bnxt_en: Prevent kernel panic when receiving unexpected PHC_UPDATE event

The firmware can send PHC_RTC_UPDATE async event on a PF that may not
have PTP registered. In such a case, there will be a null pointer
deference for bp->ptp_cfg when we try to handle the event.

Fix it by not registering for this event with the firmware if !bp->ptp_cfg.
Also, check that bp->ptp_cfg is valid before proceeding when we receive
the event.

Fixes: 8bcf6f04 ("bnxt_en: Handle async event when the PHC is updated in RTC mode")
Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

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

@@ -2365,6 +2365,9 @@ static int bnxt_async_event_process(struct bnxt *bp,
 				struct bnxt_ptp_cfg *ptp = bp->ptp_cfg;
 				u64 ns;
 
+				if (!ptp)
+					goto async_event_process_exit;
+
 				spin_lock_bh(&ptp->ptp_lock);
 				bnxt_ptp_update_current_time(bp);
 				ns = (((u64)BNXT_EVENT_PHC_RTC_UPDATE(data1) <<
@@ -4763,6 +4766,9 @@ int bnxt_hwrm_func_drv_rgtr(struct bnxt *bp, unsigned long *bmap, int bmap_size,
 		if (event_id == ASYNC_EVENT_CMPL_EVENT_ID_ERROR_RECOVERY &&
 		    !(bp->fw_cap & BNXT_FW_CAP_ERROR_RECOVERY))
 			continue;
+		if (event_id == ASYNC_EVENT_CMPL_EVENT_ID_PHC_UPDATE &&
+		    !bp->ptp_cfg)
+			continue;
 		__set_bit(bnxt_async_events_arr[i], async_events_bmap);
 	}
 	if (bmap && bmap_size) {

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

@@ -952,6 +952,7 @@ int bnxt_ptp_init(struct bnxt *bp, bool phc_cfg)
 		bnxt_ptp_timecounter_init(bp, true);
 		bnxt_ptp_adjfine_rtc(bp, 0);
 	}
+	bnxt_hwrm_func_drv_rgtr(bp, NULL, 0, true);
 
 	ptp->ptp_info = bnxt_ptp_caps;
 	if ((bp->fw_cap & BNXT_FW_CAP_PTP_PPS)) {