Merge tag 'nand/for-6.14' into mtd/next

* Raw NAND changes

A new controller driver, from Nuvoton, has been merged.

Bastien Curutchet has contributed a series improving the Davinci
controller driver, both on the organization of the code, but also on the
performance side. The binding has also been converted to yaml, received
a new OOB layout and now supports on-die ECC engines.

The Qualcomm controller driver has been deeply cleaned to extract some
parts of the code into a shared file with the Qualcomm SPI memory
controller.

Aside from these main changes, the Cadence binding has been converted to
yaml, the brcmnand controller driver has received a small fix, otherwise
some more minor changes have also made their way in.

* SPI NAND changes

The SPI NAND subsystem has seen a great improvement, with the advent of
DTR operations (DDR operations, which may be extended to the address
cycles). The first vendor driver to benefit from these improvements is
the Winbond driver.

A new manufacturer driver is added SkyHigh, with a new constraint for
the core, it is impossible to disable the on-die ECC engine.

A Foresee device is also now supported.

1 files changed, 16 insertions, 2 deletions

diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 4d1d2062f6eb..fd3e97192ed8 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -519,7 +519,15 @@ impl_has_work! {
     impl{T} HasWork<Self> for ClosureWork<T> { self.work }
 }
 
-// SAFETY: TODO.
+// SAFETY: The `__enqueue` implementation in RawWorkItem uses a `work_struct` initialized with the
+// `run` method of this trait as the function pointer because:
+//   - `__enqueue` gets the `work_struct` from the `Work` field, using `T::raw_get_work`.
+//   - The only safe way to create a `Work` object is through `Work::new`.
+//   - `Work::new` makes sure that `T::Pointer::run` is passed to `init_work_with_key`.
+//   - Finally `Work` and `RawWorkItem` guarantee that the correct `Work` field
+//     will be used because of the ID const generic bound. This makes sure that `T::raw_get_work`
+//     uses the correct offset for the `Work` field, and `Work::new` picks the correct
+//     implementation of `WorkItemPointer` for `Arc<T>`.
 unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Arc<T>
 where
     T: WorkItem<ID, Pointer = Self>,
@@ -537,7 +545,13 @@ where
     }
 }
 
-// SAFETY: TODO.
+// SAFETY: The `work_struct` raw pointer is guaranteed to be valid for the duration of the call to
+// the closure because we get it from an `Arc`, which means that the ref count will be at least 1,
+// and we don't drop the `Arc` ourselves. If `queue_work_on` returns true, it is further guaranteed
+// to be valid until a call to the function pointer in `work_struct` because we leak the memory it
+// points to, and only reclaim it if the closure returns false, or in `WorkItemPointer::run`, which
+// is what the function pointer in the `work_struct` must be pointing to, according to the safety
+// requirements of `WorkItemPointer`.
 unsafe impl<T, const ID: u64> RawWorkItem<ID> for Arc<T>
 where
     T: WorkItem<ID, Pointer = Self>,