[PATCH v3 00/27] rust: device: Higher-Ranked Lifetime Types for device drivers

[PATCH v3 00/27] rust: device: Higher-Ranked Lifetime Types for device drivers

[Danilo Krummrich]

Currently, Rust device drivers access device resources such as PCI BAR mappings
and I/O memory regions through Devres<T>.

Devres::access() provides zero-overhead access by taking a &Device<Bound>
reference as proof that the device is still bound. Since a &Device<Bound> is
available in almost all contexts by design, Devres is mostly a type-system level
proof that the resource is valid, but it can also be used from scopes without
this guarantee through its try_access() accessor.

This works well in general, but has a few limitations:

  - Every access to a device resource goes through Devres::access(), which
    despite zero cost, adds boilerplate to every access site.

  - Destructors do not receive a &Device<Bound>, so they must use try_access(),
    which can fail. In practice the access succeeds if teardown ordering is
    correct, but the type system can't express this, forcing drivers to handle a
    failure path that should never be taken.

  - Sharing a resource across components (e.g. passing a BAR to a sub-component)
    requires Arc<Devres<T>>.

  - Device references must be stored as ARef<Device> rather than plain &Device
    borrows.

These limitations stem from the driver's bus device private data being 'static
-- the driver struct cannot borrow from the device reference it receives in
probe(), even though it structurally cannot outlive the device binding.

This series introduces Higher-Ranked Lifetime Types (HRT) for Rust device
drivers. An HRT is a type that is generic over a lifetime -- it does not have a
fixed lifetime, but can be instantiated with any lifetime chosen by the caller.

Bus driver traits use a Generic Associated Type (GAT) type Data<'bound> to
introduce the lifetime on the private data, rather than parameterizing the
Driver trait itself. This avoids a driver trait global lifetime and avoids the
need for ForLt for bus device private data, making the bus implementations much
simpler. ForLt is only needed for auxiliary registration data, where the
lifetime is not introduced by a trait callback but must be threaded through
Registration.

With HRT, driver structs carry a lifetime parameter tied to the device binding
scope -- the interval of a bus device being bound to a driver. Device resources
like pci::Bar<'bound> and IoMem<'bound> are handed out with this lifetime, so
the compiler enforces at build time that they do not escape the binding scope.

Before:

	struct MyDriver {
	    pdev: ARef<pci::Device>,
	    bar: Devres<pci::Bar<BAR_SIZE>>,
	}

	let io = self.bar.access(dev)?;
	io.read32(OFFSET);

After:

	struct MyDriver<'bound> {
	    pdev: &'bound pci::Device,
	    bar: pci::Bar<'bound, BAR_SIZE>,
	}

	self.bar.read32(OFFSET);

Lifetime-parameterized device resources can be put into a Devres at any point
via Bar::into_devres() / IoMem::into_devres(), providing the exact same
semantics as before. This is useful for resources shared across subsystem
boundaries where revocation is needed.

This also synergizes with the upcoming self-referential initialization support
in pin-init, which allows one field of the driver struct to borrow another
during initialization without unsafe code.

The same pattern is applied to auxiliary device registration data as a first
example beyond bus device private data. Registration<F: ForLt> can hold
lifetime-parameterized data tied to the parent driver's binding scope. Since the
auxiliary bus guarantees that the parent remains bound while the auxiliary
device is registered, the registration data can safely borrow the parent's
device resources.

More generally, binding resource lifetimes to a registration scope applies to
every registration that is scoped to a driver binding -- auxiliary devices,
class devices, IRQ handlers, workqueues.

A follow-up series extends this to class device registrations, starting with
DRM, so that class device callbacks (IOCTLs, etc.) can safely access device
resources through the separate registration data bound to the registration's
lifetime without Devres indirection.

The series contains a few driver patches for reference, indicated by the REF
suffix.

Thanks to Gary for coming up with the ForLt implementation; thanks to Alice for
the early discussions around lifetime-parameterized private data that helped
shape the direction of this work.

Changes in v3:
  - Rework all bus "make Driver trait lifetime-parameterized" patches to use a
    GAT (type Data<'bound>); in the context of adding a 'bound lifetime, this
    avoids a driver trait global lifetime and avoids ForLt for bus device
    private data making the bus implementations much simpler

Changes in v2:
  - Add 'a bound to ForLt::Of<'a> and WithLt::Of, making the lifetime bound
    inherent to the trait; remove all F::Of<'static>: 'static where clauses
  - Drop "rust: devres: add ForLt support to Devres"; Devres itself stays
    unchanged -- ForLt-aware access is introduced later through DevresLt in a
    separate series
  - Use 'bound instead of 'a; add patches to consistently use 'bound for
    pre-existing 'a

Danilo Krummrich (24):
  rust: driver: decouple driver private data from driver type
  rust: driver core: drop drvdata before devres release
  rust: pci: implement Sync for Device<Bound>
  rust: platform: implement Sync for Device<Bound>
  rust: auxiliary: implement Sync for Device<Bound>
  rust: usb: implement Sync for Device<Bound>
  rust: device: implement Sync for Device<Bound>
  rust: pci: make Driver trait lifetime-parameterized
  rust: platform: make Driver trait lifetime-parameterized
  rust: auxiliary: make Driver trait lifetime-parameterized
  rust: usb: make Driver trait lifetime-parameterized
  rust: i2c: make Driver trait lifetime-parameterized
  rust: driver: update module documentation for GAT-based Data type
  rust: auxiliary: generalize Registration over ForLt
  samples: rust: rust_driver_auxiliary: showcase lifetime-bound
    registration data
  rust: pci: make Bar lifetime-parameterized
  rust: io: make IoMem and ExclusiveIoMem lifetime-parameterized
  samples: rust: rust_driver_pci: use HRT lifetime for Bar
  rust: driver-core: rename 'a lifetime to 'bound
  gpu: nova-core: rename 'a lifetime to 'bound
  gpu: nova-core: use lifetime for Bar
  gpu: nova-core: unregister sysmem flush page from Drop
  gpu: nova-core: replace ARef<Device> with &'bound Device in
    SysmemFlush
  gpu: drm: tyr: use lifetime for IoMem

Gary Guo (3):
  rust: alloc: remove `'static` bound on `ForeignOwnable`
  rust: driver: move 'static bounds to constructor
  rust: types: add `ForLt` trait for higher-ranked lifetime support

 drivers/base/dd.c                        |   2 +-
 drivers/cpufreq/rcpufreq_dt.rs           |   9 +-
 drivers/gpu/drm/nova/driver.rs           |   6 +-
 drivers/gpu/drm/tyr/driver.rs            |  23 ++-
 drivers/gpu/drm/tyr/gpu.rs               |  62 +++---
 drivers/gpu/drm/tyr/regs.rs              |  21 +-
 drivers/gpu/nova-core/driver.rs          |  51 ++---
 drivers/gpu/nova-core/fb.rs              |  31 ++-
 drivers/gpu/nova-core/firmware/gsp.rs    |   8 +-
 drivers/gpu/nova-core/gpu.rs             |  38 ++--
 drivers/gpu/nova-core/gsp/commands.rs    |  10 +-
 drivers/gpu/nova-core/gsp/fw/commands.rs |   4 +-
 drivers/gpu/nova-core/nova_core.rs       |   2 +-
 drivers/pwm/pwm_th1520.rs                |  13 +-
 include/linux/device/driver.h            |   4 +-
 rust/Makefile                            |   1 +
 rust/kernel/alloc/kbox.rs                |  24 ++-
 rust/kernel/auxiliary.rs                 |  98 +++++----
 rust/kernel/cpufreq.rs                   |   9 +-
 rust/kernel/device.rs                    |  12 +-
 rust/kernel/devres.rs                    |  16 +-
 rust/kernel/driver.rs                    |  37 ++--
 rust/kernel/i2c.rs                       |  62 +++---
 rust/kernel/io/mem.rs                    | 133 +++++++------
 rust/kernel/pci.rs                       |  39 ++--
 rust/kernel/pci/io.rs                    |  68 ++++---
 rust/kernel/pci/irq.rs                   |  38 ++--
 rust/kernel/platform.rs                  |  62 +++---
 rust/kernel/types.rs                     |  12 +-
 rust/kernel/types/for_lt.rs              | 117 +++++++++++
 rust/kernel/usb.rs                       |  53 +++--
 rust/macros/for_lt.rs                    | 242 +++++++++++++++++++++++
 rust/macros/lib.rs                       |  12 ++
 samples/rust/rust_debugfs.rs             |   9 +-
 samples/rust/rust_dma.rs                 |   6 +-
 samples/rust/rust_driver_auxiliary.rs    |  41 ++--
 samples/rust/rust_driver_i2c.rs          |  13 +-
 samples/rust/rust_driver_pci.rs          |  90 ++++-----
 samples/rust/rust_driver_platform.rs     |   9 +-
 samples/rust/rust_driver_usb.rs          |  13 +-
 samples/rust/rust_i2c_client.rs          |  14 +-
 samples/rust/rust_soc.rs                 |   9 +-
 42 files changed, 1011 insertions(+), 512 deletions(-)
 create mode 100644 rust/kernel/types/for_lt.rs
 create mode 100644 rust/macros/for_lt.rs


base-commit: 8d3bea93f483cb8f92b9f85d1528268a6469af28
-- 
2.54.0

[PATCH v3 01/27] rust: alloc: remove `'static` bound on `ForeignOwnable`

[Danilo Krummrich]

From: Gary Guo <gary@garyguo.net>

The `'static` bound is currently necessary because there's no
restriction on the lifetime of the GAT. Add a `Self: 'a` bound to
restrict possible lifetimes on `Borrowed` and `BorrowedMut`, and lift
the `'static` requirement.

Signed-off-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/alloc/kbox.rs | 24 ++++++++++++++++++------
 rust/kernel/types.rs      |  8 ++++++--
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index c824ed6e1523..2f8c16473c2c 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -477,7 +477,7 @@ fn try_init<E>(init: impl Init<T, E>, flags: Flags) -> Result<Self, E>
 
 // SAFETY: The pointer returned by `into_foreign` comes from a well aligned
 // pointer to `T` allocated by `A`.
-unsafe impl<T: 'static, A> ForeignOwnable for Box<T, A>
+unsafe impl<T, A> ForeignOwnable for Box<T, A>
 where
     A: Allocator,
 {
@@ -487,8 +487,14 @@ unsafe impl<T: 'static, A> ForeignOwnable for Box<T, A>
         core::mem::align_of::<T>()
     };
 
-    type Borrowed<'a> = &'a T;
-    type BorrowedMut<'a> = &'a mut T;
+    type Borrowed<'a>
+        = &'a T
+    where
+        Self: 'a;
+    type BorrowedMut<'a>
+        = &'a mut T
+    where
+        Self: 'a;
 
     fn into_foreign(self) -> *mut c_void {
         Box::into_raw(self).cast()
@@ -516,13 +522,19 @@ unsafe fn borrow_mut<'a>(ptr: *mut c_void) -> &'a mut T {
 
 // SAFETY: The pointer returned by `into_foreign` comes from a well aligned
 // pointer to `T` allocated by `A`.
-unsafe impl<T: 'static, A> ForeignOwnable for Pin<Box<T, A>>
+unsafe impl<T, A> ForeignOwnable for Pin<Box<T, A>>
 where
     A: Allocator,
 {
     const FOREIGN_ALIGN: usize = <Box<T, A> as ForeignOwnable>::FOREIGN_ALIGN;
-    type Borrowed<'a> = Pin<&'a T>;
-    type BorrowedMut<'a> = Pin<&'a mut T>;
+    type Borrowed<'a>
+        = Pin<&'a T>
+    where
+        Self: 'a;
+    type BorrowedMut<'a>
+        = Pin<&'a mut T>
+    where
+        Self: 'a;
 
     fn into_foreign(self) -> *mut c_void {
         // SAFETY: We are still treating the box as pinned.
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 4329d3c2c2e5..9cf9f869d195 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -27,10 +27,14 @@ pub unsafe trait ForeignOwnable: Sized {
     const FOREIGN_ALIGN: usize;
 
     /// Type used to immutably borrow a value that is currently foreign-owned.
-    type Borrowed<'a>;
+    type Borrowed<'a>
+    where
+        Self: 'a;
 
     /// Type used to mutably borrow a value that is currently foreign-owned.
-    type BorrowedMut<'a>;
+    type BorrowedMut<'a>
+    where
+        Self: 'a;
 
     /// Converts a Rust-owned object to a foreign-owned one.
     ///
-- 
2.54.0

[PATCH v3 02/27] rust: driver: move 'static bounds to constructor

[Danilo Krummrich]

From: Gary Guo <gary@garyguo.net>

With the ForeignOwnable lifetime change, the 'static bound is no longer
necessary on the drvdata methods or bus adapter impls. Move it to the
Registration constructor instead.

Signed-off-by: Gary Guo <gary@garyguo.net>
Co-developed-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/auxiliary.rs | 6 +++---
 rust/kernel/device.rs    | 8 ++++----
 rust/kernel/driver.rs    | 7 +++++--
 rust/kernel/i2c.rs       | 8 ++++----
 rust/kernel/pci.rs       | 6 +++---
 rust/kernel/platform.rs  | 8 ++++----
 rust/kernel/usb.rs       | 6 +++---
 7 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs
index 19aec94aa95b..35b44d194f67 100644
--- a/rust/kernel/auxiliary.rs
+++ b/rust/kernel/auxiliary.rs
@@ -44,7 +44,7 @@
 // - `T` is the type of the driver's device private data.
 // - `struct auxiliary_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
-unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::auxiliary_driver;
     type DriverData = T;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
@@ -52,7 +52,7 @@ unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
 
 // SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
-unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
+unsafe impl<T: Driver> driver::RegistrationOps for Adapter<T> {
     unsafe fn register(
         adrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
@@ -78,7 +78,7 @@ unsafe fn unregister(adrv: &Opaque<Self::DriverType>) {
     }
 }
 
-impl<T: Driver + 'static> Adapter<T> {
+impl<T: Driver> Adapter<T> {
     extern "C" fn probe_callback(
         adev: *mut bindings::auxiliary_device,
         id: *const bindings::auxiliary_device_id,
diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index fd50399aadea..5df8fa108a52 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -203,7 +203,7 @@ pub unsafe fn as_bound(&self) -> &Device<Bound> {
 
 impl Device<CoreInternal> {
     /// Store a pointer to the bound driver's private data.
-    pub fn set_drvdata<T: 'static>(&self, data: impl PinInit<T, Error>) -> Result {
+    pub fn set_drvdata<T>(&self, data: impl PinInit<T, Error>) -> Result {
         let data = KBox::pin_init(data, GFP_KERNEL)?;
 
         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
@@ -218,7 +218,7 @@ pub fn set_drvdata<T: 'static>(&self, data: impl PinInit<T, Error>) -> Result {
     ///
     /// - The type `T` must match the type of the `ForeignOwnable` previously stored by
     ///   [`Device::set_drvdata`].
-    pub(crate) unsafe fn drvdata_obtain<T: 'static>(&self) -> Option<Pin<KBox<T>>> {
+    pub(crate) unsafe fn drvdata_obtain<T>(&self) -> Option<Pin<KBox<T>>> {
         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
         let ptr = unsafe { bindings::dev_get_drvdata(self.as_raw()) };
 
@@ -244,7 +244,7 @@ pub(crate) unsafe fn drvdata_obtain<T: 'static>(&self) -> Option<Pin<KBox<T>>> {
     ///   device is fully unbound.
     /// - The type `T` must match the type of the `ForeignOwnable` previously stored by
     ///   [`Device::set_drvdata`].
-    pub unsafe fn drvdata_borrow<T: 'static>(&self) -> Pin<&T> {
+    pub unsafe fn drvdata_borrow<T>(&self) -> Pin<&T> {
         // SAFETY: `drvdata_unchecked()` has the exact same safety requirements as the ones
         // required by this method.
         unsafe { self.drvdata_unchecked() }
@@ -260,7 +260,7 @@ impl Device<Bound> {
     ///   the device is fully unbound.
     /// - The type `T` must match the type of the `ForeignOwnable` previously stored by
     ///   [`Device::set_drvdata`].
-    unsafe fn drvdata_unchecked<T: 'static>(&self) -> Pin<&T> {
+    unsafe fn drvdata_unchecked<T>(&self) -> Pin<&T> {
         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
         let ptr = unsafe { bindings::dev_get_drvdata(self.as_raw()) };
 
diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs
index 93e5dd6ae371..586091cfa45c 100644
--- a/rust/kernel/driver.rs
+++ b/rust/kernel/driver.rs
@@ -181,7 +181,7 @@ unsafe impl<T: RegistrationOps> Sync for Registration<T> {}
 // any thread, so `Registration` is `Send`.
 unsafe impl<T: RegistrationOps> Send for Registration<T> {}
 
-impl<T: RegistrationOps + 'static> Registration<T> {
+impl<T: RegistrationOps> Registration<T> {
     extern "C" fn post_unbind_callback(dev: *mut bindings::device) {
         // SAFETY: The driver core only ever calls the post unbind callback with a valid pointer to
         // a `struct device`.
@@ -215,7 +215,10 @@ fn callbacks_attach(drv: &Opaque<T::DriverType>) {
     }
 
     /// Creates a new instance of the registration object.
-    pub fn new(name: &'static CStr, module: &'static ThisModule) -> impl PinInit<Self, Error> {
+    pub fn new(name: &'static CStr, module: &'static ThisModule) -> impl PinInit<Self, Error>
+    where
+        T: 'static,
+    {
         try_pin_init!(Self {
             reg <- Opaque::try_ffi_init(|ptr: *mut T::DriverType| {
                 // SAFETY: `try_ffi_init` guarantees that `ptr` is valid for write.
diff --git a/rust/kernel/i2c.rs b/rust/kernel/i2c.rs
index 7b908f0c5a58..4ccee4ba4f23 100644
--- a/rust/kernel/i2c.rs
+++ b/rust/kernel/i2c.rs
@@ -96,7 +96,7 @@ macro_rules! i2c_device_table {
 // - `T` is the type of the driver's device private data.
 // - `struct i2c_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
-unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::i2c_driver;
     type DriverData = T;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
@@ -104,7 +104,7 @@ unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
 
 // SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
-unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
+unsafe impl<T: Driver> driver::RegistrationOps for Adapter<T> {
     unsafe fn register(
         idrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
@@ -151,7 +151,7 @@ unsafe fn unregister(idrv: &Opaque<Self::DriverType>) {
     }
 }
 
-impl<T: Driver + 'static> Adapter<T> {
+impl<T: Driver> Adapter<T> {
     extern "C" fn probe_callback(idev: *mut bindings::i2c_client) -> kernel::ffi::c_int {
         // SAFETY: The I2C bus only ever calls the probe callback with a valid pointer to a
         // `struct i2c_client`.
@@ -222,7 +222,7 @@ fn i2c_id_info(dev: &I2cClient) -> Option<&'static <Self as driver::Adapter>::Id
     }
 }
 
-impl<T: Driver + 'static> driver::Adapter for Adapter<T> {
+impl<T: Driver> driver::Adapter for Adapter<T> {
     type IdInfo = T::IdInfo;
 
     fn of_id_table() -> Option<of::IdTable<Self::IdInfo>> {
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index af74ddff6114..17a33819dc0a 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -62,7 +62,7 @@
 // - `T` is the type of the driver's device private data.
 // - `struct pci_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
-unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::pci_driver;
     type DriverData = T;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
@@ -70,7 +70,7 @@ unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
 
 // SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
-unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
+unsafe impl<T: Driver> driver::RegistrationOps for Adapter<T> {
     unsafe fn register(
         pdrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
@@ -96,7 +96,7 @@ unsafe fn unregister(pdrv: &Opaque<Self::DriverType>) {
     }
 }
 
-impl<T: Driver + 'static> Adapter<T> {
+impl<T: Driver> Adapter<T> {
     extern "C" fn probe_callback(
         pdev: *mut bindings::pci_dev,
         id: *const bindings::pci_device_id,
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 8917d4ee499f..c7a3dcdde3b1 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -48,7 +48,7 @@
 // - `T` is the type of the driver's device private data.
 // - `struct platform_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
-unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::platform_driver;
     type DriverData = T;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
@@ -56,7 +56,7 @@ unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
 
 // SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
-unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
+unsafe impl<T: Driver> driver::RegistrationOps for Adapter<T> {
     unsafe fn register(
         pdrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
@@ -91,7 +91,7 @@ unsafe fn unregister(pdrv: &Opaque<Self::DriverType>) {
     }
 }
 
-impl<T: Driver + 'static> Adapter<T> {
+impl<T: Driver> Adapter<T> {
     extern "C" fn probe_callback(pdev: *mut bindings::platform_device) -> kernel::ffi::c_int {
         // SAFETY: The platform bus only ever calls the probe callback with a valid pointer to a
         // `struct platform_device`.
@@ -124,7 +124,7 @@ extern "C" fn remove_callback(pdev: *mut bindings::platform_device) {
     }
 }
 
-impl<T: Driver + 'static> driver::Adapter for Adapter<T> {
+impl<T: Driver> driver::Adapter for Adapter<T> {
     type IdInfo = T::IdInfo;
 
     fn of_id_table() -> Option<of::IdTable<Self::IdInfo>> {
diff --git a/rust/kernel/usb.rs b/rust/kernel/usb.rs
index 9c17a672cd27..3f62da585281 100644
--- a/rust/kernel/usb.rs
+++ b/rust/kernel/usb.rs
@@ -39,7 +39,7 @@
 // - `T` is the type of the driver's device private data.
 // - `struct usb_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
-unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::usb_driver;
     type DriverData = T;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
@@ -47,7 +47,7 @@ unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
 
 // SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
-unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
+unsafe impl<T: Driver> driver::RegistrationOps for Adapter<T> {
     unsafe fn register(
         udrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
@@ -73,7 +73,7 @@ unsafe fn unregister(udrv: &Opaque<Self::DriverType>) {
     }
 }
 
-impl<T: Driver + 'static> Adapter<T> {
+impl<T: Driver> Adapter<T> {
     extern "C" fn probe_callback(
         intf: *mut bindings::usb_interface,
         id: *const bindings::usb_device_id,
-- 
2.54.0

[PATCH v3 03/27] rust: driver: decouple driver private data from driver type

[Danilo Krummrich]

Add a type Data<'bound> associated type to all bus driver traits,
decoupling the driver's bus device private data type from the driver
struct itself.

In the context of adding a 'bound lifetime, making this an associated
type has the advantage that it allows us to avoid a driver trait global
lifetime and it avoids the need for ForLt for bus device private data;
both of which make the subsequent implementation by buses much simpler.

