[PATCH v2 u-boot] pci: fsl: Do not access PCI BAR0 register of PCIe Root Port

[Pali Rohár]

Freescale PCIe Root Port has PEXCSRBAR register at position of PCI BAR0.
PCIe Root Port does not have any PCIe memory, so returns zero when trying
to read from PCIe Root Port BAR0 and ignore any writes.

Signed-off-by: Pali Rohár <pali at kernel.org>
---
 drivers/pci/pcie_fsl.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/pci/pcie_fsl.c b/drivers/pci/pcie_fsl.c
index 4600652f2b1b..8d89a1e5919c 100644
--- a/drivers/pci/pcie_fsl.c
+++ b/drivers/pci/pcie_fsl.c
@@ -58,6 +58,14 @@ static int fsl_pcie_read_config(const struct udevice *bus, pci_dev_t bdf,
 		return 0;
 	}
 
+	/* Skip Freescale PCIe controller's PEXCSRBAR register */
+	if (PCI_BUS(bdf) - dev_seq(bus) == 0 &&
+	    PCI_DEV(bdf) == 0 && PCI_FUNC(bdf) == 0 &&
+	    (offset & ~3) == PCI_BASE_ADDRESS_0) {
+		*valuep = 0;
+		return 0;
+	}
+
 	val = PCI_CONF1_EXT_ADDRESS(PCI_BUS(bdf) - dev_seq(bus),
 				    PCI_DEV(bdf), PCI_FUNC(bdf),
 				    offset);
@@ -95,6 +103,12 @@ static int fsl_pcie_write_config(struct udevice *bus, pci_dev_t bdf,
 	if (fsl_pcie_addr_valid(pcie, bdf))
 		return 0;
 
+	/* Skip Freescale PCIe controller's PEXCSRBAR register */
+	if (PCI_BUS(bdf) - dev_seq(bus) == 0 &&
+	    PCI_DEV(bdf) == 0 && PCI_FUNC(bdf) == 0 &&
+	    (offset & ~3) == PCI_BASE_ADDRESS_0)
+		return 0;
+
 	val = PCI_CONF1_EXT_ADDRESS(PCI_BUS(bdf) - dev_seq(bus),
 				    PCI_DEV(bdf), PCI_FUNC(bdf),
 				    offset);
-- 
2.20.1