[PATCH v6 11/16] samples: rust: add Rust PCI sample driver

Danilo Krummrich
2024-12-12T16:36:12Z

This commit adds a sample Rust PCI driver for QEMU's "pci-testdev"
device. To enable this device QEMU has to be called with
`-device pci-testdev`.

The same driver shows how to use the PCI device / driver abstractions,
as well as how to request and map PCI BARs, including a short sequence of
MMIO operations.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
MAINTAINERS | 1 +
samples/rust/Kconfig | 11 ++++
samples/rust/Makefile | 1 +
samples/rust/rust_driver_pci.rs | 110 ++++++++++++++++++++++++++++++++
4 files changed, 123 insertions(+)
create mode 100644 samples/rust/rust_driver_pci.rs

diff --git a/MAINTAINERS b/MAINTAINERS
index e143969265aa..b15eb7c6b23f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18103,6 +18103,7 @@ F: include/linux/of_pci.h
F: include/linux/pci*
F: include/uapi/linux/pci*
F: rust/kernel/pci.rs
+F: samples/rust/rust_driver_pci.rs

PCIE BANDWIDTH CONTROLLER
M: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig
index b0f74a81c8f9..6d468193cdd8 100644
--- a/samples/rust/Kconfig
+++ b/samples/rust/Kconfig
@@ -30,6 +30,17 @@ config SAMPLE_RUST_PRINT

If unsure, say N.

+config SAMPLE_RUST_DRIVER_PCI
+ tristate "PCI Driver"
+ depends on PCI
+ help
+ This option builds the Rust PCI driver sample.
+
+ To compile this as a module, choose M here:
+ the module will be called driver_pci.
+
+ If unsure, say N.
+
config SAMPLE_RUST_HOSTPROGS
bool "Host programs"
help
diff --git a/samples/rust/Makefile b/samples/rust/Makefile
index c1a5c1655395..2f5b6bdb2fa5 100644
--- a/samples/rust/Makefile
+++ b/samples/rust/Makefile
@@ -3,6 +3,7 @@ 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

rust_print-y := rust_print_main.o rust_print_events.o

diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs
new file mode 100644
index 000000000000..94710b245834
--- /dev/null
+++ b/samples/rust/rust_driver_pci.rs
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust PCI driver sample (based on QEMU's `pci-testdev`).
+//!
+//! To make this driver probe, QEMU must be run with `-device pci-testdev`.
+
+use kernel::{bindings, c_str, devres::Devres, pci, prelude::*};
+
+struct Regs;
+
+impl Regs {
+ const TEST: usize = 0x0;
+ const OFFSET: usize = 0x4;
+ const DATA: usize = 0x8;
+ const COUNT: usize = 0xC;
+ const END: usize = 0x10;
+}
+
+type Bar0 = pci::Bar<{ Regs::END }>;
+
+#[derive(Debug)]
+struct TestIndex(u8);
+
+impl TestIndex {
+ const NO_EVENTFD: Self = Self(0);
+}
+
+struct SampleDriver {
+ pdev: pci::Device,
+ bar: Devres<Bar0>,
+}
+
+kernel::pci_device_table!(
+ PCI_TABLE,
+ MODULE_PCI_TABLE,
+ <SampleDriver as pci::Driver>::IdInfo,
+ [(
+ pci::DeviceId::new(bindings::PCI_VENDOR_ID_REDHAT, 0x5),
+ TestIndex::NO_EVENTFD
+ )]
+);
+
+impl SampleDriver {
+ fn testdev(index: &TestIndex, bar: &Bar0) -> Result<u32> {
+ // Select the test.
+ bar.writeb(index.0, Regs::TEST);
+
+ let offset = u32::from_le(bar.readl(Regs::OFFSET)) as usize;
+ let data = bar.readb(Regs::DATA);
+
+ // Write `data` to `offset` to increase `count` by one.
+ //
+ // Note that we need `try_writeb`, since `offset` can't be checked at compile-time.
+ bar.try_writeb(data, offset)?;
+
+ Ok(bar.readl(Regs::COUNT))
+ }
+}
+
+impl pci::Driver for SampleDriver {
+ type IdInfo = TestIndex;
+
+ const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
+
+ fn probe(pdev: &mut pci::Device, info: &Self::IdInfo) -> Result<Pin<KBox<Self>>> {
+ dev_dbg!(
+ pdev.as_ref(),
+ "Probe Rust PCI driver sample (PCI ID: 0x{:x}, 0x{:x}).\n",
+ pdev.vendor_id(),
+ pdev.device_id()
+ );
+
+ pdev.enable_device_mem()?;
+ pdev.set_master();
+
+ let bar = pdev.iomap_region_sized::<{ Regs::END }>(0, c_str!("rust_driver_pci"))?;
+
+ let drvdata = KBox::new(
+ Self {
+ pdev: pdev.clone(),
+ bar,
+ },
+ GFP_KERNEL,
+ )?;
+
+ let bar = drvdata.bar.try_access().ok_or(ENXIO)?;
+
+ dev_info!(
+ pdev.as_ref(),
+ "pci-testdev data-match count: {}\n",
+ Self::testdev(info, &bar)?
+ );
+
+ Ok(drvdata.into())
+ }
+}
+
+impl Drop for SampleDriver {
+ fn drop(&mut self) {
+ dev_dbg!(self.pdev.as_ref(), "Remove Rust PCI driver sample.\n");
+ }
+}
+
+kernel::module_pci_driver! {
+ type: SampleDriver,
+ name: "rust_driver_pci",
+ author: "Danilo Krummrich",
+ description: "Rust PCI driver",
+ license: "GPL v2",
+}
--
2.47.1