On Mon, Jan 19, 2026 at 03:09:18PM -0500, Frank Li wrote: > On Sun, Jan 18, 2026 at 10:54:13PM +0900, Koichiro Den wrote: > > 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) > > I remember if there are inline, needn't __maybe_unused.
My bad, I'll drop it. Thanks, Koichiro > > Reviewed-by: Frank Li <[email protected]> > > +{ > > + 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 > >
