rust: qdev: add minimal clock bindings

Add the minimal support that is needed by pl011's event and tracepoint.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20250929154938.594389-11-pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

rust/hw/core/src/qdev.rs

@@ -411,6 +411,39 @@ where
 
 impl<R: ObjectDeref> DeviceMethods for R where R::Target: IsA<DeviceState> {}
 
+impl Clock {
+    pub const PERIOD_1SEC: u64 = bindings::CLOCK_PERIOD_1SEC;
+
+    pub const fn period_from_ns(ns: u64) -> u64 {
+        ns * Self::PERIOD_1SEC / 1_000_000_000
+    }
+
+    pub const fn period_from_hz(hz: u64) -> u64 {
+        if hz == 0 {
+            0
+        } else {
+            Self::PERIOD_1SEC / hz
+        }
+    }
+
+    pub const fn period_to_hz(period: u64) -> u64 {
+        if period == 0 {
+            0
+        } else {
+            Self::PERIOD_1SEC / period
+        }
+    }
+
+    pub const fn period(&self) -> u64 {
+        // SAFETY: Clock is returned by init_clock_in with zero value for period
+        unsafe { &*self.0.as_ptr() }.period
+    }
+
+    pub const fn hz(&self) -> u64 {
+        Self::period_to_hz(self.period())
+    }
+}
+
 unsafe impl ObjectType for Clock {
     type Class = ObjectClass;
     const TYPE_NAME: &'static CStr =