PCI: mvebu: Dynamically detect if the PEX link is up to enable hot plug

Otherwise hotplugging the PEX doesn't work at all since the driver
detects the link state at probe time. Simply replacing the two tests
of haslink with a register read is enough to fix it.

Tested on kirkwood with repeated plug/unplug of the link partner.
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/pci/host/pci-mvebu.c

@@ -120,7 +120,6 @@ struct mvebu_pcie_port {
 	char *name;
 	void __iomem *base;
 	spinlock_t conf_lock;
-	int haslink;
 	u32 port;
 	u32 lane;
 	int devfn;
@@ -560,7 +559,7 @@ static int mvebu_pcie_wr_conf(struct pci_bus *bus, u32 devfn,
 	if (bus->number == 0)
 		return mvebu_sw_pci_bridge_write(port, where, size, val);
 
-	if (!port->haslink)
+	if (!mvebu_pcie_link_up(port))
 		return PCIBIOS_DEVICE_NOT_FOUND;
 
 	/*
@@ -602,7 +601,7 @@ static int mvebu_pcie_rd_conf(struct pci_bus *bus, u32 devfn, int where,
 	if (bus->number == 0)
 		return mvebu_sw_pci_bridge_read(port, where, size, val);
 
-	if (!port->haslink) {
+	if (!mvebu_pcie_link_up(port)) {
 		*val = 0xffffffff;
 		return PCIBIOS_DEVICE_NOT_FOUND;
 	}
@@ -950,14 +949,12 @@ static int mvebu_pcie_probe(struct platform_device *pdev)
 
 		mvebu_pcie_set_local_dev_nr(port, 1);
 
-		if (mvebu_pcie_link_up(port)) {
-			port->haslink = 1;
-			dev_info(&pdev->dev, "PCIe%d.%d: link up\n",
-				 port->port, port->lane);
-		} else {
-			port->haslink = 0;
-			dev_info(&pdev->dev, "PCIe%d.%d: link down\n",
-				 port->port, port->lane);
+		port->clk = of_clk_get_by_name(child, NULL);
+		if (IS_ERR(port->clk)) {
+			dev_err(&pdev->dev, "PCIe%d.%d: cannot get clock\n",
+			       port->port, port->lane);
+			iounmap(port->base);
+			continue;
 		}
 
 		port->dn = child;