Re: [PATCH v2] rust: ACPI: fix missing match data for PRP0001

[Rafael J. Wysocki]

On Sun, Apr 5, 2026 at 7:03 PM Markus Probst <markus.probst@xxxxxxxxx> wrote:
>
> Export `acpi_of_match_device` function and use it to match the of device
> table against ACPI PRP0001 in Rust.
>
> This fixes id_info being None on ACPI PRP0001 devices.
>
> Using `device_get_match_data` is not possible, because Rust stores an
> index in the of device id instead of a data pointer. This was done this
> way to provide a convenient and obvious API for drivers, which can be
> evaluated in const context without the use of any unstable language
> features.
>
> Fixes: 7a718a1f26d1 ("rust: driver: implement `Adapter`")
> Signed-off-by: Markus Probst <markus.probst@xxxxxxxxx>
> ---
> Changes in v2:
> - keep unsafe block as short as possible
> - don't export acpi_of_match_device
> - add implementation decisions to commit msg
> - Link to v1: https://lore.kernel.org/r/20260401-rust_acpi_prp0001-v1-1-f6a4d2ef9244@xxxxxxxxx
> ---
>  MAINTAINERS                     |  1 +
>  drivers/acpi/bus.c              |  6 ++--
>  drivers/acpi/internal.h         |  4 +++
>  rust/bindings/bindings_helper.h |  5 +++
>  rust/helpers/acpi.c             |  8 +++++
>  rust/helpers/helpers.c          |  1 +
>  rust/kernel/driver.rs           | 70 ++++++++++++++++++++++++++++++++---------
>  7 files changed, 78 insertions(+), 17 deletions(-)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c3fe46d7c4bc..3a7b3b5f2a28 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -302,6 +302,7 @@ F:  include/linux/acpi.h
>  F:     include/linux/fwnode.h
>  F:     include/linux/fw_table.h
>  F:     lib/fw_table.c
> +F:     rust/helpers/acpi.c
>  F:     rust/kernel/acpi.rs
>  F:     tools/power/acpi/
>
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index 2ec095e2009e..554dbddb1c8c 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -831,9 +831,9 @@ const struct acpi_device *acpi_companion_match(const struct device *dev)
>   * identifiers and a _DSD object with the "compatible" property, use that
>   * property to match against the given list of identifiers.
>   */
> -static bool acpi_of_match_device(const struct acpi_device *adev,
> -                                const struct of_device_id *of_match_table,
> -                                const struct of_device_id **of_id)
> +bool acpi_of_match_device(const struct acpi_device *adev,
> +                         const struct of_device_id *of_match_table,
> +                         const struct of_device_id **of_id)
>  {
>         const union acpi_object *of_compatible, *obj;
>         int i, nval;
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 40f875b265a9..f2e743175e93 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -99,6 +99,10 @@ static inline int acpi_arch_thermal_cpufreq_pctg(void)
>  }
>  #endif
>
> +bool acpi_of_match_device(const struct acpi_device *adev,
> +                         const struct of_device_id *of_match_table,
> +                         const struct of_device_id **of_id);
> +

I'd put it into include/acpi/acpi_bus.h.  internal.h is meant to be,
well, internal.

