PCI: revise VPD access interface

Change PCI VPD API which was only used by sysfs to something usable
in drivers.
   * move iteration over multiple words to the low level
   * use conventional types for arguments
   * add exportable wrapper

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 170f9ae..76079e1 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -687,6 +687,10 @@
 /* Functions for PCI Hotplug drivers to use */
 int pci_bus_find_capability(struct pci_bus *bus, unsigned int devfn, int cap);
 
+/* Vital product data routines */
+ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf);
+ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void *buf);
+
 /* Helper functions for low-level code (drivers/pci/setup-[bus,res].c) */
 void pci_bus_assign_resources(struct pci_bus *bus);
 void pci_bus_size_bridges(struct pci_bus *bus);