link_mode: Support convert EthtoolLinkModeDuplex to u8

Signed-off-by: Gris Ge <fge@redhat.com>

Author: cathay4t

src/link_mode/attr.rs

@@ -23,7 +23,7 @@ const DUPLEX_HALF: u8 = 0x00;
 const DUPLEX_FULL: u8 = 0x01;
 const DUPLEX_UNKNOWN: u8 = 0xff;
 
-#[derive(Debug, PartialEq, Eq, Clone)]
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub enum EthtoolLinkModeDuplex {
     Half,
     Full,
@@ -42,6 +42,17 @@ impl From<u8> for EthtoolLinkModeDuplex {
     }
 }
 
+impl From<EthtoolLinkModeDuplex> for u8 {
+    fn from(v: EthtoolLinkModeDuplex) -> u8 {
+        match v {
+            EthtoolLinkModeDuplex::Half => DUPLEX_HALF,
+            EthtoolLinkModeDuplex::Full => DUPLEX_FULL,
+            EthtoolLinkModeDuplex::Unknown => DUPLEX_UNKNOWN,
+            EthtoolLinkModeDuplex::Other(d) => d,
+        }
+    }
+}
+
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub enum EthtoolLinkModeAttr {
     Header(Vec<EthtoolHeader>),