On Sun, Jan 18, 2026 at 10:54:11PM +0900, Koichiro Den wrote: > At the BAR level, multiple MWs may be packed into a single BAR. In > addition, a single MW may itself be subdivided into multiple address > subranges, each of which can be mapped independently by the underlying > NTB hardware. > > Introduce an optional ntb_dev_ops callback, .mw_set_trans_ranges(), to > describe and program such layouts explicitly. The helper allows an NTB > driver to provide, for each MW, a list of contiguous subranges that > together cover the MW address space. > > Signed-off-by: Koichiro Den <[email protected]> > ---
Reviewed-by: Frank Li <[email protected]> > include/linux/ntb.h | 46 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 46 insertions(+) > > diff --git a/include/linux/ntb.h b/include/linux/ntb.h > index 8ff9d663096b..84908753f446 100644 > --- a/include/linux/ntb.h > +++ b/include/linux/ntb.h > @@ -206,6 +206,11 @@ static inline int ntb_ctx_ops_is_valid(const struct > ntb_ctx_ops *ops) > 1; > } > > +struct ntb_mw_subrange { > + dma_addr_t addr; > + resource_size_t size; > +}; > + > /** > * struct ntb_dev_ops - ntb device operations > * @port_number: See ntb_port_number(). > @@ -218,6 +223,7 @@ static inline int ntb_ctx_ops_is_valid(const struct > ntb_ctx_ops *ops) > * @mw_count: See ntb_mw_count(). > * @mw_get_align: See ntb_mw_get_align(). > * @mw_set_trans: See ntb_mw_set_trans(). > + * @mw_set_trans_ranges:See ntb_mw_set_trans_ranges(). > * @mw_clear_trans: See ntb_mw_clear_trans(). > * @peer_mw_count: See ntb_peer_mw_count(). > * @peer_mw_get_addr: See ntb_peer_mw_get_addr(). > @@ -276,6 +282,9 @@ struct ntb_dev_ops { > resource_size_t *size_max); > int (*mw_set_trans)(struct ntb_dev *ntb, int pidx, int widx, > dma_addr_t addr, resource_size_t size); > + int (*mw_set_trans_ranges)(struct ntb_dev *ntb, int pidx, int widx, > + unsigned int num_ranges, > + const struct ntb_mw_subrange *ranges); > int (*mw_clear_trans)(struct ntb_dev *ntb, int pidx, int widx); > int (*peer_mw_count)(struct ntb_dev *ntb); > int (*peer_mw_get_addr)(struct ntb_dev *ntb, int widx, > @@ -350,6 +359,7 @@ static inline int ntb_dev_ops_is_valid(const struct > ntb_dev_ops *ops) > ops->mw_get_align && > (ops->mw_set_trans || > ops->peer_mw_set_trans) && > + /* ops->mw_set_trans_ranges && */ > /* ops->mw_clear_trans && */ > ops->peer_mw_count && > ops->peer_mw_get_addr && > @@ -860,6 +870,42 @@ static inline int ntb_mw_set_trans(struct ntb_dev *ntb, > int pidx, int widx, > return ntb->ops->mw_set_trans(ntb, pidx, widx, addr, size); > } > > +/** > + * ntb_mw_set_trans_ranges() - set the translations of an inbound memory > + * window, composed of multiple subranges. > + * @ntb: NTB device context. > + * @pidx: Port index of peer device. > + * @widx: Memory window index. > + * @num_ranges: The number of ranges described by @ranges array. > + * @ranges: Array of subranges. The subranges are interpreted in ascending > + * window offset order (i.e. ranges[0] maps the first part of the > MW, > + * ranges[1] the next part, ...). > + * > + * Return: Zero on success, otherwise an error number. If the driver does > + * not implement the callback, return -EOPNOTSUPP. > + */ > +static inline int ntb_mw_set_trans_ranges(struct ntb_dev *ntb, int pidx, int > widx, > + unsigned int num_ranges, > + const struct ntb_mw_subrange *ranges) > +{ > + if (!num_ranges || !ranges) > + return -EINVAL; > + > + if (ntb->ops->mw_set_trans_ranges) > + return ntb->ops->mw_set_trans_ranges(ntb, pidx, widx, > + num_ranges, ranges); > + > + /* > + * Fallback for drivers that only support the legacy single-range > + * translation API. > + */ > + if (num_ranges == 1) > + return ntb_mw_set_trans(ntb, pidx, widx, > + ranges[0].addr, ranges[0].size); > + > + return -EOPNOTSUPP; > +} > + > /** > * ntb_mw_clear_trans() - clear the translation address of an inbound memory > * window > -- > 2.51.0 >
