[PATCH v2 4/4] samples: rust: add Rust serial device bus sample device driver

[Markus Probst <markus.probst@posteo.de>]

Add a sample Rust serial device bus device driver illustrating the usage
of the serial device bus abstractions.

This drivers probes through either a match of device / driver name or a
match within the OF ID table.

Signed-off-by: Markus Probst <markus.probst@posteo.de>
---
 samples/rust/Kconfig               | 11 +++++
 samples/rust/Makefile              |  1 +
 samples/rust/rust_driver_serdev.rs | 86 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 98 insertions(+)

diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig
index c49ab9106345..a421470d2c52 100644
--- a/samples/rust/Kconfig
+++ b/samples/rust/Kconfig
@@ -161,6 +161,17 @@ config SAMPLE_RUST_DRIVER_AUXILIARY
 
 	  If unsure, say N.
 
+config SAMPLE_RUST_DRIVER_SERDEV
+	tristate "Serial Device Bus Device Driver"
+	depends on SERIAL_DEV_BUS
+	help
+	  This option builds the Rust serial device bus driver sample.
+
+	  To compile this as a module, choose M here:
+	  the module will be called rust_driver_serdev.
+
+	  If unsure, say N.
+
 config SAMPLE_RUST_SOC
 	tristate "SoC Driver"
 	select SOC_BUS
diff --git a/samples/rust/Makefile b/samples/rust/Makefile
index 6c0aaa58cccc..b986b681cde5 100644
--- a/samples/rust/Makefile
+++ b/samples/rust/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_SAMPLE_RUST_DRIVER_PLATFORM)	+= rust_driver_platform.o
 obj-$(CONFIG_SAMPLE_RUST_DRIVER_USB)		+= rust_driver_usb.o
 obj-$(CONFIG_SAMPLE_RUST_DRIVER_FAUX)		+= rust_driver_faux.o
 obj-$(CONFIG_SAMPLE_RUST_DRIVER_AUXILIARY)	+= rust_driver_auxiliary.o
+obj-$(CONFIG_SAMPLE_RUST_DRIVER_SERDEV)		+= rust_driver_serdev.o
 obj-$(CONFIG_SAMPLE_RUST_CONFIGFS)		+= rust_configfs.o
 obj-$(CONFIG_SAMPLE_RUST_SOC)			+= rust_soc.o
 
diff --git a/samples/rust/rust_driver_serdev.rs b/samples/rust/rust_driver_serdev.rs
new file mode 100644
index 000000000000..8cf3fb451b22
--- /dev/null
+++ b/samples/rust/rust_driver_serdev.rs
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust Serial device bus device driver sample.
+
+use kernel::{
+    acpi,
+    device::{
+        Bound,
+        Core, //
+    },
+    of,
+    prelude::*,
+    serdev,
+    sync::aref::ARef, //
+};
+
+struct SampleDriver {
+    sdev: ARef<serdev::Device>,
+}
+
+kernel::of_device_table!(
+    OF_TABLE,
+    MODULE_OF_TABLE,
+    <SampleDriver as serdev::Driver>::IdInfo,
+    [(of::DeviceId::new(c"test,rust_driver_serdev"), ())]
+);
+
+kernel::acpi_device_table!(
+    ACPI_TABLE,
+    MODULE_ACPI_TABLE,
+    <SampleDriver as serdev::Driver>::IdInfo,
+    [(acpi::DeviceId::new(c"LNUXBEEF"), ())]
+);
+
+#[vtable]
+impl serdev::Driver for SampleDriver {
+    type IdInfo = ();
+    const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
+    const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
+
+    fn probe(
+        sdev: &serdev::Device<Core>,
+        _info: Option<&Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> {
+        let dev = sdev.as_ref();
+
+        dev_dbg!(dev, "Probe Rust Serial device bus device driver sample.\n");
+
+        if sdev
+            .set_baudrate(
+                dev.fwnode()
+                    .and_then(|fwnode| fwnode.property_read(c"baudrate").optional())
+                    .unwrap_or(115200),
+            )
+            .is_err()
+        {
+            return Err(EINVAL);
+        }
+        sdev.set_flow_control(false);
+        sdev.set_parity(serdev::Parity::None)?;
+
+        Ok(Self { sdev: sdev.into() })
+    }
+
+    fn receive(sdev: &serdev::Device<Bound>, _this: Pin<&Self>, data: &[u8]) -> usize {
+        let _ = sdev.write_all(data, serdev::Timeout::Max);
+        data.len()
+    }
+}
+
+impl Drop for SampleDriver {
+    fn drop(&mut self) {
+        dev_dbg!(
+            self.sdev.as_ref(),
+            "Remove Rust Serial device bus device driver sample.\n"
+        );
+    }
+}
+
+kernel::module_serdev_device_driver! {
+    type: SampleDriver,
+    name: "rust_driver_serdev",
+    authors: ["Markus Probst"],
+    description: "Rust Serial device bus device driver",
+    license: "GPL v2",
+}

-- 
2.52.0