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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>
This commit is contained in:
James Bottomley 2007-10-16 01:23:55 -07:00 committed by Linus Torvalds
parent 64da82efae
commit 32e8f70230
1 changed files with 7 additions and 0 deletions
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7
include/linux/dma-mapping.h
View File

@ -24,6 +24,8 @@ enum dma_data_direction {
#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 @@ static inline int valid_dma_direction(int dma_direction)
(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