All existing drivers and doc examples set type Data = Self to preserve
the current behavior.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/cpufreq/rcpufreq_dt.rs        |  1 +
 drivers/gpu/drm/nova/driver.rs        |  1 +
 drivers/gpu/drm/tyr/driver.rs         |  1 +
 drivers/gpu/nova-core/driver.rs       |  1 +
 drivers/pwm/pwm_th1520.rs             |  1 +
 rust/kernel/auxiliary.rs              | 18 +++++++++-------
 rust/kernel/cpufreq.rs                |  1 +
 rust/kernel/driver.rs                 | 22 ++++++++++++--------
 rust/kernel/i2c.rs                    | 30 +++++++++++++++------------
 rust/kernel/io/mem.rs                 |  2 ++
 rust/kernel/pci.rs                    | 19 ++++++++++-------
 rust/kernel/platform.rs               | 18 +++++++++-------
 rust/kernel/usb.rs                    | 20 +++++++++++-------
 samples/rust/rust_debugfs.rs          |  1 +
 samples/rust/rust_dma.rs              |  1 +
 samples/rust/rust_driver_auxiliary.rs |  2 ++
 samples/rust/rust_driver_i2c.rs       |  1 +
 samples/rust/rust_driver_pci.rs       |  1 +
 samples/rust/rust_driver_platform.rs  |  1 +
 samples/rust/rust_driver_usb.rs       |  1 +
 samples/rust/rust_i2c_client.rs       |  1 +
 samples/rust/rust_soc.rs              |  1 +
 22 files changed, 94 insertions(+), 51 deletions(-)

diff --git a/drivers/cpufreq/rcpufreq_dt.rs b/drivers/cpufreq/rcpufreq_dt.rs
index f17bf64c22e2..b7eeb2730eb0 100644
--- a/drivers/cpufreq/rcpufreq_dt.rs
+++ b/drivers/cpufreq/rcpufreq_dt.rs
@@ -201,6 +201,7 @@ fn register_em(policy: &mut cpufreq::Policy) {
 
 impl platform::Driver for CPUFreqDTDriver {
     type IdInfo = ();
+    type Data = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
 
     fn probe(
diff --git a/drivers/gpu/drm/nova/driver.rs b/drivers/gpu/drm/nova/driver.rs
index b1af0a099551..08136ec0bccb 100644
--- a/drivers/gpu/drm/nova/driver.rs
+++ b/drivers/gpu/drm/nova/driver.rs
@@ -51,6 +51,7 @@ pub(crate) struct NovaData {
 
 impl auxiliary::Driver for NovaDriver {
     type IdInfo = ();
+    type Data = Self;
     const ID_TABLE: auxiliary::IdTable<Self::IdInfo> = &AUX_TABLE;
 
     fn probe(adev: &auxiliary::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
diff --git a/drivers/gpu/drm/tyr/driver.rs b/drivers/gpu/drm/tyr/driver.rs
index 279710b36a10..c81bf217743d 100644
--- a/drivers/gpu/drm/tyr/driver.rs
+++ b/drivers/gpu/drm/tyr/driver.rs
@@ -91,6 +91,7 @@ fn issue_soft_reset(dev: &Device<Bound>, iomem: &Devres<IoMem>) -> Result {
 
 impl platform::Driver for TyrPlatformDriverData {
     type IdInfo = ();
+    type Data = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
 
     fn probe(
diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index 8fe484d357f6..699e27046c93 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -74,6 +74,7 @@ pub(crate) struct NovaCore {
 
 impl pci::Driver for NovaCore {
     type IdInfo = ();
+    type Data = Self;
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 
     fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
diff --git a/drivers/pwm/pwm_th1520.rs b/drivers/pwm/pwm_th1520.rs
index ddd44a5ce497..07795910a0b5 100644
--- a/drivers/pwm/pwm_th1520.rs
+++ b/drivers/pwm/pwm_th1520.rs
@@ -316,6 +316,7 @@ fn drop(self: Pin<&mut Self>) {
 
 impl platform::Driver for Th1520PwmPlatformDriver {
     type IdInfo = ();
+    type Data = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
 
     fn probe(
diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs
index 35b44d194f67..1b6ff3817a4d 100644
--- a/rust/kernel/auxiliary.rs
+++ b/rust/kernel/auxiliary.rs
@@ -41,12 +41,12 @@
 
 // SAFETY:
 // - `bindings::auxiliary_driver` is a C type declared as `repr(C)`.
-// - `T` is the type of the driver's device private data.
+// - `T::Data` is the type of the driver's device private data.
 // - `struct auxiliary_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::auxiliary_driver;
-    type DriverData = T;
+    type DriverData<'bound> = T::Data;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -111,8 +111,8 @@ extern "C" fn remove_callback(adev: *mut bindings::auxiliary_device) {
 
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
-        // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { adev.as_ref().drvdata_borrow::<T>() };
+        // and stored a `Pin<KBox<T::Data>>`.
+        let data = unsafe { adev.as_ref().drvdata_borrow::<T::Data>() };
 
         T::unbind(adev, data);
     }
@@ -202,13 +202,17 @@ pub trait Driver {
     /// type IdInfo: 'static = ();
     type IdInfo: 'static;
 
+    /// The type of the driver's bus device private data.
+    type Data;
+
     /// The table of device ids supported by the driver.
     const ID_TABLE: IdTable<Self::IdInfo>;
 
     /// Auxiliary driver probe.
     ///
     /// Called when an auxiliary device is matches a corresponding driver.
-    fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo) -> impl PinInit<Self, Error>;
+    fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo)
+        -> impl PinInit<Self::Data, Error>;
 
     /// Auxiliary driver unbind.
     ///
@@ -219,8 +223,8 @@ pub trait Driver {
     /// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O
     /// operations to gracefully tear down the device.
     ///
-    /// Otherwise, release operations for driver resources should be performed in `Self::drop`.
-    fn unbind(dev: &Device<device::Core>, this: Pin<&Self>) {
+    /// Otherwise, release operations for driver resources should be performed in `Drop`.
+    fn unbind(dev: &Device<device::Core>, this: Pin<&Self::Data>) {
         let _ = (dev, this);
     }
 }
diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index d8d26870bea2..50dd2a2c3e81 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -888,6 +888,7 @@ fn register_em(_policy: &mut Policy) {
 ///
 /// impl platform::Driver for SampleDriver {
 ///     type IdInfo = ();
+///     type Data = Self;
 ///     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
 ///
 ///     fn probe(
diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs
index 586091cfa45c..3506b4e8bff9 100644
--- a/rust/kernel/driver.rs
+++ b/rust/kernel/driver.rs
@@ -17,6 +17,9 @@
 //!     /// The type holding information about each device ID supported by the driver.
 //!     type IdInfo: 'static;
 //!
+//!     /// The type of the driver's bus device private data.
+//!     type Data;
+//!
 //!     /// The table of OF device ids supported by the driver.
 //!     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
 //!
@@ -24,10 +27,11 @@
 //!     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = None;
 //!
 //!     /// Driver probe.
-//!     fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo) -> impl PinInit<Self, Error>;
+//!     fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo)
+//!         -> impl PinInit<Self::Data, Error>;
 //!
 //!     /// Driver unbind (optional).
-//!     fn unbind(dev: &Device<device::Core>, this: Pin<&Self>) {
+//!     fn unbind(dev: &Device<device::Core>, this: Pin<&Self::Data>) {
 //!         let _ = (dev, this);
 //!     }
 //! }
@@ -42,9 +46,9 @@
 )]
 #![cfg_attr(CONFIG_PCI, doc = "* [`pci::Driver`](kernel::pci::Driver)")]
 //!
-//! The `probe()` callback should return a `impl PinInit<Self, Error>`, i.e. the driver's private
-//! data. The bus abstraction should store the pointer in the corresponding bus device. The generic
-//! [`Device`] infrastructure provides common helpers for this purpose on its
+//! The `probe()` callback should return a `impl PinInit<Self::Data, Error>`, i.e. the driver's
+//! private data. The bus abstraction should store the pointer in the corresponding bus device. The
+//! generic [`Device`] infrastructure provides common helpers for this purpose on its
 //! [`Device<CoreInternal>`] implementation.
 //!
 //! All driver callbacks should provide a reference to the driver's private data. Once the driver
@@ -118,8 +122,8 @@ pub unsafe trait DriverLayout {
     /// The specific driver type embedding a `struct device_driver`.
     type DriverType: Default;
 
-    /// The type of the driver's device private data.
-    type DriverData;
+    /// The type of the driver's bus device private data.
+    type DriverData<'bound>;
 
     /// Byte offset of the embedded `struct device_driver` within `DriverType`.
     ///
@@ -193,8 +197,8 @@ extern "C" fn post_unbind_callback(dev: *mut bindings::device) {
         // driver's device private data.
         //
         // SAFETY: By the safety requirements of the `Driver` trait, `T::DriverData` is the
-        // driver's device private data type.
-        drop(unsafe { dev.drvdata_obtain::<T::DriverData>() });
+        // driver's bus device private data type.
+        drop(unsafe { dev.drvdata_obtain::<T::DriverData<'_>>() });
     }
 
     /// Attach generic `struct device_driver` callbacks.
diff --git a/rust/kernel/i2c.rs b/rust/kernel/i2c.rs
index 4ccee4ba4f23..5a4014f379d5 100644
--- a/rust/kernel/i2c.rs
+++ b/rust/kernel/i2c.rs
@@ -93,12 +93,12 @@ macro_rules! i2c_device_table {
 
 // SAFETY:
 // - `bindings::i2c_driver` is a C type declared as `repr(C)`.
-// - `T` is the type of the driver's device private data.
+// - `T::Data` is the type of the driver's device private data.
 // - `struct i2c_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::i2c_driver;
-    type DriverData = T;
+    type DriverData<'bound> = T::Data;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -176,8 +176,8 @@ extern "C" fn remove_callback(idev: *mut bindings::i2c_client) {
 
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `I2cClient::set_drvdata()` has been called
-        // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { idev.as_ref().drvdata_borrow::<T>() };
+        // and stored a `Pin<KBox<T::Data>>`.
+        let data = unsafe { idev.as_ref().drvdata_borrow::<T::Data>() };
 
         T::unbind(idev, data);
     }
@@ -188,8 +188,8 @@ extern "C" fn shutdown_callback(idev: *mut bindings::i2c_client) {
 
         // SAFETY: `shutdown_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
-        // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { idev.as_ref().drvdata_borrow::<T>() };
+        // and stored a `Pin<KBox<T::Data>>`.
+        let data = unsafe { idev.as_ref().drvdata_borrow::<T::Data>() };
 
         T::shutdown(idev, data);
     }
@@ -294,6 +294,7 @@ macro_rules! module_i2c_driver {
 ///
 /// impl i2c::Driver for MyDriver {
 ///     type IdInfo = ();
+///     type Data = Self;
 ///     const I2C_ID_TABLE: Option<i2c::IdTable<Self::IdInfo>> = Some(&I2C_TABLE);
 ///     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
 ///     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
@@ -301,11 +302,11 @@ macro_rules! module_i2c_driver {
 ///     fn probe(
 ///         _idev: &i2c::I2cClient<Core>,
 ///         _id_info: Option<&Self::IdInfo>,
-///     ) -> impl PinInit<Self, Error> {
+///     ) -> impl PinInit<Self::Data, Error> {
 ///         Err(ENODEV)
 ///     }
 ///
-///     fn shutdown(_idev: &i2c::I2cClient<Core>, this: Pin<&Self>) {
+///     fn shutdown(_idev: &i2c::I2cClient<Core>, this: Pin<&Self::Data>) {
 ///     }
 /// }
 ///```
@@ -318,6 +319,9 @@ pub trait Driver: Send {
     // ```
     type IdInfo: 'static;
 
+    /// The type of the driver's bus device private data.
+    type Data;
+
     /// The table of device ids supported by the driver.
     const I2C_ID_TABLE: Option<IdTable<Self::IdInfo>> = None;
 
@@ -334,7 +338,7 @@ pub trait Driver: Send {
     fn probe(
         dev: &I2cClient<device::Core>,
         id_info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self, Error>;
+    ) -> impl PinInit<Self::Data, Error>;
 
     /// I2C driver shutdown.
     ///
@@ -346,8 +350,8 @@ fn probe(
     ///
     /// This callback is distinct from final resource cleanup, as the driver instance remains valid
     /// after it returns. Any deallocation or teardown of driver-owned resources should instead be
-    /// handled in `Self::drop`.
-    fn shutdown(dev: &I2cClient<device::Core>, this: Pin<&Self>) {
+    /// handled in `Drop`.
+    fn shutdown(dev: &I2cClient<device::Core>, this: Pin<&Self::Data>) {
         let _ = (dev, this);
     }
 
@@ -360,8 +364,8 @@ fn shutdown(dev: &I2cClient<device::Core>, this: Pin<&Self>) {
     /// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O
     /// operations to gracefully tear down the device.
     ///
-    /// Otherwise, release operations for driver resources should be performed in `Self::drop`.
-    fn unbind(dev: &I2cClient<device::Core>, this: Pin<&Self>) {
+    /// Otherwise, release operations for driver resources should be performed in `Drop`.
+    fn unbind(dev: &I2cClient<device::Core>, this: Pin<&Self::Data>) {
         let _ = (dev, this);
     }
 }
diff --git a/rust/kernel/io/mem.rs b/rust/kernel/io/mem.rs
index 7dc78d547f7a..e136b676d372 100644
--- a/rust/kernel/io/mem.rs
+++ b/rust/kernel/io/mem.rs
@@ -62,6 +62,7 @@ pub(crate) unsafe fn new(device: &'a Device<Bound>, resource: &'a Resource) -> S
     ///
     /// impl platform::Driver for SampleDriver {
     ///    # type IdInfo = ();
+    ///    # type Data = Self;
     ///
     ///    fn probe(
     ///       pdev: &platform::Device<Core>,
@@ -126,6 +127,7 @@ pub fn iomap_exclusive_sized<const SIZE: usize>(
     ///
     /// impl platform::Driver for SampleDriver {
     ///    # type IdInfo = ();
+    ///    # type Data = Self;
     ///
     ///    fn probe(
     ///       pdev: &platform::Device<Core>,
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 17a33819dc0a..ffaf05bf9aaa 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -59,12 +59,12 @@
 
 // SAFETY:
 // - `bindings::pci_driver` is a C type declared as `repr(C)`.
-// - `T` is the type of the driver's device private data.
+// - `T::Data` is the type of the driver's device private data.
 // - `struct pci_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::pci_driver;
-    type DriverData = T;
+    type DriverData<'bound> = T::Data;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -129,8 +129,8 @@ extern "C" fn remove_callback(pdev: *mut bindings::pci_dev) {
 
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
-        // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { pdev.as_ref().drvdata_borrow::<T>() };
+        // and stored a `Pin<KBox<T::Data>>`.
+        let data = unsafe { pdev.as_ref().drvdata_borrow::<T::Data>() };
 
         T::unbind(pdev, data);
     }
@@ -279,6 +279,7 @@ macro_rules! pci_device_table {
 ///
 /// impl pci::Driver for MyDriver {
 ///     type IdInfo = ();
+///     type Data = Self;
 ///     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 ///
 ///     fn probe(
@@ -300,6 +301,9 @@ pub trait Driver: Send {
     // ```
     type IdInfo: 'static;
 
+    /// The type of the driver's bus device private data.
+    type Data;
+
     /// The table of device ids supported by the driver.
     const ID_TABLE: IdTable<Self::IdInfo>;
 
@@ -307,7 +311,8 @@ pub trait Driver: Send {
     ///
     /// Called when a new pci device is added or discovered. Implementers should
     /// attempt to initialize the device here.
-    fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo) -> impl PinInit<Self, Error>;
+    fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo)
+        -> impl PinInit<Self::Data, Error>;
 
     /// PCI driver unbind.
     ///
@@ -318,8 +323,8 @@ pub trait Driver: Send {
     /// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O
     /// operations to gracefully tear down the device.
     ///
-    /// Otherwise, release operations for driver resources should be performed in `Self::drop`.
-    fn unbind(dev: &Device<device::Core>, this: Pin<&Self>) {
+    /// Otherwise, release operations for driver resources should be performed in `Drop`.
+    fn unbind(dev: &Device<device::Core>, this: Pin<&Self::Data>) {
         let _ = (dev, this);
     }
 }
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index c7a3dcdde3b1..a74d2f6c8f02 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -45,12 +45,12 @@
 
 // SAFETY:
 // - `bindings::platform_driver` is a C type declared as `repr(C)`.
-// - `T` is the type of the driver's device private data.
+// - `T::Data` is the type of the driver's device private data.
 // - `struct platform_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::platform_driver;
-    type DriverData = T;
+    type DriverData<'bound> = T::Data;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -117,8 +117,8 @@ extern "C" fn remove_callback(pdev: *mut bindings::platform_device) {
 
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
-        // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { pdev.as_ref().drvdata_borrow::<T>() };
+        // and stored a `Pin<KBox<T::Data>>`.
+        let data = unsafe { pdev.as_ref().drvdata_borrow::<T::Data>() };
 
         T::unbind(pdev, data);
     }
@@ -192,6 +192,7 @@ macro_rules! module_platform_driver {
 ///
 /// impl platform::Driver for MyDriver {
 ///     type IdInfo = ();
+///     type Data = Self;
 ///     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
 ///     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
 ///
@@ -212,6 +213,9 @@ pub trait Driver: Send {
     // ```
     type IdInfo: 'static;
 
+    /// The type of the driver's bus device private data.
+    type Data;
+
     /// The table of OF device ids supported by the driver.
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
 
@@ -225,7 +229,7 @@ pub trait Driver: Send {
     fn probe(
         dev: &Device<device::Core>,
         id_info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self, Error>;
+    ) -> impl PinInit<Self::Data, Error>;
 
     /// Platform driver unbind.
     ///
@@ -236,8 +240,8 @@ fn probe(
     /// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O
     /// operations to gracefully tear down the device.
     ///
-    /// Otherwise, release operations for driver resources should be performed in `Self::drop`.
-    fn unbind(dev: &Device<device::Core>, this: Pin<&Self>) {
+    /// Otherwise, release operations for driver resources should be performed in `Drop`.
+    fn unbind(dev: &Device<device::Core>, this: Pin<&Self::Data>) {
         let _ = (dev, this);
     }
 }
diff --git a/rust/kernel/usb.rs b/rust/kernel/usb.rs
index 3f62da585281..794abe06f5bd 100644
--- a/rust/kernel/usb.rs
+++ b/rust/kernel/usb.rs
@@ -36,12 +36,12 @@
 
 // SAFETY:
 // - `bindings::usb_driver` is a C type declared as `repr(C)`.
-// - `T` is the type of the driver's device private data.
+// - `T::Data` is the type of the driver's device private data.
 // - `struct usb_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::usb_driver;
-    type DriverData = T;
+    type DriverData<'bound> = T::Data;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -109,8 +109,8 @@ extern "C" fn disconnect_callback(intf: *mut bindings::usb_interface) {
 
         // SAFETY: `disconnect_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
-        // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { dev.drvdata_borrow::<T>() };
+        // and stored a `Pin<KBox<T::Data>>`.
+        let data = unsafe { dev.drvdata_borrow::<T::Data>() };
 
         T::disconnect(intf, data);
     }
@@ -287,23 +287,27 @@ macro_rules! usb_device_table {
 ///
 /// impl usb::Driver for MyDriver {
 ///     type IdInfo = ();
+///     type Data = Self;
 ///     const ID_TABLE: usb::IdTable<Self::IdInfo> = &USB_TABLE;
 ///
 ///     fn probe(
 ///         _interface: &usb::Interface<Core>,
 ///         _id: &usb::DeviceId,
 ///         _info: &Self::IdInfo,
-///     ) -> impl PinInit<Self, Error> {
+///     ) -> impl PinInit<Self::Data, Error> {
 ///         Err(ENODEV)
 ///     }
 ///
-///     fn disconnect(_interface: &usb::Interface<Core>, _data: Pin<&Self>) {}
+///     fn disconnect(_interface: &usb::Interface<Core>, _data: Pin<&Self::Data>) {}
 /// }
 ///```
 pub trait Driver {
     /// The type holding information about each one of the device ids supported by the driver.
     type IdInfo: 'static;
 
+    /// The type of the driver's bus device private data.
+    type Data;
+
     /// The table of device ids supported by the driver.
     const ID_TABLE: IdTable<Self::IdInfo>;
 
@@ -315,12 +319,12 @@ fn probe(
         interface: &Interface<device::Core>,
         id: &DeviceId,
         id_info: &Self::IdInfo,
-    ) -> impl PinInit<Self, Error>;
+    ) -> impl PinInit<Self::Data, Error>;
 
     /// USB driver disconnect.
     ///
     /// Called when the USB interface is about to be unbound from this driver.
-    fn disconnect(interface: &Interface<device::Core>, data: Pin<&Self>);
+    fn disconnect(interface: &Interface<device::Core>, data: Pin<&Self::Data>);
 }
 
 /// A USB interface.
diff --git a/samples/rust/rust_debugfs.rs b/samples/rust/rust_debugfs.rs
index 0963efe19f93..478c4f693deb 100644
--- a/samples/rust/rust_debugfs.rs
+++ b/samples/rust/rust_debugfs.rs
@@ -117,6 +117,7 @@ fn from_str(s: &str) -> Result<Self> {
 
 impl platform::Driver for RustDebugFs {
     type IdInfo = ();
+    type Data = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
 
diff --git a/samples/rust/rust_dma.rs b/samples/rust/rust_dma.rs
index 129bb4b39c04..e583c6b8390a 100644
--- a/samples/rust/rust_dma.rs
+++ b/samples/rust/rust_dma.rs
@@ -58,6 +58,7 @@ unsafe impl kernel::transmute::FromBytes for MyStruct {}
 
 impl pci::Driver for DmaSampleDriver {
     type IdInfo = ();
+    type Data = Self;
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 
     fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
diff --git a/samples/rust/rust_driver_auxiliary.rs b/samples/rust/rust_driver_auxiliary.rs
index 319ef734c02b..61d5bf2e8c0d 100644
--- a/samples/rust/rust_driver_auxiliary.rs
+++ b/samples/rust/rust_driver_auxiliary.rs
@@ -31,6 +31,7 @@
 
 impl auxiliary::Driver for AuxiliaryDriver {
     type IdInfo = ();
+    type Data = Self;
 
     const ID_TABLE: auxiliary::IdTable<Self::IdInfo> = &AUX_TABLE;
 
@@ -65,6 +66,7 @@ struct ParentDriver {
 
 impl pci::Driver for ParentDriver {
     type IdInfo = ();
+    type Data = Self;
 
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 
diff --git a/samples/rust/rust_driver_i2c.rs b/samples/rust/rust_driver_i2c.rs
index 6be79f9e9fb5..8269f1798611 100644
--- a/samples/rust/rust_driver_i2c.rs
+++ b/samples/rust/rust_driver_i2c.rs
@@ -35,6 +35,7 @@
 
 impl i2c::Driver for SampleDriver {
     type IdInfo = u32;
+    type Data = Self;
 
     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
     const I2C_ID_TABLE: Option<i2c::IdTable<Self::IdInfo>> = Some(&I2C_TABLE);
diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs
index 47d3e84fab63..f43c6a660b39 100644
--- a/samples/rust/rust_driver_pci.rs
+++ b/samples/rust/rust_driver_pci.rs
@@ -140,6 +140,7 @@ fn config_space(pdev: &pci::Device<Bound>) {
 
 impl pci::Driver for SampleDriver {
     type IdInfo = TestIndex;
+    type Data = Self;
 
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 
diff --git a/samples/rust/rust_driver_platform.rs b/samples/rust/rust_driver_platform.rs
index f2229d176fb9..6505902f8200 100644
--- a/samples/rust/rust_driver_platform.rs
+++ b/samples/rust/rust_driver_platform.rs
@@ -101,6 +101,7 @@ struct SampleDriver {
 
 impl platform::Driver for SampleDriver {
     type IdInfo = Info;
+    type Data = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
 
diff --git a/samples/rust/rust_driver_usb.rs b/samples/rust/rust_driver_usb.rs
index ab72e99e1274..5942e4b01fd8 100644
--- a/samples/rust/rust_driver_usb.rs
+++ b/samples/rust/rust_driver_usb.rs
@@ -26,6 +26,7 @@ struct SampleDriver {
 
 impl usb::Driver for SampleDriver {
     type IdInfo = ();
+    type Data = Self;
     const ID_TABLE: usb::IdTable<Self::IdInfo> = &USB_TABLE;
 
     fn probe(
diff --git a/samples/rust/rust_i2c_client.rs b/samples/rust/rust_i2c_client.rs
index 8d2c12e535b0..5956b647294d 100644
--- a/samples/rust/rust_i2c_client.rs
+++ b/samples/rust/rust_i2c_client.rs
@@ -106,6 +106,7 @@ struct SampleDriver {
 
 impl platform::Driver for SampleDriver {
     type IdInfo = ();
+    type Data = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
 
diff --git a/samples/rust/rust_soc.rs b/samples/rust/rust_soc.rs
index 8079c1c48416..a5e72582f4a2 100644
--- a/samples/rust/rust_soc.rs
+++ b/samples/rust/rust_soc.rs
@@ -37,6 +37,7 @@ struct SampleSocDriver {
 
 impl platform::Driver for SampleSocDriver {
     type IdInfo = ();
+    type Data = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
 
-- 
2.54.0

[PATCH v3 04/27] rust: driver core: drop drvdata before devres release

[Danilo Krummrich]

Move the post_unbind_rust callback before devres_release_all() in
device_unbind_cleanup().

