sata: ahci-da850: get the sata clock using a connection id

In preparation for using two clocks in the driver (the sysclk2-based
clock and the external REFCLK), check if we got the functional clock
after calling ahci_platform_get_resources(). If not, retry calling
clk_get() with con_id specified.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>

drivers/ata/ahci_da850.c

@@ -71,12 +71,28 @@ static int ahci_da850_probe(struct platform_device *pdev)
 	struct ahci_host_priv *hpriv;
 	struct resource *res;
 	void __iomem *pwrdn_reg;
+	struct clk *clk;
 	int rc;
 
 	hpriv = ahci_platform_get_resources(pdev);
 	if (IS_ERR(hpriv))
 		return PTR_ERR(hpriv);
 
+	/*
+	 * Internally ahci_platform_get_resources() calls clk_get(dev, NULL)
+	 * when trying to obtain the functional clock. This SATA controller
+	 * uses two clocks for which we specify two connection ids. If we don't
+	 * have the functional clock at this point - call clk_get() again with
+	 * con_id = "fck".
+	 */
+	if (!hpriv->clks[0]) {
+		clk = clk_get(dev, "fck");
+		if (IS_ERR(clk))
+			return PTR_ERR(clk);
+
+		hpriv->clks[0] = clk;
+	}
+
 	rc = ahci_platform_enable_resources(hpriv);
 	if (rc)
 		return rc;