net: bgmac: improve handling PHY

1. Use info from DT if available

It allows describing for example a fixed link. It's more accurate than
just guessing there may be one (depending on a chipset).

2. Verify PHY ID before trying to connect PHY

PHY addr 0x1e (30) is special in Broadcom routers and means a switch
connected as MDIO devices instead of a real PHY. Don't try connecting to
it.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bgmac-bcma.c

@@ -11,6 +11,7 @@
 #include <linux/bcma/bcma.h>
 #include <linux/brcmphy.h>
 #include <linux/etherdevice.h>
+#include <linux/of_mdio.h>
 #include <linux/of_net.h>
 #include "bgmac.h"
 
@@ -86,17 +87,28 @@ static int bcma_phy_connect(struct bgmac *bgmac)
 	struct phy_device *phy_dev;
 	char bus_id[MII_BUS_ID_SIZE + 3];
 
+	/* DT info should be the most accurate */
+	phy_dev = of_phy_get_and_connect(bgmac->net_dev, bgmac->dev->of_node,
+					 bgmac_adjust_link);
+	if (phy_dev)
+		return 0;
+
 	/* Connect to the PHY */
-	snprintf(bus_id, sizeof(bus_id), PHY_ID_FMT, bgmac->mii_bus->id,
-		 bgmac->phyaddr);
-	phy_dev = phy_connect(bgmac->net_dev, bus_id, bgmac_adjust_link,
-			      PHY_INTERFACE_MODE_MII);
-	if (IS_ERR(phy_dev)) {
-		dev_err(bgmac->dev, "PHY connection failed\n");
-		return PTR_ERR(phy_dev);
+	if (bgmac->mii_bus && bgmac->phyaddr != BGMAC_PHY_NOREGS) {
+		snprintf(bus_id, sizeof(bus_id), PHY_ID_FMT, bgmac->mii_bus->id,
+			 bgmac->phyaddr);
+		phy_dev = phy_connect(bgmac->net_dev, bus_id, bgmac_adjust_link,
+				      PHY_INTERFACE_MODE_MII);
+		if (IS_ERR(phy_dev)) {
+			dev_err(bgmac->dev, "PHY connection failed\n");
+			return PTR_ERR(phy_dev);
+		}
+
+		return 0;
 	}
 
-	return 0;
+	/* Assume a fixed link to the switch port */
+	return bgmac_phy_connect_direct(bgmac);
 }
 
 static const struct bcma_device_id bgmac_bcma_tbl[] = {
@@ -297,10 +309,7 @@ static int bgmac_probe(struct bcma_device *core)
 	bgmac->cco_ctl_maskset = bcma_bgmac_cco_ctl_maskset;
 	bgmac->get_bus_clock = bcma_bgmac_get_bus_clock;
 	bgmac->cmn_maskset32 = bcma_bgmac_cmn_maskset32;
-	if (bgmac->mii_bus)
-		bgmac->phy_connect = bcma_phy_connect;
-	else
-		bgmac->phy_connect = bgmac_phy_connect_direct;
+	bgmac->phy_connect = bcma_phy_connect;
 
 	err = bgmac_enet_probe(bgmac);
 	if (err)