With drvdata() removed, the driver's bus device private data is only
accessible by the owning driver itself. It is hence safe to drop the
driver's bus device private data before devres actions are released.

This reordering is the key enabler for Higher-Ranked Lifetime Types
(HRT) in Rust device drivers -- it allows driver structs to hold direct
references to devres-managed resources, because the bus device private
data (and with it all such references) is guaranteed to be dropped while
the underlying devres resources are still alive.

Without this change, devres resources would be freed first, leaving the
driver's bus device private data with dangling references during its
destructor.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/base/dd.c             | 2 +-
 include/linux/device/driver.h | 4 ++--
 rust/kernel/driver.rs         | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 5799a60fd058..be59d2e13a15 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -593,9 +593,9 @@ static DEVICE_ATTR_RW(state_synced);
 
 static void device_unbind_cleanup(struct device *dev)
 {
-	devres_release_all(dev);
 	if (dev->driver->p_cb.post_unbind_rust)
 		dev->driver->p_cb.post_unbind_rust(dev);
+	devres_release_all(dev);
 	arch_teardown_dma_ops(dev);
 	kfree(dev->dma_range_map);
 	dev->dma_range_map = NULL;
diff --git a/include/linux/device/driver.h b/include/linux/device/driver.h
index bbc67ec513ed..38e9a4679447 100644
--- a/include/linux/device/driver.h
+++ b/include/linux/device/driver.h
@@ -123,8 +123,8 @@ struct device_driver {
 	struct driver_private *p;
 	struct {
 		/*
-		 * Called after remove() and after all devres entries have been
-		 * processed. This is a Rust only callback.
+		 * Called after remove() but before devres entries are released.
+		 * This is a Rust only callback.
 		 */
 		void (*post_unbind_rust)(struct device *dev);
 	} p_cb;
diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs
index 3506b4e8bff9..d8898f2115d5 100644
--- a/rust/kernel/driver.rs
+++ b/rust/kernel/driver.rs
@@ -193,8 +193,8 @@ extern "C" fn post_unbind_callback(dev: *mut bindings::device) {
         // INVARIANT: `dev` is valid for the duration of the `post_unbind_callback()`.
         let dev = unsafe { &*dev.cast::<device::Device<device::CoreInternal>>() };
 
-        // `remove()` and all devres callbacks have been completed at this point, hence drop the
-        // driver's device private data.
+        // `remove()` has been completed at this point; devres resources are still valid and will
+        // be released after the driver's bus device private data is dropped.
         //
         // SAFETY: By the safety requirements of the `Driver` trait, `T::DriverData` is the
         // driver's bus device private data type.
-- 
2.54.0

[PATCH v3 05/27] rust: pci: implement Sync for Device<Bound>

[Danilo Krummrich]

Implement Sync for Device<Bound> in addition to Device<Normal>.

Device<Bound> uses the same underlying struct pci_dev as Device<Normal>;
Bound is a zero-sized type-state marker that does not affect thread
safety.

This is needed for drivers to store &'bound pci::Device<Bound> in their
private data while remaining Send.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/pci.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index ffaf05bf9aaa..c06ac3fb2a64 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -528,3 +528,7 @@ unsafe impl Send for Device {}
 // SAFETY: `Device` can be shared among threads because all methods of `Device`
 // (i.e. `Device<Normal>) are thread safe.
 unsafe impl Sync for Device {}
+
+// SAFETY: Same as `Device<Normal>` -- the underlying `struct pci_dev` is the same;
+// `Bound` is a zero-sized type-state marker that does not affect thread safety.
+unsafe impl Sync for Device<device::Bound> {}
-- 
2.54.0

[PATCH v3 06/27] rust: platform: implement Sync for Device<Bound>

[Danilo Krummrich]

Implement Sync for Device<Bound> in addition to Device<Normal>.

Device<Bound> uses the same underlying struct platform_device as
Device<Normal>; Bound is a zero-sized type-state marker that does not
affect thread safety.

This is needed for drivers to store &'bound platform::Device<Bound> in
their private data while remaining Send.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/platform.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index a74d2f6c8f02..a72ad5366931 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -565,3 +565,7 @@ unsafe impl Send for Device {}
 // SAFETY: `Device` can be shared among threads because all methods of `Device`
 // (i.e. `Device<Normal>) are thread safe.
 unsafe impl Sync for Device {}
+
+// SAFETY: Same as `Device<Normal>` -- the underlying `struct platform_device` is the same;
+// `Bound` is a zero-sized type-state marker that does not affect thread safety.
+unsafe impl Sync for Device<device::Bound> {}
-- 
2.54.0

[PATCH v3 07/27] rust: auxiliary: implement Sync for Device<Bound>

[Danilo Krummrich]

Implement Sync for Device<Bound> in addition to Device<Normal>.

Device<Bound> uses the same underlying struct auxiliary_device as
Device<Normal>; Bound is a zero-sized type-state marker that does not
affect thread safety.

This is needed for drivers to store &'bound auxiliary::Device<Bound> in
their private data while remaining Send.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/auxiliary.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs
index 1b6ff3817a4d..c6d97c95c3e7 100644
--- a/rust/kernel/auxiliary.rs
+++ b/rust/kernel/auxiliary.rs
@@ -369,6 +369,10 @@ unsafe impl Send for Device {}
 // (i.e. `Device<Normal>) are thread safe.
 unsafe impl Sync for Device {}
 
+// SAFETY: Same as `Device<Normal>` -- the underlying `struct auxiliary_device` is the same;
+// `Bound` is a zero-sized type-state marker that does not affect thread safety.
+unsafe impl Sync for Device<device::Bound> {}
+
 /// Wrapper that stores a [`TypeId`] alongside the registration data for runtime type checking.
 #[repr(C)]
 #[pin_data]
-- 
2.54.0

[PATCH v3 08/27] rust: usb: implement Sync for Device<Bound>

[Danilo Krummrich]

Implement Sync for Device<Bound> in addition to Device<Normal>.

Device<Bound> uses the same underlying struct usb_device as
Device<Normal>; Bound is a zero-sized type-state marker that does not
affect thread safety.

This is needed for drivers to store &'bound usb::Device<Bound> in their
private data while remaining Send.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/usb.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/rust/kernel/usb.rs b/rust/kernel/usb.rs
index 794abe06f5bd..995221d327b8 100644
--- a/rust/kernel/usb.rs
+++ b/rust/kernel/usb.rs
@@ -468,6 +468,10 @@ unsafe impl Send for Device {}
 // allow any mutation through a shared reference.
 unsafe impl Sync for Device {}
 
+// SAFETY: Same as `Device<Normal>` -- the underlying `struct usb_device` is the same;
+// `Bound` is a zero-sized type-state marker that does not affect thread safety.
+unsafe impl Sync for Device<device::Bound> {}
+
 /// Declares a kernel module that exposes a single USB driver.
 ///
 /// # Examples
-- 
2.54.0

[PATCH v3 09/27] rust: device: implement Sync for Device<Bound>

[Danilo Krummrich]

Implement Sync for Device<Bound> in addition to Device<Normal>.

Device<Bound> uses the same underlying struct device as Device<Normal>;
Bound is a zero-sized type-state marker that does not affect thread
safety.

This is needed for types that hold &'bound Device<Bound>, such as
io::mem::IoMem, to be Send.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/device.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index 5df8fa108a52..c4486f4b8c40 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -467,6 +467,10 @@ unsafe impl Send for Device {}
 // synchronization in `struct device`.
 unsafe impl Sync for Device {}
 
+// SAFETY: Same as `Device<Normal>` -- the underlying `struct device` is the same; `Bound` is a
+// zero-sized type-state marker that does not affect thread safety.
+unsafe impl Sync for Device<Bound> {}
+
 /// Marker trait for the context or scope of a bus specific device.
 ///
 /// [`DeviceContext`] is a marker trait for types representing the context of a bus specific
-- 
2.54.0

[PATCH v3 10/27] rust: pci: make Driver trait lifetime-parameterized

[Danilo Krummrich]

Add a 'bound lifetime to the associated Data, changing type Data to type
Data<'bound>.

This allows the driver's bus device private data to capture the device /
driver bound lifetime; device resources can be stored directly by
reference rather than requiring Devres.

The probe() and unbind() callbacks thus gain a 'bound lifetime parameter
on the methods themselves; avoiding a global lifetime on the trait impl.

Existing drivers set type Data<'bound> = Self, preserving the current
behavior.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/nova-core/driver.rs       |  9 ++++++---
 rust/kernel/pci.rs                    | 24 +++++++++++++-----------
 samples/rust/rust_dma.rs              |  7 +++++--
 samples/rust/rust_driver_auxiliary.rs |  7 +++++--
 samples/rust/rust_driver_pci.rs       |  7 +++++--
 5 files changed, 34 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index 699e27046c93..fe4eafe1ebf0 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -74,10 +74,13 @@ pub(crate) struct NovaCore {
 
 impl pci::Driver for NovaCore {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 
-    fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound pci::Device<Core>,
+        _info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self, Error> + 'bound {
         pin_init::pin_init_scope(move || {
             dev_dbg!(pdev, "Probe Nova Core GPU driver.\n");
 
@@ -109,7 +112,7 @@ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, E
         })
     }
 
-    fn unbind(pdev: &pci::Device<Core>, this: Pin<&Self>) {
+    fn unbind<'bound>(pdev: &'bound pci::Device<Core>, this: Pin<&'bound Self>) {
         this.gpu.unbind(pdev.as_ref());
     }
 }
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index c06ac3fb2a64..8060861199d4 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -64,7 +64,7 @@
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::pci_driver;
-    type DriverData<'bound> = T::Data;
+    type DriverData<'bound> = T::Data<'bound>;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -130,7 +130,7 @@ extern "C" fn remove_callback(pdev: *mut bindings::pci_dev) {
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
         // and stored a `Pin<KBox<T::Data>>`.
-        let data = unsafe { pdev.as_ref().drvdata_borrow::<T::Data>() };
+        let data = unsafe { pdev.as_ref().drvdata_borrow::<T::Data<'_>>() };
 
         T::unbind(pdev, data);
     }
@@ -279,13 +279,13 @@ macro_rules! pci_device_table {
 ///
 /// impl pci::Driver for MyDriver {
 ///     type IdInfo = ();
-///     type Data = Self;
+///     type Data<'bound> = Self;
 ///     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 ///
-///     fn probe(
-///         _pdev: &pci::Device<Core>,
-///         _id_info: &Self::IdInfo,
-///     ) -> impl PinInit<Self, Error> {
+///     fn probe<'bound>(
+///         _pdev: &'bound pci::Device<Core>,
+///         _id_info: &'bound Self::IdInfo,
+///     ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound {
 ///         Err(ENODEV)
 ///     }
 /// }
@@ -302,7 +302,7 @@ pub trait Driver: Send {
     type IdInfo: 'static;
 
     /// The type of the driver's bus device private data.
-    type Data;
+    type Data<'bound>: 'bound;
 
     /// The table of device ids supported by the driver.
     const ID_TABLE: IdTable<Self::IdInfo>;
@@ -311,8 +311,10 @@ pub trait Driver: Send {
     ///
     /// Called when a new pci device is added or discovered. Implementers should
     /// attempt to initialize the device here.
-    fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo)
-        -> impl PinInit<Self::Data, Error>;
+    fn probe<'bound>(
+        dev: &'bound Device<device::Core>,
+        id_info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound;
 
     /// PCI driver unbind.
     ///
@@ -324,7 +326,7 @@ fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo)
     /// operations to gracefully tear down the device.
     ///
     /// Otherwise, release operations for driver resources should be performed in `Drop`.
-    fn unbind(dev: &Device<device::Core>, this: Pin<&Self::Data>) {
+    fn unbind<'bound>(dev: &'bound Device<device::Core>, this: Pin<&'bound Self::Data<'bound>>) {
         let _ = (dev, this);
     }
 }
diff --git a/samples/rust/rust_dma.rs b/samples/rust/rust_dma.rs
index e583c6b8390a..943655a85ec6 100644
--- a/samples/rust/rust_dma.rs
+++ b/samples/rust/rust_dma.rs
@@ -58,10 +58,13 @@ unsafe impl kernel::transmute::FromBytes for MyStruct {}
 
 impl pci::Driver for DmaSampleDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 
-    fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound pci::Device<Core>,
+        _info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self, Error> + 'bound {
         pin_init::pin_init_scope(move || {
             dev_info!(pdev, "Probe DMA test driver.\n");
 
diff --git a/samples/rust/rust_driver_auxiliary.rs b/samples/rust/rust_driver_auxiliary.rs
index 61d5bf2e8c0d..2f57912fe87f 100644
--- a/samples/rust/rust_driver_auxiliary.rs
+++ b/samples/rust/rust_driver_auxiliary.rs
@@ -66,11 +66,14 @@ struct ParentDriver {
 
 impl pci::Driver for ParentDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
 
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 
-    fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound pci::Device<Core>,
+        _info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self, Error> + 'bound {
         Ok(Self {
             _reg0: auxiliary::Registration::new(
                 pdev.as_ref(),
diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs
index f43c6a660b39..30b9311812f3 100644
--- a/samples/rust/rust_driver_pci.rs
+++ b/samples/rust/rust_driver_pci.rs
@@ -140,11 +140,14 @@ fn config_space(pdev: &pci::Device<Bound>) {
 
 impl pci::Driver for SampleDriver {
     type IdInfo = TestIndex;
-    type Data = Self;
+    type Data<'bound> = Self;
 
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 
-    fn probe(pdev: &pci::Device<Core>, info: &Self::IdInfo) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound pci::Device<Core>,
+        info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self, Error> + 'bound {
         pin_init::pin_init_scope(move || {
             let vendor = pdev.vendor_id();
             dev_dbg!(
-- 
2.54.0

[PATCH v3 11/27] rust: platform: make Driver trait lifetime-parameterized

[Danilo Krummrich]

Add a 'bound lifetime to the associated Data, changing type Data to type
Data<'bound>.

This allows the driver's bus device private data to capture the device /
driver bound lifetime; device resources can be stored directly by
reference rather than requiring Devres.

The probe() and unbind() callbacks thus gain a 'bound lifetime parameter
on the methods themselves; avoiding a global lifetime on the trait impl.

Existing drivers set type Data<'bound> = Self, preserving the current
behavior.

Acked-by: Uwe Kleine-König <ukleinek@kernel.org>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/cpufreq/rcpufreq_dt.rs       | 10 +++++-----
 drivers/gpu/drm/tyr/driver.rs        | 10 +++++-----
 drivers/pwm/pwm_th1520.rs            | 10 +++++-----
 rust/kernel/cpufreq.rs               | 10 +++++-----
 rust/kernel/io/mem.rs                | 20 ++++++++++----------
 rust/kernel/platform.rs              | 26 +++++++++++++-------------
 samples/rust/rust_debugfs.rs         | 10 +++++-----
 samples/rust/rust_driver_platform.rs | 10 +++++-----
 samples/rust/rust_i2c_client.rs      | 15 +++++++++------
 samples/rust/rust_soc.rs             | 10 +++++-----
 10 files changed, 67 insertions(+), 64 deletions(-)

diff --git a/drivers/cpufreq/rcpufreq_dt.rs b/drivers/cpufreq/rcpufreq_dt.rs
index b7eeb2730eb0..bd64586ceb06 100644
--- a/drivers/cpufreq/rcpufreq_dt.rs
+++ b/drivers/cpufreq/rcpufreq_dt.rs
@@ -201,13 +201,13 @@ fn register_em(policy: &mut cpufreq::Policy) {
 
 impl platform::Driver for CPUFreqDTDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
 
-    fn probe(
-        pdev: &platform::Device<Core>,
-        _id_info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound platform::Device<Core>,
+        _id_info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> + 'bound {
         cpufreq::Registration::<CPUFreqDTDriver>::new_foreign_owned(pdev.as_ref())?;
         Ok(Self {})
     }
diff --git a/drivers/gpu/drm/tyr/driver.rs b/drivers/gpu/drm/tyr/driver.rs
index c81bf217743d..3ac3b9979264 100644
--- a/drivers/gpu/drm/tyr/driver.rs
+++ b/drivers/gpu/drm/tyr/driver.rs
@@ -91,13 +91,13 @@ fn issue_soft_reset(dev: &Device<Bound>, iomem: &Devres<IoMem>) -> Result {
 
 impl platform::Driver for TyrPlatformDriverData {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
 
-    fn probe(
-        pdev: &platform::Device<Core>,
-        _info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound platform::Device<Core>,
+        _info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> + 'bound {
         let core_clk = Clk::get(pdev.as_ref(), Some(c"core"))?;
         let stacks_clk = OptionalClk::get(pdev.as_ref(), Some(c"stacks"))?;
         let coregroup_clk = OptionalClk::get(pdev.as_ref(), Some(c"coregroup"))?;
diff --git a/drivers/pwm/pwm_th1520.rs b/drivers/pwm/pwm_th1520.rs
index 07795910a0b5..1abf580653fa 100644
--- a/drivers/pwm/pwm_th1520.rs
+++ b/drivers/pwm/pwm_th1520.rs
@@ -316,13 +316,13 @@ fn drop(self: Pin<&mut Self>) {
 
 impl platform::Driver for Th1520PwmPlatformDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
 
-    fn probe(
-        pdev: &platform::Device<Core>,
-        _id_info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound platform::Device<Core>,
+        _id_info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> + 'bound {
         let dev = pdev.as_ref();
         let request = pdev.io_request_by_index(0).ok_or(ENODEV)?;
 
diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 50dd2a2c3e81..208c055a39f3 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -888,13 +888,13 @@ fn register_em(_policy: &mut Policy) {
 ///
 /// impl platform::Driver for SampleDriver {
 ///     type IdInfo = ();
-///     type Data = Self;
+///     type Data<'bound> = Self;
 ///     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
 ///
-///     fn probe(
-///         pdev: &platform::Device<Core>,
-///         _id_info: Option<&Self::IdInfo>,
-///     ) -> impl PinInit<Self, Error> {
+///     fn probe<'bound>(
+///         pdev: &'bound platform::Device<Core>,
+///         _id_info: Option<&'bound Self::IdInfo>,
+///     ) -> impl PinInit<Self, Error> + 'bound {
 ///         cpufreq::Registration::<SampleDriver>::new_foreign_owned(pdev.as_ref())?;
 ///         Ok(Self {})
 ///     }
diff --git a/rust/kernel/io/mem.rs b/rust/kernel/io/mem.rs
index e136b676d372..1b34f7ebd929 100644
--- a/rust/kernel/io/mem.rs
+++ b/rust/kernel/io/mem.rs
@@ -62,12 +62,12 @@ pub(crate) unsafe fn new(device: &'a Device<Bound>, resource: &'a Resource) -> S
     ///
     /// impl platform::Driver for SampleDriver {
     ///    # type IdInfo = ();
-    ///    # type Data = Self;
+    ///    # type Data<'bound> = Self;
     ///
-    ///    fn probe(
-    ///       pdev: &platform::Device<Core>,
-    ///       info: Option<&Self::IdInfo>,
-    ///    ) -> impl PinInit<Self, Error> {
+    ///    fn probe<'bound>(
+    ///       pdev: &'bound platform::Device<Core>,
+    ///       info: Option<&'bound Self::IdInfo>,
+    ///    ) -> impl PinInit<Self, Error> + 'bound {
     ///       let offset = 0; // Some offset.
     ///
     ///       // If the size is known at compile time, use [`Self::iomap_sized`].
@@ -127,12 +127,12 @@ pub fn iomap_exclusive_sized<const SIZE: usize>(
     ///
     /// impl platform::Driver for SampleDriver {
     ///    # type IdInfo = ();
-    ///    # type Data = Self;
+    ///    # type Data<'bound> = Self;
     ///
-    ///    fn probe(
-    ///       pdev: &platform::Device<Core>,
-    ///       info: Option<&Self::IdInfo>,
-    ///    ) -> impl PinInit<Self, Error> {
+    ///    fn probe<'bound>(
+    ///       pdev: &'bound platform::Device<Core>,
+    ///       info: Option<&'bound Self::IdInfo>,
+    ///    ) -> impl PinInit<Self, Error> + 'bound {
     ///       let offset = 0; // Some offset.
     ///
     ///       // Unlike [`Self::iomap_sized`], here the size of the memory region
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index a72ad5366931..6e4437866c30 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -50,7 +50,7 @@
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::platform_driver;
-    type DriverData<'bound> = T::Data;
+    type DriverData<'bound> = T::Data<'bound>;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -118,7 +118,7 @@ extern "C" fn remove_callback(pdev: *mut bindings::platform_device) {
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
         // and stored a `Pin<KBox<T::Data>>`.
-        let data = unsafe { pdev.as_ref().drvdata_borrow::<T::Data>() };
+        let data = unsafe { pdev.as_ref().drvdata_borrow::<T::Data<'_>>() };
 
         T::unbind(pdev, data);
     }
@@ -192,14 +192,14 @@ macro_rules! module_platform_driver {
 ///
 /// impl platform::Driver for MyDriver {
 ///     type IdInfo = ();
-///     type Data = Self;
+///     type Data<'bound> = Self;
 ///     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(
-///         _pdev: &platform::Device<Core>,
-///         _id_info: Option<&Self::IdInfo>,
-///     ) -> impl PinInit<Self, Error> {
+///     fn probe<'bound>(
+///         _pdev: &'bound platform::Device<Core>,
+///         _id_info: Option<&'bound Self::IdInfo>,
+///     ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound {
 ///         Err(ENODEV)
 ///     }
 /// }
@@ -214,7 +214,7 @@ pub trait Driver: Send {
     type IdInfo: 'static;
 
     /// The type of the driver's bus device private data.
-    type Data;
+    type Data<'bound>: 'bound;
 
     /// The table of OF device ids supported by the driver.
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
@@ -226,10 +226,10 @@ pub trait Driver: Send {
     ///
     /// Called when a new platform device is added or discovered.
     /// Implementers should attempt to initialize the device here.
-    fn probe(
-        dev: &Device<device::Core>,
-        id_info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self::Data, Error>;
+    fn probe<'bound>(
+        dev: &'bound Device<device::Core>,
+        id_info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound;
 
     /// Platform driver unbind.
     ///
@@ -241,7 +241,7 @@ fn probe(
     /// operations to gracefully tear down the device.
     ///
     /// Otherwise, release operations for driver resources should be performed in `Drop`.
-    fn unbind(dev: &Device<device::Core>, this: Pin<&Self::Data>) {
+    fn unbind<'bound>(dev: &'bound Device<device::Core>, this: Pin<&'bound Self::Data<'bound>>) {
         let _ = (dev, this);
     }
 }
diff --git a/samples/rust/rust_debugfs.rs b/samples/rust/rust_debugfs.rs
index 478c4f693deb..5f02f2ad88b6 100644
--- a/samples/rust/rust_debugfs.rs
+++ b/samples/rust/rust_debugfs.rs
@@ -117,14 +117,14 @@ fn from_str(s: &str) -> Result<Self> {
 
 impl platform::Driver for RustDebugFs {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
 
-    fn probe(
-        pdev: &platform::Device<Core>,
-        _info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound platform::Device<Core>,
+        _info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> + 'bound {
         RustDebugFs::new(pdev).pin_chain(|this| {
             this.counter.store(91, Relaxed);
             {
diff --git a/samples/rust/rust_driver_platform.rs b/samples/rust/rust_driver_platform.rs
index 6505902f8200..0760d60b7737 100644
--- a/samples/rust/rust_driver_platform.rs
+++ b/samples/rust/rust_driver_platform.rs
@@ -101,14 +101,14 @@ struct SampleDriver {
 
 impl platform::Driver for SampleDriver {
     type IdInfo = Info;
-    type Data = Self;
+    type Data<'bound> = Self;
     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(
-        pdev: &platform::Device<Core>,
-        info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound platform::Device<Core>,
+        info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> + 'bound {
         let dev = pdev.as_ref();
 
         dev_dbg!(dev, "Probe Rust Platform driver sample.\n");
diff --git a/samples/rust/rust_i2c_client.rs b/samples/rust/rust_i2c_client.rs
index 5956b647294d..3ac4008a2eaa 100644
--- a/samples/rust/rust_i2c_client.rs
+++ b/samples/rust/rust_i2c_client.rs
@@ -106,14 +106,14 @@ struct SampleDriver {
 
 impl platform::Driver for SampleDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     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(
-        pdev: &platform::Device<device::Core>,
-        _info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound platform::Device<device::Core>,
+        _info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> + 'bound {
         dev_info!(
             pdev.as_ref(),
             "Probe Rust I2C Client registration sample.\n"
@@ -130,7 +130,10 @@ fn probe(
         })
     }
 
-    fn unbind(pdev: &platform::Device<device::Core>, _this: Pin<&Self>) {
+    fn unbind<'bound>(
+        pdev: &'bound platform::Device<device::Core>,
+        _this: Pin<&'bound Self::Data<'bound>>,
+    ) {
         dev_info!(
             pdev.as_ref(),
             "Unbind Rust I2C Client registration sample.\n"
diff --git a/samples/rust/rust_soc.rs b/samples/rust/rust_soc.rs
index a5e72582f4a2..2dfcb2131e25 100644
--- a/samples/rust/rust_soc.rs
+++ b/samples/rust/rust_soc.rs
@@ -37,14 +37,14 @@ struct SampleSocDriver {
 
 impl platform::Driver for SampleSocDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     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(
-        pdev: &platform::Device<Core>,
-        _info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        pdev: &'bound platform::Device<Core>,
+        _info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> + 'bound {
         dev_dbg!(pdev, "Probe Rust SoC driver sample.\n");
 
         let pdev = pdev.into();
-- 
2.54.0

[PATCH v3 12/27] rust: auxiliary: make Driver trait lifetime-parameterized

[Danilo Krummrich]

Add a 'bound lifetime to the associated Data, changing type Data to type
Data<'bound>.

