net: bcmgenet: use MAC link status for fixed phy

BugLink: https://bugs.launchpad.net/bugs/1797563

[ Upstream commit c3c397c1 ]

When using the fixed PHY with GENET (e.g. MOCA) the PHY link
status can be determined from the internal link status captured
by the MAC. This allows the PHY state machine to use the correct
link state with the fixed PHY even if MAC link event interrupts
are missed when the net device is opened.

Fixes: 8d88c6eb ("net: bcmgenet: enable MoCA link state change detection")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/net/ethernet/broadcom/genet/bcmgenet.h

@@ -185,6 +185,9 @@ struct bcmgenet_mib_counters {
 #define UMAC_MAC1			0x010
 #define UMAC_MAX_FRAME_LEN		0x014
 
+#define UMAC_MODE			0x44
+#define  MODE_LINK_STATUS		(1 << 5)
+
 #define UMAC_EEE_CTRL			0x064
 #define  EN_LPI_RX_PAUSE		(1 << 0)
 #define  EN_LPI_TX_PFC			(1 << 1)

drivers/net/ethernet/broadcom/genet/bcmmii.c

@@ -167,8 +167,14 @@ void bcmgenet_mii_setup(struct net_device *dev)
 static int bcmgenet_fixed_phy_link_update(struct net_device *dev,
 					  struct fixed_phy_status *status)
 {
-	if (dev && dev->phydev && status)
-		status->link = dev->phydev->link;
+	struct bcmgenet_priv *priv;
+	u32 reg;
+
+	if (dev && dev->phydev && status) {
+		priv = netdev_priv(dev);
+		reg = bcmgenet_umac_readl(priv, UMAC_MODE);
+		status->link = !!(reg & MODE_LINK_STATUS);
+	}
 
 	return 0;
 }