rust: qom: move bridge for TypeInfo functions out of pl011

Allow the ObjectImpl trait to expose Rust functions that avoid raw
pointers (though INSTANCE_INIT for example is still unsafe).
ObjectImpl::TYPE_INFO adds thunks around the functions in
ObjectImpl.

While at it, document `TypeInfo`.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 12 insertions, 28 deletions

diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs
index 56403c3660..b9f8fb134b 100644
--- a/rust/hw/char/pl011/src/device.rs
+++ b/rust/hw/char/pl011/src/device.rs
@@ -110,7 +110,7 @@ impl ObjectImpl for PL011State {
     type Class = PL011Class;
     const TYPE_NAME: &'static CStr = crate::TYPE_PL011;
     const PARENT_TYPE_NAME: Option<&'static CStr> = Some(TYPE_SYS_BUS_DEVICE);
-    const INSTANCE_INIT: Option<unsafe extern "C" fn(obj: *mut Object)> = Some(pl011_init);
+    const INSTANCE_INIT: Option<unsafe fn(&mut Self)> = Some(Self::init);
 }
 
 #[repr(C)]
@@ -615,19 +615,6 @@ pub unsafe extern "C" fn pl011_create(
     }
 }
 
-/// # Safety
-///
-/// We expect the FFI user of this function to pass a valid pointer, that has
-/// the same size as [`PL011State`]. We also expect the device is
-/// readable/writeable from one thread at any time.
-pub unsafe extern "C" fn pl011_init(obj: *mut Object) {
-    unsafe {
-        debug_assert!(!obj.is_null());
-        let mut state = NonNull::new_unchecked(obj.cast::<PL011State>());
-        state.as_mut().init();
-    }
-}
-
 #[repr(C)]
 #[derive(Debug, qemu_api_macros::Object)]
 /// PL011 Luminary device model.
@@ -640,19 +627,16 @@ pub struct PL011LuminaryClass {
     _inner: [u8; 0],
 }
 
-/// Initializes a pre-allocated, unitialized instance of `PL011Luminary`.
-///
-/// # Safety
-///
-/// We expect the FFI user of this function to pass a valid pointer, that has
-/// the same size as [`PL011Luminary`]. We also expect the device is
-/// readable/writeable from one thread at any time.
-pub unsafe extern "C" fn pl011_luminary_init(obj: *mut Object) {
-    unsafe {
-        debug_assert!(!obj.is_null());
-        let mut state = NonNull::new_unchecked(obj.cast::<PL011Luminary>());
-        let state = state.as_mut();
-        state.parent_obj.device_id = DeviceId::Luminary;
+impl PL011Luminary {
+    /// Initializes a pre-allocated, unitialized instance of `PL011Luminary`.
+    ///
+    /// # Safety
+    ///
+    /// We expect the FFI user of this function to pass a valid pointer, that
+    /// has the same size as [`PL011Luminary`]. We also expect the device is
+    /// readable/writeable from one thread at any time.
+    unsafe fn init(&mut self) {
+        self.parent_obj.device_id = DeviceId::Luminary;
     }
 }
 
@@ -660,7 +644,7 @@ impl ObjectImpl for PL011Luminary {
     type Class = PL011LuminaryClass;
     const TYPE_NAME: &'static CStr = crate::TYPE_PL011_LUMINARY;
     const PARENT_TYPE_NAME: Option<&'static CStr> = Some(crate::TYPE_PL011);
-    const INSTANCE_INIT: Option<unsafe extern "C" fn(obj: *mut Object)> = Some(pl011_luminary_init);
+    const INSTANCE_INIT: Option<unsafe fn(&mut Self)> = Some(Self::init);
 }
 
 impl DeviceImpl for PL011Luminary {}