[PATCH v2 2/2] samples: rust: fwctl: add sample code for fwctl

Zhi Wang
2026-01-22T21:00:17Z

This patch adds a sample Rust driver demonstrating the usage of the fwctl
Rust abstractions. Add sample code for creating a FwCtl device, getting
device info and issuing an RPC.

Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
---
samples/rust/Kconfig | 11 +++
samples/rust/Makefile | 1 +
samples/rust/rust_driver_fwctl.rs | 136 ++++++++++++++++++++++++++++++
3 files changed, 148 insertions(+)
create mode 100644 samples/rust/rust_driver_fwctl.rs

diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig
index c49ab9106345..3d0b223caa89 100644
--- a/samples/rust/Kconfig
+++ b/samples/rust/Kconfig
@@ -172,6 +172,17 @@ config SAMPLE_RUST_SOC

If unsure, say N.

+config SAMPLE_RUST_DRIVER_FWCTL
+ tristate "Fwctl Driver"
+ depends on FWCTL
+ help
+ This option builds the Rust Fwctl driver sample.
+
+ To compile this as a module, choose M here:
+ the module will be called rust_driver_fwctl.
+
+ If unsure, say N.
+
config SAMPLE_RUST_HOSTPROGS
bool "Host programs"
help
diff --git a/samples/rust/Makefile b/samples/rust/Makefile
index 6c0aaa58cccc..6f6030e64727 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-$(CONFIG_SAMPLE_RUST_DRIVER_FWCTL) += rust_driver_fwctl.o
obj-$(CONFIG_SAMPLE_RUST_CONFIGFS) += rust_configfs.o
obj-$(CONFIG_SAMPLE_RUST_SOC) += rust_soc.o

diff --git a/samples/rust/rust_driver_fwctl.rs b/samples/rust/rust_driver_fwctl.rs
new file mode 100644
index 000000000000..ac5f979fd73b
--- /dev/null
+++ b/samples/rust/rust_driver_fwctl.rs
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust fwctl API test (based on QEMU's `pci-testdev`).
+//!
+//! To make this driver probe, QEMU must be run with `-device pci-testdev`.
+
+use kernel::{
+ bindings,
+ device,
+ device::Core,
+ devres::Devres,
+ fwctl,
+ pci,
+ prelude::*,
+ sync::aref::ARef,
+ types,
+};
+
+struct FwctlSampleUserCtx {
+ _drvdata: u32,
+}
+
+struct FwctlSampleOps;
+
+impl fwctl::Operations for FwctlSampleOps {
+ type UserCtx = FwctlSampleUserCtx;
+
+ const DEVICE_TYPE: fwctl::DeviceType = fwctl::DeviceType::RustFwctlTest;
+
+ fn open(
+ fwctl_uctx: &types::Opaque<bindings::fwctl_uctx>
+ ) -> Result<impl PinInit<Self::UserCtx, Error>, Error> {
+ let dev = fwctl::UserCtx::<Self::UserCtx>::parent_device_from_raw(fwctl_uctx);
+
+ dev_info!(dev, "fwctl test driver: open_uctx()");
+
+ // Return an initializer for the user context.
+ // The framework will initialize this in-place in the C-allocated memory.
+ Ok(try_init!(FwctlSampleUserCtx {
+ _drvdata: 0,
+ }))
+ }
+
+ fn close(uctx: &mut fwctl::UserCtx<FwctlSampleUserCtx>) {
+ let dev = uctx.get_parent_device();
+
+ dev_info!(dev, "fwctl test driver: close_uctx()");
+ }
+
+ fn info(uctx: &mut fwctl::UserCtx<FwctlSampleUserCtx>) -> Result<KVec<u8>, Error> {
+ let dev = uctx.get_parent_device();
+
+ dev_info!(dev, "fwctl test driver: info()");
+
+ let mut infobuf = KVec::<u8>::new();
+ infobuf.push(0xef, GFP_KERNEL)?;
+ infobuf.push(0xbe, GFP_KERNEL)?;
+ infobuf.push(0xad, GFP_KERNEL)?;
+ infobuf.push(0xde, GFP_KERNEL)?;
+
+ Ok(infobuf)
+ }
+
+ fn fw_rpc(
+ uctx: &mut fwctl::UserCtx<FwctlSampleUserCtx>,
+ scope: u32,
+ rpc_in: &mut [u8],
+ _out_len: *mut usize,
+ ) -> Result<Option<KVec<u8>>, Error> {
+ let dev = uctx.get_parent_device();
+
+ dev_info!(dev, "fwctl test driver: fw_rpc() scope {}", scope);
+
+ if rpc_in.len() != 4 {
+ return Err(EINVAL);
+ }
+
+ dev_info!(
+ dev,
+ "fwctl test driver: inbuf len{} bytes[0-3] {:x} {:x} {:x} {:x}",
+ rpc_in.len(),
+ rpc_in[0],
+ rpc_in[1],
+ rpc_in[2],
+ rpc_in[3]
+ );
+
+ let mut outbuf = KVec::<u8>::new();
+ outbuf.push(0xef, GFP_KERNEL)?;
+ outbuf.push(0xbe, GFP_KERNEL)?;
+ outbuf.push(0xad, GFP_KERNEL)?;
+ outbuf.push(0xde, GFP_KERNEL)?;
+
+ Ok(Some(outbuf))
+ }
+}
+
+#[pin_data]
+struct FwctlSampleDriver {
+ pdev: ARef<pci::Device>,
+ #[pin]
+ fwctl: Devres<fwctl::Registration<FwctlSampleOps>>,
+}
+
+kernel::pci_device_table!(
+ PCI_TABLE,
+ MODULE_PCI_TABLE,
+ <FwctlSampleDriver as pci::Driver>::IdInfo,
+ [(pci::DeviceId::from_id(pci::Vendor::REDHAT, 0x5), ())]
+);
+
+impl pci::Driver for FwctlSampleDriver {
+ type IdInfo = ();
+ const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
+
+ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
+ dev_info!(pdev.as_ref(), "Probe fwctl test driver");
+
+ // `pdev` is `Device<Core>`, which derefs to `Device<Bound>` during probe.
+ let pdev_bound: &pci::Device<device::Bound> = pdev;
+
+ try_pin_init!(Self {
+ pdev: pdev.into(),
+ fwctl <- fwctl::Registration::<FwctlSampleOps>::new(pdev_bound.as_ref()),
+ })
+ }
+}
+
+kernel::module_pci_driver! {
+ type: FwctlSampleDriver,
+ name: "rust_driver_fwctl",
+ authors: ["Zhi Wang"],
+ description: "Rust fwctl test",
+ license: "GPL v2",
+ imports_ns: ["FWCTL"],
+}
--
2.51.0