[ARM] make page_to_dma() highmem aware
If a machine class has a custom __virt_to_bus() implementation then it
must provide a __arch_page_to_dma() implementation as well which is
_not_ based on page_address() to support highmem.
This patch fixes existing __arch_page_to_dma() and provide a default
implementation otherwise. The default implementation for highmem is
based on __pfn_to_bus() which is defined only when no custom
__virt_to_bus() is provided by the machine class.
That leaves only ebsa110 and footbridge which cannot support highmem
until they provide their own __arch_page_to_dma() implementation.
But highmem support on those legacy platforms with limited memory is
certainly not a priority.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index ae472bc..85763db 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -188,6 +188,7 @@
#ifndef __virt_to_bus
#define __virt_to_bus __virt_to_phys
#define __bus_to_virt __phys_to_virt
+#define __pfn_to_bus(x) ((x) << PAGE_SHIFT)
#endif
static inline __deprecated unsigned long virt_to_bus(void *x)