diff options
| author | Koichiro Den <den@valinux.co.jp> | 2026-05-13 11:49:18 +0900 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2026-06-23 11:37:27 -0500 |
| commit | 2579f3f7f52090463596765040aaad71e91ef4d5 (patch) | |
| tree | 54cf3f34dda54eb3451882459d8e00b1c7b1f86b | |
| parent | 823468a4ea1613f1c1235bd16af8b9c6eb9c9677 (diff) | |
PCI: endpoint: pci-epf-vntb: Implement .db_vector_count()/mask() for doorbells
Implement .db_vector_count() and .db_vector_mask() so NTB core/clients can
map doorbell events to per-vector work and avoid the thundering-herd
behavior.
pci-epf-vntb reserves two slots in db_count: slot 0 for link events and
slot 1 which is historically unused. Therefore the number of doorbell
vectors is (db_count - 2).
Report vectors as 0..N-1 and return BIT_ULL(db_vector) for the
corresponding doorbell bit. Build db_valid_mask from a validated vector
count so out-of-range db_count values cannot create invalid shifts.
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260513024923.451765-8-den@valinux.co.jp
| -rw-r--r-- | drivers/pci/endpoint/functions/pci-epf-vntb.c | 42 |
1 files changed, 40 insertions, 2 deletions
diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c index 58e41d95d029..c3caec927d74 100644 --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c @@ -1362,12 +1362,48 @@ static int vntb_epf_peer_mw_count(struct ntb_dev *ntb) return ntb_ndev(ntb)->num_mws; } +static int vntb_epf_db_vector_count(struct ntb_dev *ntb) +{ + struct epf_ntb *ndev = ntb_ndev(ntb); + u32 db_count = READ_ONCE(ndev->db_count); + + /* + * db_count is the total number of doorbell slots exposed to + * the peer, including: + * - slot #0 reserved for link events + * - slot #1 historically unused (kept for protocol compatibility) + * + * Report only usable per-vector doorbell interrupts. + */ + if (db_count < MIN_DB_COUNT || db_count > MAX_DB_COUNT) + return 0; + + return db_count - EPF_IRQ_DB_START; +} + static u64 vntb_epf_db_valid_mask(struct ntb_dev *ntb) { - if (ntb_ndev(ntb)->db_count < EPF_IRQ_DB_START) + int nr_vec = vntb_epf_db_vector_count(ntb); + + if (!nr_vec) + return 0; + + return GENMASK_ULL(nr_vec - 1, 0); +} + +static u64 vntb_epf_db_vector_mask(struct ntb_dev *ntb, int db_vector) +{ + int nr_vec; + + /* + * Doorbell vectors are numbered [0 .. nr_vec - 1], where nr_vec + * excludes the two reserved slots described above. + */ + nr_vec = vntb_epf_db_vector_count(ntb); + if (db_vector < 0 || db_vector >= nr_vec) return 0; - return BIT_ULL(ntb_ndev(ntb)->db_count - EPF_IRQ_DB_START) - 1; + return BIT_ULL(db_vector); } static int vntb_epf_db_set_mask(struct ntb_dev *ntb, u64 db_bits) @@ -1617,6 +1653,8 @@ static const struct ntb_dev_ops vntb_epf_ops = { .spad_count = vntb_epf_spad_count, .peer_mw_count = vntb_epf_peer_mw_count, .db_valid_mask = vntb_epf_db_valid_mask, + .db_vector_count = vntb_epf_db_vector_count, + .db_vector_mask = vntb_epf_db_vector_mask, .db_set_mask = vntb_epf_db_set_mask, .mw_set_trans = vntb_epf_mw_set_trans, .mw_clear_trans = vntb_epf_mw_clear_trans, |