ARM: Add fixed PCI i/o mapping

This adds a fixed virtual mapping for PCI i/o addresses. The mapping is
located at the last 2MB of vmalloc region (0xfee00000-0xff000000). 2MB
is used to align with PMD size, but IO_SPACE_LIMIT is 1MB. The space
is reserved after .map_io and can be mapped at any time later with
pci_ioremap_io. Platforms which need early i/o mapping (e.g. for vga
console) can call pci_map_io_early in their .map_io function.

This has changed completely from the 1st implementation which only
supported creating the static mapping at .map_io.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Nicolas Pitre <nico@linaro.org>

arch/arm/include/asm/mach/pci.h

@@ -11,6 +11,7 @@
 #ifndef __ASM_MACH_PCI_H
 #define __ASM_MACH_PCI_H
 
+
 struct pci_sys_data;
 struct pci_ops;
 struct pci_bus;
@@ -54,6 +55,15 @@ struct pci_sys_data {
  */
 void pci_common_init(struct hw_pci *);
 
+/*
+ * Setup early fixed I/O mapping.
+ */
+#if defined(CONFIG_PCI)
+extern void pci_map_io_early(unsigned long pfn);
+#else
+static inline void pci_map_io_early(unsigned long pfn) {}
+#endif
+
 /*
  * PCI controllers
  */