wifi: wlcore: add pn16 support

TI Wl18xx firmware adds a "pn16" field for AES and TKIP keys as per
their patch:

https://git.ti.com/cgit/wilink8-wlan/build-utilites/tree/patches/kernel_patches/4.19.38/0023-wlcore-Fixing-PN-drift-on-encrypted-link-after-recov.patch?h=r8.9&id=a2ee50aa5190ed3b334373d6cd09b1bff56ffcf7

Add support for this, but rather than requiring the field to be
present (which would break existing firmwares), make it optional.
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/E1sBsy7-00E8vu-Nc@rmk-PC.armlinux.org.uk

drivers/net/wireless/ti/wlcore/cmd.c

@@ -332,6 +332,14 @@ int wl12xx_allocate_link(struct wl1271 *wl, struct wl12xx_vif *wlvif, u8 *hlid)
 			wl->fw_status->counters.tx_lnk_free_pkts[link];
 	wl->links[link].wlvif = wlvif;
 
+	/*
+	 * Take the last sec_pn16 value from the current FW status. On recovery,
+	 * we might not have fw_status yet, and tx_lnk_sec_pn16[] will be NULL.
+	 */
+	if (wl->fw_status->counters.tx_lnk_sec_pn16)
+		wl->links[link].prev_sec_pn16 =
+			le16_to_cpu(wl->fw_status->counters.tx_lnk_sec_pn16[link]);
+
 	/*
 	 * Take saved value for total freed packets from wlvif, in case this is
 	 * recovery/resume
@@ -360,6 +368,7 @@ void wl12xx_free_link(struct wl1271 *wl, struct wl12xx_vif *wlvif, u8 *hlid)
 
 	wl->links[*hlid].allocated_pkts = 0;
 	wl->links[*hlid].prev_freed_pkts = 0;
+	wl->links[*hlid].prev_sec_pn16 = 0;
 	wl->links[*hlid].ba_bitmap = 0;
 	eth_zero_addr(wl->links[*hlid].addr);
 

drivers/net/wireless/ti/wlcore/main.c

@@ -379,6 +379,8 @@ static void wl12xx_irq_update_links_status(struct wl1271 *wl,
 
 static int wlcore_fw_status(struct wl1271 *wl, struct wl_fw_status *status)
 {
+	struct wl12xx_vif *wlvifsta;
+	struct wl12xx_vif *wlvifap;
 	struct wl12xx_vif *wlvif;
 	u32 old_tx_blk_count = wl->tx_blocks_available;
 	int avail, freed_blocks;
@@ -410,23 +412,100 @@ static int wlcore_fw_status(struct wl1271 *wl, struct wl_fw_status *status)
 		wl->tx_pkts_freed[i] = status->counters.tx_released_pkts[i];
 	}
 
+	/* Find an authorized STA vif */
+	wlvifsta = NULL;
+	wl12xx_for_each_wlvif_sta(wl, wlvif) {
+		if (wlvif->sta.hlid != WL12XX_INVALID_LINK_ID &&
+		    test_bit(WLVIF_FLAG_STA_AUTHORIZED, &wlvif->flags)) {
+			wlvifsta = wlvif;
+			break;
+		}
+	}
+
+	/* Find a started AP vif */
+	wlvifap = NULL;
+	wl12xx_for_each_wlvif(wl, wlvif) {
+		if (wlvif->bss_type == BSS_TYPE_AP_BSS &&
+		    wlvif->inconn_count == 0 &&
+		    test_bit(WLVIF_FLAG_AP_STARTED, &wlvif->flags)) {
+			wlvifap = wlvif;
+			break;
+		}
+	}
 
 	for_each_set_bit(i, wl->links_map, wl->num_links) {
+		u16 diff16, sec_pn16;
 		u8 diff, tx_lnk_free_pkts;
+
 		lnk = &wl->links[i];
 
 		/* prevent wrap-around in freed-packets counter */
 		tx_lnk_free_pkts = status->counters.tx_lnk_free_pkts[i];
 		diff = (tx_lnk_free_pkts - lnk->prev_freed_pkts) & 0xff;
 
-		if (diff == 0)
+		if (diff) {
+			lnk->allocated_pkts -= diff;
+			lnk->prev_freed_pkts = tx_lnk_free_pkts;
+		}
+
+		/* Get the current sec_pn16 value if present */
+		if (status->counters.tx_lnk_sec_pn16)
+			sec_pn16 = __le16_to_cpu(status->counters.tx_lnk_sec_pn16[i]);
+		else
+			sec_pn16 = 0;
+		/* prevent wrap-around in pn16 counter */
+		diff16 = (sec_pn16 - lnk->prev_sec_pn16) & 0xffff;
+
+		/* FIXME: since free_pkts is a 8-bit counter of packets that
+		 * rolls over, it can become zero. If it is zero, then we
+		 * omit processing below. Is that really correct?
+		 */
+		if (tx_lnk_free_pkts <= 0)
 			continue;
 
-		lnk->allocated_pkts -= diff;
-		lnk->prev_freed_pkts = tx_lnk_free_pkts;
+		/* For a station that has an authorized link: */
+		if (wlvifsta && wlvifsta->sta.hlid == i) {
+			if (wlvifsta->encryption_type == KEY_TKIP ||
+			    wlvifsta->encryption_type == KEY_AES) {
+				if (diff16) {
+					lnk->prev_sec_pn16 = sec_pn16;
+					/* accumulate the prev_freed_pkts
+					 * counter according to the PN from
+					 * firmware
+					 */
+					lnk->total_freed_pkts += diff16;
+				}
+			} else {
+				if (diff)
+					/* accumulate the prev_freed_pkts
+					 * counter according to the free packets
+					 * count from firmware
+					 */
+					lnk->total_freed_pkts += diff;
+			}
+		}
 
-		/* accumulate the prev_freed_pkts counter */
-		lnk->total_freed_pkts += diff;
+		/* For an AP that has been started */
+		if (wlvifap && test_bit(i, wlvifap->ap.sta_hlid_map)) {
+			if (wlvifap->encryption_type == KEY_TKIP ||
+			    wlvifap->encryption_type == KEY_AES) {
+				if (diff16) {
+					lnk->prev_sec_pn16 = sec_pn16;
+					/* accumulate the prev_freed_pkts
+					 * counter according to the PN from
+					 * firmware
+					 */
+					lnk->total_freed_pkts += diff16;
+				}
+			} else {
+				if (diff)
+					/* accumulate the prev_freed_pkts
+					 * counter according to the free packets
+					 * count from firmware
+					 */
+					lnk->total_freed_pkts += diff;
+			}
+		}
 	}
 
 	/* prevent wrap-around in total blocks counter */

drivers/net/wireless/ti/wlcore/wlcore_i.h

@@ -151,6 +151,9 @@ struct wl_fw_status {
 		 */
 		u8 *tx_lnk_free_pkts;
 
+		/* PN16 of last TKIP/AES seq-num per HLID */
+		__le16 *tx_lnk_sec_pn16;
+
 		/* Cumulative counter of released Voice memory blocks */
 		u8 tx_voice_released_blks;
 
@@ -259,6 +262,7 @@ struct wl1271_link {
 	/* accounting for allocated / freed packets in FW */
 	u8 allocated_pkts;
 	u8 prev_freed_pkts;
+	u16 prev_sec_pn16;
 
 	u8 addr[ETH_ALEN];