This allows the driver's bus device private data to capture the device /
driver bound lifetime; device resources can be stored directly by
reference rather than requiring Devres.

The probe() and unbind() callbacks thus gain a 'bound lifetime parameter
on the methods themselves; avoiding a global lifetime on the trait impl.

Existing drivers set type Data<'bound> = Self, preserving the current
behavior.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/drm/nova/driver.rs        |  7 +++++--
 rust/kernel/auxiliary.rs              | 14 ++++++++------
 samples/rust/rust_driver_auxiliary.rs |  7 +++++--
 3 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/nova/driver.rs b/drivers/gpu/drm/nova/driver.rs
index 08136ec0bccb..1d73c595dda4 100644
--- a/drivers/gpu/drm/nova/driver.rs
+++ b/drivers/gpu/drm/nova/driver.rs
@@ -51,10 +51,13 @@ pub(crate) struct NovaData {
 
 impl auxiliary::Driver for NovaDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     const ID_TABLE: auxiliary::IdTable<Self::IdInfo> = &AUX_TABLE;
 
-    fn probe(adev: &auxiliary::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        adev: &'bound auxiliary::Device<Core>,
+        _info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self, Error> + 'bound {
         let data = try_pin_init!(NovaData { adev: adev.into() });
 
         let drm = drm::Device::<Self>::new(adev.as_ref(), data)?;
diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs
index c6d97c95c3e7..3f1e2966c03a 100644
--- a/rust/kernel/auxiliary.rs
+++ b/rust/kernel/auxiliary.rs
@@ -46,7 +46,7 @@
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::auxiliary_driver;
-    type DriverData<'bound> = T::Data;
+    type DriverData<'bound> = T::Data<'bound>;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -112,7 +112,7 @@ extern "C" fn remove_callback(adev: *mut bindings::auxiliary_device) {
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
         // and stored a `Pin<KBox<T::Data>>`.
-        let data = unsafe { adev.as_ref().drvdata_borrow::<T::Data>() };
+        let data = unsafe { adev.as_ref().drvdata_borrow::<T::Data<'_>>() };
 
         T::unbind(adev, data);
     }
@@ -203,7 +203,7 @@ pub trait Driver {
     type IdInfo: 'static;
 
     /// The type of the driver's bus device private data.
-    type Data;
+    type Data<'bound>: 'bound;
 
     /// The table of device ids supported by the driver.
     const ID_TABLE: IdTable<Self::IdInfo>;
@@ -211,8 +211,10 @@ pub trait Driver {
     /// Auxiliary driver probe.
     ///
     /// Called when an auxiliary device is matches a corresponding driver.
-    fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo)
-        -> impl PinInit<Self::Data, Error>;
+    fn probe<'bound>(
+        dev: &'bound Device<device::Core>,
+        id_info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound;
 
     /// Auxiliary driver unbind.
     ///
@@ -224,7 +226,7 @@ fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo)
     /// operations to gracefully tear down the device.
     ///
     /// Otherwise, release operations for driver resources should be performed in `Drop`.
-    fn unbind(dev: &Device<device::Core>, this: Pin<&Self::Data>) {
+    fn unbind<'bound>(dev: &'bound Device<device::Core>, this: Pin<&'bound Self::Data<'bound>>) {
         let _ = (dev, this);
     }
 }
diff --git a/samples/rust/rust_driver_auxiliary.rs b/samples/rust/rust_driver_auxiliary.rs
index 2f57912fe87f..972a3d5b25e7 100644
--- a/samples/rust/rust_driver_auxiliary.rs
+++ b/samples/rust/rust_driver_auxiliary.rs
@@ -31,11 +31,14 @@
 
 impl auxiliary::Driver for AuxiliaryDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
 
     const ID_TABLE: auxiliary::IdTable<Self::IdInfo> = &AUX_TABLE;
 
-    fn probe(adev: &auxiliary::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        adev: &'bound auxiliary::Device<Core>,
+        _info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self, Error> + 'bound {
         dev_info!(
             adev,
             "Probing auxiliary driver for auxiliary device with id={}\n",
-- 
2.54.0

[PATCH v3 13/27] rust: usb: make Driver trait lifetime-parameterized

[Danilo Krummrich]

Add a 'bound lifetime to the associated Data, changing type Data to type
Data<'bound>.

This allows the driver's bus device private data to capture the device /
driver bound lifetime; device resources can be stored directly by
reference rather than requiring Devres.

The probe() and unbind() callbacks thus gain a 'bound lifetime parameter
on the methods themselves; avoiding a global lifetime on the trait impl.

Existing drivers set type Data<'bound> = Self, preserving the current
behavior.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/usb.rs              | 39 +++++++++++++++++++--------------
 samples/rust/rust_driver_usb.rs | 14 ++++++------
 2 files changed, 30 insertions(+), 23 deletions(-)

diff --git a/rust/kernel/usb.rs b/rust/kernel/usb.rs
index 995221d327b8..ec67e4d2416f 100644
--- a/rust/kernel/usb.rs
+++ b/rust/kernel/usb.rs
@@ -41,7 +41,7 @@
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::usb_driver;
-    type DriverData<'bound> = T::Data;
+    type DriverData<'bound> = T::Data<'bound>;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -110,7 +110,7 @@ extern "C" fn disconnect_callback(intf: *mut bindings::usb_interface) {
         // SAFETY: `disconnect_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
         // and stored a `Pin<KBox<T::Data>>`.
-        let data = unsafe { dev.drvdata_borrow::<T::Data>() };
+        let data = unsafe { dev.drvdata_borrow::<T::Data<'_>>() };
 
         T::disconnect(intf, data);
     }
@@ -287,18 +287,22 @@ macro_rules! usb_device_table {
 ///
 /// impl usb::Driver for MyDriver {
 ///     type IdInfo = ();
-///     type Data = Self;
+///     type Data<'bound> = Self;
 ///     const ID_TABLE: usb::IdTable<Self::IdInfo> = &USB_TABLE;
 ///
-///     fn probe(
-///         _interface: &usb::Interface<Core>,
-///         _id: &usb::DeviceId,
-///         _info: &Self::IdInfo,
-///     ) -> impl PinInit<Self::Data, Error> {
+///     fn probe<'bound>(
+///         _interface: &'bound usb::Interface<Core>,
+///         _id: &'bound usb::DeviceId,
+///         _info: &'bound Self::IdInfo,
+///     ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound {
 ///         Err(ENODEV)
 ///     }
 ///
-///     fn disconnect(_interface: &usb::Interface<Core>, _data: Pin<&Self::Data>) {}
+///     fn disconnect<'bound>(
+///         _interface: &'bound usb::Interface<Core>,
+///         _data: Pin<&'bound Self::Data<'bound>>,
+///     ) {
+///     }
 /// }
 ///```
 pub trait Driver {
@@ -306,7 +310,7 @@ pub trait Driver {
     type IdInfo: 'static;
 
     /// The type of the driver's bus device private data.
-    type Data;
+    type Data<'bound>: 'bound;
 
     /// The table of device ids supported by the driver.
     const ID_TABLE: IdTable<Self::IdInfo>;
@@ -315,16 +319,19 @@ pub trait Driver {
     ///
     /// Called when a new USB interface is bound to this driver.
     /// Implementers should attempt to initialize the interface here.
-    fn probe(
-        interface: &Interface<device::Core>,
-        id: &DeviceId,
-        id_info: &Self::IdInfo,
-    ) -> impl PinInit<Self::Data, Error>;
+    fn probe<'bound>(
+        interface: &'bound Interface<device::Core>,
+        id: &'bound DeviceId,
+        id_info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound;
 
     /// USB driver disconnect.
     ///
     /// Called when the USB interface is about to be unbound from this driver.
-    fn disconnect(interface: &Interface<device::Core>, data: Pin<&Self::Data>);
+    fn disconnect<'bound>(
+        interface: &'bound Interface<device::Core>,
+        data: Pin<&'bound Self::Data<'bound>>,
+    );
 }
 
 /// A USB interface.
diff --git a/samples/rust/rust_driver_usb.rs b/samples/rust/rust_driver_usb.rs
index 5942e4b01fd8..4403bd758db9 100644
--- a/samples/rust/rust_driver_usb.rs
+++ b/samples/rust/rust_driver_usb.rs
@@ -26,21 +26,21 @@ struct SampleDriver {
 
 impl usb::Driver for SampleDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     const ID_TABLE: usb::IdTable<Self::IdInfo> = &USB_TABLE;
 
-    fn probe(
-        intf: &usb::Interface<Core>,
-        _id: &usb::DeviceId,
-        _info: &Self::IdInfo,
-    ) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        intf: &'bound usb::Interface<Core>,
+        _id: &'bound usb::DeviceId,
+        _info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self, Error> + 'bound {
         let dev: &device::Device<Core> = intf.as_ref();
         dev_info!(dev, "Rust USB driver sample probed\n");
 
         Ok(Self { _intf: intf.into() })
     }
 
-    fn disconnect(intf: &usb::Interface<Core>, _data: Pin<&Self>) {
+    fn disconnect<'bound>(intf: &'bound usb::Interface<Core>, _data: Pin<&'bound Self>) {
         let dev: &device::Device<Core> = intf.as_ref();
         dev_info!(dev, "Rust USB driver sample disconnected\n");
     }
-- 
2.54.0

[PATCH v3 14/27] rust: i2c: make Driver trait lifetime-parameterized

[Danilo Krummrich]

Add a 'bound lifetime to the associated Data, changing type Data to type
Data<'bound>.

This allows the driver's bus device private data to capture the device /
driver bound lifetime; device resources can be stored directly by
reference rather than requiring Devres.

The probe() and unbind() callbacks thus gain a 'bound lifetime parameter
on the methods themselves; avoiding a global lifetime on the trait impl.

Existing drivers set type Data<'bound> = Self, preserving the current
behavior.

Acked-by: Igor Korotin <igor.korotin@linux.dev>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/i2c.rs              | 38 +++++++++++++++++++--------------
 samples/rust/rust_driver_i2c.rs | 14 ++++++------
 2 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/rust/kernel/i2c.rs b/rust/kernel/i2c.rs
index 5a4014f379d5..7b92d42a2b98 100644
--- a/rust/kernel/i2c.rs
+++ b/rust/kernel/i2c.rs
@@ -98,7 +98,7 @@ macro_rules! i2c_device_table {
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::i2c_driver;
-    type DriverData<'bound> = T::Data;
+    type DriverData<'bound> = T::Data<'bound>;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -177,7 +177,7 @@ extern "C" fn remove_callback(idev: *mut bindings::i2c_client) {
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `I2cClient::set_drvdata()` has been called
         // and stored a `Pin<KBox<T::Data>>`.
-        let data = unsafe { idev.as_ref().drvdata_borrow::<T::Data>() };
+        let data = unsafe { idev.as_ref().drvdata_borrow::<T::Data<'_>>() };
 
         T::unbind(idev, data);
     }
@@ -189,7 +189,7 @@ extern "C" fn shutdown_callback(idev: *mut bindings::i2c_client) {
         // SAFETY: `shutdown_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
         // and stored a `Pin<KBox<T::Data>>`.
-        let data = unsafe { idev.as_ref().drvdata_borrow::<T::Data>() };
+        let data = unsafe { idev.as_ref().drvdata_borrow::<T::Data<'_>>() };
 
         T::shutdown(idev, data);
     }
@@ -294,19 +294,22 @@ macro_rules! module_i2c_driver {
 ///
 /// impl i2c::Driver for MyDriver {
 ///     type IdInfo = ();
-///     type Data = Self;
+///     type Data<'bound> = Self;
 ///     const I2C_ID_TABLE: Option<i2c::IdTable<Self::IdInfo>> = Some(&I2C_TABLE);
 ///     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(
-///         _idev: &i2c::I2cClient<Core>,
-///         _id_info: Option<&Self::IdInfo>,
-///     ) -> impl PinInit<Self::Data, Error> {
+///     fn probe<'bound>(
+///         _idev: &'bound i2c::I2cClient<Core>,
+///         _id_info: Option<&'bound Self::IdInfo>,
+///     ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound {
 ///         Err(ENODEV)
 ///     }
 ///
-///     fn shutdown(_idev: &i2c::I2cClient<Core>, this: Pin<&Self::Data>) {
+///     fn shutdown<'bound>(
+///         _idev: &'bound i2c::I2cClient<Core>,
+///         this: Pin<&'bound Self::Data<'bound>>,
+///     ) {
 ///     }
 /// }
 ///```
@@ -320,7 +323,7 @@ pub trait Driver: Send {
     type IdInfo: 'static;
 
     /// The type of the driver's bus device private data.
-    type Data;
+    type Data<'bound>: 'bound;
 
     /// The table of device ids supported by the driver.
     const I2C_ID_TABLE: Option<IdTable<Self::IdInfo>> = None;
@@ -335,10 +338,10 @@ pub trait Driver: Send {
     ///
     /// Called when a new i2c client is added or discovered.
     /// Implementers should attempt to initialize the client here.
-    fn probe(
-        dev: &I2cClient<device::Core>,
-        id_info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self::Data, Error>;
+    fn probe<'bound>(
+        dev: &'bound I2cClient<device::Core>,
+        id_info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound;
 
     /// I2C driver shutdown.
     ///
@@ -351,7 +354,10 @@ fn probe(
     /// This callback is distinct from final resource cleanup, as the driver instance remains valid
     /// after it returns. Any deallocation or teardown of driver-owned resources should instead be
     /// handled in `Drop`.
-    fn shutdown(dev: &I2cClient<device::Core>, this: Pin<&Self::Data>) {
+    fn shutdown<'bound>(
+        dev: &'bound I2cClient<device::Core>,
+        this: Pin<&'bound Self::Data<'bound>>,
+    ) {
         let _ = (dev, this);
     }
 
@@ -365,7 +371,7 @@ fn shutdown(dev: &I2cClient<device::Core>, this: Pin<&Self::Data>) {
     /// operations to gracefully tear down the device.
     ///
     /// Otherwise, release operations for driver resources should be performed in `Drop`.
-    fn unbind(dev: &I2cClient<device::Core>, this: Pin<&Self::Data>) {
+    fn unbind<'bound>(dev: &'bound I2cClient<device::Core>, this: Pin<&'bound Self::Data<'bound>>) {
         let _ = (dev, this);
     }
 }
diff --git a/samples/rust/rust_driver_i2c.rs b/samples/rust/rust_driver_i2c.rs
index 8269f1798611..6fa3b786d652 100644
--- a/samples/rust/rust_driver_i2c.rs
+++ b/samples/rust/rust_driver_i2c.rs
@@ -35,16 +35,16 @@
 
 impl i2c::Driver for SampleDriver {
     type IdInfo = u32;
-    type Data = Self;
+    type Data<'bound> = Self;
 
     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
     const I2C_ID_TABLE: Option<i2c::IdTable<Self::IdInfo>> = Some(&I2C_TABLE);
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
 
-    fn probe(
-        idev: &i2c::I2cClient<Core>,
-        info: Option<&Self::IdInfo>,
-    ) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        idev: &'bound i2c::I2cClient<Core>,
+        info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> + 'bound {
         let dev = idev.as_ref();
 
         dev_info!(dev, "Probe Rust I2C driver sample.\n");
@@ -56,11 +56,11 @@ fn probe(
         Ok(Self)
     }
 
-    fn shutdown(idev: &i2c::I2cClient<Core>, _this: Pin<&Self>) {
+    fn shutdown<'bound>(idev: &'bound i2c::I2cClient<Core>, _this: Pin<&'bound Self>) {
         dev_info!(idev.as_ref(), "Shutdown Rust I2C driver sample.\n");
     }
 
-    fn unbind(idev: &i2c::I2cClient<Core>, _this: Pin<&Self>) {
+    fn unbind<'bound>(idev: &'bound i2c::I2cClient<Core>, _this: Pin<&'bound Self>) {
         dev_info!(idev.as_ref(), "Unbind Rust I2C driver sample.\n");
     }
 }
-- 
2.54.0

[PATCH v3 15/27] rust: driver: update module documentation for GAT-based Data type

[Danilo Krummrich]

Now that all bus driver traits use type Data<'bound>: 'bound, update the
illustrative driver trait in the module documentation to reflect the GAT
pattern and lifetime-parameterized callbacks.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/driver.rs | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs
index d8898f2115d5..0dbfbe468c94 100644
--- a/rust/kernel/driver.rs
+++ b/rust/kernel/driver.rs
@@ -18,7 +18,7 @@
 //!     type IdInfo: 'static;
 //!
 //!     /// The type of the driver's bus device private data.
-//!     type Data;
+//!     type Data<'bound>: 'bound;
 //!
 //!     /// The table of OF device ids supported by the driver.
 //!     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
@@ -27,11 +27,16 @@
 //!     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = None;
 //!
 //!     /// Driver probe.
-//!     fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo)
-//!         -> impl PinInit<Self::Data, Error>;
+//!     fn probe<'bound>(
+//!         dev: &'bound Device<device::Core>,
+//!         id_info: &'bound Self::IdInfo,
+//!     ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound;
 //!
 //!     /// Driver unbind (optional).
-//!     fn unbind(dev: &Device<device::Core>, this: Pin<&Self::Data>) {
+//!     fn unbind<'bound>(
+//!         dev: &'bound Device<device::Core>,
+//!         this: Pin<&'bound Self::Data<'bound>>,
+//!     ) {
 //!         let _ = (dev, this);
 //!     }
 //! }
@@ -46,9 +51,10 @@
 )]
 #![cfg_attr(CONFIG_PCI, doc = "* [`pci::Driver`](kernel::pci::Driver)")]
 //!
-//! The `probe()` callback should return a `impl PinInit<Self::Data, Error>`, i.e. the driver's
-//! private data. The bus abstraction should store the pointer in the corresponding bus device. The
-//! generic [`Device`] infrastructure provides common helpers for this purpose on its
+//! The `probe()` callback should return a
+//! `impl PinInit<Self::Data<'bound>, Error>`, i.e. the driver's private data. The bus
+//! abstraction should store the pointer in the corresponding bus device. The generic
+//! [`Device`] infrastructure provides common helpers for this purpose on its
 //! [`Device<CoreInternal>`] implementation.
 //!
 //! All driver callbacks should provide a reference to the driver's private data. Once the driver
-- 
2.54.0

[PATCH v3 16/27] rust: types: add `ForLt` trait for higher-ranked lifetime support

[Danilo Krummrich]

From: Gary Guo <gary@garyguo.net>

There are a few cases, e.g. when dealing with data referencing each other,
one might want to write code that are generic over lifetimes. For example,
if you want take a function that takes `&'a Foo` and gives `Bar<'a>`, you
can write:

    f: impl for<'a> FnOnce(&'a Foo) -> Bar<'a>,

However, it becomes tricky when you want that function to not have a fixed
`Bar`, but have it be generic again. In this case, one needs something that
is generic over types that are themselves generic over lifetimes.

`ForLt` provides such support. It provides a trait `ForLt` which describes
a type generic over lifetime. One may use `ForLt::Of<'a>` to get an
instance of a type for a specific lifetime.

For the case of cross referencing, one would almost always want the
lifetime to be covariant. Therefore this is also made a requirement for the
`ForLt` trait, so functions with `ForLt` trait bound can assume covariance.

A macro `ForLt!()` is provided to be able to obtain a type that implements
`ForLt`. For example, `ForLt!(for<'a> Bar<'a>)` would yield a type that
`<TheType as ForLt>::Of<'a>` is `Bar<'a>`. This also works with lifetime
elision, e.g. `ForLt!(Bar<'_>)` or for types without lifetime at all, e.g.
`ForLt!(u32)`.

The API design draws inspiration from the higher-kinded-types [1] crate,
however different design decision has been taken (e.g. covariance
requirement) and the implementation is independent.

License headers use "Apache-2.0 OR MIT" because I anticipate this to be
used in pin-init crate too which is licensed as such.

