[PATCH 10/10] NTB: epf: Implement db_vector_count/mask for doorbells

[Koichiro Den]

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.

Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
 drivers/ntb/hw/epf/ntb_hw_epf.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/ntb/hw/epf/ntb_hw_epf.c b/drivers/ntb/hw/epf/ntb_hw_epf.c
index 0018adc35f16..7c76039a79d2 100644
--- a/drivers/ntb/hw/epf/ntb_hw_epf.c
+++ b/drivers/ntb/hw/epf/ntb_hw_epf.c
@@ -414,6 +414,34 @@ 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);
+
+	/*
+	 * ndev->db_count includes an extra skipped slot due to the legacy
+	 * doorbell layout. Expose only the real doorbell vectors.
+	 */
+	if (ndev->db_count < 1)
+		return 0;
+
+	return ntb_ndev(ntb)->db_count - 1;
+}
+
+static u64 ntb_epf_db_vector_mask(struct ntb_dev *ntb, int db_vector)
+{
+	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
+
+	/*
+	 * ndev->db_count includes one skipped slot in the legacy layout. Valid
+	 * doorbell vectors are therefore [0 .. (db_count - 2)].
+	 */
+	if (db_vector < 0 || db_vector >= ndev->db_count - 1)
+		return 0;
+
+	return BIT_ULL(db_vector);
+}
+
 static int ntb_epf_db_set_mask(struct ntb_dev *ntb, u64 db_bits)
 {
 	return 0;
@@ -548,6 +576,8 @@ 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,
-- 
2.51.0