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Diffstat (limited to 'drivers/pci/pci-acpi.c')
| -rw-r--r-- | drivers/pci/pci-acpi.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index 004575091596..9cc447da9475 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -119,6 +119,28 @@ phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle) return (phys_addr_t)mcfg_addr; } +bool pci_acpi_preserve_config(struct pci_host_bridge *host_bridge) +{ + if (ACPI_HANDLE(&host_bridge->dev)) { + union acpi_object *obj; + + /* + * Evaluate the "PCI Boot Configuration" _DSM Function. If it + * exists and returns 0, we must preserve any PCI resource + * assignments made by firmware for this host bridge. + */ + obj = acpi_evaluate_dsm_typed(ACPI_HANDLE(&host_bridge->dev), + &pci_acpi_dsm_guid, + 1, DSM_PCI_PRESERVE_BOOT_CONFIG, + NULL, ACPI_TYPE_INTEGER); + if (obj && obj->integer.value == 0) + return true; + ACPI_FREE(obj); + } + + return false; +} + /* _HPX PCI Setting Record (Type 0); same as _HPP */ struct hpx_type0 { u32 revision; /* Not present in _HPP */ |