The common practice in C drivers is to store pointers into `driver_data`
field of device IDs. The Rust code is however currently storing indices
into the fields and then carry a side table that maps the index to
pointers.
It is much simpler to just have `DeviceId` carry the pointer like C code
does. However, just doing so naively would cause a "pointers cannot be cast
to integers during const eval" error, as kernel_ulong_t does not have
provenance while pointers do, and Rust forbids `expose_provenance` during
consteval.
Work around this limitation by wrapping raw IDs in `MaybeUninit`.
`MaybeUninit` is allowed to host arbitrary bytes with or without
provenance, so we can just then use `unsafe` to store a pointer with
provenance there. This has the same effect as changing the C-side
definition to use `void*` instead of `kernel_ulong_t`, but without actually
changing the C side.
Signed-off-by: Gary Guo <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Danilo Krummrich <[email protected]>
Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.
Signed-off-by: Tamir Duberstein <[email protected]>
Reviewed-by: Benno Lossin <[email protected]>
Signed-off-by: Miguel Ojeda <[email protected]>
Introduce a new trait `RawDeviceIdIndex`, which extends `RawDeviceId`
to provide support for device ID types that include an index or
context field (e.g., `driver_data`). This separates the concerns of
layout compatibility and index-based data embedding, and allows
`RawDeviceId` to be implemented for types that do not contain a
`driver_data` field. Several such structures are defined in
include/linux/mod_devicetable.h.
Refactor `IdArray::new()` into a generic `build()` function, which
takes an optional offset. Based on the presence of `RawDeviceIdIndex`,
index writing is conditionally enabled. A new `new_without_index()`
constructor is also provided for use cases where no index should be
written.
This refactoring is a preparation for enabling the PHY abstractions to
use the RawDeviceId trait.
The changes to acpi.rs and driver.rs were made by Danilo.
Reviewed-by: Trevor Gross <[email protected]>
Signed-off-by: FUJITA Tomonori <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Danilo Krummrich <[email protected]>
A future Clippy warning, `clippy::as_underscore`, is getting enabled in
parallel in the rust-next tree:
error: using `as _` conversion
--> rust/kernel/acpi.rs:25:9
|
25 | self.0.driver_data as _
| ^^^^^^^^^^^^^^^^^^^^^^-
| |
| help: consider giving the type explicitly: `usize`
The type is already `ulong`, which nowadays is always `usize`, so the
cast is unneeded. Thus remove it, which in turn will avoid the warning
in the future.
Other abstractions of device tables do not use a cast here either.
Signed-off-by: Miguel Ojeda <[email protected]>
Reviewed-by: Trevor Gross <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
`acpi::DeviceId` is an abstraction around `struct acpi_device_id`.
Enable drivers to build ACPI device ID tables, to be consumed by the
corresponding bus abstractions, such as platform or I2C.
Signed-off-by: Igor Korotin <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ Always inline DeviceId::new() and use &'static CStr; slightly reword
commit message. - Danilo ]
Signed-off-by: Danilo Krummrich <[email protected]>
Gary Guo