This helper iterates over a DMA-mapped SGL and returns contiguous
memory blocks aligned to a HW supported page size.
Suggested-by: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Gal Pressman <galpress@xxxxxxxxxx>
Signed-off-by: Shiraz Saleem <shiraz.saleem@xxxxxxxxx>
---
drivers/infiniband/core/verbs.c | 34 +++++++++++++++++++++++++++++
include/rdma/ib_verbs.h | 47 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 81 insertions(+)
diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
index 7313edc..3806038 100644
--- a/drivers/infiniband/core/verbs.c
+++ b/drivers/infiniband/core/verbs.c
@@ -2711,3 +2711,37 @@ int rdma_init_netdev(struct ib_device *device, u8 port_num,
netdev, params.param);
}
EXPORT_SYMBOL(rdma_init_netdev);
+
+void __rdma_block_iter_start(struct ib_block_iter *biter,
+ struct scatterlist *sglist, unsigned int nents,
+ unsigned long pgsz)
+{
+ memset(biter, 0, sizeof(struct ib_block_iter));
+ biter->__sg = sglist;
+ biter->__sg_nents = nents;
+
+ /* Driver provides best block size to use */
+ biter->__pg_bit = __fls(pgsz);
+}
+EXPORT_SYMBOL(__rdma_block_iter_start);
+
+bool __rdma_block_iter_next(struct ib_block_iter *biter)
+{
+ unsigned int block_offset;
+
+ if (!biter->__sg_nents || !biter->__sg)
+ return false;
+
+ biter->__dma_addr = sg_dma_address(biter->__sg) + biter->__sg_advance;
+ block_offset = biter->__dma_addr & (BIT_ULL(biter->__pg_bit) - 1);
+ biter->__sg_advance += BIT_ULL(biter->__pg_bit) - block_offset;
+
+ if (biter->__sg_advance >= sg_dma_len(biter->__sg)) {
+ biter->__sg_advance = 0;
+ biter->__sg = sg_next(biter->__sg);
+ biter->__sg_nents--;
+ }
+
+ return true;
+}
+EXPORT_SYMBOL(__rdma_block_iter_next);
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 5391c24..8a5ed04 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2711,6 +2711,21 @@ struct ib_client {
u8 no_kverbs_req:1;
};
+/*
+ * IB block DMA iterator
+ *
+ * Iterates the DMA-mapped SGL in contiguous memory blocks aligned
+ * to a HW supported page size.
+ */
+struct ib_block_iter {
+ /* internal states */
+ struct scatterlist *__sg; /* sg holding the current aligned block */
+ dma_addr_t __dma_addr; /* unaligned DMA address of this block */
+ unsigned int __sg_nents; /* number of SG entries */
+ unsigned int __sg_advance; /* number of bytes to advance in sg in next step */
+ unsigned int __pg_bit; /* alignment of current block */
+};
+
struct ib_device *_ib_alloc_device(size_t size);
#define ib_alloc_device(drv_struct, member) \
container_of(_ib_alloc_device(sizeof(struct drv_struct) + \
@@ -2731,6 +2746,38 @@ struct ib_client {
int ib_register_client (struct ib_client *client);
void ib_unregister_client(struct ib_client *client);
+void __rdma_block_iter_start(struct ib_block_iter *biter,
+ struct scatterlist *sglist,
+ unsigned int nents,
+ unsigned long pgsz);
+bool __rdma_block_iter_next(struct ib_block_iter *biter);
+
+/**
+ * rdma_block_iter_dma_address - get the aligned dma address of the current
+ * block held by the block iterator.
+ * @biter: block iterator holding the memory block
+ */
+static inline dma_addr_t
+rdma_block_iter_dma_address(struct ib_block_iter *biter)
+{
+ return biter->__dma_addr & ~(BIT_ULL(biter->__pg_bit) - 1);
+}
+
+/**
+ * rdma_for_each_block - iterate over contiguous memory blocks of the sg list
+ * @sglist: sglist to iterate over
+ * @biter: block iterator holding the memory block
+ * @nents: maximum number of sg entries to iterate over
+ * @pgsz: best HW supported page size to use
+ *
+ * Callers may use rdma_block_iter_dma_address() to get each
+ * blocks aligned DMA address.
+ */
+#define rdma_for_each_block(sglist, biter, nents, pgsz) \
+ for (__rdma_block_iter_start(biter, sglist, nents, \
+ pgsz); \
+ __rdma_block_iter_next(biter);)
+
/**
* ib_get_client_data - Get IB client context
* @device:Device to get context for
--
1.8.3.1
