PCI: j721e: Add support to provide refclk to PCIe connector

Add support to provide refclk to PCIe connector.

Link: https://lore.kernel.org/r/20210308063550.6227-5-kishon@ti.com
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/controller/cadence/pci-j721e.c

@@ -6,6 +6,7 @@
  * Author: Kishon Vijay Abraham I <kishon@ti.com>
  */
 
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/io.h>
@@ -50,6 +51,7 @@ enum link_status {
 
 struct j721e_pcie {
 	struct device		*dev;
+	struct clk		*refclk;
 	u32			mode;
 	u32			num_lanes;
 	struct cdns_pcie	*cdns_pcie;
@@ -312,6 +314,7 @@ static int j721e_pcie_probe(struct platform_device *pdev)
 	struct cdns_pcie_ep *ep;
 	struct gpio_desc *gpiod;
 	void __iomem *base;
+	struct clk *clk;
 	u32 num_lanes;
 	u32 mode;
 	int ret;
@@ -411,6 +414,20 @@ static int j721e_pcie_probe(struct platform_device *pdev)
 			goto err_get_sync;
 		}
 
+		clk = devm_clk_get_optional(dev, "pcie_refclk");
+		if (IS_ERR(clk)) {
+			ret = PTR_ERR(clk);
+			dev_err(dev, "failed to get pcie_refclk\n");
+			goto err_pcie_setup;
+		}
+
+		ret = clk_prepare_enable(clk);
+		if (ret) {
+			dev_err(dev, "failed to enable pcie_refclk\n");
+			goto err_get_sync;
+		}
+		pcie->refclk = clk;
+
 		/*
 		 * "Power Sequencing and Reset Signal Timings" table in
 		 * PCI EXPRESS CARD ELECTROMECHANICAL SPECIFICATION, REV. 3.0
@@ -425,8 +442,10 @@ static int j721e_pcie_probe(struct platform_device *pdev)
 		}
 
 		ret = cdns_pcie_host_setup(rc);
-		if (ret < 0)
+		if (ret < 0) {
+			clk_disable_unprepare(pcie->refclk);
 			goto err_pcie_setup;
+		}
 
 		break;
 	case PCI_MODE_EP:
@@ -479,6 +498,7 @@ static int j721e_pcie_remove(struct platform_device *pdev)
 	struct cdns_pcie *cdns_pcie = pcie->cdns_pcie;
 	struct device *dev = &pdev->dev;
 
+	clk_disable_unprepare(pcie->refclk);
 	cdns_pcie_disable_phy(cdns_pcie);
 	pm_runtime_put(dev);
 	pm_runtime_disable(dev);