From 9901addae63b9033335fb484a5f0c4367322df8b Mon Sep 17 00:00:00 2001
From: Abdiel Janulgue <abdiel.janulgue@gmail.com>
Date: Mon, 17 Mar 2025 20:52:10 +0200
Subject: samples: rust: add Rust dma test sample driver

Add a simple driver to exercise the basics of the Rust DMA
coherent allocator bindings.

Suggested-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Abdiel Janulgue <abdiel.janulgue@gmail.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250317185345.2608976-4-abdiel.janulgue@gmail.com
[ Renamed Kconfig symbol and moved it up. Migrated to the new
  `authors` key in `module!`. Fixed module name in description
  and typo in commit message. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 samples/rust/rust_dma.rs | 97 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 samples/rust/rust_dma.rs

(limited to 'samples/rust/rust_dma.rs')

diff --git a/samples/rust/rust_dma.rs b/samples/rust/rust_dma.rs
new file mode 100644
index 000000000000..908acd34b8db
--- /dev/null
+++ b/samples/rust/rust_dma.rs
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust DMA api test (based on QEMU's `pci-testdev`).
+//!
+//! To make this driver probe, QEMU must be run with `-device pci-testdev`.
+
+use kernel::{bindings, dma::CoherentAllocation, pci, prelude::*};
+
+struct DmaSampleDriver {
+    pdev: pci::Device,
+    ca: CoherentAllocation<MyStruct>,
+}
+
+const TEST_VALUES: [(u32, u32); 5] = [
+    (0xa, 0xb),
+    (0xc, 0xd),
+    (0xe, 0xf),
+    (0xab, 0xba),
+    (0xcd, 0xef),
+];
+
+struct MyStruct {
+    h: u32,
+    b: u32,
+}
+
+impl MyStruct {
+    fn new(h: u32, b: u32) -> Self {
+        Self { h, b }
+    }
+}
+// SAFETY: All bit patterns are acceptable values for `MyStruct`.
+unsafe impl kernel::transmute::AsBytes for MyStruct {}
+// SAFETY: Instances of `MyStruct` have no uninitialized portions.
+unsafe impl kernel::transmute::FromBytes for MyStruct {}
+
+kernel::pci_device_table!(
+    PCI_TABLE,
+    MODULE_PCI_TABLE,
+    <DmaSampleDriver as pci::Driver>::IdInfo,
+    [(
+        pci::DeviceId::from_id(bindings::PCI_VENDOR_ID_REDHAT, 0x5),
+        ()
+    )]
+);
+
+impl pci::Driver for DmaSampleDriver {
+    type IdInfo = ();
+    const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
+
+    fn probe(pdev: &mut pci::Device, _info: &Self::IdInfo) -> Result<Pin<KBox<Self>>> {
+        dev_info!(pdev.as_ref(), "Probe DMA test driver.\n");
+
+        let ca: CoherentAllocation<MyStruct> =
+            CoherentAllocation::alloc_coherent(pdev.as_ref(), TEST_VALUES.len(), GFP_KERNEL)?;
+
+        || -> Result {
+            for (i, value) in TEST_VALUES.into_iter().enumerate() {
+                kernel::dma_write!(ca[i] = MyStruct::new(value.0, value.1));
+            }
+
+            Ok(())
+        }()?;
+
+        let drvdata = KBox::new(
+            Self {
+                pdev: pdev.clone(),
+                ca,
+            },
+            GFP_KERNEL,
+        )?;
+
+        Ok(drvdata.into())
+    }
+}
+
+impl Drop for DmaSampleDriver {
+    fn drop(&mut self) {
+        dev_info!(self.pdev.as_ref(), "Unload DMA test driver.\n");
+
+        let _ = || -> Result {
+            for (i, value) in TEST_VALUES.into_iter().enumerate() {
+                assert_eq!(kernel::dma_read!(self.ca[i].h), value.0);
+                assert_eq!(kernel::dma_read!(self.ca[i].b), value.1);
+            }
+            Ok(())
+        }();
+    }
+}
+
+kernel::module_pci_driver! {
+    type: DmaSampleDriver,
+    name: "rust_dma",
+    authors: ["Abdiel Janulgue"],
+    description: "Rust DMA test",
+    license: "GPL v2",
+}
-- 
cgit