PCI: iproc: Fix NULL pointer dereference for BCMA

With the inbound DMA mapping supported added, the iProc PCIe driver
parses DT property "dma-ranges" through call to
"of_pci_dma_range_parser_init()". In the case of BCMA, this results in a
NULL pointer deference due to a missing of_node.

Fix this by adding a guard in pcie-iproc-platform.c to only enable the
inbound DMA mapping logic when DT property "dma-ranges" is present.

Fixes: dd9d4e7498de3 ("PCI: iproc: Add inbound DMA mapping support")
Reported-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Ray Jui <ray.jui@broadcom.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Rafał Miłecki <rafal@milecki.pl>
cc: <stable@vger.kernel.org> # 4.10+

drivers/pci/host/pcie-iproc-platform.c

@@ -92,6 +92,13 @@ static int iproc_pcie_pltfm_probe(struct platform_device *pdev)
 		pcie->need_ob_cfg = true;
 	}
 
+	/*
+	 * DT nodes are not used by all platforms that use the iProc PCIe
+	 * core driver. For platforms that require explict inbound mapping
+	 * configuration, "dma-ranges" would have been present in DT
+	 */
+	pcie->need_ib_cfg = of_property_read_bool(np, "dma-ranges");
+
 	/* PHY use is optional */
 	pcie->phy = devm_phy_get(dev, "pcie-phy");
 	if (IS_ERR(pcie->phy)) {

drivers/pci/host/pcie-iproc.c

@@ -1378,9 +1378,11 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res)
 		}
 	}
 
-	ret = iproc_pcie_map_dma_ranges(pcie);
-	if (ret && ret != -ENOENT)
-		goto err_power_off_phy;
+	if (pcie->need_ib_cfg) {
+		ret = iproc_pcie_map_dma_ranges(pcie);
+		if (ret && ret != -ENOENT)
+			goto err_power_off_phy;
+	}
 
 #ifdef CONFIG_ARM
 	pcie->sysdata.private_data = pcie;

drivers/pci/host/pcie-iproc.h

@@ -74,6 +74,7 @@ struct iproc_msi;
  * @ob: outbound mapping related parameters
  * @ob_map: outbound mapping related parameters specific to the controller
  *
+ * @need_ib_cfg: indicates SW needs to configure the inbound mapping window
  * @ib: inbound mapping related parameters
  * @ib_map: outbound mapping region related parameters
  *
@@ -101,6 +102,7 @@ struct iproc_pcie {
 	struct iproc_pcie_ob ob;
 	const struct iproc_pcie_ob_map *ob_map;
 
+	bool need_ib_cfg;
 	struct iproc_pcie_ib ib;
 	const struct iproc_pcie_ib_map *ib_map;