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

[Dirk Behme <dirk.behme@gmail.com>]

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",
-}