PCI: Add PCI ROM helper for platform-provided ROM images

It turns out that some UEFI systems provide apparently an apparently valid
PCI ROM BAR that turns out to contain garbage, so the attempt in 547b52463
to prefer the ROM from the BAR actually breaks a different set of machines.
As Linus pointed out, the graphics drivers are probably in the best
position to make this judgement, so this basically reverts 547b52463 and
f9a37be0f and adds a new helper function. Followup patches will add support
to nouveau and radeon for probing this ROM source if they can't find a ROM
from some other source.

[bhelgaas: added reporter and bugzilla pointers, s/f4eb5ff05/547b52463]
Reference: https://bugzilla.redhat.com/show_bug.cgi?id=927451
Reference: http://lkml.kernel.org/r/kg69ef$vdb$1@ger.gmane.org
Reported-by: Mantas Mikulėnas <grawity@gmail.com>
Reported-by: Chris Murphy <bugzilla@colorremedies.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 2461033a7987..710067f3618c 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -916,6 +916,7 @@ void pci_disable_rom(struct pci_dev *pdev);
 void __iomem __must_check *pci_map_rom(struct pci_dev *pdev, size_t *size);
 void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom);
 size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size);
+void __iomem __must_check *pci_platform_rom(struct pci_dev *pdev, size_t *size);
 
 /* Power management related routines */
 int pci_save_state(struct pci_dev *dev);