NTB: epf: 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.

Report vectors as 0..(db_count - 2) (skipping the unused slot) and return
BIT_ULL(db_vector) for the corresponding doorbell bit. Use
ntb_epf_db_vector_count() for bounds checks in ntb_epf_db_vector_mask(), so
the same lower-bound guard is applied before building the bitmask.

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: Dave Jiang <dave.jiang@intel.com>
Link: https://patch.msgid.link/20260513024923.451765-13-den@valinux.co.jp

diff --git a/drivers/ntb/hw/epf/ntb_hw_epf.c b/drivers/ntb/hw/epf/ntb_hw_epf.c
index 10618e462229a1ef73142d059f9d8a4a272bad1f..af575547284299699337a9b24b09585833cada04 100644 (file)
--- a/drivers/ntb/hw/epf/ntb_hw_epf.c
+++ b/drivers/ntb/hw/epf/ntb_hw_epf.c
@@ -434,6 +434,36 @@ static u64 ntb_epf_db_valid_mask(struct ntb_dev *ntb)
        return ntb_ndev(ntb)->db_valid_mask;
 }
 
+static int ntb_epf_db_vector_count(struct ntb_dev *ntb)
+{
+       struct ntb_epf_dev *ndev = ntb_ndev(ntb);
+       unsigned int db_count = ndev->db_count;
+
+       /*
+        * db_count includes an extra skipped slot due to the legacy
+        * doorbell layout. Expose only the real doorbell vectors.
+        */
+       if (db_count < NTB_EPF_MIN_DB_COUNT)
+               return 0;
+
+       return db_count - 1;
+}
+
+static u64 ntb_epf_db_vector_mask(struct ntb_dev *ntb, int db_vector)
+{
+       int nr_vec;
+
+       /*
+        * db_count includes one skipped slot in the legacy layout. Valid
+        * doorbell vectors are therefore [0 .. (db_count - 2)].
+        */
+       nr_vec = ntb_epf_db_vector_count(ntb);
+       if (db_vector < 0 || db_vector >= nr_vec)
+               return 0;
+
+       return BIT_ULL(db_vector);
+}
+
 static int ntb_epf_db_set_mask(struct ntb_dev *ntb, u64 db_bits)
 {
        return 0;
@@ -568,6 +598,8 @@ static const struct ntb_dev_ops ntb_epf_ops = {
        .spad_count             = ntb_epf_spad_count,
        .peer_mw_count          = ntb_epf_peer_mw_count,
        .db_valid_mask          = ntb_epf_db_valid_mask,
+       .db_vector_count        = ntb_epf_db_vector_count,
+       .db_vector_mask         = ntb_epf_db_vector_mask,
        .db_set_mask            = ntb_epf_db_set_mask,
        .mw_set_trans           = ntb_epf_mw_set_trans,
        .mw_clear_trans         = ntb_epf_mw_clear_trans,