diff options
author | FUJITA Tomonori <tomof@acm.org> | 2008-02-04 22:27:55 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-05 09:44:10 -0800 |
commit | 6b7b651055221127304a4e373ee9b762398d54d7 (patch) | |
tree | 06a8383d5d20011a5ffe04b4e78234a8fcc98f51 /include/linux/dma-mapping.h | |
parent | 7bbdc3d51cf793dd81c38f794f4cb73df58d1527 (diff) |
iommu sg merging: add device_dma_parameters structure
IOMMUs merges scatter/gather segments without considering a low level
driver's restrictions. The problem is that IOMMUs can't access to the
limitations because they are in request_queue.
This patchset introduces a new structure, device_dma_parameters,
including dma information. A pointer to device_dma_parameters is added
to struct device. The bus specific structures (like pci_dev) includes
device_dma_parameters. Low level drivers can use dma_set_max_seg_size
to tell IOMMUs about the restrictions.
We can move more dma stuff in struct device (like dma_mask) to struct
device_dma_parameters later (needs some cleanups before that).
This includes patches for all the IOMMUs that could merge sg (x86_64,
ppc, IA64, alpha, sparc64, and parisc) though only the ppc patch was
tested. The patches for other IOMMUs are only compile tested.
This patch:
Add a new structure, device_dma_parameters, including dma information. A
pointer to device_dma_parameters is added to struct device.
- there are only max_segment_size and segment_boundary_mask there but we'll
move more dma stuff in struct device (like dma_mask) to struct
device_dma_parameters later. segment_boundary_mask is not supported yet.
- new accessors for the dma parameters are added. So we can easily change
where to place struct device_dma_parameters in the future.
- dma_get_max_seg_size returns 64K if dma_parms in struct device isn't set
up properly. 64K is the default max_segment_size in the block layer.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Jeff Garzik <jeff@garzik.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/dma-mapping.h')
-rw-r--r-- | include/linux/dma-mapping.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 4470950892b..df3a3610caf 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -60,6 +60,21 @@ static inline int is_device_dma_capable(struct device *dev) extern u64 dma_get_required_mask(struct device *dev); +static inline unsigned int dma_get_max_seg_size(struct device *dev) +{ + return dev->dma_parms ? dev->dma_parms->max_segment_size : 65536; +} + +static inline unsigned int dma_set_max_seg_size(struct device *dev, + unsigned int size) +{ + if (dev->dma_parms) { + dev->dma_parms->max_segment_size = size; + return 0; + } else + return -EIO; +} + /* flags for the coherent memory api */ #define DMA_MEMORY_MAP 0x01 #define DMA_MEMORY_IO 0x02 |