Not all NTB implementations are able to naturally do DMA mapping through the NTB PCI device itself (e.g. due to IOMMU topology or non-PCI backing devices).
Add an optional .get_dma_dev() callback and helper so clients can use the appropriate struct device for DMA API allocations and mappings. Signed-off-by: Koichiro Den <[email protected]> --- include/linux/ntb.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/include/linux/ntb.h b/include/linux/ntb.h index aa888219732a..7ac8cb13e90d 100644 --- a/include/linux/ntb.h +++ b/include/linux/ntb.h @@ -262,6 +262,7 @@ struct ntb_mw_subrange { * @msg_clear_mask: See ntb_msg_clear_mask(). * @msg_read: See ntb_msg_read(). * @peer_msg_write: See ntb_peer_msg_write(). + * @get_dma_dev: See ntb_get_dma_dev(). * @get_private_data: See ntb_get_private_data(). */ struct ntb_dev_ops { @@ -339,6 +340,7 @@ struct ntb_dev_ops { int (*msg_clear_mask)(struct ntb_dev *ntb, u64 mask_bits); u32 (*msg_read)(struct ntb_dev *ntb, int *pidx, int midx); int (*peer_msg_write)(struct ntb_dev *ntb, int pidx, int midx, u32 msg); + struct device *(*get_dma_dev)(struct ntb_dev *ntb); void *(*get_private_data)(struct ntb_dev *ntb); }; @@ -405,6 +407,7 @@ static inline int ntb_dev_ops_is_valid(const struct ntb_dev_ops *ops) !ops->peer_msg_write == !ops->msg_count && /* Miscellaneous optional callbacks */ + /* ops->get_dma_dev && */ /* ops->get_private_data && */ 1; } @@ -1614,6 +1617,21 @@ static inline int ntb_peer_msg_write(struct ntb_dev *ntb, int pidx, int midx, return ntb->ops->peer_msg_write(ntb, pidx, midx, msg); } +/** + * ntb_get_dma_dev() - get the device suitable for DMA mapping + * @ntb: NTB device context. + * + * Retrieve a struct device which is suitable for DMA mapping. + * + * Return: Pointer to struct device. + */ +static inline struct device __maybe_unused *ntb_get_dma_dev(struct ntb_dev *ntb) +{ + if (!ntb->ops->get_dma_dev) + return ntb->dev.parent; + return ntb->ops->get_dma_dev(ntb); +} + /** * ntb_get_private_data() - get private data specific to the hardware driver * @ntb: NTB device context. -- 2.51.0
