net: phy: realtek: Disable interrupt on Realtek Ethernet PHY drivers

Some Realtek Ethernet PHYs, like RTL8211D(G/N) and RTL8211E(G), have
interrupts enabled by default. If the interrupt is not treated later by
the OS and the PHY's interrupt line is enabled and shared with other
interrupts, the system will get an interrupt storm. This patch disables
the interrupt for PHY devices that use one of the current Realtek
Ethernet PHY drivers. Some of Realtek Ethernet PHYs, such as RTL8211B(L)
have the interrupt masked. In this case, the functionality of the PHY
should not be afected since this patch brings INER and INSR registers to
their default values.

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@freescale.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/net/phy/realtek.c

@@ -3,7 +3,7 @@
  *
  * SPDX-License-Identifier:	GPL-2.0+
  *
- * Copyright 2010-2011 Freescale Semiconductor, Inc.
+ * Copyright 2010-2011, 2015 Freescale Semiconductor, Inc.
  * author Andy Fleming
  */
 #include <config.h>
@@ -21,12 +21,28 @@
 #define MIIM_RTL8211x_PHYSTAT_SPDDONE  0x0800
 #define MIIM_RTL8211x_PHYSTAT_LINK     0x0400
 
+/* RTL8211x PHY Interrupt Enable Register */
+#define MIIM_RTL8211x_PHY_INER         0x12
+#define MIIM_RTL8211x_PHY_INTR_ENA     0x9f01
+#define MIIM_RTL8211x_PHY_INTR_DIS     0x0000
+
+/* RTL8211x PHY Interrupt Status Register */
+#define MIIM_RTL8211x_PHY_INSR         0x13
 
 /* RealTek RTL8211x */
 static int rtl8211x_config(struct phy_device *phydev)
 {
 	phy_write(phydev, MDIO_DEVAD_NONE, MII_BMCR, BMCR_RESET);
 
+	/* mask interrupt at init; if the interrupt is
+	 * needed indeed, it should be explicitly enabled
+	 */
+	phy_write(phydev, MDIO_DEVAD_NONE, MIIM_RTL8211x_PHY_INER,
+		  MIIM_RTL8211x_PHY_INTR_DIS);
+
+	/* read interrupt status just to clear it */
+	phy_read(phydev, MDIO_DEVAD_NONE, MIIM_RTL8211x_PHY_INER);
+
 	genphy_config_aneg(phydev);
 
 	return 0;