[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/common/dmabounce.c b/arch/arm/common/dmabounce.c
index f030f07..734ac91 100644
--- a/arch/arm/common/dmabounce.c
+++ b/arch/arm/common/dmabounce.c
@@ -25,6 +25,7 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
+#include <linux/page-flags.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
@@ -349,6 +350,12 @@
BUG_ON(!valid_dma_direction(dir));
+ if (PageHighMem(page)) {
+ dev_err(dev, "DMA buffer bouncing of HIGHMEM pages "
+ "is not supported\n");
+ return ~0;
+ }
+
return map_single(dev, page_address(page) + offset, size, dir);
}
EXPORT_SYMBOL(dma_map_page);