arch/*/io.h: Add ioremap_wt() to all architectures

Add ioremap_wt() to all arch-specific asm/io.h headers which
define ioremap_wc() locally. These headers do not include
<asm-generic/iomap.h>. Some of them include <asm-generic/io.h>,
but ioremap_wt() is defined for consistency since they define
all ioremap_xxx locally.

In all architectures without Write-Through support, ioremap_wt()
is defined indentical to ioremap_nocache().

frv and m68k already have ioremap_writethrough(). On those we
add ioremap_wt() indetical to ioremap_writethrough() and defines
ARCH_HAS_IOREMAP_WT in both architectures.

The ioremap_wt() interface is exported to drivers.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Elliott@hp.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arnd@arndb.de
Cc: hch@lst.de
Cc: hmh@hmh.eng.br
Cc: jgross@suse.com
Cc: konrad.wilk@oracle.com
Cc: linux-mm <linux-mm@kvack.org>
Cc: linux-nvdimm@lists.01.org
Cc: stefan.bader@canonical.com
Cc: yigal@plexistor.com
Link: http://lkml.kernel.org/r/1433436928-31903-9-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/m68k/include/asm/io_no.h

@@ -3,6 +3,8 @@
 
 #ifdef __KERNEL__
 
+#define ARCH_HAS_IOREMAP_WT
+
 #include <asm/virtconvert.h>
 #include <asm-generic/iomap.h>
 
@@ -157,6 +159,10 @@ static inline void *ioremap_writethrough(unsigned long physaddr, unsigned long s
 {
 	return __ioremap(physaddr, size, IOMAP_WRITETHROUGH);
 }
+static inline void *ioremap_wt(unsigned long physaddr, unsigned long size)
+{
+	return __ioremap(physaddr, size, IOMAP_WRITETHROUGH);
+}
 static inline void *ioremap_fullcache(unsigned long physaddr, unsigned long size)
 {
 	return __ioremap(physaddr, size, IOMAP_FULL_CACHING);