Separate out message info helpers for MSI capabilities

Author: IsaacWoods

src/capability/msi.rs

@@ -113,31 +113,40 @@ impl MsiCapability {
         MultipleMessageSupport::try_from(reg.get_bits(4..7) as u8).unwrap_or(MultipleMessageSupport::Int1)
     }
 
-    /// Set the memory address that will be written to when the interrupt fires.
+    /// Set the memory address that will be written to when the interrupt fires, and the data that
+    /// will be written to it.
+    pub fn set_message_info(&self, address: u64, data: u32, access: impl ConfigRegionAccess) {
+        unsafe {
+            access.write(self.address.address, self.address.offset + 0x04, address.get_bits(0..32) as u32);
+            if self.is_64bit {
+                access.write(self.address.address, self.address.offset + 0x08, address.get_bits(32..64) as u32);
+            }
+        }
+        let data_offset = if self.is_64bit { 0x0c } else { 0x08 };
+        unsafe {
+            access.write(self.address.address, self.address.offset + data_offset, data);
+        }
+    }
+
+    /// Set the memory address that will be written to when the interrupt fires, and the data that
+    /// will be written to it, specialised for the message format the LAPIC expects.
     ///
     /// # Arguments
     /// * `address` - Target Local APIC address (if not changed, can be calculated with `0xfee00000 | (processor << 12)`)
     /// * `vector` - Which interrupt vector should be triggered on LAPIC
     /// * `trigger_mode` - When interrupt should be triggered
     /// * `access` - PCI Configuration Space accessor
-    pub fn set_message_info(
+    pub fn set_message_info_lapic(
         &self,
         address: u64,
         vector: u8,
         trigger_mode: TriggerMode,
         access: impl ConfigRegionAccess,
     ) {
-        unsafe {
-            access.write(self.address.address, self.address.offset + 0x04, address.get_bits(0..32) as u32);
-            if self.is_64bit {
-                access.write(self.address.address, self.address.offset + 0x08, address.get_bits(32..64) as u32);
-            }
-        }
-        let data_offset = if self.is_64bit { 0x0c } else { 0x08 };
-        let mut data = unsafe { access.read(self.address.address, self.address.offset + data_offset) };
+        let mut data = 0;
         data.set_bits(0..8, vector as u32);
         data.set_bits(14..16, trigger_mode as u32);
-        unsafe { access.write(self.address.address, self.address.offset + data_offset, data) }
+        self.set_message_info(address, data, access);
     }
 
     /// Get interrupt mask