Link: https://docs.rs/higher-kinded-types/ [1]

Signed-off-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/Makefile               |   1 +
 rust/kernel/types.rs        |   4 +
 rust/kernel/types/for_lt.rs | 117 +++++++++++++++++
 rust/macros/for_lt.rs       | 242 ++++++++++++++++++++++++++++++++++++
 rust/macros/lib.rs          |  12 ++
 5 files changed, 376 insertions(+)
 create mode 100644 rust/kernel/types/for_lt.rs
 create mode 100644 rust/macros/for_lt.rs

diff --git a/rust/Makefile b/rust/Makefile
index b361bfedfdf0..c5a9a3339416 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -110,6 +110,7 @@ syn-cfgs := \
     feature="parsing" \
     feature="printing" \
     feature="proc-macro" \
+    feature="visit" \
     feature="visit-mut"
 
 syn-flags := \
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 9cf9f869d195..ac316fd7b538 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -11,6 +11,10 @@
 };
 use pin_init::{PinInit, Wrapper, Zeroable};
 
+#[doc(hidden)]
+pub mod for_lt;
+pub use for_lt::ForLt;
+
 /// Used to transfer ownership to and from foreign (non-Rust) languages.
 ///
 /// Ownership is transferred from Rust to a foreign language by calling [`Self::into_foreign`] and
diff --git a/rust/kernel/types/for_lt.rs b/rust/kernel/types/for_lt.rs
new file mode 100644
index 000000000000..22b4518a115b
--- /dev/null
+++ b/rust/kernel/types/for_lt.rs
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! Provide implementation and test of the `ForLt` trait and macro.
+//!
+//! This module is hidden and user should just use `ForLt!` directly.
+
+use core::marker::PhantomData;
+
+/// Representation of types generic over a lifetime.
+///
+/// The type must be covariant over the generic lifetime, i.e. the lifetime parameter
+/// can be soundly shorterned.
+///
+/// The lifetime involved must be covariant.
+///
+/// # Macro
+///
+/// It is not recommended to implement this trait directly. `ForLt!` macro is provided to obtain a
+/// type that implements this trait.
+///
+/// The full syntax is
+/// ```
+/// # use kernel::types::ForLt;
+/// # fn expect_lt<F: ForLt>() {}
+/// # struct TypeThatUse<'a>(&'a ());
+/// # expect_lt::<
+/// ForLt!(for<'a> TypeThatUse<'a>)
+/// # >();
+/// ```
+/// which gives a type so that `<ForLt!(for<'a> TypeThatUse<'a>) as ForLt>::Of<'b>`
+/// is `TypeThatUse<'b>`.
+///
+/// You may also use a short-hand syntax which works similar to lifetime elision.
+/// The macro also accepts types that does not involved lifetime at all.
+/// ```
+/// # use kernel::types::ForLt;
+/// # fn expect_lt<F: ForLt>() {}
+/// # struct TypeThatUse<'a>(&'a ());
+/// # expect_lt::<
+/// ForLt!(TypeThatUse<'_>) // Equivalent to `ForLt!(for<'a> TypeThatUse<'a>)`
+/// # >();
+/// # expect_lt::<
+/// ForLt!(&u32) // Equivalent to `ForLt!(for<'a> &'a u32)`
+/// # >();
+/// # expect_lt::<
+/// ForLt!(u32) // Equivalent to `ForLt!(for<'a> u32)`
+/// # >();
+/// ```
+///
+/// The macro will attempt to prove that the type is indeed covariant over the lifetime supplied.
+/// When it cannot be syntactically proven, it will emit checks to ask the Rust compiler to prove
+/// it.
+/// ```ignore,compile_fail
+/// # use kernel::types::ForLt;
+/// # fn expect_lt<F: ForLt>() {}
+/// # expect_lt::<
+/// ForLt!(fn(&u32)) // Contravariant, will fail compilation.
+/// # >();
+/// ```
+///
+/// There is a limitation if the type refer to generic parameters; if the macro cannot prove the
+/// covariance syntactically, the emitted checks will fail the compilation as it needs to refer to
+/// the generic parameter but is in a separate item.
+/// ```
+/// # use kernel::types::ForLt;
+/// fn expect_lt<F: ForLt>() {}
+/// # #[allow(clippy::unnecessary_safety_comment, reason = "false positive")]
+/// fn generic_fn<T: 'static>() {
+///     // Syntactically proven by the macro
+///     expect_lt::<ForLt!(&T)>();
+///     // Syntactically proven by the macro
+///     expect_lt::<ForLt!(&KBox<T>)>();
+///     // Cannot be syntactically proven, need to check covariance of `KBox`
+///     // expect_lt::<ForLt!(&KBox<&T>)>();
+/// }
+/// ```
+///
+/// # Safety
+///
+/// `Self::Of<'a>` must be covariant over the lifetime `'a`.
+pub unsafe trait ForLt {
+    /// The type parameterized by the lifetime.
+    type Of<'a>: 'a;
+
+    /// Cast a reference to a shorter lifetime.
+    #[inline(always)]
+    fn cast_ref<'r, 'short: 'r, 'long: 'short>(long: &'r Self::Of<'long>) -> &'r Self::Of<'short> {
+        // SAFETY: This is sound as this trait guarantees covariance.
+        unsafe { core::mem::transmute(long) }
+    }
+}
+pub use macros::ForLt;
+
+/// This is intended to be an "unsafe-to-refer-to" type.
+///
+/// Must only be used by the `ForLt!` macro.
+///
+/// `T` is the magic `dyn for<'a> WithLt<'a, TypeThatUse<'a>>` generated by macro.
+///
+/// `WF` is a type that the macro can use to assert some specific type is well-formed.
+///
+/// `N` is to provide the macro a place to emit arbitrary items, in case it needs to prove
+/// additional properties.
+#[doc(hidden)]
+pub struct UnsafeForLtImpl<T: ?Sized, WF, const N: usize>(PhantomData<(WF, T)>);
+
+// This is a helper trait for implementation `ForLt` to be able to use HRTB.
+#[doc(hidden)]
+pub trait WithLt<'a> {
+    type Of: 'a;
+}
+
+// SAFETY: In `ForLt!` macro, a covariance proof is generated when naming `UnsafeForLtImpl`
+// and it will fail to evaluate if the type is not covariant.
+unsafe impl<T: ?Sized + for<'a> WithLt<'a>, WF> ForLt for UnsafeForLtImpl<T, WF, 0> {
+    type Of<'a> = <T as WithLt<'a>>::Of;
+}
diff --git a/rust/macros/for_lt.rs b/rust/macros/for_lt.rs
new file mode 100644
index 000000000000..df2027789713
--- /dev/null
+++ b/rust/macros/for_lt.rs
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use proc_macro2::{
+    Span,
+    TokenStream, //
+};
+use quote::{
+    format_ident,
+    quote, //
+};
+use syn::{
+    parse::{
+        Parse,
+        ParseStream, //
+    },
+    visit::Visit,
+    visit_mut::VisitMut,
+    Lifetime,
+    Result,
+    Token,
+    Type, //
+};
+
+pub(crate) enum HigherRankedType {
+    Explicit {
+        _for_token: Token![for],
+        _lt_token: Token![<],
+        lifetime: Lifetime,
+        _gt_token: Token![>],
+        ty: Type,
+    },
+    Implicit {
+        ty: Type,
+    },
+}
+
+impl Parse for HigherRankedType {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
+        if input.peek(Token![for]) {
+            Ok(Self::Explicit {
+                _for_token: input.parse()?,
+                _lt_token: input.parse()?,
+                lifetime: input.parse()?,
+                _gt_token: input.parse()?,
+                ty: input.parse()?,
+            })
+        } else {
+            Ok(Self::Implicit { ty: input.parse()? })
+        }
+    }
+}
+
+trait TypeExt {
+    fn expand_elided_lifetime(&self, explicit_lt: &Lifetime) -> Type;
+    fn replace_lifetime(&self, src: &Lifetime, dst: &Lifetime) -> Type;
+    fn has_lifetime(&self, lt: &Lifetime) -> bool;
+}
+
+impl TypeExt for Type {
+    fn expand_elided_lifetime(&self, explicit_lt: &Lifetime) -> Type {
+        struct ElidedLifetimeExpander<'a>(&'a Lifetime);
+
+        impl VisitMut for ElidedLifetimeExpander<'_> {
+            fn visit_lifetime_mut(&mut self, lifetime: &mut Lifetime) {
+                // Expand explicit `'_`
+                if lifetime.ident == "_" {
+                    *lifetime = self.0.clone();
+                }
+            }
+
+            fn visit_type_reference_mut(&mut self, reference: &mut syn::TypeReference) {
+                syn::visit_mut::visit_type_reference_mut(self, reference);
+
+                if reference.lifetime.is_none() {
+                    reference.lifetime = Some(self.0.clone());
+                }
+            }
+        }
+
+        let mut ret = self.clone();
+        ElidedLifetimeExpander(explicit_lt).visit_type_mut(&mut ret);
+        ret
+    }
+
+    fn replace_lifetime(&self, src: &Lifetime, dst: &Lifetime) -> Type {
+        struct LifetimeReplacer<'a>(&'a Lifetime, &'a Lifetime);
+
+        impl VisitMut for LifetimeReplacer<'_> {
+            fn visit_lifetime_mut(&mut self, lifetime: &mut Lifetime) {
+                if lifetime.ident == self.0.ident {
+                    *lifetime = self.1.clone();
+                }
+            }
+        }
+
+        let mut ret = self.clone();
+        LifetimeReplacer(src, dst).visit_type_mut(&mut ret);
+        ret
+    }
+
+    fn has_lifetime(&self, lt: &Lifetime) -> bool {
+        struct HasLifetime<'a>(&'a Lifetime, bool);
+
+        impl Visit<'_> for HasLifetime<'_> {
+            fn visit_lifetime(&mut self, lifetime: &Lifetime) {
+                if lifetime.ident == self.0.ident {
+                    self.1 = true;
+                }
+            }
+        }
+
+        let mut visitor = HasLifetime(lt, false);
+        visitor.visit_type(self);
+        visitor.1
+    }
+}
+
+struct Prover<'a>(&'a Lifetime, Vec<&'a Type>);
+
+impl<'a> Prover<'a> {
+    /// Prove that `ty` is covariant over `'lt`.
+    ///
+    /// This also needs to prove that it'll be wellformed for any instance of `'lt`.
+    /// It can be assumed that `ty` will be wellformed if `'lt` is substituted to `'static`.
+    fn prove(&mut self, ty: &'a Type) {
+        match ty {
+            Type::Paren(ty) => self.prove(&ty.elem),
+            Type::Group(ty) => self.prove(&ty.elem),
+
+            // No lifetime involved
+            Type::Never(_) => {}
+
+            // `[T; N]` and `[T]` is covariant over `T`.
+            Type::Array(ty) => self.prove(&ty.elem),
+            Type::Slice(ty) => self.prove(&ty.elem),
+
+            Type::Tuple(ty) => {
+                for elem in &ty.elems {
+                    self.prove(elem);
+                }
+            }
+
+            // `*const T` is covariant over `T`
+            Type::Ptr(ty) if ty.const_token.is_some() => self.prove(&ty.elem),
+
+            // `&T` is covariant over `T` and lifetime.
+            //
+            // Note that if we encounter `&'other_lt T`, then we still need to make sure the type
+            // is wellformed if `T` involves `&'lt`, so we defer to the compiler.
+            //
+            // This is to block cases like `ForLt!(for<'a> &'static &'a u32)`, as the presence of
+            // the type implies `'a: 'static` but this is unsound.
+            Type::Reference(ty)
+                if ty.mutability.is_none() && ty.lifetime.as_ref() == Some(self.0) =>
+            {
+                self.prove(&ty.elem)
+            }
+
+            // `&[mut] T` is covariant over lifetime.
+            // In case we have `&[mut] NoLifetime`, we don't need to do additional checks.
+            Type::Reference(ty) if !ty.elem.has_lifetime(self.0) => (),
+
+            // No mention of lifetime at all, no need to perform compiler check.
+            ty if !ty.has_lifetime(self.0) => (),
+
+            // Otherwise, we need to emit checks so that compiler can determine if the types are
+            // actually covariant.
+            ty => self.1.push(ty),
+        }
+    }
+}
+
+pub(crate) fn for_lt(input: HigherRankedType) -> TokenStream {
+    let (ty, lifetime) = match input {
+        HigherRankedType::Explicit { lifetime, ty, .. } => (ty, lifetime),
+        HigherRankedType::Implicit { ty } => {
+            // If there's no explicit `for<'a>` binder, inject a synthetic `'__elided` lifetime
+            // and expand elided sites.
+            let lifetime = Lifetime {
+                apostrophe: Span::mixed_site(),
+                ident: format_ident!("__elided", span = Span::mixed_site()),
+            };
+            (ty.expand_elided_lifetime(&lifetime), lifetime)
+        }
+    };
+
+    let mut prover = Prover(&lifetime, Vec::new());
+    prover.prove(&ty);
+
+    let mut proof = Vec::new();
+
+    // Emit proofs for every type that requires additional compiler help in proving covariance.
+    for (idx, required_proof) in prover.1.into_iter().enumerate() {
+        // Insert a proof that the type is well-formed.
+        //
+        // This is intended to workaround a Rust compiler soundness bug related to HRTB.
+        // https://github.com/rust-lang/rust/issues/152489
+        //
+        // This needs to be a struct instead of fn to avoid the implied WF bounds.
+        let wf_proof_name = format_ident!("ProveWf{idx}");
+        proof.push(quote!(
+            struct #wf_proof_name<#lifetime>(
+                ::core::marker::PhantomData<&#lifetime ()>, #required_proof
+            );
+        ));
+
+        // Insert a proof that the type is covariant.
+        let cov_proof_name = format_ident!("prove_covariant_{idx}");
+        proof.push(quote!(
+            fn #cov_proof_name<'__short, '__long: '__short>(
+                long: #wf_proof_name<'__long>
+            ) -> #wf_proof_name<'__short> {
+                long
+            }
+        ));
+    }
+
+    // Make sure that the type is wellformed when substituting lifetime with `'static`.
+    //
+    // Currently the Rust compiler doesn't check this, see the above ProveWf documentation.
+    //
+    // We prefer to use this way of proving WF-ness as it can work when generics are involved.
+    let ty_static = ty.replace_lifetime(
+        &lifetime,
+        &Lifetime {
+            apostrophe: Span::mixed_site(),
+            ident: format_ident!("static"),
+        },
+    );
+
+    quote!(
+        ::kernel::types::for_lt::UnsafeForLtImpl::<
+            dyn for<#lifetime> ::kernel::types::for_lt::WithLt<#lifetime, Of = #ty>,
+            #ty_static,
+            {
+                #(#proof)*
+
+                0
+            }
+        >
+    )
+}
diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
index 2cfd59e0f9e7..e5f6f8318112 100644
--- a/rust/macros/lib.rs
+++ b/rust/macros/lib.rs
@@ -17,6 +17,7 @@
 mod concat_idents;
 mod export;
 mod fmt;
+mod for_lt;
 mod helpers;
 mod kunit;
 mod module;
@@ -489,3 +490,14 @@ pub fn kunit_tests(attr: TokenStream, input: TokenStream) -> TokenStream {
         .unwrap_or_else(|e| e.into_compile_error())
         .into()
 }
+
+/// Obtain a type that implements `ForLt` for the given higher-ranked type.
+///
+/// Please refer to the documentation of [`ForLt`] trait.
+///
+/// [`ForLt`]: trait.ForLt.html
+#[proc_macro]
+#[allow(non_snake_case)] // The macro shares the name with the trait.
+pub fn ForLt(input: TokenStream) -> TokenStream {
+    for_lt::for_lt(parse_macro_input!(input)).into()
+}
-- 
2.54.0

[PATCH v3 17/27] rust: auxiliary: generalize Registration over ForLt

[Danilo Krummrich]

Generalize Registration<T> to Registration<F: ForLt> and
Device::registration_data<F: ForLt>() to return Pin<&F::Of<'_>>.

The stored 'static lifetime is shortened to the borrow lifetime of &self
via ForLt::cast_ref; ForLt's covariance guarantee makes this sound.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/nova-core/driver.rs       |  4 +-
 rust/kernel/auxiliary.rs              | 68 +++++++++++++++++----------
 samples/rust/rust_driver_auxiliary.rs |  8 ++--
 3 files changed, 52 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index fe4eafe1ebf0..ab0d7f2b516c 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -21,6 +21,7 @@
         },
         Arc,
     },
+    types::ForLt,
 };
 
 use crate::gpu::Gpu;
@@ -32,7 +33,8 @@
 pub(crate) struct NovaCore {
     #[pin]
     pub(crate) gpu: Gpu,
-    _reg: Devres<auxiliary::Registration<()>>,
+    #[allow(clippy::type_complexity)]
+    _reg: Devres<auxiliary::Registration<ForLt!(())>>,
 }
 
 const BAR0_SIZE: usize = SZ_16M;
diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs
index 3f1e2966c03a..db3d56106ea2 100644
--- a/rust/kernel/auxiliary.rs
+++ b/rust/kernel/auxiliary.rs
@@ -20,6 +20,7 @@
     },
     prelude::*,
     types::{
+        ForLt,
         ForeignOwnable,
         Opaque, //
     },
@@ -271,12 +272,16 @@ pub fn parent(&self) -> &device::Device<device::Bound> {
 
     /// Returns a pinned reference to the registration data set by the registering (parent) driver.
     ///
-    /// Returns [`EINVAL`] if `T` does not match the type used by the parent driver when calling
+    /// `F` is the [`ForLt`](trait@ForLt) encoding of the data type. The returned
+    /// reference has its lifetime shortened from `'static` to `&self`'s borrow lifetime via
+    /// [`ForLt::cast_ref`].
+    ///
+    /// Returns [`EINVAL`] if `F` does not match the type used by the parent driver when calling
     /// [`Registration::new()`].
     ///
     /// Returns [`ENOENT`] if no registration data has been set, e.g. when the device was
     /// registered by a C driver.
-    pub fn registration_data<T: 'static>(&self) -> Result<Pin<&T>> {
+    pub fn registration_data<F: ForLt>(&self) -> Result<Pin<&F::Of<'_>>> {
         // SAFETY: By the type invariant, `self.as_raw()` is a valid `struct auxiliary_device`.
         let ptr = unsafe { (*self.as_raw()).registration_data_rust };
         if ptr.is_null() {
@@ -289,18 +294,23 @@ pub fn registration_data<T: 'static>(&self) -> Result<Pin<&T>> {
 
         // SAFETY: `ptr` is non-null and was set via `into_foreign()` in `Registration::new()`;
         // `RegistrationData` is `#[repr(C)]` with `type_id` at offset 0, so reading a `TypeId`
-        // at the start of the allocation is valid regardless of `T`.
+        // at the start of the allocation is valid regardless of `F`.
         let type_id = unsafe { ptr.cast::<TypeId>().read() };
-        if type_id != TypeId::of::<T>() {
+        if type_id != TypeId::of::<F::Of<'static>>() {
             return Err(EINVAL);
         }
 
-        // SAFETY: The `TypeId` check above confirms that the stored type is `T`; `ptr` remains
-        // valid until `Registration::drop()` calls `from_foreign()`.
-        let wrapper = unsafe { Pin::<KBox<RegistrationData<T>>>::borrow(ptr) };
+        // SAFETY: The `TypeId` check above confirms that the stored type matches
+        // `F::Of<'static>`; `ptr` remains valid until `Registration::drop()` calls
+        // `from_foreign()`.
+        let wrapper = unsafe { Pin::<KBox<RegistrationData<F::Of<'static>>>>::borrow(ptr) };
 
         // SAFETY: `data` is a structurally pinned field of `RegistrationData`.
-        Ok(unsafe { wrapper.map_unchecked(|w| &w.data) })
+        let pinned: Pin<&F::Of<'static>> = unsafe { wrapper.map_unchecked(|w| &w.data) };
+
+        // SAFETY: The data was pinned when stored; `cast_ref` only shortens
+        // the lifetime, so the pinning guarantee is preserved.
+        Ok(unsafe { Pin::new_unchecked(F::cast_ref(pinned.get_ref())) })
     }
 }
 
@@ -389,43 +399,51 @@ struct RegistrationData<T> {
 /// This type represents the registration of a [`struct auxiliary_device`]. When its parent device
 /// is unbound, the corresponding auxiliary device will be unregistered from the system.
 ///
-/// The type parameter `T` is the type of the registration data owned by the registering (parent)
-/// driver. It can be accessed by the auxiliary driver through
-/// [`Device::registration_data()`].
+/// The type parameter `F` is a [`ForLt`](trait@ForLt) encoding of the registration
+/// data type. For non-lifetime-parameterized types, use [`ForLt!(T)`](macro@ForLt).
+/// The data can be accessed by the auxiliary driver through [`Device::registration_data()`].
 ///
 /// # Invariants
 ///
 /// `self.adev` always holds a valid pointer to an initialized and registered
 /// [`struct auxiliary_device`] whose `registration_data_rust` field points to a
-/// valid `Pin<KBox<RegistrationData<T>>>`.
-pub struct Registration<T: 'static> {
+/// valid `Pin<KBox<RegistrationData<F::Of<'static>>>>`.
+pub struct Registration<F: ForLt> {
     adev: NonNull<bindings::auxiliary_device>,
-    _data: PhantomData<T>,
+    _data: PhantomData<F>,
 }
 
-impl<T: Send + Sync + 'static> Registration<T> {
+impl<F: ForLt> Registration<F>
+where
+    for<'a> F::Of<'a>: Send + Sync,
+{
     /// Create and register a new auxiliary device with the given registration data.
     ///
     /// The `data` is owned by the registration and can be accessed through the auxiliary device
     /// via [`Device::registration_data()`].
-    pub fn new<E>(
-        parent: &device::Device<device::Bound>,
+    pub fn new<'bound, E>(
+        parent: &'bound device::Device<device::Bound>,
         name: &CStr,
         id: u32,
         modname: &CStr,
-        data: impl PinInit<T, E>,
+        data: impl PinInit<F::Of<'bound>, E>,
     ) -> Result<Devres<Self>>
     where
         Error: From<E>,
     {
         let data = KBox::pin_init::<Error>(
             try_pin_init!(RegistrationData {
-                type_id: TypeId::of::<T>(),
+                type_id: TypeId::of::<F::Of<'static>>(),
                 data <- data,
             }),
             GFP_KERNEL,
         )?;
 
+        // SAFETY: Lifetimes are erased and do not affect layout, so RegistrationData<F::Of<'bound>>
+        // and RegistrationData<F::Of<'static>> have identical representation.
+        let data: Pin<KBox<RegistrationData<F::Of<'static>>>> =
+            unsafe { core::mem::transmute(data) };
+
         let boxed: KBox<Opaque<bindings::auxiliary_device>> = KBox::zeroed(GFP_KERNEL)?;
         let adev = boxed.get();
 
@@ -455,7 +473,9 @@ pub fn new<E>(
         if ret != 0 {
             // SAFETY: `registration_data` was set above via `into_foreign()`.
             drop(unsafe {
-                Pin::<KBox<RegistrationData<T>>>::from_foreign((*adev).registration_data_rust)
+                Pin::<KBox<RegistrationData<F::Of<'static>>>>::from_foreign(
+                    (*adev).registration_data_rust,
+                )
             });
 
             // SAFETY: `adev` is guaranteed to be a valid pointer to a
@@ -478,7 +498,7 @@ pub fn new<E>(
     }
 }
 
-impl<T: 'static> Drop for Registration<T> {
+impl<F: ForLt> Drop for Registration<F> {
     fn drop(&mut self) {
         // SAFETY: By the type invariant of `Self`, `self.adev.as_ptr()` is a valid registered
         // `struct auxiliary_device`.
@@ -486,7 +506,7 @@ fn drop(&mut self) {
 
         // SAFETY: `registration_data` was set in `new()` via `into_foreign()`.
         drop(unsafe {
-            Pin::<KBox<RegistrationData<T>>>::from_foreign(
+            Pin::<KBox<RegistrationData<F::Of<'static>>>>::from_foreign(
                 (*self.adev.as_ptr()).registration_data_rust,
             )
         });
@@ -500,7 +520,7 @@ fn drop(&mut self) {
 }
 
 // SAFETY: A `Registration` of a `struct auxiliary_device` can be released from any thread.
-unsafe impl<T: Send + Sync> Send for Registration<T> {}
+unsafe impl<F: ForLt> Send for Registration<F> where for<'a> F::Of<'a>: Send {}
 
 // SAFETY: `Registration` does not expose any methods or fields that need synchronization.
-unsafe impl<T: Send + Sync> Sync for Registration<T> {}
+unsafe impl<F: ForLt> Sync for Registration<F> where for<'a> F::Of<'a>: Send {}
diff --git a/samples/rust/rust_driver_auxiliary.rs b/samples/rust/rust_driver_auxiliary.rs
index 972a3d5b25e7..7b15a107fed4 100644
--- a/samples/rust/rust_driver_auxiliary.rs
+++ b/samples/rust/rust_driver_auxiliary.rs
@@ -14,6 +14,7 @@
     driver,
     pci,
     prelude::*,
+    types::ForLt,
     InPlaceModule, //
 };
 
@@ -55,9 +56,10 @@ struct Data {
     index: u32,
 }
 
+#[allow(clippy::type_complexity)]
 struct ParentDriver {
-    _reg0: Devres<auxiliary::Registration<Data>>,
-    _reg1: Devres<auxiliary::Registration<Data>>,
+    _reg0: Devres<auxiliary::Registration<ForLt!(Data)>>,
+    _reg1: Devres<auxiliary::Registration<ForLt!(Data)>>,
 }
 
 kernel::pci_device_table!(
@@ -101,7 +103,7 @@ fn connect(adev: &auxiliary::Device<Bound>) -> Result {
         let dev = adev.parent();
         let pdev: &pci::Device<Bound> = dev.try_into()?;
 
-        let data = adev.registration_data::<Data>()?;
+        let data = adev.registration_data::<ForLt!(Data)>()?;
 
         dev_info!(
             dev,
-- 
2.54.0

[PATCH v3 18/27] samples: rust: rust_driver_auxiliary: showcase lifetime-bound registration data

[Danilo Krummrich]

Make the Data struct lifetime-parameterized, storing a reference to the
parent pci::Device<Bound>. This demonstrates that registration data can
hold device resources tied to the parent driver's lifetime.

