[ARM] remove a common set of __virt_to_bus definitions

Let's provide an overridable default instead of having every machine
class define __virt_to_bus and __bus_to_virt to the same thing.  What
most platforms are using is bus_addr == phys_addr so such is the default.

One exception is ebsa110 which has no DMA what so ever, so the actual
definition is not important except only for proper compilation.  Also
added a comment about the special footbridge bus translation.

Let's also remove comments alluding to set_dma_addr which is not
(and should not) be commonly used.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index 7238b3b50643..0202a7c20e62 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -178,6 +178,11 @@ static inline void *phys_to_virt(unsigned long x)
  * memory.  Use of these is *deprecated* (and that doesn't mean
  * use the __ prefixed forms instead.)  See dma-mapping.h.
  */
+#ifndef __virt_to_bus
+#define __virt_to_bus   __virt_to_phys
+#define __bus_to_virt   __phys_to_virt
+#endif
+
 static inline __deprecated unsigned long virt_to_bus(void *x)
 {
         return __virt_to_bus((unsigned long)x);