bgmac: support up to 3 cores (devices) on a bus

Broadcom buses may have more than 1 Ethernet device. This is used e.g.
to have few interfaces connected to different switch ports. So far we
saw chipsets with only 2 devices (e.g. BCM4706) but recent ones have
up to 3 (e.g. Netgear R8000 uses 3rd interface for most of switch
traffic, lower interfaces are for some kind of offloading).
Signed-off-by: NRafał Miłecki <zajec5@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bgmac.c

@@ -1549,11 +1549,20 @@ static int bgmac_probe(struct bcma_device *core)
 	struct net_device *net_dev;
 	struct bgmac *bgmac;
 	struct ssb_sprom *sprom = &core->bus->sprom;
-	u8 *mac = core->core_unit ? sprom->et1mac : sprom->et0mac;
+	u8 *mac;
 	int err;
 
-	/* We don't support 2nd, 3rd, ... units, SPROM has to be adjusted */
-	if (core->core_unit > 1) {
+	switch (core->core_unit) {
+	case 0:
+		mac = sprom->et0mac;
+		break;
+	case 1:
+		mac = sprom->et1mac;
+		break;
+	case 2:
+		mac = sprom->et2mac;
+		break;
+	default:
 		pr_err("Unsupported core_unit %d\n", core->core_unit);
 		return -ENOTSUPP;
 	}
@@ -1588,8 +1597,17 @@ static int bgmac_probe(struct bcma_device *core)
 	}
 	bgmac->cmn = core->bus->drv_gmac_cmn.core;
 
-	bgmac->phyaddr = core->core_unit ? sprom->et1phyaddr :
-			 sprom->et0phyaddr;
+	switch (core->core_unit) {
+	case 0:
+		bgmac->phyaddr = sprom->et0phyaddr;
+		break;
+	case 1:
+		bgmac->phyaddr = sprom->et1phyaddr;
+		break;
+	case 2:
+		bgmac->phyaddr = sprom->et2phyaddr;
+		break;
+	}
 	bgmac->phyaddr &= BGMAC_PHY_MASK;
 	if (bgmac->phyaddr == BGMAC_PHY_MASK) {
 		bgmac_err(bgmac, "No PHY found\n");