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authorFUJITA Tomonori <tomof@acm.org>2008-02-04 22:27:55 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-05 09:44:10 -0800
commit6b7b651055221127304a4e373ee9b762398d54d7 (patch)
tree06a8383d5d20011a5ffe04b4e78234a8fcc98f51
parent7bbdc3d51cf793dd81c38f794f4cb73df58d1527 (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>
-rw-r--r--include/linux/device.h11
-rw-r--r--include/linux/dma-mapping.h15
2 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/device.h b/include/linux/device.h
index 479c0b31593..2258d89bf52 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -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
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