[test] kernel/protocols: Add log buffer as OCP source

Introduce a fake log buffer struct and implement on top of it
the new trait.

This will be dropped once the real log buffer will be introduced.

Signed-off-by: Nicola Ramacciotti <niko.ramak@gmail.com>

Author: n-ramacciotti

kernel/src/protocols/ocp.rs

@@ -19,9 +19,9 @@ use zerocopy::{Immutable, IntoBytes};
 const OCP_SOURCE_NAME_LEN: usize = 124;
 const OCP_SOURCE_ENTRY_SIZE: usize = 128;
 
-const OCP_SOURCES_LEN: usize = 0;
+const OCP_SOURCES_LEN: usize = 1;
 
-static OCP_SOURCES: [&dyn OcpSourceOperations; OCP_SOURCES_LEN] = [];
+static OCP_SOURCES: [&dyn OcpSourceOperations; OCP_SOURCES_LEN] = [&LOG_BUFFER];
 
 // OCP protocol services
 const SVSM_OCP_LIST: u32 = 0;
@@ -34,6 +34,26 @@ const LOW_32_BITS: u64 = 0xffff_ffff;
 pub const OBSERVABILITY_CONFIGURATION_PROTOCOL_VERSION_MIN: u32 = 1;
 pub const OBSERVABILITY_CONFIGURATION_PROTOCOL_VERSION_MAX: u32 = 1;
 
+struct LogBuffer {
+    ocp_source_entry: OcpSource,
+}
+
+impl LogBuffer {
+    const fn new(name: &str, writable: bool) -> Self {
+        Self {
+            ocp_source_entry: OcpSource::new(writable, name),
+        }
+    }
+}
+
+impl OcpSourceOperations for LogBuffer {
+    fn get_source_entry(&self) -> &OcpSource {
+        &self.ocp_source_entry
+    }
+}
+
+static LOG_BUFFER: LogBuffer = LogBuffer::new("LogBuffer", false);
+
 #[bitfield(u32)]
 #[derive(IntoBytes, Immutable)]
 struct OcpSourceFlags {