>  /* --------------------------------------------------------------------------
>                       Device Node Initialization / Removal
>     -------------------------------------------------------------------------- */
> diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
> index 083cc44aa952..9a1ae3dce746 100644
> --- a/rust/bindings/bindings_helper.h
> +++ b/rust/bindings/bindings_helper.h
> @@ -96,6 +96,11 @@
>   */
>  #include <../../drivers/base/base.h>
>
> +/*
> + * The driver-core Rust code needs to call `acpi_of_match_device`.
> + */
> +#include <../../drivers/acpi/internal.h>
> +
>  #if defined(CONFIG_DRM_PANIC_SCREEN_QR_CODE)
>  // Used by `#[export]` in `drivers/gpu/drm/drm_panic_qr.rs`.
>  #include <drm/drm_panic.h>
> diff --git a/rust/helpers/acpi.c b/rust/helpers/acpi.c
> new file mode 100644
> index 000000000000..f2aa00ec99c2
> --- /dev/null
> +++ b/rust/helpers/acpi.c
> @@ -0,0 +1,8 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/acpi.h>
> +
> +__rust_helper struct acpi_device *rust_helper_to_acpi_device_node(struct fwnode_handle *fwnode)
> +{
> +       return to_acpi_device_node(fwnode);
> +}
> diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
> index a3c42e51f00a..8ecd1580aa69 100644
> --- a/rust/helpers/helpers.c
> +++ b/rust/helpers/helpers.c
> @@ -9,6 +9,7 @@
>
>  #define __rust_helper
>
> +#include "acpi.c"
>  #include "atomic.c"
>  #include "atomic_ext.c"
>  #include "auxiliary.c"
> diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs
> index 36de8098754d..62d7d1ab776c 100644
> --- a/rust/kernel/driver.rs
> +++ b/rust/kernel/driver.rs
> @@ -96,13 +96,18 @@
>
>  use crate::{
>      acpi,
> -    device,
> +    device::{
> +        self,
> +        property::FwNode, //
> +    },
>      of,
>      prelude::*,
>      types::Opaque,
>      ThisModule, //
>  };
>
> +use core::ptr;
> +
>  /// Trait describing the layout of a specific device driver.
>  ///
>  /// This trait describes the layout of a specific driver structure, such as `struct pci_driver` or
> @@ -278,6 +283,18 @@ fn init(
>      }
>  }
>
> +#[inline(never)]
> +#[allow(clippy::missing_safety_doc)]
> +#[must_use]
> +unsafe fn acpi_of_match_device(
> +    adev: *const bindings::acpi_device,
> +    of_match_table: *const bindings::of_device_id,
> +    of_id: *mut *const bindings::of_device_id,
> +) -> bool {
> +    // SAFETY: Safety requirements are the same as `bindings::acpi_device_id`.
> +    unsafe { bindings::acpi_of_match_device(adev, of_match_table, of_id) }
> +}
> +
>  /// The bus independent adapter to match a drivers and a devices.
>  ///
>  /// This trait should be implemented by the bus specific adapter, which represents the connection
> @@ -329,35 +346,60 @@ fn acpi_id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
>      ///
>      /// If this returns `None`, it means there is no match with an entry in the [`of::IdTable`].
>      fn of_id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
> -        #[cfg(not(CONFIG_OF))]
> +        let table = Self::of_id_table()?;
> +
> +        #[cfg(not(any(CONFIG_OF, CONFIG_ACPI)))]
>          {
> -            let _ = dev;
> -            None
> +            let _ = (dev, table);
>          }
>
>          #[cfg(CONFIG_OF)]
>          {
> -            let table = Self::of_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 `dev.as_raw()`.
>              let raw_id = unsafe { bindings::of_match_device(table.as_ptr(), dev.as_raw()) };
>
> -            if raw_id.is_null() {
> -                None
> -            } else {
> +            if !raw_id.is_null() {
>                  // SAFETY: `DeviceId` is a `#[repr(transparent)]` wrapper of `struct of_device_id`
>                  // and does not add additional invariants, so it's safe to transmute.
>                  let id = unsafe { &*raw_id.cast::<of::DeviceId>() };
>
> -                Some(
> -                    table.info(<of::DeviceId as crate::device_id::RawDeviceIdIndex>::index(
> -                        id,
> -                    )),
> -                )
> +                return Some(table.info(
> +                    <of::DeviceId as crate::device_id::RawDeviceIdIndex>::index(id),
> +                ));
>              }
>          }
> +
> +        #[cfg(CONFIG_ACPI)]
> +        {
> +            let mut raw_id = ptr::null();
> +
> +            let fwnode = dev.fwnode().map_or(ptr::null_mut(), FwNode::as_raw);
> +
> +            // SAFETY: `fwnode` is a pointer to a valid `fwnode_handle`. A null pointer will be
> +            // passed through the function.
> +            let adev = unsafe { bindings::to_acpi_device_node(fwnode) };
> +
> +            // SAFETY:
> +            // - `adev` is a valid pointer to `acpi_device` or is null. It is guaranteed to be
> +            //   valid as long as `dev` is alive.
> +            // - `table` has static lifetime, hence it's valid for read.
> +            if unsafe { acpi_of_match_device(adev, table.as_ptr(), &raw mut raw_id) } {
> +                // SAFETY:
> +                // - the function returns true, therefore `raw_id` has been set to a pointer to a
> +                //   valid `of_device_id`.
> +                // - `DeviceId` is a `#[repr(transparent)]` wrapper of `struct of_device_id`
> +                //   and does not add additional invariants, so it's safe to transmute.
> +                let id = unsafe { &*raw_id.cast::<of::DeviceId>() };
> +
> +                return Some(table.info(
> +                    <of::DeviceId as crate::device_id::RawDeviceIdIndex>::index(id),
> +                ));
> +            }
> +        }
> +
> +        None
>      }
>
>      /// Returns the driver's private data from the matching entry of any of the ID tables, if any.
>
> ---
> base-commit: b6c7d19951061de1be08fb8f5714e630b24bcc1c
> change-id: 20260401-rust_acpi_prp0001-a2971543b555
>
>