net: macb: add support for SGMII phy interface

This patch adds support for the sgmii phy interface,
available only to DM users, dictated by current driver
design.

Signed-off-by: Ramon Fried <rfried.dev@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Tested-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/drivers/net/macb.c b/drivers/net/macb.c
index a968a4b..cf76270 100644
--- a/drivers/net/macb.c
+++ b/drivers/net/macb.c
@@ -759,6 +759,13 @@
 			gem_writel(macb, USRIO, GEM_BIT(RGMII));
 		else
 			gem_writel(macb, USRIO, 0);
+
+		if (macb->phy_interface == PHY_INTERFACE_MODE_SGMII) {
+			unsigned int ncfgr = macb_readl(macb, NCFGR);
+
+			ncfgr |= GEM_BIT(SGMIIEN) | GEM_BIT(PCSSEL);
+			macb_writel(macb, NCFGR, ncfgr);
+		}
 #else
 #if defined(CONFIG_RGMII) || defined(CONFIG_RMII)
 		gem_writel(macb, USRIO, GEM_BIT(RGMII));