introduce DMA_MASK_NONE as a signal for unable to do DMA
Some devices are incapable of DMA and need to be recognised as such.
Introduce a NONE dma mask to facilitate this plus an inline function:
is_device_dma_capable() to check this.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Natalie Protasevich <protasnb@gmail.com>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 2dc21cb..0ebfafb 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -24,6 +24,8 @@
#define DMA_28BIT_MASK 0x000000000fffffffULL
#define DMA_24BIT_MASK 0x0000000000ffffffULL
+#define DMA_MASK_NONE 0x0ULL
+
static inline int valid_dma_direction(int dma_direction)
{
return ((dma_direction == DMA_BIDIRECTIONAL) ||
@@ -31,6 +33,11 @@
(dma_direction == DMA_FROM_DEVICE));
}
+static inline int is_device_dma_capable(struct device *dev)
+{
+ return dev->dma_mask != NULL && *dev->dma_mask != DMA_MASK_NONE;
+}
+
#ifdef CONFIG_HAS_DMA
#include <asm/dma-mapping.h>
#else