[mii] Add separate mii_restart() function

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/mii.c

@@ -30,6 +30,37 @@ FILE_LICENCE ( GPL2_OR_LATER );
  *
  */
 
+/**
+ * Restart autonegotiation
+ *
+ * @v mii		MII interface
+ * @ret rc		Return status code
+ */
+int mii_restart ( struct mii_interface *mii ) {
+	int bmcr;
+	int rc;
+
+	/* Read BMCR */
+	bmcr = mii_read ( mii, MII_BMCR );
+	if ( bmcr < 0 ) {
+		rc = bmcr;
+		DBGC ( mii, "MII %p could not read BMCR: %s\n",
+		       mii, strerror ( rc ) );
+		return rc;
+	}
+
+	/* Enable and restart autonegotiation */
+	bmcr |= ( BMCR_ANENABLE | BMCR_ANRESTART );
+	if ( ( rc = mii_write ( mii, MII_BMCR, bmcr ) ) != 0 ) {
+		DBGC ( mii, "MII %p could not write BMCR: %s\n",
+		       mii, strerror ( rc ) );
+		return rc;
+	}
+
+	DBGC ( mii, "MII %p restarted autonegotiation\n", mii );
+	return 0;
+}
+
 /**
  * Reset MII interface
  *
@@ -70,11 +101,8 @@ int mii_reset ( struct mii_interface *mii ) {
 		/* Force autonegotation on again, in case it was
 		 * cleared by the reset.
 		 */
-		if ( ( rc = mii_write ( mii, MII_BMCR, BMCR_ANENABLE ) ) != 0 ){
-			DBGC ( mii, "MII %p could not write BMCR: %s\n",
-			       mii, strerror ( rc ) );
+		if ( ( rc = mii_restart ( mii ) ) != 0 )
 			return rc;
-		}
 
 		DBGC ( mii, "MII %p reset after %dms\n", mii, i );
 		return 0;

src/include/ipxe/mii.h

@@ -81,6 +81,7 @@ mii_write ( struct mii_interface *mii, unsigned int reg, unsigned int data ) {
 /** Maximum time to wait for a reset, in milliseconds */
 #define MII_RESET_MAX_WAIT_MS 500
 
+extern int mii_restart ( struct mii_interface *mii );
 extern int mii_reset ( struct mii_interface *mii );
 
 #endif /* _IPXE_MII_H */