samples: rust: add Rust platform sample driver

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.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Author: Danilo Krummrich

MAINTAINERS

@@ -7037,6 +7037,7 @@ 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>

drivers/of/unittest-data/tests-platform.dtsi

@@ -33,6 +33,11 @@
 					reg = <0x100>;
 				};
 			};
+
+			test-device@2 {
+				compatible = "test,rust-device";
+				reg = <0x2>;
+			};
 		};
 	};
 };

samples/rust/Kconfig

@@ -41,6 +41,16 @@ 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

samples/rust/Makefile

@@ -4,6 +4,7 @@ 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
 

samples/rust/rust_driver_platform.rs

@@ -0,0 +1,49 @@
+// 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: Option<of::IdTable<Self::IdInfo>> = Some(&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",
+}