Commit 6b7b6510 authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Linus Torvalds

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: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: default avatarJeff Garzik <jeff@garzik.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Acked-by: default avatarJens Axboe <jens.axboe@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7bbdc3d5
......@@ -410,6 +410,15 @@ extern int devres_release_group(struct device *dev, void *id);
extern void *devm_kzalloc(struct device *dev, size_t size, gfp_t gfp);
extern void devm_kfree(struct device *dev, void *p);
struct device_dma_parameters {
/*
* a low level driver may set these to teach IOMMU code about
* sg limitations.
*/
unsigned int max_segment_size;
unsigned long segment_boundary_mask;
};
struct device {
struct klist klist_children;
struct klist_node knode_parent; /* node in sibling list */
......@@ -445,6 +454,8 @@ struct device {
64 bit addresses for consistent
allocations such descriptors. */
struct device_dma_parameters *dma_parms;
struct list_head dma_pools; /* dma pools (if dma'ble) */
struct dma_coherent_mem *dma_mem; /* internal for coherent mem
......
......@@ -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
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment