1 files changed, 44 insertions, 29 deletions

diff --git a/drivers/pci/rom.c b/drivers/pci/rom.c
index d087e0817715..dbbcc04abd1a 100644
--- a/drivers/pci/rom.c
+++ b/drivers/pci/rom.c
@@ -54,6 +54,49 @@ static void pci_disable_rom(struct pci_dev *pdev)
 }
 
 /**
+ * pci_get_rom_size - obtain the actual size of the ROM image
+ * @rom: kernel virtual pointer to image of ROM
+ * @size: size of PCI window
+ *  return: size of actual ROM image
+ *
+ * Determine the actual length of the ROM image.
+ * The PCI window size could be much larger than the
+ * actual image size.
+ */
+size_t pci_get_rom_size(void __iomem *rom, size_t size)
+{
+        void __iomem *image;
+        int last_image;
+
+        image = rom;
+        do {
+                void __iomem *pds;
+                /* Standard PCI ROMs start out with these bytes 55 AA */
+                if (readb(image) != 0x55)
+                        break;
+                if (readb(image + 1) != 0xAA)
+                        break;
+                /* get the PCI data structure and check its signature */
+                pds = image + readw(image + 24);
+                if (readb(pds) != 'P')
+                        break;
+                if (readb(pds + 1) != 'C')
+                        break;
+                if (readb(pds + 2) != 'I')
+                        break;
+                if (readb(pds + 3) != 'R')
+                        break;
+                last_image = readb(pds + 21) & 0x80;
+                /* this length is reliable */
+                image += readw(pds + 16) * 512;
+        } while (!last_image);
+
+        /* never return a size larger than the PCI resource window */
+        /* there are known ROMs that get the size wrong */
+        return min((size_t)(image - rom), size);
+}
+
+/**
  * pci_map_rom - map a PCI ROM to kernel space
  * @pdev: pointer to pci device struct
  * @size: pointer to receive size of pci window over ROM
@@ -68,8 +111,6 @@ void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
         struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
         loff_t start;
         void __iomem *rom;
-        void __iomem *image;
-        int last_image;
 
         /*
          * IORESOURCE_ROM_SHADOW set on x86, x86_64 and IA64 supports legacy
@@ -117,33 +158,7 @@ void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
          * size is much larger than the actual size of the ROM.
          * True size is important if the ROM is going to be copied.
          */
-        image = rom;
-        do {
-                void __iomem *pds;
-                /* Standard PCI ROMs start out with these bytes 55 AA */
-                if (readb(image) != 0x55)
-                        break;
-                if (readb(image + 1) != 0xAA)
-                        break;
-                /* get the PCI data structure and check its signature */
-                pds = image + readw(image + 24);
-                if (readb(pds) != 'P')
-                        break;
-                if (readb(pds + 1) != 'C')
-                        break;
-                if (readb(pds + 2) != 'I')
-                        break;
-                if (readb(pds + 3) != 'R')
-                        break;
-                last_image = readb(pds + 21) & 0x80;
-                /* this length is reliable */
-                image += readw(pds + 16) * 512;
-        } while (!last_image);
-
-        /* never return a size larger than the PCI resource window */
-        /* there are known ROMs that get the size wrong */
-        *size = min((size_t)(image - rom), *size);
-
+        *size = pci_get_rom_size(rom, *size);
         return rom;
 }