bnxt_en: Implement the new toggle bit doorbell mechanism on P7 chips

The new chip family passes the Toggle bits to the driver in the NQE
notification.  The driver now stores this value and sends it back to
hardware when it re-arms the RX and TX CQs.  Together with the earlier
patch that guarantees the driver will only re-arm the CQ at the end of
NAPI polling if it has seen a new NQE, this method allows the hardware
to detect any dropped doorbells.

Signed-off-by: Michael Chan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Michael Chan

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -2880,13 +2880,18 @@ static void __bnxt_poll_cqs_done(struct bnxt *bp, struct bnxt_napi *bnapi,
 		struct bnxt_db_info *db;
 
 		if (cpr2->had_work_done) {
+			u32 tgl = 0;
+
+			if (dbr_type == DBR_TYPE_CQ_ARMALL) {
+				cpr2->had_nqe_notify = 0;
+				tgl = cpr2->toggle;
+			}
 			db = &cpr2->cp_db;
-			bnxt_writeq(bp, db->db_key64 | dbr_type |
+			bnxt_writeq(bp,
+				    db->db_key64 | dbr_type | DB_TOGGLE(tgl) |
 				    DB_RING_IDX(db, cpr2->cp_raw_cons),
 				    db->doorbell);
 			cpr2->had_work_done = 0;
-			if (dbr_type == DBR_TYPE_CQ_ARMALL)
-				cpr2->had_nqe_notify = 0;
 		}
 	}
 	__bnxt_poll_work_done(bp, bnapi, budget);
@@ -2912,6 +2917,8 @@ static int bnxt_poll_p5(struct napi_struct *napi, int budget)
 		work_done = __bnxt_poll_cqs(bp, bnapi, budget);
 	}
 	while (1) {
+		u16 type;
+
 		cons = RING_CMP(raw_cons);
 		nqcmp = &cpr->nq_desc_ring[CP_RING(cons)][CP_IDX(cons)];
 
@@ -2933,7 +2940,8 @@ static int bnxt_poll_p5(struct napi_struct *napi, int budget)
 		 */
 		dma_rmb();
 
-		if (nqcmp->type == cpu_to_le16(NQ_CN_TYPE_CQ_NOTIFICATION)) {
+		type = le16_to_cpu(nqcmp->type);
+		if (NQE_CN_TYPE(type) == NQ_CN_TYPE_CQ_NOTIFICATION) {
 			u32 idx = le32_to_cpu(nqcmp->cq_handle_low);
 			u32 cq_type = BNXT_NQ_HDL_TYPE(idx);
 			struct bnxt_cp_ring_info *cpr2;
@@ -2946,6 +2954,7 @@ static int bnxt_poll_p5(struct napi_struct *napi, int budget)
 			idx = BNXT_NQ_HDL_IDX(idx);
 			cpr2 = &cpr->cp_ring_arr[idx];
 			cpr2->had_nqe_notify = 1;
+			cpr2->toggle = NQE_CN_TOGGLE(type);
 			work_done += __bnxt_poll_work(bp, cpr2,
 						      budget - work_done);
 			cpr->has_more_work |= cpr2->has_more_work;

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -1038,6 +1038,7 @@ struct bnxt_cp_ring_info {
 	u8			had_work_done:1;
 	u8			has_more_work:1;
 	u8			had_nqe_notify:1;
+	u8			toggle;
 
 	u8			cp_ring_type;
 	u8			cp_idx;