stmmac: link status reporting

kernel/driver/net/stmmac/src/lib.rs

@@ -60,13 +60,25 @@ struct Stmmac {
 
 impl Inner {
     fn link_state(&self) -> LinkState {
-        // TODO read the link state properly, i.e., read from PHY's registers, I guess? I didn't
-        //      find a nice way to read the link state from the MAC itself, it only seems to report
-        //      the MAC<->PHY link state (which is always up, obviously)
-        LinkState::Ethernet(EthernetLinkState::Up(
-            EthernetSpeed::Unknown,
-            Duplex::Unknown,
-        ))
+        let status = self.regs.lock().MAC.MACPHYCSR.extract();
+        let link = if status.matches_all(MACPHYCSR::LNKSTS::Up) {
+            let speed = match status.read_as_enum(MACPHYCSR::LNKSPEED) {
+                Some(MACPHYCSR::LNKSPEED::Value::Speed2_5MHz) => EthernetSpeed::Speed10,
+                Some(MACPHYCSR::LNKSPEED::Value::Speed25MHz) => EthernetSpeed::Speed100,
+                Some(MACPHYCSR::LNKSPEED::Value::Speed125MHz) => EthernetSpeed::Speed1000,
+                _ => EthernetSpeed::Unknown,
+            };
+            let duplex = if status.matches_all(MACPHYCSR::LNKMOD::FullDuplex) {
+                Duplex::Full
+            } else {
+                Duplex::Half
+            };
+            EthernetLinkState::Up(speed, duplex)
+        } else {
+            EthernetLinkState::Down
+        };
+
+        LinkState::Ethernet(link)
     }
 }