arm64: PCI: Search ACPI namespace to ensure ECAM space is reserved

The static MCFG table tells us the base of ECAM space, but it does not
reserve the space -- the reservation should be done via a device in the
ACPI namespace whose _CRS includes the ECAM region.

Use acpi_resource_consumer() to check whether the ECAM space is reserved by
an ACPI namespace device.  If it is, emit a message showing which device
reserves it.  If not, emit a "[Firmware Bug]" warning.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
index 8183c98..216dff6 100644 (file)
--- a/arch/arm64/kernel/pci.c
+++ b/arch/arm64/kernel/pci.c
@@ -124,8 +124,9 @@ pci_acpi_setup_ecam_mapping(struct acpi_pci_root *root)
        struct device *dev = &root->device->dev;
        struct resource *bus_res = &root->secondary;
        u16 seg = root->segment;
-       struct pci_config_window *cfg;
        struct resource cfgres;
+       struct acpi_device *adev;
+       struct pci_config_window *cfg;
        unsigned int bsz;
 
        /* Use address from _CBA if present, otherwise lookup MCFG */
@@ -141,6 +142,15 @@ pci_acpi_setup_ecam_mapping(struct acpi_pci_root *root)
        cfgres.start = root->mcfg_addr + bus_res->start * bsz;
        cfgres.end = cfgres.start + resource_size(bus_res) * bsz - 1;
        cfgres.flags = IORESOURCE_MEM;
+
+       adev = acpi_resource_consumer(&cfgres);
+       if (adev)
+               dev_info(dev, "ECAM area %pR reserved by %s\n", &cfgres,
+                        dev_name(&adev->dev));
+       else
+               dev_warn(dev, FW_BUG "ECAM area %pR not reserved in ACPI namespace\n",
+                        &cfgres);
+
        cfg = pci_ecam_create(dev, &cfgres, bus_res, &pci_generic_ecam_ops);
        if (IS_ERR(cfg)) {
                dev_err(dev, "%04x:%pR error %ld mapping ECAM\n", seg, bus_res,