[PATCH 20/24] samples: rust: rust_driver_pci: use HRT lifetime for Bar

[Danilo Krummrich <dakr@kernel.org>]

Convert the sample driver to SampleDriver<'a>, taking advantage of the
lifetime-parameterized Driver trait.

The driver struct holds &'a pci::Device directly instead of
ARef<pci::Device>, and pci::Bar<'a> directly instead of
Devres<pci::Bar>. This removes PinnedDrop, pin_init_scope, and runtime
revocation checks on BAR access.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 samples/rust/rust_driver_pci.rs | 89 +++++++++++++++------------------
 1 file changed, 39 insertions(+), 50 deletions(-)

diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs
index 38d639731229..7f763f43a38d 100644
--- a/samples/rust/rust_driver_pci.rs
+++ b/samples/rust/rust_driver_pci.rs
@@ -9,7 +9,6 @@
         Bound,
         Core, //
     },
-    devres::Devres,
     io::{
         register,
         register::Array,
@@ -17,8 +16,7 @@
     },
     num::Bounded,
     pci,
-    prelude::*,
-    sync::aref::ARef, //
+    prelude::*, //
 };
 
 mod regs {
@@ -45,7 +43,7 @@ mod regs {
     pub(super) const END: usize = 0x10;
 }
 
-type Bar0 = pci::Bar<'static, { regs::END }>;
+type Bar0<'a> = pci::Bar<'a, { regs::END }>;
 
 #[derive(Copy, Clone, Debug)]
 struct TestIndex(u8);
@@ -66,26 +64,24 @@ impl TestIndex {
     const NO_EVENTFD: Self = Self(0);
 }
 
-#[pin_data(PinnedDrop)]
-struct SampleDriver {
-    pdev: ARef<pci::Device>,
-    #[pin]
-    bar: Devres<Bar0>,
+struct SampleDriver<'a> {
+    pdev: &'a pci::Device,
+    bar: Bar0<'a>,
     index: TestIndex,
 }
 
 kernel::pci_device_table!(
     PCI_TABLE,
     MODULE_PCI_TABLE,
-    <SampleDriver as pci::Driver<'_>>::IdInfo,
+    <SampleDriver<'_> as pci::Driver<'_>>::IdInfo,
     [(
         pci::DeviceId::from_id(pci::Vendor::REDHAT, 0x5),
         TestIndex::NO_EVENTFD
     )]
 );
 
-impl SampleDriver {
-    fn testdev(index: &TestIndex, bar: &Bar0) -> Result<u32> {
+impl SampleDriver<'_> {
+    fn testdev(index: &TestIndex, bar: &Bar0<'_>) -> Result<u32> {
         // Select the test.
         bar.write_reg(regs::TEST::zeroed().with_index(*index));
 
@@ -138,7 +134,7 @@ fn config_space(pdev: &pci::Device<Bound>) {
     }
 }
 
-impl<'a> pci::Driver<'a> for SampleDriver {
+impl<'a> pci::Driver<'a> for SampleDriver<'a> {
     type IdInfo = TestIndex;
 
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
@@ -147,54 +143,47 @@ fn probe(
         pdev: &'a pci::Device<Core>,
         info: &'a Self::IdInfo,
     ) -> impl PinInit<Self, Error> + 'a {
-        pin_init::pin_init_scope(move || {
-            let vendor = pdev.vendor_id();
-            dev_dbg!(
-                pdev,
-                "Probe Rust PCI driver sample (PCI ID: {}, 0x{:x}).\n",
-                vendor,
-                pdev.device_id()
-            );
-
-            pdev.enable_device_mem()?;
-            pdev.set_master();
-
-            Ok(try_pin_init!(Self {
-                bar: pdev.iomap_region_sized::<{ regs::END }>(0, c"rust_driver_pci")?
-                    .into_devres()?,
-                index: *info,
-                _: {
-                    let bar = bar.access(pdev.as_ref())?;
-
-                    dev_info!(
-                        pdev,
-                        "pci-testdev data-match count: {}\n",
-                        Self::testdev(info, bar)?
-                    );
-                    Self::config_space(pdev);
-                },
-                pdev: pdev.into(),
-            }))
+        let vendor = pdev.vendor_id();
+        dev_dbg!(
+            pdev,
+            "Probe Rust PCI driver sample (PCI ID: {}, 0x{:x}).\n",
+            vendor,
+            pdev.device_id()
+        );
+
+        pdev.enable_device_mem()?;
+        pdev.set_master();
+
+        let bar = pdev.iomap_region_sized::<{ regs::END }>(0, c"rust_driver_pci")?;
+
+        dev_info!(
+            pdev,
+            "pci-testdev data-match count: {}\n",
+            Self::testdev(info, &bar)?
+        );
+        Self::config_space(pdev);
+
+        Ok(Self {
+            pdev,
+            bar,
+            index: *info,
         })
     }
 
-    fn unbind(pdev: &'a pci::Device<Core>, this: Pin<&'a Self>) {
-        if let Ok(bar) = this.bar.access(pdev.as_ref()) {
-            // Reset pci-testdev by writing a new test index.
-            bar.write_reg(regs::TEST::zeroed().with_index(this.index));
-        }
+    fn unbind(_pdev: &'a pci::Device<Core>, this: Pin<&'a Self>) {
+        this.bar
+            .write_reg(regs::TEST::zeroed().with_index(this.index));
     }
 }
 
-#[pinned_drop]
-impl PinnedDrop for SampleDriver {
-    fn drop(self: Pin<&mut Self>) {
+impl Drop for SampleDriver<'_> {
+    fn drop(&mut self) {
         dev_dbg!(self.pdev, "Remove Rust PCI driver sample.\n");
     }
 }
 
 kernel::module_pci_driver! {
-    type: SampleDriver,
+    type: SampleDriver<'_>,
     name: "rust_driver_pci",
     authors: ["Danilo Krummrich"],
     description: "Rust PCI driver",
-- 
2.54.0