net: ethernet: ravb: Enable optional refclk

For devices that use a programmable clock for the AVB reference clock,
the driver may need to enable them.  Add code to find the optional clock
and enable it when available.
Signed-off-by: NAdam Ford <aford173@gmail.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/ravb.h

@@ -993,6 +993,7 @@ struct ravb_private {
 	struct platform_device *pdev;
 	void __iomem *addr;
 	struct clk *clk;
+	struct clk *refclk;
 	struct mdiobb_ctrl mdiobb;
 	u32 num_rx_ring[NUM_RX_QUEUE];
 	u32 num_tx_ring[NUM_TX_QUEUE];

drivers/net/ethernet/renesas/ravb_main.c

@@ -2148,6 +2148,13 @@ static int ravb_probe(struct platform_device *pdev)
 		goto out_release;
 	}
 
+	priv->refclk = devm_clk_get_optional(&pdev->dev, "refclk");
+	if (IS_ERR(priv->refclk)) {
+		error = PTR_ERR(priv->refclk);
+		goto out_release;
+	}
+	clk_prepare_enable(priv->refclk);
+
 	ndev->max_mtu = 2048 - (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN);
 	ndev->min_mtu = ETH_MIN_MTU;
 
@@ -2244,6 +2251,7 @@ static int ravb_probe(struct platform_device *pdev)
 	if (chip_id != RCAR_GEN2)
 		ravb_ptp_stop(ndev);
 out_release:
+	clk_disable_unprepare(priv->refclk);
 	free_netdev(ndev);
 
 	pm_runtime_put(&pdev->dev);
@@ -2260,6 +2268,8 @@ static int ravb_remove(struct platform_device *pdev)
 	if (priv->chip_id != RCAR_GEN2)
 		ravb_ptp_stop(ndev);
 
+	clk_disable_unprepare(priv->refclk);
+
 	dma_free_coherent(ndev->dev.parent, priv->desc_bat_size, priv->desc_bat,
 			  priv->desc_bat_dma);
 	/* Set reset mode */