PCI: mvebu: Fix support for DEVCAP2, DEVCTL2 and LNKCTL2 registers on emulated bridge

Armada XP and new hardware supports access to DEVCAP2, DEVCTL2 and LNKCTL2
configuration registers of PCIe core via PCIE_CAP_PCIEXP. So export them
via emulated software root bridge.

Pre-XP hardware does not support these registers and returns zeros.

Link: https://lore.kernel.org/r/20211125124605.25915-16-pali@kernel.org
Fixes: 1f08673e ("PCI: mvebu: Convert to PCI emulated bridge config space")
Signed-off-by: NPali Rohár <pali@kernel.org>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/controller/pci-mvebu.c

@@ -560,6 +560,18 @@ mvebu_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
 		*value = mvebu_readl(port, PCIE_RC_RTSTA);
 		break;
 
+	case PCI_EXP_DEVCAP2:
+		*value = mvebu_readl(port, PCIE_CAP_PCIEXP + PCI_EXP_DEVCAP2);
+		break;
+
+	case PCI_EXP_DEVCTL2:
+		*value = mvebu_readl(port, PCIE_CAP_PCIEXP + PCI_EXP_DEVCTL2);
+		break;
+
+	case PCI_EXP_LNKCTL2:
+		*value = mvebu_readl(port, PCIE_CAP_PCIEXP + PCI_EXP_LNKCTL2);
+		break;
+
 	default:
 		return PCI_BRIDGE_EMUL_NOT_HANDLED;
 	}
@@ -672,6 +684,17 @@ mvebu_pci_bridge_emul_pcie_conf_write(struct pci_bridge_emul *bridge,
 		if (new & PCI_EXP_RTSTA_PME)
 			mvebu_writel(port, ~PCIE_INT_PM_PME, PCIE_INT_CAUSE_OFF);
 		break;
+
+	case PCI_EXP_DEVCTL2:
+		mvebu_writel(port, new, PCIE_CAP_PCIEXP + PCI_EXP_DEVCTL2);
+		break;
+
+	case PCI_EXP_LNKCTL2:
+		mvebu_writel(port, new, PCIE_CAP_PCIEXP + PCI_EXP_LNKCTL2);
+		break;
+
+	default:
+		break;
 	}
 }