In connect(), retrieve the parent PCI device from the registration data
rather than casting through adev.parent().

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 samples/rust/rust_driver_auxiliary.rs | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/samples/rust/rust_driver_auxiliary.rs b/samples/rust/rust_driver_auxiliary.rs
index 7b15a107fed4..84d18bbfafc5 100644
--- a/samples/rust/rust_driver_auxiliary.rs
+++ b/samples/rust/rust_driver_auxiliary.rs
@@ -52,14 +52,15 @@ fn probe<'bound>(
     }
 }
 
-struct Data {
+struct Data<'bound> {
     index: u32,
+    parent: &'bound pci::Device<Bound>,
 }
 
 #[allow(clippy::type_complexity)]
 struct ParentDriver {
-    _reg0: Devres<auxiliary::Registration<ForLt!(Data)>>,
-    _reg1: Devres<auxiliary::Registration<ForLt!(Data)>>,
+    _reg0: Devres<auxiliary::Registration<ForLt!(Data<'_>)>>,
+    _reg1: Devres<auxiliary::Registration<ForLt!(Data<'_>)>>,
 }
 
 kernel::pci_device_table!(
@@ -85,14 +86,20 @@ fn probe<'bound>(
                 AUXILIARY_NAME,
                 0,
                 MODULE_NAME,
-                Data { index: 0 },
+                Data {
+                    index: 0,
+                    parent: pdev,
+                },
             )?,
             _reg1: auxiliary::Registration::new(
                 pdev.as_ref(),
                 AUXILIARY_NAME,
                 1,
                 MODULE_NAME,
-                Data { index: 1 },
+                Data {
+                    index: 1,
+                    parent: pdev,
+                },
             )?,
         })
     }
@@ -100,13 +107,11 @@ fn probe<'bound>(
 
 impl ParentDriver {
     fn connect(adev: &auxiliary::Device<Bound>) -> Result {
-        let dev = adev.parent();
-        let pdev: &pci::Device<Bound> = dev.try_into()?;
-
-        let data = adev.registration_data::<ForLt!(Data)>()?;
+        let data = adev.registration_data::<ForLt!(Data<'_>)>()?;
+        let pdev = data.parent;
 
         dev_info!(
-            dev,
+            pdev,
             "Connect auxiliary {} with parent: VendorID={}, DeviceID={:#x}\n",
             adev.id(),
             pdev.vendor_id(),
@@ -114,7 +119,7 @@ fn connect(adev: &auxiliary::Device<Bound>) -> Result {
         );
 
         dev_info!(
-            dev,
+            pdev,
             "Connected to auxiliary device with index {}.\n",
             data.index
         );
-- 
2.54.0

[PATCH v3 19/27] rust: pci: make Bar lifetime-parameterized

[Danilo Krummrich]

Convert pci::Bar<SIZE> to pci::Bar<'bound, SIZE>, storing &'bound
Device<Bound> to tie the BAR mapping lifetime to the device.

iomap_region_sized() now returns Result<Bar<'bound, SIZE>> directly instead
of impl PinInit<Devres<Bar<SIZE>>, Error>.

Add Bar::into_devres() to consume the bar and register it as a
device-managed resource, returning Devres<Bar<'static, SIZE>>. The
lifetime is erased to 'static because Devres guarantees the bar does not
actually outlive the device -- access is revoked on unbind.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/nova-core/driver.rs |  7 ++--
 rust/kernel/devres.rs           |  2 +-
 rust/kernel/pci/io.rs           | 68 +++++++++++++++++----------------
 samples/rust/rust_driver_pci.rs |  5 ++-
 4 files changed, 44 insertions(+), 38 deletions(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index ab0d7f2b516c..3f6d8cedf5ab 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -47,7 +47,7 @@ pub(crate) struct NovaCore {
 // DMA addresses. These systems should be quite rare.
 const GPU_DMA_BITS: u32 = 47;
 
-pub(crate) type Bar0 = pci::Bar<BAR0_SIZE>;
+pub(crate) type Bar0 = pci::Bar<'static, BAR0_SIZE>;
 
 kernel::pci_device_table!(
     PCI_TABLE,
@@ -94,8 +94,9 @@ fn probe<'bound>(
             // other threads of execution.
             unsafe { pdev.dma_set_mask_and_coherent(DmaMask::new::<GPU_DMA_BITS>())? };
 
-            let bar = Arc::pin_init(
-                pdev.iomap_region_sized::<BAR0_SIZE>(0, c"nova-core/bar0"),
+            let bar = Arc::new(
+                pdev.iomap_region_sized::<BAR0_SIZE>(0, c"nova-core/bar0")?
+                    .into_devres()?,
                 GFP_KERNEL,
             )?;
 
diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
index 9e5f93aed20c..ec63317665f4 100644
--- a/rust/kernel/devres.rs
+++ b/rust/kernel/devres.rs
@@ -304,7 +304,7 @@ pub fn device(&self) -> &Device {
     ///     pci, //
     /// };
     ///
-    /// fn from_core(dev: &pci::Device<Core>, devres: Devres<pci::Bar<0x4>>) -> Result {
+    /// fn from_core(dev: &pci::Device<Core>, devres: Devres<pci::Bar<'_, 0x4>>) -> Result {
     ///     let bar = devres.access(dev.as_ref())?;
     ///
     ///     let _ = bar.read32(0x0);
diff --git a/rust/kernel/pci/io.rs b/rust/kernel/pci/io.rs
index ae78676c927f..5668394a155b 100644
--- a/rust/kernel/pci/io.rs
+++ b/rust/kernel/pci/io.rs
@@ -14,8 +14,7 @@
         Mmio,
         MmioRaw, //
     },
-    prelude::*,
-    sync::aref::ARef, //
+    prelude::*, //
 };
 use core::{
     marker::PhantomData,
@@ -78,15 +77,15 @@ impl ConfigSpaceKind for Extended {
 /// The generic parameter `S` indicates the maximum size of the configuration space.
 /// Use [`Normal`] for 256-byte legacy configuration space or [`Extended`] for
 /// 4096-byte PCIe extended configuration space (default).
-pub struct ConfigSpace<'a, S: ConfigSpaceKind = Extended> {
-    pub(crate) pdev: &'a Device<device::Bound>,
+pub struct ConfigSpace<'bound, S: ConfigSpaceKind = Extended> {
+    pub(crate) pdev: &'bound Device<device::Bound>,
     _marker: PhantomData<S>,
 }
 
 /// Implements [`IoCapable`] on [`ConfigSpace`] for `$ty` using `$read_fn` and `$write_fn`.
 macro_rules! impl_config_space_io_capable {
     ($ty:ty, $read_fn:ident, $write_fn:ident) => {
-        impl<'a, S: ConfigSpaceKind> IoCapable<$ty> for ConfigSpace<'a, S> {
+        impl<'bound, S: ConfigSpaceKind> IoCapable<$ty> for ConfigSpace<'bound, S> {
             unsafe fn io_read(&self, address: usize) -> $ty {
                 let mut val: $ty = 0;
 
@@ -119,7 +118,7 @@ unsafe fn io_write(&self, value: $ty, address: usize) {
 impl_config_space_io_capable!(u16, pci_read_config_word, pci_write_config_word);
 impl_config_space_io_capable!(u32, pci_read_config_dword, pci_write_config_dword);
 
-impl<'a, S: ConfigSpaceKind> Io for ConfigSpace<'a, S> {
+impl<'bound, S: ConfigSpaceKind> Io for ConfigSpace<'bound, S> {
     /// Returns the base address of the I/O region. It is always 0 for configuration space.
     #[inline]
     fn addr(&self) -> usize {
@@ -133,7 +132,7 @@ fn maxsize(&self) -> usize {
     }
 }
 
-impl<'a, S: ConfigSpaceKind> IoKnownSize for ConfigSpace<'a, S> {
+impl<'bound, S: ConfigSpaceKind> IoKnownSize for ConfigSpace<'bound, S> {
     const MIN_SIZE: usize = S::SIZE;
 }
 
@@ -146,14 +145,14 @@ impl<'a, S: ConfigSpaceKind> IoKnownSize for ConfigSpace<'a, S> {
 ///
 /// `Bar` always holds an `IoRaw` instance that holds a valid pointer to the start of the I/O
 /// memory mapped PCI BAR and its size.
-pub struct Bar<const SIZE: usize = 0> {
-    pdev: ARef<Device>,
+pub struct Bar<'bound, const SIZE: usize = 0> {
+    pdev: &'bound Device<device::Bound>,
     io: MmioRaw<SIZE>,
     num: i32,
 }
 
-impl<const SIZE: usize> Bar<SIZE> {
-    pub(super) fn new(pdev: &Device, num: u32, name: &CStr) -> Result<Self> {
+impl<'bound, const SIZE: usize> Bar<'bound, SIZE> {
+    pub(super) fn new(pdev: &'bound Device<device::Bound>, num: u32, name: &CStr) -> Result<Self> {
         let len = pdev.resource_len(num)?;
         if len == 0 {
             return Err(ENOMEM);
@@ -196,11 +195,7 @@ pub(super) fn new(pdev: &Device, num: u32, name: &CStr) -> Result<Self> {
             }
         };
 
-        Ok(Bar {
-            pdev: pdev.into(),
-            io,
-            num,
-        })
+        Ok(Bar { pdev, io, num })
     }
 
     /// # Safety
@@ -219,11 +214,24 @@ unsafe fn do_release(pdev: &Device, ioptr: usize, num: i32) {
 
     fn release(&self) {
         // SAFETY: The safety requirements are guaranteed by the type invariant of `self.pdev`.
-        unsafe { Self::do_release(&self.pdev, self.io.addr(), self.num) };
+        unsafe { Self::do_release(self.pdev, self.io.addr(), self.num) };
+    }
+
+    /// Consume the `Bar` and register it as a device-managed resource.
+    ///
+    /// The returned `Devres<Bar<'static, SIZE>>` can outlive the original lifetime `'bound`. Access
+    /// to the BAR is revoked when the device is unbound.
+    pub fn into_devres(self) -> Result<Devres<Bar<'static, SIZE>>> {
+        // SAFETY: Casting to `'static` is sound because `Devres` guarantees the `Bar` does not
+        // actually outlive the device -- access is revoked and the resource is released when the
+        // device is unbound.
+        let bar: Bar<'static, SIZE> = unsafe { core::mem::transmute(self) };
+        let pdev = bar.pdev;
+        Devres::new(pdev.as_ref(), bar)
     }
 }
 
-impl Bar {
+impl Bar<'_> {
     #[inline]
     pub(super) fn index_is_valid(index: u32) -> bool {
         // A `struct pci_dev` owns an array of resources with at most `PCI_NUM_RESOURCES` entries.
@@ -231,13 +239,13 @@ pub(super) fn index_is_valid(index: u32) -> bool {
     }
 }
 
-impl<const SIZE: usize> Drop for Bar<SIZE> {
+impl<const SIZE: usize> Drop for Bar<'_, SIZE> {
     fn drop(&mut self) {
         self.release();
     }
 }
 
-impl<const SIZE: usize> Deref for Bar<SIZE> {
+impl<const SIZE: usize> Deref for Bar<'_, SIZE> {
     type Target = Mmio<SIZE>;
 
     fn deref(&self) -> &Self::Target {
@@ -249,20 +257,16 @@ fn deref(&self) -> &Self::Target {
 impl Device<device::Bound> {
     /// Maps an entire PCI BAR after performing a region-request on it. I/O operation bound checks
     /// can be performed on compile time for offsets (plus the requested type size) < SIZE.
-    pub fn iomap_region_sized<'a, const SIZE: usize>(
-        &'a self,
+    pub fn iomap_region_sized<'bound, const SIZE: usize>(
+        &'bound self,
         bar: u32,
-        name: &'a CStr,
-    ) -> impl PinInit<Devres<Bar<SIZE>>, Error> + 'a {
-        Devres::new(self.as_ref(), Bar::<SIZE>::new(self, bar, name))
+        name: &CStr,
+    ) -> Result<Bar<'bound, SIZE>> {
+        Bar::new(self, bar, name)
     }
 
     /// Maps an entire PCI BAR after performing a region-request on it.
-    pub fn iomap_region<'a>(
-        &'a self,
-        bar: u32,
-        name: &'a CStr,
-    ) -> impl PinInit<Devres<Bar>, Error> + 'a {
+    pub fn iomap_region<'bound>(&'bound self, bar: u32, name: &CStr) -> Result<Bar<'bound>> {
         self.iomap_region_sized::<0>(bar, name)
     }
 
@@ -282,7 +286,7 @@ pub fn cfg_size(&self) -> ConfigSpaceSize {
     }
 
     /// Return an initialized normal (256-byte) config space object.
-    pub fn config_space<'a>(&'a self) -> ConfigSpace<'a, Normal> {
+    pub fn config_space<'bound>(&'bound self) -> ConfigSpace<'bound, Normal> {
         ConfigSpace {
             pdev: self,
             _marker: PhantomData,
@@ -290,7 +294,7 @@ pub fn config_space<'a>(&'a self) -> ConfigSpace<'a, Normal> {
     }
 
     /// Return an initialized extended (4096-byte) config space object.
-    pub fn config_space_extended<'a>(&'a self) -> Result<ConfigSpace<'a, Extended>> {
+    pub fn config_space_extended<'bound>(&'bound self) -> Result<ConfigSpace<'bound, Extended>> {
         if self.cfg_size() != ConfigSpaceSize::Extended {
             return Err(EINVAL);
         }
diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs
index 30b9311812f3..7791363df0a0 100644
--- a/samples/rust/rust_driver_pci.rs
+++ b/samples/rust/rust_driver_pci.rs
@@ -45,7 +45,7 @@ mod regs {
     pub(super) const END: usize = 0x10;
 }
 
-type Bar0 = pci::Bar<{ regs::END }>;
+type Bar0 = pci::Bar<'static, { regs::END }>;
 
 #[derive(Copy, Clone, Debug)]
 struct TestIndex(u8);
@@ -161,7 +161,8 @@ fn probe<'bound>(
             pdev.set_master();
 
             Ok(try_pin_init!(Self {
-                bar <- pdev.iomap_region_sized::<{ regs::END }>(0, c"rust_driver_pci"),
+                bar: pdev.iomap_region_sized::<{ regs::END }>(0, c"rust_driver_pci")?
+                    .into_devres()?,
                 index: *info,
                 _: {
                     let bar = bar.access(pdev.as_ref())?;
-- 
2.54.0

[PATCH v3 20/27] rust: io: make IoMem and ExclusiveIoMem lifetime-parameterized

[Danilo Krummrich]

Add a lifetime parameter to IoMem<'bound, SIZE> and
ExclusiveIoMem<'bound, SIZE>, storing a &'bound Device<Bound> reference
to tie the mapping to the device's lifetime.

This mirrors the pci::Bar<'bound, SIZE> design and enables drivers to
hold I/O memory mappings directly in their HRT private data, tied to the
device lifetime.

IoRequest::iomap_* methods now return the mapping directly instead of
wrapping it in Devres. Callers that need device-managed revocation can
call the new into_devres() method.

Acked-by: Uwe Kleine-König <ukleinek@kernel.org>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/drm/tyr/driver.rs |   4 +-
 drivers/pwm/pwm_th1520.rs     |   4 +-
 rust/kernel/io/mem.rs         | 115 +++++++++++++++++-----------------
 3 files changed, 62 insertions(+), 61 deletions(-)

diff --git a/drivers/gpu/drm/tyr/driver.rs b/drivers/gpu/drm/tyr/driver.rs
index 3ac3b9979264..8c916913e976 100644
--- a/drivers/gpu/drm/tyr/driver.rs
+++ b/drivers/gpu/drm/tyr/driver.rs
@@ -37,7 +37,7 @@
     regs, //
 };
 
-pub(crate) type IoMem = kernel::io::mem::IoMem<SZ_2M>;
+pub(crate) type IoMem = kernel::io::mem::IoMem<'static, SZ_2M>;
 
 pub(crate) struct TyrDrmDriver;
 
@@ -110,7 +110,7 @@ fn probe<'bound>(
         let sram_regulator = Regulator::<regulator::Enabled>::get(pdev.as_ref(), c"sram")?;
 
         let request = pdev.io_request_by_index(0).ok_or(ENODEV)?;
-        let iomem = Arc::pin_init(request.iomap_sized::<SZ_2M>(), GFP_KERNEL)?;
+        let iomem = Arc::new(request.iomap_sized::<SZ_2M>()?.into_devres()?, GFP_KERNEL)?;
 
         issue_soft_reset(pdev.as_ref(), &iomem)?;
         gpu::l2_power_on(pdev.as_ref(), &iomem)?;
diff --git a/drivers/pwm/pwm_th1520.rs b/drivers/pwm/pwm_th1520.rs
index 1abf580653fa..c84321a4d94e 100644
--- a/drivers/pwm/pwm_th1520.rs
+++ b/drivers/pwm/pwm_th1520.rs
@@ -92,7 +92,7 @@ struct Th1520WfHw {
 #[pin_data(PinnedDrop)]
 struct Th1520PwmDriverData {
     #[pin]
-    iomem: devres::Devres<IoMem<TH1520_PWM_REG_SIZE>>,
+    iomem: devres::Devres<IoMem<'static, TH1520_PWM_REG_SIZE>>,
     clk: Clk,
 }
 
@@ -352,7 +352,7 @@ fn probe<'bound>(
             dev,
             TH1520_MAX_PWM_NUM,
             try_pin_init!(Th1520PwmDriverData {
-                iomem <- request.iomap_sized::<TH1520_PWM_REG_SIZE>(),
+                iomem <- request.iomap_sized::<TH1520_PWM_REG_SIZE>()?.into_devres(),
                 clk <- clk,
             }),
         )?;
diff --git a/rust/kernel/io/mem.rs b/rust/kernel/io/mem.rs
index 1b34f7ebd929..b5015d020efa 100644
--- a/rust/kernel/io/mem.rs
+++ b/rust/kernel/io/mem.rs
@@ -23,19 +23,19 @@
 };
 
 /// An IO request for a specific device and resource.
-pub struct IoRequest<'a> {
-    device: &'a Device<Bound>,
-    resource: &'a Resource,
+pub struct IoRequest<'bound> {
+    device: &'bound Device<Bound>,
+    resource: &'bound Resource,
 }
 
-impl<'a> IoRequest<'a> {
+impl<'bound> IoRequest<'bound> {
     /// Creates a new [`IoRequest`] instance.
     ///
     /// # Safety
     ///
     /// Callers must ensure that `resource` is valid for `device` during the
-    /// lifetime `'a`.
-    pub(crate) unsafe fn new(device: &'a Device<Bound>, resource: &'a Resource) -> Self {
+    /// lifetime `'bound`.
+    pub(crate) unsafe fn new(device: &'bound Device<Bound>, resource: &'bound Resource) -> Self {
         IoRequest { device, resource }
     }
 
@@ -74,22 +74,19 @@ pub(crate) unsafe fn new(device: &'a Device<Bound>, resource: &'a Resource) -> S
     ///       //
     ///       // No runtime checks will apply when reading and writing.
     ///       let request = pdev.io_request_by_index(0).ok_or(ENODEV)?;
-    ///       let iomem = request.iomap_sized::<42>();
-    ///       let iomem = KBox::pin_init(iomem, GFP_KERNEL)?;
-    ///
-    ///       let io = iomem.access(pdev.as_ref())?;
+    ///       let iomem = request.iomap_sized::<42>()?;
     ///
     ///       // Read and write a 32-bit value at `offset`.
-    ///       let data = io.read32(offset);
+    ///       let data = iomem.read32(offset);
     ///
-    ///       io.write32(data, offset);
+    ///       iomem.write32(data, offset);
     ///
     ///       # Ok(SampleDriver)
     ///     }
     /// }
     /// ```
-    pub fn iomap_sized<const SIZE: usize>(self) -> impl PinInit<Devres<IoMem<SIZE>>, Error> + 'a {
-        IoMem::new(self)
+    pub fn iomap_sized<const SIZE: usize>(self) -> Result<IoMem<'bound, SIZE>> {
+        IoMem::ioremap(self.device, self.resource)
     }
 
     /// Same as [`Self::iomap_sized`] but with exclusive access to the
@@ -98,10 +95,8 @@ pub fn iomap_sized<const SIZE: usize>(self) -> impl PinInit<Devres<IoMem<SIZE>>,
     /// This uses the [`ioremap()`] C API.
     ///
     /// [`ioremap()`]: https://docs.kernel.org/driver-api/device-io.html#getting-access-to-the-device
-    pub fn iomap_exclusive_sized<const SIZE: usize>(
-        self,
-    ) -> impl PinInit<Devres<ExclusiveIoMem<SIZE>>, Error> + 'a {
-        ExclusiveIoMem::new(self)
+    pub fn iomap_exclusive_sized<const SIZE: usize>(self) -> Result<ExclusiveIoMem<'bound, SIZE>> {
+        ExclusiveIoMem::ioremap(self.device, self.resource)
     }
 
     /// Maps an [`IoRequest`] where the size is not known at compile time,
@@ -140,27 +135,24 @@ pub fn iomap_exclusive_sized<const SIZE: usize>(
     ///       // family of functions should be used, leading to runtime checks on every
     ///       // access.
     ///       let request = pdev.io_request_by_index(0).ok_or(ENODEV)?;
-    ///       let iomem = request.iomap();
-    ///       let iomem = KBox::pin_init(iomem, GFP_KERNEL)?;
-    ///
-    ///       let io = iomem.access(pdev.as_ref())?;
+    ///       let iomem = request.iomap()?;
     ///
-    ///       let data = io.try_read32(offset)?;
+    ///       let data = iomem.try_read32(offset)?;
     ///
-    ///       io.try_write32(data, offset)?;
+    ///       iomem.try_write32(data, offset)?;
     ///
     ///       # Ok(SampleDriver)
     ///     }
     /// }
     /// ```
-    pub fn iomap(self) -> impl PinInit<Devres<IoMem<0>>, Error> + 'a {
-        Self::iomap_sized::<0>(self)
+    pub fn iomap(self) -> Result<IoMem<'bound>> {
+        self.iomap_sized::<0>()
     }
 
     /// Same as [`Self::iomap`] but with exclusive access to the underlying
     /// region.
-    pub fn iomap_exclusive(self) -> impl PinInit<Devres<ExclusiveIoMem<0>>, Error> + 'a {
-        Self::iomap_exclusive_sized::<0>(self)
+    pub fn iomap_exclusive(self) -> Result<ExclusiveIoMem<'bound, 0>> {
+        self.iomap_exclusive_sized::<0>()
     }
 }
 
@@ -169,9 +161,9 @@ pub fn iomap_exclusive(self) -> impl PinInit<Devres<ExclusiveIoMem<0>>, Error> +
 /// # Invariants
 ///
 /// - [`ExclusiveIoMem`] has exclusive access to the underlying [`IoMem`].
-pub struct ExclusiveIoMem<const SIZE: usize> {
+pub struct ExclusiveIoMem<'bound, const SIZE: usize> {
     /// The underlying `IoMem` instance.
-    iomem: IoMem<SIZE>,
+    iomem: IoMem<'bound, SIZE>,
 
     /// The region abstraction. This represents exclusive access to the
     /// range represented by the underlying `iomem`.
@@ -180,9 +172,9 @@ pub struct ExclusiveIoMem<const SIZE: usize> {
     _region: Region,
 }
 
