[PATCH] PCI: rcar-host: Validate IO/MEM resource count in DT ranges property

[Marek Vasut]

The R-Car Gen3 PCIEC controller supports up to 4 memory area mappings.
Count the IO and MEM ranges described in DT 'ranges' property of the
controller DT node, and in case there are more than 4, refuse to probe
the controller driver, because such DT does not describe valid hardware
configuration. Do the IO and MEM counting early to avoid controller
configuration rollback in case of failure.

Fixes: 5d2917d469fa ("PCI: rcar: Convert to DT resource parsing API")
Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
---
Cc: "Krzysztof Wilczyński" <kwilczynski@xxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Cc: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
Cc: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx>
Cc: Magnus Damm <magnus.damm@xxxxxxxxx>
Cc: Manivannan Sadhasivam <mani@xxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-pci@xxxxxxxxxxxxxxx
Cc: linux-renesas-soc@xxxxxxxxxxxxxxx
---
 drivers/pci/controller/pcie-rcar-host.c | 31 +++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/pci/controller/pcie-rcar-host.c b/drivers/pci/controller/pcie-rcar-host.c
index cd9171eebc289..4bcc8c3051ac4 100644
--- a/drivers/pci/controller/pcie-rcar-host.c
+++ b/drivers/pci/controller/pcie-rcar-host.c
@@ -341,6 +341,32 @@ static void rcar_pcie_force_speedup(struct rcar_pcie *pcie)
 		 (macsr & LINK_SPEED) == LINK_SPEED_5_0GTS ? "5" : "2.5");
 }
 
+static int rcar_pcie_validate_resource_count(struct rcar_pcie_host *host)
+{
+	struct pci_host_bridge *bridge = pci_host_bridge_from_priv(host);
+	struct rcar_pcie *pcie = &host->pcie;
+	struct resource_entry *win;
+	int i = 0;
+
+	resource_list_for_each_entry(win, &bridge->windows) {
+		struct resource *res = win->res;
+		unsigned long type = resource_type(res);
+
+		if (!res->flags)
+			continue;
+
+		if (type == IORESOURCE_IO || type == IORESOURCE_MEM)
+			i++;
+
+		if (i > RCAR_PCI_MAX_RESOURCES)
+			return dev_err_probe(pcie->dev, -ENOSPC,
+					     "Too many IO/MEM entries in DT 'ranges' property, limit is %d\n",
+					     RCAR_PCI_MAX_RESOURCES);
+	}
+
+	return 0;
+}
+
 static void rcar_pcie_hw_enable(struct rcar_pcie_host *host)
 {
 	struct rcar_pcie *pcie = &host->pcie;
@@ -947,6 +973,11 @@ static int rcar_pcie_probe(struct platform_device *pdev)
 	host = pci_host_bridge_priv(bridge);
 	pcie = &host->pcie;
 	pcie->dev = dev;
+
+	err = rcar_pcie_validate_resource_count(host);
+	if (err)
+		return err;
+
 	platform_set_drvdata(pdev, host);
 
 	for (i = 0; i < ARRAY_SIZE(rcar_pcie_supplies); i++) {
-- 
2.53.0