Re: [PATCH v4 13/13] samples: rust: add Rust platform sample driver

Dirk Behme
2024-12-05T17:09:14Z

Hi Danilo,

On 05.12.24 15:14, Danilo Krummrich wrote:
> Add a sample Rust platform driver illustrating the usage of the platform
> bus abstractions.
>
> This driver probes through either a match of device / driver name or a
> match within the OF ID table.
>
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Not a review comment, but a question/proposal:

What do you think to convert the platform sample into an example/test?
And drop it in samples/rust then? Like [1] below?

We would have (a) a complete example in the documentation and (b) some
(KUnit) test coverage and (c) have one patch less in the series and
(d) one file less to maintain long term.

I think to remember that it was mentioned somewhere that a
documentation example / KUnit test is preferred over samples/rust (?).

Just an idea :)

Best regards

Dirk

[1]

diff --git a/MAINTAINERS b/MAINTAINERS
index ae576c842c51..365fc48b7041 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7035,7 +7035,6 @@ F: rust/kernel/device_id.rs
F: rust/kernel/devres.rs
F: rust/kernel/driver.rs
F: rust/kernel/platform.rs
-F: samples/rust/rust_driver_platform.rs

DRIVERS FOR OMAP ADAPTIVE VOLTAGE SCALING (AVS)
M: Nishanth Menon <nm@ti.com>
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 868cfddb75a2..77aeb6fc2120 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -142,30 +142,55 @@ macro_rules! module_platform_driver {
/// # Example
///
///```
-/// # use kernel::{bindings, c_str, of, platform};
+/// # mod mydriver {
+/// #
+/// # // Get this into the scope of the module to make the
assert_eq!() buildable
+/// # static __DOCTEST_ANCHOR: i32 = core::line!() as i32 - 4;
+/// #
+/// # use kernel::{c_str, of, platform, prelude::*};
+/// #
+/// struct MyDriver {
+/// pdev: platform::Device,
+/// }
///
-/// struct MyDriver;
+/// struct Info(u32);
///
/// kernel::of_device_table!(
/// OF_TABLE,
/// MODULE_OF_TABLE,
/// <MyDriver as platform::Driver>::IdInfo,
-/// [
-/// (of::DeviceId::new(c_str!("test,device")), ())
-/// ]
+/// [(of::DeviceId::new(c_str!("test,rust-device")), Info(42))]
/// );
///
/// impl platform::Driver for MyDriver {
-/// type IdInfo = ();
+/// type IdInfo = Info;
/// const OF_ID_TABLE: platform::IdTable<Self::IdInfo> = &OF_TABLE;
///
-/// fn probe(
-/// _pdev: &mut platform::Device,
-/// _id_info: Option<&Self::IdInfo>,
-/// ) -> Result<Pin<KBox<Self>>> {
-/// Err(ENODEV)
+/// fn probe(pdev: &mut platform::Device, info:
Option<&Self::IdInfo>) -> Result<Pin<KBox<Self>>> {
+/// dev_dbg!(pdev.as_ref(), "Probe Rust Platform driver
sample.\n");
+///
+/// assert_eq!(info.unwrap().0, 42);
+///
+/// let drvdata = KBox::new(Self { pdev: pdev.clone() },
GFP_KERNEL)?;
+///
+/// Ok(drvdata.into())
+/// }
+/// }
+///
+/// impl Drop for MyDriver {
+/// fn drop(&mut self) {
+/// dev_dbg!(self.pdev.as_ref(), "Remove Rust Platform driver
sample.\n");
/// }
/// }
+///
+/// kernel::module_platform_driver! {
+/// type: MyDriver,
+/// name: "rust_driver_platform",
+/// author: "Danilo Krummrich",
+/// description: "Rust Platform driver",
+/// license: "GPL v2",
+/// }
+/// # }
///```
pub trait Driver {
/// The type holding information about each device id supported
by the driver.
diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig
index 70126b750426..6d468193cdd8 100644
--- a/samples/rust/Kconfig
+++ b/samples/rust/Kconfig
@@ -41,16 +41,6 @@ config SAMPLE_RUST_DRIVER_PCI

If unsure, say N.

-config SAMPLE_RUST_DRIVER_PLATFORM
- tristate "Platform Driver"
- help
- This option builds the Rust Platform driver sample.
-
- To compile this as a module, choose M here:
- the module will be called rust_driver_platform.
-
- If unsure, say N.
-
config SAMPLE_RUST_HOSTPROGS
bool "Host programs"
help
diff --git a/samples/rust/Makefile b/samples/rust/Makefile
index 761d13fff018..2f5b6bdb2fa5 100644
--- a/samples/rust/Makefile
+++ b/samples/rust/Makefile
@@ -4,7 +4,6 @@ ccflags-y += -I$(src) # needed for trace events
obj-$(CONFIG_SAMPLE_RUST_MINIMAL) += rust_minimal.o
obj-$(CONFIG_SAMPLE_RUST_PRINT) += rust_print.o
obj-$(CONFIG_SAMPLE_RUST_DRIVER_PCI) += rust_driver_pci.o
-obj-$(CONFIG_SAMPLE_RUST_DRIVER_PLATFORM) += rust_driver_platform.o

rust_print-y := rust_print_main.o rust_print_events.o

diff --git a/samples/rust/rust_driver_platform.rs
b/samples/rust/rust_driver_platform.rs
deleted file mode 100644
index 2f0dbbe69e10..000000000000
--- a/samples/rust/rust_driver_platform.rs
+++ /dev/null
@@ -1,49 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-//! Rust Platform driver sample.
-
-use kernel::{c_str, of, platform, prelude::*};
-
-struct SampleDriver {
- pdev: platform::Device,
-}
-
-struct Info(u32);
-
-kernel::of_device_table!(
- OF_TABLE,
- MODULE_OF_TABLE,
- <SampleDriver as platform::Driver>::IdInfo,
- [(of::DeviceId::new(c_str!("test,rust-device")), Info(42))]
-);
-
-impl platform::Driver for SampleDriver {
- type IdInfo = Info;
- const OF_ID_TABLE: platform::IdTable<Self::IdInfo> = &OF_TABLE;
-
- fn probe(pdev: &mut platform::Device, info:
Option<&Self::IdInfo>) -> Result<Pin<KBox<Self>>> {
- dev_dbg!(pdev.as_ref(), "Probe Rust Platform driver sample.\n");
-
- if let Some(info) = info {
- dev_info!(pdev.as_ref(), "Probed with info: '{}'.\n",
info.0);
- }
-
- let drvdata = KBox::new(Self { pdev: pdev.clone() },
GFP_KERNEL)?;
-
- Ok(drvdata.into())
- }
-}
-
-impl Drop for SampleDriver {
- fn drop(&mut self) {
- dev_dbg!(self.pdev.as_ref(), "Remove Rust Platform driver
sample.\n");
- }
-}
-
-kernel::module_platform_driver! {
- type: SampleDriver,
- name: "rust_driver_platform",
- author: "Danilo Krummrich",
- description: "Rust Platform driver",
- license: "GPL v2",
-}