-impl<const SIZE: usize> ExclusiveIoMem<SIZE> {
+impl<'bound, const SIZE: usize> ExclusiveIoMem<'bound, SIZE> {
     /// Creates a new `ExclusiveIoMem` instance.
-    fn ioremap(resource: &Resource) -> Result<Self> {
+    fn ioremap(dev: &'bound Device<Bound>, resource: &Resource) -> Result<Self> {
         let start = resource.start();
         let size = resource.size();
         let name = resource.name().unwrap_or_default();
@@ -196,26 +188,29 @@ fn ioremap(resource: &Resource) -> Result<Self> {
             )
             .ok_or(EBUSY)?;
 
-        let iomem = IoMem::ioremap(resource)?;
+        let iomem = IoMem::ioremap(dev, resource)?;
 
-        let iomem = ExclusiveIoMem {
+        Ok(ExclusiveIoMem {
             iomem,
             _region: region,
-        };
-
-        Ok(iomem)
+        })
     }
 
-    /// Creates a new `ExclusiveIoMem` instance from a previously acquired [`IoRequest`].
-    pub fn new<'a>(io_request: IoRequest<'a>) -> impl PinInit<Devres<Self>, Error> + 'a {
-        let dev = io_request.device;
-        let res = io_request.resource;
-
-        Devres::new(dev, Self::ioremap(res))
+    /// Consume the `ExclusiveIoMem` and register it as a device-managed resource.
+    ///
+    /// The returned `Devres<ExclusiveIoMem<'static, SIZE>>` can outlive the original lifetime
+    /// `'bound`. Access to the I/O memory is revoked when the device is unbound.
+    pub fn into_devres(self) -> Result<Devres<ExclusiveIoMem<'static, SIZE>>> {
+        // SAFETY: Casting to `'static` is sound because `Devres` guarantees the
+        // `ExclusiveIoMem` does not actually outlive the device -- access is revoked and the
+        // resource is released when the device is unbound.
+        let iomem: ExclusiveIoMem<'static, SIZE> = unsafe { core::mem::transmute(self) };
+        let dev = iomem.iomem.dev;
+        Devres::new(dev, iomem)
     }
 }
 
-impl<const SIZE: usize> Deref for ExclusiveIoMem<SIZE> {
+impl<const SIZE: usize> Deref for ExclusiveIoMem<'_, SIZE> {
     type Target = Mmio<SIZE>;
 
     fn deref(&self) -> &Self::Target {
@@ -232,12 +227,13 @@ fn deref(&self) -> &Self::Target {
 ///
 /// [`IoMem`] always holds an [`MmioRaw`] instance that holds a valid pointer to the
 /// start of the I/O memory mapped region.
-pub struct IoMem<const SIZE: usize = 0> {
+pub struct IoMem<'bound, const SIZE: usize = 0> {
+    dev: &'bound Device<Bound>,
     io: MmioRaw<SIZE>,
 }
 
-impl<const SIZE: usize> IoMem<SIZE> {
-    fn ioremap(resource: &Resource) -> Result<Self> {
+impl<'bound, const SIZE: usize> IoMem<'bound, SIZE> {
+    fn ioremap(dev: &'bound Device<Bound>, resource: &Resource) -> Result<Self> {
         // Note: Some ioremap() implementations use types that depend on the CPU
         // word width rather than the bus address width.
         //
@@ -269,28 +265,33 @@ fn ioremap(resource: &Resource) -> Result<Self> {
         }
 
         let io = MmioRaw::new(addr as usize, size)?;
-        let io = IoMem { io };
 
-        Ok(io)
+        Ok(IoMem { dev, io })
     }
 
-    /// Creates a new `IoMem` instance from a previously acquired [`IoRequest`].
-    pub fn new<'a>(io_request: IoRequest<'a>) -> impl PinInit<Devres<Self>, Error> + 'a {
-        let dev = io_request.device;
-        let res = io_request.resource;
-
-        Devres::new(dev, Self::ioremap(res))
+    /// Consume the `IoMem` and register it as a device-managed resource.
+    ///
+    /// The returned `Devres<IoMem<'static, SIZE>>` can outlive the original
+    /// lifetime `'bound`. Access to the I/O memory is revoked when the device
+    /// is unbound.
+    pub fn into_devres(self) -> Result<Devres<IoMem<'static, SIZE>>> {
+        // SAFETY: Casting to `'static` is sound because `Devres` guarantees the `IoMem` does not
+        // actually outlive the device -- access is revoked and the resource is released when the
+        // device is unbound.
+        let iomem: IoMem<'static, SIZE> = unsafe { core::mem::transmute(self) };
+        let dev = iomem.dev;
+        Devres::new(dev, iomem)
     }
 }
 
-impl<const SIZE: usize> Drop for IoMem<SIZE> {
+impl<const SIZE: usize> Drop for IoMem<'_, SIZE> {
     fn drop(&mut self) {
         // SAFETY: Safe as by the invariant of `Io`.
         unsafe { bindings::iounmap(self.io.addr() as *mut c_void) }
     }
 }
 
-impl<const SIZE: usize> Deref for IoMem<SIZE> {
+impl<const SIZE: usize> Deref for IoMem<'_, SIZE> {
     type Target = Mmio<SIZE>;
 
     fn deref(&self) -> &Self::Target {
-- 
2.54.0

[PATCH v3 21/27] samples: rust: rust_driver_pci: use HRT lifetime for Bar

[Danilo Krummrich]

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

The driver struct holds &'bound pci::Device directly instead of
ARef<pci::Device>, and pci::Bar<'bound> 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, 40 insertions(+), 49 deletions(-)

diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs
index 7791363df0a0..f7240025bb0c 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<'bound> = pci::Bar<'bound, { regs::END }>;
 
 #[derive(Copy, Clone, Debug)]
 struct TestIndex(u8);
@@ -66,14 +64,14 @@ impl TestIndex {
     const NO_EVENTFD: Self = Self(0);
 }
 
-#[pin_data(PinnedDrop)]
-struct SampleDriver {
-    pdev: ARef<pci::Device>,
-    #[pin]
-    bar: Devres<Bar0>,
+struct SampleDriverData<'bound> {
+    pdev: &'bound pci::Device,
+    bar: Bar0<'bound>,
     index: TestIndex,
 }
 
+struct SampleDriver;
+
 kernel::pci_device_table!(
     PCI_TABLE,
     MODULE_PCI_TABLE,
@@ -84,8 +82,8 @@ struct SampleDriver {
     )]
 );
 
-impl SampleDriver {
-    fn testdev(index: &TestIndex, bar: &Bar0) -> Result<u32> {
+impl SampleDriverData<'_> {
+    fn testdev(index: &TestIndex, bar: &Bar0<'_>) -> Result<u32> {
         // Select the test.
         bar.write_reg(regs::TEST::zeroed().with_index(*index));
 
@@ -140,56 +138,49 @@ fn config_space(pdev: &pci::Device<Bound>) {
 
 impl pci::Driver for SampleDriver {
     type IdInfo = TestIndex;
-    type Data<'bound> = Self;
+    type Data<'bound> = SampleDriverData<'bound>;
 
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 
     fn probe<'bound>(
         pdev: &'bound pci::Device<Core>,
         info: &'bound Self::IdInfo,
-    ) -> impl PinInit<Self, Error> + 'bound {
-        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(),
-            }))
+    ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound {
+        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",
+            SampleDriverData::testdev(info, &bar)?
+        );
+        SampleDriverData::config_space(pdev);
+
+        Ok(SampleDriverData {
+            pdev,
+            bar,
+            index: *info,
         })
     }
 
-    fn unbind(pdev: &pci::Device<Core>, this: Pin<&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<'bound>(_pdev: &'bound pci::Device<Core>, this: Pin<&'bound Self::Data<'bound>>) {
+        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 SampleDriverData<'_> {
+    fn drop(&mut self) {
         dev_dbg!(self.pdev, "Remove Rust PCI driver sample.\n");
     }
 }
-- 
2.54.0

[PATCH v3 22/27] rust: driver-core: rename 'a lifetime to 'bound

[Danilo Krummrich]

Rename the generic lifetime parameter from 'a to 'bound in pci,
platform, i2c and devres. This makes it explicit that the lifetime
represents the device binding scope, consistent with the convention
established by the HRT series.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/devres.rs   | 14 +++++++++-----
 rust/kernel/i2c.rs      |  6 +++---
 rust/kernel/pci/irq.rs  | 38 +++++++++++++++++++-------------------
 rust/kernel/platform.rs | 18 +++++++++---------
 4 files changed, 40 insertions(+), 36 deletions(-)

diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
index ec63317665f4..58efe80474bd 100644
--- a/rust/kernel/devres.rs
+++ b/rust/kernel/devres.rs
@@ -280,10 +280,11 @@ pub fn device(&self) -> &Device {
         &self.dev
     }
 
-    /// Obtain `&'a T`, bypassing the [`Revocable`].
+    /// Obtain `&'bound T`, bypassing the [`Revocable`].
     ///
-    /// This method allows to directly obtain a `&'a T`, bypassing the [`Revocable`], by presenting
-    /// a `&'a Device<Bound>` of the same [`Device`] this [`Devres`] instance has been created with.
+    /// This method allows to directly obtain a `&'bound T`, bypassing the
+    /// [`Revocable`], by presenting a `&'bound Device<Bound>` of the same
+    /// [`Device`] this [`Devres`] instance has been created with.
     ///
     /// # Errors
     ///
@@ -316,7 +317,7 @@ pub fn device(&self) -> &Device {
     ///     Ok(())
     /// }
     /// ```
-    pub fn access<'a>(&'a self, dev: &'a Device<Bound>) -> Result<&'a T> {
+    pub fn access<'bound>(&'bound self, dev: &'bound Device<Bound>) -> Result<&'bound T> {
         if self.dev.as_raw() != dev.as_raw() {
             return Err(EINVAL);
         }
@@ -338,7 +339,10 @@ pub fn try_access_with<R, F: FnOnce(&T) -> R>(&self, f: F) -> Option<R> {
     }
 
     /// [`Devres`] accessor for [`Revocable::try_access_with_guard`].
-    pub fn try_access_with_guard<'a>(&'a self, guard: &'a rcu::Guard) -> Option<&'a T> {
+    pub fn try_access_with_guard<'bound>(
+        &'bound self,
+        guard: &'bound rcu::Guard,
+    ) -> Option<&'bound T> {
         self.data().try_access_with_guard(guard)
     }
 }
diff --git a/rust/kernel/i2c.rs b/rust/kernel/i2c.rs
index 7b92d42a2b98..2bb7e54922e5 100644
--- a/rust/kernel/i2c.rs
+++ b/rust/kernel/i2c.rs
@@ -566,11 +566,11 @@ unsafe impl Sync for I2cClient {}
 
 impl Registration {
     /// The C `i2c_new_client_device` function wrapper for manual I2C client creation.
-    pub fn new<'a>(
+    pub fn new<'bound>(
         i2c_adapter: &I2cAdapter,
         i2c_board_info: &I2cBoardInfo,
-        parent_dev: &'a device::Device<device::Bound>,
-    ) -> impl PinInit<Devres<Self>, Error> + 'a {
+        parent_dev: &'bound device::Device<device::Bound>,
+    ) -> impl PinInit<Devres<Self>, Error> + 'bound {
         Devres::new(parent_dev, Self::try_new(i2c_adapter, i2c_board_info))
     }
 
diff --git a/rust/kernel/pci/irq.rs b/rust/kernel/pci/irq.rs
index d9230e105541..92207fd46403 100644
--- a/rust/kernel/pci/irq.rs
+++ b/rust/kernel/pci/irq.rs
@@ -76,19 +76,19 @@ const fn as_raw(self) -> u32 {
 /// This type ties an IRQ vector to the device it was allocated for,
 /// ensuring the vector is only used with the correct device.
 #[derive(Clone, Copy)]
-pub struct IrqVector<'a> {
-    dev: &'a Device<Bound>,
+pub struct IrqVector<'bound> {
+    dev: &'bound Device<Bound>,
     index: u32,
 }
 
-impl<'a> IrqVector<'a> {
+impl<'bound> IrqVector<'bound> {
     /// Creates a new [`IrqVector`] for the given device and index.
     ///
     /// # Safety
     ///
     /// - `index` must be a valid IRQ vector index for `dev`.
     /// - `dev` must point to a [`Device`] that has successfully allocated IRQ vectors.
-    unsafe fn new(dev: &'a Device<Bound>, index: u32) -> Self {
+    unsafe fn new(dev: &'bound Device<Bound>, index: u32) -> Self {
         Self { dev, index }
     }
 
@@ -98,10 +98,10 @@ fn index(&self) -> u32 {
     }
 }
 
-impl<'a> TryInto<IrqRequest<'a>> for IrqVector<'a> {
+impl<'bound> TryInto<IrqRequest<'bound>> for IrqVector<'bound> {
     type Error = Error;
 
-    fn try_into(self) -> Result<IrqRequest<'a>> {
+    fn try_into(self) -> Result<IrqRequest<'bound>> {
         // SAFETY: `self.as_raw` returns a valid pointer to a `struct pci_dev`.
         let irq = unsafe { bindings::pci_irq_vector(self.dev.as_raw(), self.index()) };
         if irq < 0 {
@@ -129,12 +129,12 @@ impl IrqVectorRegistration {
     ///
     /// Allocates IRQ vectors and registers them with devres for automatic cleanup.
     /// Returns a range of valid IRQ vectors.
-    fn register<'a>(
-        dev: &'a Device<Bound>,
+    fn register<'bound>(
+        dev: &'bound Device<Bound>,
         min_vecs: u32,
         max_vecs: u32,
         irq_types: IrqTypes,
-    ) -> Result<RangeInclusive<IrqVector<'a>>> {
+    ) -> Result<RangeInclusive<IrqVector<'bound>>> {
         // SAFETY:
         // - `dev.as_raw()` is guaranteed to be a valid pointer to a `struct pci_dev`
         //   by the type invariant of `Device`.
@@ -173,13 +173,13 @@ fn drop(&mut self) {
 
 impl Device<device::Bound> {
     /// Returns a [`kernel::irq::Registration`] for the given IRQ vector.
-    pub fn request_irq<'a, T: crate::irq::Handler + 'static>(
-        &'a self,
-        vector: IrqVector<'a>,
+    pub fn request_irq<'bound, T: crate::irq::Handler + 'static>(
+        &'bound self,
+        vector: IrqVector<'bound>,
         flags: irq::Flags,
         name: &'static CStr,
-        handler: impl PinInit<T, Error> + 'a,
-    ) -> impl PinInit<irq::Registration<T>, Error> + 'a {
+        handler: impl PinInit<T, Error> + 'bound,
+    ) -> impl PinInit<irq::Registration<T>, Error> + 'bound {
         pin_init::pin_init_scope(move || {
             let request = vector.try_into()?;
 
@@ -188,13 +188,13 @@ pub fn request_irq<'a, T: crate::irq::Handler + 'static>(
     }
 
     /// Returns a [`kernel::irq::ThreadedRegistration`] for the given IRQ vector.
-    pub fn request_threaded_irq<'a, T: crate::irq::ThreadedHandler + 'static>(
-        &'a self,
-        vector: IrqVector<'a>,
+    pub fn request_threaded_irq<'bound, T: crate::irq::ThreadedHandler + 'static>(
+        &'bound self,
+        vector: IrqVector<'bound>,
         flags: irq::Flags,
         name: &'static CStr,
-        handler: impl PinInit<T, Error> + 'a,
-    ) -> impl PinInit<irq::ThreadedRegistration<T>, Error> + 'a {
+        handler: impl PinInit<T, Error> + 'bound,
+    ) -> impl PinInit<irq::ThreadedRegistration<T>, Error> + 'bound {
         pin_init::pin_init_scope(move || {
             let request = vector.try_into()?;
 
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 6e4437866c30..44f68da5432d 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -337,13 +337,13 @@ macro_rules! define_irq_accessor_by_index {
         $handler_trait:ident
     ) => {
         $(#[$meta])*
-        pub fn $fn_name<'a, T: irq::$handler_trait + 'static>(
-            &'a self,
+        pub fn $fn_name<'bound, T: irq::$handler_trait + 'static>(
+            &'bound self,
             flags: irq::Flags,
             index: u32,
             name: &'static CStr,
-            handler: impl PinInit<T, Error> + 'a,
-        ) -> impl PinInit<irq::$reg_type<T>, Error> + 'a {
+            handler: impl PinInit<T, Error> + 'bound,
+        ) -> impl PinInit<irq::$reg_type<T>, Error> + 'bound {
             pin_init::pin_init_scope(move || {
                 let request = self.$request_fn(index)?;
 
@@ -366,13 +366,13 @@ macro_rules! define_irq_accessor_by_name {
         $handler_trait:ident
     ) => {
         $(#[$meta])*
-        pub fn $fn_name<'a, T: irq::$handler_trait + 'static>(
-            &'a self,
+        pub fn $fn_name<'bound, T: irq::$handler_trait + 'static>(
+            &'bound self,
             flags: irq::Flags,
-            irq_name: &'a CStr,
+            irq_name: &'bound CStr,
             name: &'static CStr,
-            handler: impl PinInit<T, Error> + 'a,
-        ) -> impl PinInit<irq::$reg_type<T>, Error> + 'a {
+            handler: impl PinInit<T, Error> + 'bound,
+        ) -> impl PinInit<irq::$reg_type<T>, Error> + 'bound {
             pin_init::pin_init_scope(move || {
                 let request = self.$request_fn(irq_name)?;
 
-- 
2.54.0

[PATCH REF v3 23/27] gpu: nova-core: rename 'a lifetime to 'bound

[Danilo Krummrich]

Rename the generic lifetime parameter from 'a to 'bound in nova-core.
This makes it explicit that the lifetime represents the device binding
scope, consistent with the convention established by the HRT series.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/nova-core/firmware/gsp.rs    |  8 ++++----
 drivers/gpu/nova-core/gpu.rs             |  8 ++++----
 drivers/gpu/nova-core/gsp/commands.rs    | 10 +++++-----
 drivers/gpu/nova-core/gsp/fw/commands.rs |  4 +++-
 4 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/nova-core/firmware/gsp.rs b/drivers/gpu/nova-core/firmware/gsp.rs
index 2fcc255c3bc8..9dbd88c55f7e 100644
--- a/drivers/gpu/nova-core/firmware/gsp.rs
+++ b/drivers/gpu/nova-core/firmware/gsp.rs
@@ -65,11 +65,11 @@ pub(crate) struct GspFirmware {
 impl GspFirmware {
     /// Loads the GSP firmware binaries, map them into `dev`'s address-space, and creates the page
     /// tables expected by the GSP bootloader to load it.
-    pub(crate) fn new<'a>(
-        dev: &'a device::Device<device::Bound>,
+    pub(crate) fn new<'bound>(
+        dev: &'bound device::Device<device::Bound>,
         chipset: Chipset,
-        ver: &'a str,
-    ) -> impl PinInit<Self, Error> + 'a {
+        ver: &'bound str,
+    ) -> impl PinInit<Self, Error> + 'bound {
         pin_init::pin_init_scope(move || {
             let firmware = super::request_firmware(dev, chipset, "gsp", ver)?;
 
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 0f6fe9a1b955..9288b30fe4c3 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -241,11 +241,11 @@ pub(crate) struct Gpu {
 }
 
 impl Gpu {
-    pub(crate) fn new<'a>(
-        pdev: &'a pci::Device<device::Bound>,
+    pub(crate) fn new<'bound>(
+        pdev: &'bound pci::Device<device::Bound>,
         devres_bar: Arc<Devres<Bar0>>,
-        bar: &'a Bar0,
-    ) -> impl PinInit<Self, Error> + 'a {
+        bar: &'bound Bar0,
+    ) -> impl PinInit<Self, Error> + 'bound {
         try_pin_init!(Self {
             spec: Spec::new(pdev.as_ref(), bar).inspect(|spec| {
                 dev_info!(pdev,"NVIDIA ({})\n", spec);
diff --git a/drivers/gpu/nova-core/gsp/commands.rs b/drivers/gpu/nova-core/gsp/commands.rs
index c89c7b57a751..0da5b92f4b27 100644
--- a/drivers/gpu/nova-core/gsp/commands.rs
+++ b/drivers/gpu/nova-core/gsp/commands.rs
@@ -35,18 +35,18 @@
 };
 
 /// The `GspSetSystemInfo` command.
-pub(crate) struct SetSystemInfo<'a> {
-    pdev: &'a pci::Device<device::Bound>,
+pub(crate) struct SetSystemInfo<'bound> {
+    pdev: &'bound pci::Device<device::Bound>,
 }
 
-impl<'a> SetSystemInfo<'a> {
+impl<'bound> SetSystemInfo<'bound> {
     /// Creates a new `GspSetSystemInfo` command using the parameters of `pdev`.
-    pub(crate) fn new(pdev: &'a pci::Device<device::Bound>) -> Self {
+    pub(crate) fn new(pdev: &'bound pci::Device<device::Bound>) -> Self {
         Self { pdev }
     }
 }
 
-impl<'a> CommandToGsp for SetSystemInfo<'a> {
+impl<'bound> CommandToGsp for SetSystemInfo<'bound> {
     const FUNCTION: MsgFunction = MsgFunction::GspSetSystemInfo;
     type Command = GspSetSystemInfo;
     type Reply = NoReply;
diff --git a/drivers/gpu/nova-core/gsp/fw/commands.rs b/drivers/gpu/nova-core/gsp/fw/commands.rs
index db46276430be..d3ef7ecdd73e 100644
--- a/drivers/gpu/nova-core/gsp/fw/commands.rs
+++ b/drivers/gpu/nova-core/gsp/fw/commands.rs
@@ -24,7 +24,9 @@ pub(crate) struct GspSetSystemInfo {
 impl GspSetSystemInfo {
     /// Returns an in-place initializer for the `GspSetSystemInfo` command.
     #[allow(non_snake_case)]
-    pub(crate) fn init<'a>(dev: &'a pci::Device<device::Bound>) -> impl Init<Self, Error> + 'a {
+    pub(crate) fn init<'bound>(
+        dev: &'bound pci::Device<device::Bound>,
+    ) -> impl Init<Self, Error> + 'bound {
         type InnerGspSystemInfo = bindings::GspSystemInfo;
         let init_inner = try_init!(InnerGspSystemInfo {
             gpuPhysAddr: dev.resource_start(0)?,
-- 
2.54.0

[PATCH REF v3 24/27] gpu: nova-core: use lifetime for Bar

[Danilo Krummrich]

Take advantage of the lifetime-parameterized pci::Bar<'bound> to hold
the BAR mapping directly in NovaCore<'bound>, and pass a borrowed
reference to Gpu<'bound>.

This eliminates the Arc<Devres<Bar0>> indirection, removes runtime
revocation checks for BAR access, and simplifies Gpu::unbind().

