PCI: Add support for non-BAR ROMs

Platforms may provide their own mechanisms for obtaining ROMs. Add support
for using data provided by the platform in that case.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Seth Forshee <seth.forshee@canonical.com>

drivers/pci/rom.c

@@ -117,12 +117,18 @@ void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
 	loff_t start;
 	void __iomem *rom;
 
+	/*
+	 * Some devices may provide ROMs via a source other than the BAR
+	 */
+	if (pdev->rom && pdev->romlen) {
+		*size = pdev->romlen;
+		return phys_to_virt((phys_addr_t)pdev->rom);
 	/*
 	 * IORESOURCE_ROM_SHADOW set on x86, x86_64 and IA64 supports legacy
 	 * memory map if the VGA enable bit of the Bridge Control register is
 	 * set for embedded VGA.
 	 */
-	if (res->flags & IORESOURCE_ROM_SHADOW) {
+	} else if (res->flags & IORESOURCE_ROM_SHADOW) {
 		/* primary video rom always starts here */
 		start = (loff_t)0xC0000;
 		*size = 0x20000; /* cover C000:0 through E000:0 */
@@ -181,6 +187,7 @@ void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)
 	if (res->flags & (IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY))
 		return;
 
+	if (!pdev->rom || !pdev->romlen)
 		iounmap(rom);
 
 	/* Disable again before continuing, leave enabled if pci=rom */

include/linux/pci.h

@@ -333,6 +333,8 @@ struct pci_dev {
 	};
 	struct pci_ats	*ats;	/* Address Translation Service */
 #endif
+	void *rom; /* Physical pointer to ROM if it's not from the BAR */
+	size_t romlen; /* Length of ROM if it's not from the BAR */
 };
 
 static inline struct pci_dev *pci_physfn(struct pci_dev *dev)