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Commit 32e8f702 authored by James Bottomley's avatar James Bottomley Committed by Linus Torvalds
Browse files

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: default avatarJames 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 64da82ef

include/linux/dma-mapping.h

+7 −0
Original line number Diff line number Diff line
@@ -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