[PATCH v7 13/16] rust: driver: implement `Adapter`

Danilo Krummrich
2024-12-19T17:06:02Z

In order to not duplicate code in bus specific implementations (e.g.
platform), implement a generic `driver::Adapter` to represent the
connection of matched drivers and devices.

Bus specific `Adapter` implementations can simply implement this trait
to inherit generic functionality, such as matching OF or ACPI device IDs
and ID table entries.

Suggested-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
rust/bindings/bindings_helper.h | 1 +
rust/kernel/driver.rs | 58 ++++++++++++++++++++++++++++++++-
2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 6d7a68e2ecb7..8fe70183a392 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -20,6 +20,7 @@
#include <linux/jump_label.h>
#include <linux/mdio.h>
#include <linux/miscdevice.h>
+#include <linux/of_device.h>
#include <linux/pci.h>
#include <linux/phy.h>
#include <linux/pid_namespace.h>
diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs
index c1957ee7bb7e..c630e65098ed 100644
--- a/rust/kernel/driver.rs
+++ b/rust/kernel/driver.rs
@@ -6,7 +6,7 @@
//! register using the [`Registration`] class.

use crate::error::{Error, Result};
-use crate::{init::PinInit, str::CStr, try_pin_init, types::Opaque, ThisModule};
+use crate::{device, init::PinInit, of, str::CStr, try_pin_init, types::Opaque, ThisModule};
use core::pin::Pin;
use macros::{pin_data, pinned_drop};

@@ -115,3 +115,59 @@ fn init(
}
}
}
+
+/// 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
+/// of a device and a driver.
+///
+/// It provides bus independent functions for device / driver interactions.
+pub trait Adapter {
+ /// The type holding driver private data about each device id supported by the driver.
+ type IdInfo: 'static;
+
+ /// The [`of::IdTable`] of the corresponding driver.
+ fn of_id_table() -> Option<of::IdTable<Self::IdInfo>>;
+
+ /// Returns the driver's private data from the matching entry in the [`of::IdTable`], if any.
+ ///
+ /// If this returns `None`, it means there is no match with an entry in the [`of::IdTable`].
+ #[cfg(CONFIG_OF)]
+ fn of_id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
+ 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 `pdev.as_ref().as_raw()`.
+ let raw_id = unsafe { bindings::of_match_device(table.as_ptr(), 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.
+ let id = unsafe { &*raw_id.cast::<of::DeviceId>() };
+
+ Some(table.info(<of::DeviceId as crate::device_id::RawDeviceId>::index(id)))
+ }
+ }
+
+ #[cfg(not(CONFIG_OF))]
+ #[allow(missing_docs)]
+ fn of_id_info(_dev: &device::Device) -> Option<&'static Self::IdInfo> {
+ None
+ }
+
+ /// Returns the driver's private data from the matching entry of any of the ID tables, if any.
+ ///
+ /// If this returns `None`, it means that there is no match in any of the ID tables directly
+ /// associated with a [`device::Device`].
+ fn id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
+ let id = Self::of_id_info(dev);
+ if id.is_some() {
+ return id;
+ }
+
+ None
+ }
+}
--
2.47.1