PCI: Document pci_iomap()

This useful interface is hardly mentioned anywhere in the in-tree
documentation.

Signed-off-by: Rolf Eike Beer <eike-kernel@sf-tec.de>
Cc: Tejun Heo <htejun@gmail.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/asm-i386/io.h b/include/asm-i386/io.h
index 7b65b5b..e8e0bd6 100644
--- a/include/asm-i386/io.h
+++ b/include/asm-i386/io.h
@@ -112,6 +112,9 @@
  * writew/writel functions and the other mmio helpers. The returned
  * address is not guaranteed to be usable directly as a virtual
  * address. 
+ *
+ * If the area you are trying to map is a PCI BAR you should have a
+ * look at pci_iomap().
  */
 
 static inline void __iomem * ioremap(unsigned long offset, unsigned long size)