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/nova-core/driver.rs    | 46 +++++++++++++++---------------
 drivers/gpu/nova-core/gpu.rs       | 27 +++++++-----------
 drivers/gpu/nova-core/nova_core.rs |  2 +-
 3 files changed, 34 insertions(+), 41 deletions(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index 3f6d8cedf5ab..fb52d21a7d92 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -14,12 +14,9 @@
     },
     prelude::*,
     sizes::SZ_16M,
-    sync::{
-        atomic::{
-            Atomic,
-            Relaxed, //
-        },
-        Arc,
+    sync::atomic::{
+        Atomic,
+        Relaxed, //
     },
     types::ForLt,
 };
@@ -30,9 +27,10 @@
 static AUXILIARY_ID_COUNTER: Atomic<u32> = Atomic::new(0);
 
 #[pin_data]
-pub(crate) struct NovaCore {
+pub(crate) struct NovaCore<'bound> {
     #[pin]
-    pub(crate) gpu: Gpu,
+    pub(crate) gpu: Gpu<'bound>,
+    bar: pci::Bar<'bound, BAR0_SIZE>,
     #[allow(clippy::type_complexity)]
     _reg: Devres<auxiliary::Registration<ForLt!(())>>,
 }
@@ -47,12 +45,14 @@ pub(crate) struct NovaCore {
 // DMA addresses. These systems should be quite rare.
 const GPU_DMA_BITS: u32 = 47;
 
-pub(crate) type Bar0 = pci::Bar<'static, BAR0_SIZE>;
+pub(crate) type Bar0 = kernel::io::Mmio<BAR0_SIZE>;
+
+pub(crate) struct NovaCoreDriver;
 
 kernel::pci_device_table!(
     PCI_TABLE,
     MODULE_PCI_TABLE,
-    <NovaCore as pci::Driver>::IdInfo,
+    <NovaCoreDriver as pci::Driver>::IdInfo,
     [
         // Modern NVIDIA GPUs will show up as either VGA or 3D controllers.
         (
@@ -74,15 +74,15 @@ pub(crate) struct NovaCore {
     ]
 );
 
-impl pci::Driver for NovaCore {
+impl pci::Driver for NovaCoreDriver {
     type IdInfo = ();
-    type Data<'bound> = Self;
+    type Data<'bound> = NovaCore<'bound>;
     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
 
     fn probe<'bound>(
         pdev: &'bound pci::Device<Core>,
         _info: &'bound Self::IdInfo,
-    ) -> impl PinInit<Self, Error> + 'bound {
+    ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound {
         pin_init::pin_init_scope(move || {
             dev_dbg!(pdev, "Probe Nova Core GPU driver.\n");
 
@@ -94,14 +94,14 @@ fn probe<'bound>(
             // other threads of execution.
             unsafe { pdev.dma_set_mask_and_coherent(DmaMask::new::<GPU_DMA_BITS>())? };
 
-            let bar = Arc::new(
-                pdev.iomap_region_sized::<BAR0_SIZE>(0, c"nova-core/bar0")?
-                    .into_devres()?,
-                GFP_KERNEL,
-            )?;
-
-            Ok(try_pin_init!(Self {
-                gpu <- Gpu::new(pdev, bar.clone(), bar.access(pdev.as_ref())?),
+            Ok(try_pin_init!(NovaCore {
+                bar: pdev.iomap_region_sized::<BAR0_SIZE>(0, c"nova-core/bar0")?,
+                // TODO: Use `&bar` self-referential pin-init syntax once available.
+                //
+                // SAFETY: `bar` is initialized before this expression is evaluated
+                // (`try_pin_init!()` initializes fields in declaration order), lives at a pinned
+                // stable address, and is dropped after `gpu` (struct field drop order).
+                gpu <- Gpu::new(pdev, unsafe { &*core::ptr::from_ref(bar) }),
                 _reg: auxiliary::Registration::new(
                     pdev.as_ref(),
                     c"nova-drm",
@@ -115,7 +115,7 @@ fn probe<'bound>(
         })
     }
 
-    fn unbind<'bound>(pdev: &'bound pci::Device<Core>, this: Pin<&'bound Self>) {
-        this.gpu.unbind(pdev.as_ref());
+    fn unbind<'bound>(_pdev: &'bound pci::Device<Core>, this: Pin<&'bound Self::Data<'bound>>) {
+        this.gpu.unbind();
     }
 }
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 9288b30fe4c3..03295fa6fb32 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -2,13 +2,11 @@
 
 use kernel::{
     device,
-    devres::Devres,
     fmt,
     io::Io,
     num::Bounded,
     pci,
-    prelude::*,
-    sync::Arc, //
+    prelude::*, //
 };
 
 use crate::{
@@ -224,10 +222,10 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 
 /// Structure holding the resources required to operate the GPU.
 #[pin_data]
-pub(crate) struct Gpu {
+pub(crate) struct Gpu<'bound> {
     spec: Spec,
-    /// MMIO mapping of PCI BAR 0
-    bar: Arc<Devres<Bar0>>,
+    /// MMIO mapping of PCI BAR 0.
+    bar: &'bound Bar0,
     /// System memory page required for flushing all pending GPU-side memory writes done through
     /// PCIE into system memory, via sysmembar (A GPU-initiated HW memory-barrier operation).
     sysmem_flush: SysmemFlush,
@@ -240,10 +238,9 @@ pub(crate) struct Gpu {
     gsp: Gsp,
 }
 
-impl Gpu {
-    pub(crate) fn new<'bound>(
+impl<'bound> Gpu<'bound> {
+    pub(crate) fn new(
         pdev: &'bound pci::Device<device::Bound>,
-        devres_bar: Arc<Devres<Bar0>>,
         bar: &'bound Bar0,
     ) -> impl PinInit<Self, Error> + 'bound {
         try_pin_init!(Self {
@@ -257,6 +254,8 @@ pub(crate) fn new<'bound>(
                     .inspect_err(|_| dev_err!(pdev, "GFW boot did not complete\n"))?;
             },
 
+            bar,
+
             sysmem_flush: SysmemFlush::register(pdev.as_ref(), bar, spec.chipset)?,
 
             gsp_falcon: Falcon::new(
@@ -270,19 +269,13 @@ pub(crate) fn new<'bound>(
             gsp <- Gsp::new(pdev),
 
             _: { gsp.boot(pdev, bar, spec.chipset, gsp_falcon, sec2_falcon)? },
-
-            bar: devres_bar,
         })
     }
 
     /// Called when the corresponding [`Device`](device::Device) is unbound.
     ///
     /// Note: This method must only be called from `Driver::unbind`.
-    pub(crate) fn unbind(&self, dev: &device::Device<device::Core>) {
-        kernel::warn_on!(self
-            .bar
-            .access(dev)
-            .inspect(|bar| self.sysmem_flush.unregister(bar))
-            .is_err());
+    pub(crate) fn unbind(&self) {
+        self.sysmem_flush.unregister(self.bar);
     }
 }
diff --git a/drivers/gpu/nova-core/nova_core.rs b/drivers/gpu/nova-core/nova_core.rs
index 04a1fa6b25f8..073d87714d3a 100644
--- a/drivers/gpu/nova-core/nova_core.rs
+++ b/drivers/gpu/nova-core/nova_core.rs
@@ -47,7 +47,7 @@ struct NovaCoreModule {
     // Fields are dropped in declaration order, so `_driver` is dropped first,
     // then `_debugfs_guard` clears `DEBUGFS_ROOT`.
     #[pin]
-    _driver: Registration<pci::Adapter<driver::NovaCore>>,
+    _driver: Registration<pci::Adapter<driver::NovaCoreDriver>>,
     _debugfs_guard: DebugfsRootGuard,
 }
 
-- 
2.54.0

[PATCH REF v3 25/27] gpu: nova-core: unregister sysmem flush page from Drop

[Danilo Krummrich]

Now that SysmemFlush can borrow the Bar via HRT lifetime, store a
&'bound Bar0 reference and implement Drop to automatically unregister
the sysmem flush page. This removes the need for manual unregister()
calls and the Gpu::unbind() method.

Reported-by: Eliot Courtney <ecourtney@nvidia.com>
Closes: https://lore.kernel.org/all/20260409-fix-systemflush-v1-1-a1d6c968f17c@nvidia.com/
Fixes: 6554ad65b589 ("gpu: nova-core: register sysmem flush page")
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/nova-core/driver.rs |  4 ----
 drivers/gpu/nova-core/fb.rs     | 22 ++++++++++------------
 drivers/gpu/nova-core/gpu.rs    |  9 +--------
 3 files changed, 11 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index fb52d21a7d92..6571a8c59d09 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -114,8 +114,4 @@ fn probe<'bound>(
             }))
         })
     }
-
-    fn unbind<'bound>(_pdev: &'bound pci::Device<Core>, this: Pin<&'bound Self::Data<'bound>>) {
-        this.gpu.unbind();
-    }
 }
diff --git a/drivers/gpu/nova-core/fb.rs b/drivers/gpu/nova-core/fb.rs
index bdd5eed760e1..a707fbfe3ced 100644
--- a/drivers/gpu/nova-core/fb.rs
+++ b/drivers/gpu/nova-core/fb.rs
@@ -46,21 +46,20 @@
 /// Because of this, the sysmem flush memory page must be registered as early as possible during
 /// driver initialization, and before any falcon is reset.
 ///
-/// Users are responsible for manually calling [`Self::unregister`] before dropping this object,
-/// otherwise the GPU might still use it even after it has been freed.
-pub(crate) struct SysmemFlush {
+pub(crate) struct SysmemFlush<'bound> {
     /// Chipset we are operating on.
     chipset: Chipset,
     device: ARef<device::Device>,
+    bar: &'bound Bar0,
     /// Keep the page alive as long as we need it.
     page: CoherentHandle,
 }
 
-impl SysmemFlush {
+impl<'bound> SysmemFlush<'bound> {
     /// Allocate a memory page and register it as the sysmem flush page.
     pub(crate) fn register(
         dev: &device::Device<device::Bound>,
-        bar: &Bar0,
+        bar: &'bound Bar0,
         chipset: Chipset,
     ) -> Result<Self> {
         let page = CoherentHandle::alloc(dev, kernel::page::PAGE_SIZE, GFP_KERNEL)?;
@@ -70,19 +69,18 @@ pub(crate) fn register(
         Ok(Self {
             chipset,
             device: dev.into(),
+            bar,
             page,
         })
     }
+}
 
-    /// Unregister the managed sysmem flush page.
-    ///
-    /// In order to gracefully tear down the GPU, users must make sure to call this method before
-    /// dropping the object.
-    pub(crate) fn unregister(&self, bar: &Bar0) {
+impl Drop for SysmemFlush<'_> {
+    fn drop(&mut self) {
         let hal = hal::fb_hal(self.chipset);
 
-        if hal.read_sysmem_flush_page(bar) == self.page.dma_handle() {
-            let _ = hal.write_sysmem_flush_page(bar, 0).inspect_err(|e| {
+        if hal.read_sysmem_flush_page(self.bar) == self.page.dma_handle() {
+            let _ = hal.write_sysmem_flush_page(self.bar, 0).inspect_err(|e| {
                 dev_warn!(
                     &self.device,
                     "failed to unregister sysmem flush page: {:?}\n",
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 03295fa6fb32..c17d068b35eb 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -228,7 +228,7 @@ pub(crate) struct Gpu<'bound> {
     bar: &'bound Bar0,
     /// System memory page required for flushing all pending GPU-side memory writes done through
     /// PCIE into system memory, via sysmembar (A GPU-initiated HW memory-barrier operation).
-    sysmem_flush: SysmemFlush,
+    sysmem_flush: SysmemFlush<'bound>,
     /// GSP falcon instance, used for GSP boot up and cleanup.
     gsp_falcon: Falcon<GspFalcon>,
     /// SEC2 falcon instance, used for GSP boot up and cleanup.
@@ -271,11 +271,4 @@ pub(crate) fn new(
             _: { gsp.boot(pdev, bar, spec.chipset, gsp_falcon, sec2_falcon)? },
         })
     }
-
-    /// Called when the corresponding [`Device`](device::Device) is unbound.
-    ///
-    /// Note: This method must only be called from `Driver::unbind`.
-    pub(crate) fn unbind(&self) {
-        self.sysmem_flush.unregister(self.bar);
-    }
 }
-- 
2.54.0

[PATCH REF v3 26/27] gpu: nova-core: replace ARef<Device> with &'bound Device in SysmemFlush

[Danilo Krummrich]

Now that SysmemFlush is lifetime-parameterized, the ARef<Device> is
unnecessary -- a plain &'bound Device reference suffices.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/nova-core/fb.rs | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/nova-core/fb.rs b/drivers/gpu/nova-core/fb.rs
index a707fbfe3ced..e22dec12ae7e 100644
--- a/drivers/gpu/nova-core/fb.rs
+++ b/drivers/gpu/nova-core/fb.rs
@@ -15,8 +15,7 @@
         Alignable,
         Alignment, //
     },
-    sizes::*,
-    sync::aref::ARef, //
+    sizes::*, //
 };
 
 use crate::{
@@ -49,7 +48,7 @@
 pub(crate) struct SysmemFlush<'bound> {
     /// Chipset we are operating on.
     chipset: Chipset,
-    device: ARef<device::Device>,
+    device: &'bound device::Device,
     bar: &'bound Bar0,
     /// Keep the page alive as long as we need it.
     page: CoherentHandle,
@@ -58,7 +57,7 @@ pub(crate) struct SysmemFlush<'bound> {
 impl<'bound> SysmemFlush<'bound> {
     /// Allocate a memory page and register it as the sysmem flush page.
     pub(crate) fn register(
-        dev: &device::Device<device::Bound>,
+        dev: &'bound device::Device<device::Bound>,
         bar: &'bound Bar0,
         chipset: Chipset,
     ) -> Result<Self> {
@@ -68,7 +67,7 @@ pub(crate) fn register(
 
         Ok(Self {
             chipset,
-            device: dev.into(),
+            device: dev,
             bar,
             page,
         })
-- 
2.54.0

[PATCH REF v3 27/27] gpu: drm: tyr: use lifetime for IoMem

[Danilo Krummrich]

Take advantage of the lifetime-parameterized IoMem<'bound> to use the
memory mapping directly during probe, eliminating the Arc<Devres<IoMem>>
indirection.

Since the IoMem is only used during probe, this also simplifies
Register::read/write to be infallible -- the Devres access check is no
longer needed, so reads return u32 directly and writes return ().

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
Not yet updated to Tyr using the register!() macro, but probably good enough for
reference.
---
 drivers/gpu/drm/tyr/driver.rs | 14 ++++----
 drivers/gpu/drm/tyr/gpu.rs    | 62 +++++++++++++++++------------------
 drivers/gpu/drm/tyr/regs.rs   | 21 +++---------
 3 files changed, 41 insertions(+), 56 deletions(-)

diff --git a/drivers/gpu/drm/tyr/driver.rs b/drivers/gpu/drm/tyr/driver.rs
index 8c916913e976..884c20ec18ce 100644
--- a/drivers/gpu/drm/tyr/driver.rs
+++ b/drivers/gpu/drm/tyr/driver.rs
@@ -10,7 +10,6 @@
         Core,
         Device, //
     },
-    devres::Devres,
     drm,
     drm::ioctl,
     io::poll,
@@ -23,7 +22,6 @@
     sizes::SZ_2M,
     sync::{
         aref::ARef,
-        Arc,
         Mutex, //
     },
     time, //
@@ -37,7 +35,7 @@
     regs, //
 };
 
-pub(crate) type IoMem = kernel::io::mem::IoMem<'static, SZ_2M>;
+pub(crate) type IoMem = kernel::io::Mmio<SZ_2M>;
 
 pub(crate) struct TyrDrmDriver;
 
@@ -65,11 +63,11 @@ pub(crate) struct TyrDrmDeviceData {
     pub(crate) gpu_info: GpuInfo,
 }
 
-fn issue_soft_reset(dev: &Device<Bound>, iomem: &Devres<IoMem>) -> Result {
-    regs::GPU_CMD.write(dev, iomem, regs::GPU_CMD_SOFT_RESET)?;
+fn issue_soft_reset(dev: &Device<Bound>, iomem: &IoMem) -> Result {
+    regs::GPU_CMD.write(iomem, regs::GPU_CMD_SOFT_RESET);
 
     poll::read_poll_timeout(
-        || regs::GPU_IRQ_RAWSTAT.read(dev, iomem),
+        || Ok(regs::GPU_IRQ_RAWSTAT.read(iomem)),
         |status| *status & regs::GPU_IRQ_RAWSTAT_RESET_COMPLETED != 0,
         time::Delta::from_millis(1),
         time::Delta::from_millis(100),
@@ -110,12 +108,12 @@ fn probe<'bound>(
         let sram_regulator = Regulator::<regulator::Enabled>::get(pdev.as_ref(), c"sram")?;
 
         let request = pdev.io_request_by_index(0).ok_or(ENODEV)?;
-        let iomem = Arc::new(request.iomap_sized::<SZ_2M>()?.into_devres()?, GFP_KERNEL)?;
+        let iomem = request.iomap_sized::<SZ_2M>()?;
 
         issue_soft_reset(pdev.as_ref(), &iomem)?;
         gpu::l2_power_on(pdev.as_ref(), &iomem)?;
 
-        let gpu_info = GpuInfo::new(pdev.as_ref(), &iomem)?;
+        let gpu_info = GpuInfo::new(&iomem);
         gpu_info.log(pdev);
 
         let platform: ARef<platform::Device> = pdev.into();
diff --git a/drivers/gpu/drm/tyr/gpu.rs b/drivers/gpu/drm/tyr/gpu.rs
index a88775160f98..bb0473c85bf7 100644
--- a/drivers/gpu/drm/tyr/gpu.rs
+++ b/drivers/gpu/drm/tyr/gpu.rs
@@ -10,7 +10,6 @@
         Bound,
         Device, //
     },
-    devres::Devres,
     io::poll,
     platform,
     prelude::*,
@@ -35,37 +34,36 @@
 pub(crate) struct GpuInfo(pub(crate) uapi::drm_panthor_gpu_info);
 
 impl GpuInfo {
-    pub(crate) fn new(dev: &Device<Bound>, iomem: &Devres<IoMem>) -> Result<Self> {
-        let gpu_id = regs::GPU_ID.read(dev, iomem)?;
-        let csf_id = regs::GPU_CSF_ID.read(dev, iomem)?;
-        let gpu_rev = regs::GPU_REVID.read(dev, iomem)?;
-        let core_features = regs::GPU_CORE_FEATURES.read(dev, iomem)?;
-        let l2_features = regs::GPU_L2_FEATURES.read(dev, iomem)?;
-        let tiler_features = regs::GPU_TILER_FEATURES.read(dev, iomem)?;
-        let mem_features = regs::GPU_MEM_FEATURES.read(dev, iomem)?;
-        let mmu_features = regs::GPU_MMU_FEATURES.read(dev, iomem)?;
-        let thread_features = regs::GPU_THREAD_FEATURES.read(dev, iomem)?;
-        let max_threads = regs::GPU_THREAD_MAX_THREADS.read(dev, iomem)?;
-        let thread_max_workgroup_size = regs::GPU_THREAD_MAX_WORKGROUP_SIZE.read(dev, iomem)?;
-        let thread_max_barrier_size = regs::GPU_THREAD_MAX_BARRIER_SIZE.read(dev, iomem)?;
-        let coherency_features = regs::GPU_COHERENCY_FEATURES.read(dev, iomem)?;
-
-        let texture_features = regs::GPU_TEXTURE_FEATURES0.read(dev, iomem)?;
-
-        let as_present = regs::GPU_AS_PRESENT.read(dev, iomem)?;
-
-        let shader_present = u64::from(regs::GPU_SHADER_PRESENT_LO.read(dev, iomem)?);
+    pub(crate) fn new(iomem: &IoMem) -> Self {
+        let gpu_id = regs::GPU_ID.read(iomem);
+        let csf_id = regs::GPU_CSF_ID.read(iomem);
+        let gpu_rev = regs::GPU_REVID.read(iomem);
+        let core_features = regs::GPU_CORE_FEATURES.read(iomem);
+        let l2_features = regs::GPU_L2_FEATURES.read(iomem);
+        let tiler_features = regs::GPU_TILER_FEATURES.read(iomem);
+        let mem_features = regs::GPU_MEM_FEATURES.read(iomem);
+        let mmu_features = regs::GPU_MMU_FEATURES.read(iomem);
+        let thread_features = regs::GPU_THREAD_FEATURES.read(iomem);
+        let max_threads = regs::GPU_THREAD_MAX_THREADS.read(iomem);
+        let thread_max_workgroup_size = regs::GPU_THREAD_MAX_WORKGROUP_SIZE.read(iomem);
+        let thread_max_barrier_size = regs::GPU_THREAD_MAX_BARRIER_SIZE.read(iomem);
+        let coherency_features = regs::GPU_COHERENCY_FEATURES.read(iomem);
+
+        let texture_features = regs::GPU_TEXTURE_FEATURES0.read(iomem);
+
+        let as_present = regs::GPU_AS_PRESENT.read(iomem);
+
+        let shader_present = u64::from(regs::GPU_SHADER_PRESENT_LO.read(iomem));
         let shader_present =
-            shader_present | u64::from(regs::GPU_SHADER_PRESENT_HI.read(dev, iomem)?) << 32;
+            shader_present | u64::from(regs::GPU_SHADER_PRESENT_HI.read(iomem)) << 32;
 
-        let tiler_present = u64::from(regs::GPU_TILER_PRESENT_LO.read(dev, iomem)?);
-        let tiler_present =
-            tiler_present | u64::from(regs::GPU_TILER_PRESENT_HI.read(dev, iomem)?) << 32;
+        let tiler_present = u64::from(regs::GPU_TILER_PRESENT_LO.read(iomem));
+        let tiler_present = tiler_present | u64::from(regs::GPU_TILER_PRESENT_HI.read(iomem)) << 32;
 
-        let l2_present = u64::from(regs::GPU_L2_PRESENT_LO.read(dev, iomem)?);
-        let l2_present = l2_present | u64::from(regs::GPU_L2_PRESENT_HI.read(dev, iomem)?) << 32;
+        let l2_present = u64::from(regs::GPU_L2_PRESENT_LO.read(iomem));
+        let l2_present = l2_present | u64::from(regs::GPU_L2_PRESENT_HI.read(iomem)) << 32;
 
-        Ok(Self(uapi::drm_panthor_gpu_info {
+        Self(uapi::drm_panthor_gpu_info {
             gpu_id,
             gpu_rev,
             csf_id,
@@ -88,7 +86,7 @@ pub(crate) fn new(dev: &Device<Bound>, iomem: &Devres<IoMem>) -> Result<Self> {
             core_features,
             pad: 0,
             gpu_features: 0,
-        }))
+        })
     }
 
     pub(crate) fn log(&self, pdev: &platform::Device) {
@@ -208,11 +206,11 @@ fn from(value: u32) -> Self {
 }
 
 /// Powers on the l2 block.
-pub(crate) fn l2_power_on(dev: &Device<Bound>, iomem: &Devres<IoMem>) -> Result {
-    regs::L2_PWRON_LO.write(dev, iomem, 1)?;
+pub(crate) fn l2_power_on(dev: &Device<Bound>, iomem: &IoMem) -> Result {
+    regs::L2_PWRON_LO.write(iomem, 1);
 
     poll::read_poll_timeout(
-        || regs::L2_READY_LO.read(dev, iomem),
+        || Ok(regs::L2_READY_LO.read(iomem)),
         |status| *status == 1,
         Delta::from_millis(1),
         Delta::from_millis(100),
diff --git a/drivers/gpu/drm/tyr/regs.rs b/drivers/gpu/drm/tyr/regs.rs
index 611870c2e6af..0881b3812afd 100644
--- a/drivers/gpu/drm/tyr/regs.rs
+++ b/drivers/gpu/drm/tyr/regs.rs
@@ -7,16 +7,7 @@
 // does.
 #![allow(dead_code)]
 
-use kernel::{
-    bits::bit_u32,
-    device::{
-        Bound,
-        Device, //
-    },
-    devres::Devres,
-    io::Io,
-    prelude::*, //
-};
+use kernel::{bits::bit_u32, io::Io};
 
 use crate::driver::IoMem;
 
@@ -29,15 +20,13 @@
 
 impl<const OFFSET: usize> Register<OFFSET> {
     #[inline]
-    pub(crate) fn read(&self, dev: &Device<Bound>, iomem: &Devres<IoMem>) -> Result<u32> {
-        let value = (*iomem).access(dev)?.read32(OFFSET);
-        Ok(value)
+    pub(crate) fn read(&self, iomem: &IoMem) -> u32 {
+        iomem.read32(OFFSET)
     }
 
     #[inline]
-    pub(crate) fn write(&self, dev: &Device<Bound>, iomem: &Devres<IoMem>, value: u32) -> Result {
-        (*iomem).access(dev)?.write32(value, OFFSET);
-        Ok(())
+    pub(crate) fn write(&self, iomem: &IoMem, value: u32) {
+        iomem.write32(value, OFFSET);
     }
 }
 
-- 
2.54.0