).
>>
>> Formatting of the comments seems a bit off (also appears in other
>> places, please reapply formatting globally to be sure).
>
> I have just re-run the `rustfmt` target on this commit, and see no
> changes. Is there something specific that you think is off?

rustfmt doesn't touch comments IIUC.

What I had in mind was for instance that the first line of the comment
for `machine` is shorter than it could be, i.e. the comments should be
re-wrapped for consistency.