PCI: iproc: Disable MSI parsing in certain PAXC blocks

The internal MSI parsing logic in certain revisions of PAXC root
complexes does not work properly and can cause corruptions on the
writes transactions so they need to be disabled.
Signed-off-by: Ray Jui <ray.jui@broadcom.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Scott Branden <scott.branden@broadcom.com>
Reviewed-by: Oza Pawandeep <poza@codeaurora.org>

drivers/pci/controller/pcie-iproc.c

@@ -1197,10 +1197,22 @@ static int iproc_pcie_paxb_v2_msi_steer(struct iproc_pcie *pcie, u64 msi_addr)
 	return ret;
 }
 
-static void iproc_pcie_paxc_v2_msi_steer(struct iproc_pcie *pcie, u64 msi_addr)
+static void iproc_pcie_paxc_v2_msi_steer(struct iproc_pcie *pcie, u64 msi_addr,
+					 bool enable)
 {
 	u32 val;
 
+	if (!enable) {
+		/*
+		 * Disable PAXC MSI steering. All write transfers will be
+		 * treated as non-MSI transfers
+		 */
+		val = iproc_pcie_read_reg(pcie, IPROC_PCIE_MSI_EN_CFG);
+		val &= ~MSI_ENABLE_CFG;
+		iproc_pcie_write_reg(pcie, IPROC_PCIE_MSI_EN_CFG, val);
+		return;
+	}
+
 	/*
 	 * Program bits [43:13] of address of GITS_TRANSLATER register into
 	 * bits [30:0] of the MSI base address register.  In fact, in all iProc
@@ -1254,7 +1266,7 @@ static int iproc_pcie_msi_steer(struct iproc_pcie *pcie,
 			return ret;
 		break;
 	case IPROC_PCIE_PAXC_V2:
-		iproc_pcie_paxc_v2_msi_steer(pcie, msi_addr);
+		iproc_pcie_paxc_v2_msi_steer(pcie, msi_addr, true);
 		break;
 	default:
 		return -EINVAL;
@@ -1480,6 +1492,24 @@ int iproc_pcie_remove(struct iproc_pcie *pcie)
 }
 EXPORT_SYMBOL(iproc_pcie_remove);
 
+/*
+ * The MSI parsing logic in certain revisions of Broadcom PAXC based root
+ * complex does not work and needs to be disabled
+ */
+static void quirk_paxc_disable_msi_parsing(struct pci_dev *pdev)
+{
+	struct iproc_pcie *pcie = iproc_data(pdev->bus);
+
+	if (pdev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
+		iproc_pcie_paxc_v2_msi_steer(pcie, 0, false);
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_BROADCOM, 0x16f0,
+			quirk_paxc_disable_msi_parsing);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_BROADCOM, 0xd802,
+			quirk_paxc_disable_msi_parsing);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_BROADCOM, 0xd804,
+			quirk_paxc_disable_msi_parsing);
+
 MODULE_AUTHOR("Ray Jui <rjui@broadcom.com>");
 MODULE_DESCRIPTION("Broadcom iPROC PCIe common driver");
 MODULE_LICENSE("GPL v2");