[realtek] Forcibly enable advertisement of 1000Mbps speeds

Some RTL8169 cards (observed with an RTL8169SC) power up advertising
only 100Mbps, despite being capable of 1000Mbps.  Forcibly enable
advertisement of 1000Mbps on any RTL8169-like card.

This change relies on the assumption that the CTRL1000 register will
not exist on 100Mbps-only RTL8169 cards such as the RTL8101.

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

src/drivers/net/realtek.c

 	return -ETIMEDOUT;
 }
 
+/**
+ * Configure PHY for Gigabit operation
+ *
+ * @v rtl		Realtek device
+ * @ret rc		Return status code
+ */
+static int realtek_phy_speed ( struct realtek_nic *rtl ) {
+	int ctrl1000;
+	int rc;
+
+	/* Read CTRL1000 register */
+	ctrl1000 = mii_read ( &rtl->mii, MII_CTRL1000 );
+	if ( ctrl1000 < 0 ) {
+		rc = ctrl1000;
+		DBGC ( rtl, "REALTEK %p could not read CTRL1000: %s\n",
+		       rtl, strerror ( rc ) );
+		return rc;
+	}
+
+	/* Advertise 1000Mbps speeds */
+	ctrl1000 |= ( ADVERTISE_1000FULL | ADVERTISE_1000HALF );
+	if ( ( rc = mii_write ( &rtl->mii, MII_CTRL1000, ctrl1000 ) ) != 0 ) {
+		DBGC ( rtl, "REALTEK %p could not write CTRL1000: %s\n",
+		       rtl, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Reset PHY
+ *
+ * @v rtl		Realtek device
+ * @ret rc		Return status code
+ */
+static int realtek_phy_reset ( struct realtek_nic *rtl ) {
+	int rc;
+
+	/* Do nothing if we have no separate PHY register access */
+	if ( ! rtl->have_phy_regs )
+		return 0;
+
+	/* Perform MII reset */
+	if ( ( rc = mii_reset ( &rtl->mii ) ) != 0 ) {
+		DBGC ( rtl, "REALTEK %p could not reset MII: %s\n",
+		       rtl, strerror ( rc ) );
+		return rc;
+	}
+
+	/* Some cards (e.g. RTL8169SC) do not advertise Gigabit by
+	 * default.  Try to enable advertisement of Gigabit speeds.
+	 */
+	if ( ( rc = realtek_phy_speed ( rtl ) ) != 0 ) {
+		/* Ignore failures, since the register may not be
+		 * present on non-Gigabit PHYs (e.g. RTL8101).
+		 */
+	}
+
+	/* Restart autonegotiation */
+	if ( ( rc = mii_restart ( &rtl->mii ) ) != 0 ) {
+		DBGC ( rtl, "REALTEK %p could not restart MII: %s\n",
+		       rtl, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
 /******************************************************************************
  *
  * Link state
 
 	/* Initialise and reset MII interface */
 	mii_init ( &rtl->mii, &realtek_mii_operations );
-	if ( rtl->have_phy_regs &&
-	     ( ( rc = mii_reset ( &rtl->mii ) ) != 0 ) ) {
-		DBGC ( rtl, "REALTEK %p could not reset MII: %s\n",
-		       rtl, strerror ( rc ) );
-		goto err_mii_reset;
-	}
+	if ( ( rc = realtek_phy_reset ( rtl ) ) != 0 )
+		goto err_phy_reset;
 
 	/* Register network device */
 	if ( ( rc = register_netdev ( netdev ) ) != 0 )
  err_register_nvo:
 	unregister_netdev ( netdev );
  err_register_netdev:
- err_mii_reset:
+ err_phy_reset:
  err_nvs_read:
 	realtek_reset ( rtl );
  err_reset: