PCI: mobiveil: Add callback function for link up check

Platforms integrating the Mobiveil GPEX can implement a specific
mechanism to check the link status.

Add a callback to enable platform specific link status functions.
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
[lorenzo.pieralisi@arm.com: updated log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Andrew Murray <andrew.murray@arm.com>

drivers/pci/controller/mobiveil/pcie-mobiveil.c

@@ -125,6 +125,9 @@ void mobiveil_csr_write(struct mobiveil_pcie *pcie, u32 val, u32 off,
 
 bool mobiveil_pcie_link_up(struct mobiveil_pcie *pcie)
 {
+	if (pcie->ops->link_up)
+		return pcie->ops->link_up(pcie);
+
 	return (mobiveil_csr_readl(pcie, LTSSM_STATUS) &
 		LTSSM_STATUS_L0_MASK) == LTSSM_STATUS_L0;
 }

drivers/pci/controller/mobiveil/pcie-mobiveil.h

@@ -148,6 +148,10 @@ struct mobiveil_root_port {
 	struct pci_host_bridge *bridge;
 };
 
+struct mobiveil_pab_ops {
+	int (*link_up)(struct mobiveil_pcie *pcie);
+};
+
 struct mobiveil_pcie {
 	struct platform_device *pdev;
 	void __iomem *csr_axi_slave_base;	/* root port config base */
@@ -157,6 +161,7 @@ struct mobiveil_pcie {
 	int ppio_wins;
 	int ob_wins_configured;		/* configured outbound windows */
 	int ib_wins_configured;		/* configured inbound windows */
+	const struct mobiveil_pab_ops *ops;
 	struct mobiveil_root_port rp;
 };