spi: aspeed: Improve handling of shared SPI

Merge series from Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>:

This patch series improves handling of SPI controllers that are
shared by spi-mem devices and other SPI peripherals.

The primary goal of this series is to support non-spi-mem devices in
the ASPEED FMC/SPI controller driver. It also addresses an issue in
the spi-mem framework observed when different types of SPI devices
operate concurrently on the same controller, ensuring that spi-mem
operations are properly serialized.

1 files changed, 20 insertions, 11 deletions

diff --git a/rust/kernel/i2c.rs b/rust/kernel/i2c.rs
index 491e6cc25cf4..39b0a9a207fd 100644
--- a/rust/kernel/i2c.rs
+++ b/rust/kernel/i2c.rs
@@ -92,13 +92,22 @@ macro_rules! i2c_device_table {
 /// An adapter for the registration of I2C drivers.
 pub struct Adapter<T: Driver>(T);
 
-// SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if
+// SAFETY:
+// - `bindings::i2c_driver` is a C type declared as `repr(C)`.
+// - `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> {
+    type DriverType = bindings::i2c_driver;
+    type DriverData = T;
+    const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
+}
+
+// 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> {
-    type RegType = bindings::i2c_driver;
-
     unsafe fn register(
-        idrv: &Opaque<Self::RegType>,
+        idrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
         module: &'static ThisModule,
     ) -> Result {
@@ -133,12 +142,12 @@ unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
             (*idrv.get()).driver.acpi_match_table = acpi_table;
         }
 
-        // SAFETY: `idrv` is guaranteed to be a valid `RegType`.
+        // SAFETY: `idrv` is guaranteed to be a valid `DriverType`.
         to_result(unsafe { bindings::i2c_register_driver(module.0, idrv.get()) })
     }
 
-    unsafe fn unregister(idrv: &Opaque<Self::RegType>) {
-        // SAFETY: `idrv` is guaranteed to be a valid `RegType`.
+    unsafe fn unregister(idrv: &Opaque<Self::DriverType>) {
+        // SAFETY: `idrv` is guaranteed to be a valid `DriverType`.
         unsafe { bindings::i2c_del_driver(idrv.get()) }
     }
 }
@@ -169,9 +178,9 @@ impl<T: Driver + 'static> Adapter<T> {
         // 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_obtain::<T>() };
+        let data = unsafe { idev.as_ref().drvdata_borrow::<T>() };
 
-        T::unbind(idev, data.as_ref());
+        T::unbind(idev, data);
     }
 
     extern "C" fn shutdown_callback(idev: *mut bindings::i2c_client) {
@@ -181,9 +190,9 @@ impl<T: Driver + 'static> Adapter<T> {
         // 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_obtain::<T>() };
+        let data = unsafe { idev.as_ref().drvdata_borrow::<T>() };
 
-        T::shutdown(idev, data.as_ref());
+        T::shutdown(idev, data);
     }
 
     /// The [`i2c::IdTable`] of the corresponding driver.