net: phy: xilinx-gmii2rgmii: Adopt clock support

Add clock support to the gmii_to_rgmii IP.
Make clk optional to keep DTB backward compatibility.
Signed-off-by: Vineeth Karumanchi <vineeth.karumanchi@amd.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/xilinx_gmii2rgmii.c

@@ -15,6 +15,7 @@
 #include <linux/mii.h>
 #include <linux/mdio.h>
 #include <linux/phy.h>
+#include <linux/clk.h>
 #include <linux/of_mdio.h>
 
 #define XILINX_GMII2RGMII_REG		0x10
@@ -85,11 +86,17 @@ static int xgmiitorgmii_probe(struct mdio_device *mdiodev)
 	struct device *dev = &mdiodev->dev;
 	struct device_node *np = dev->of_node, *phy_node;
 	struct gmii2rgmii *priv;
+	struct clk *clkin;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
 
+	clkin = devm_clk_get_optional_enabled(dev, NULL);
+	if (IS_ERR(clkin))
+		return dev_err_probe(dev, PTR_ERR(clkin),
+					"Failed to get and enable clock from Device Tree\n");
+
 	phy_node = of_parse_phandle(np, "phy-handle", 0);
 	if (!phy_node) {
 		dev_err(dev, "Couldn't parse phy-handle\n");