From: Avraham Stern <avraham.stern@intel.com>
Date: Sun, 6 Dec 2020 14:54:45 +0200
Subject: [PATCH] mac80211: support Rx timestamp calculation for all preamble
 types

Add support for calculating the Rx timestamp for HE frames.
Since now all frame types are supported, allow setting the Rx
timestamp regardless of the frame type.

Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20201206145305.4786559af475.Ia54486bb0a12e5351f9d5c60ef6fcda7c9e7141c@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---

--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1600,13 +1600,8 @@ ieee80211_have_rx_timestamp(struct ieee8
 {
 	WARN_ON_ONCE(status->flag & RX_FLAG_MACTIME_START &&
 		     status->flag & RX_FLAG_MACTIME_END);
-	if (status->flag & (RX_FLAG_MACTIME_START | RX_FLAG_MACTIME_END))
-		return true;
-	/* can't handle non-legacy preamble yet */
-	if (status->flag & RX_FLAG_MACTIME_PLCP_START &&
-	    status->encoding == RX_ENC_LEGACY)
-		return true;
-	return false;
+	return !!(status->flag & (RX_FLAG_MACTIME_START | RX_FLAG_MACTIME_END |
+				  RX_FLAG_MACTIME_PLCP_START));
 }
 
 void ieee80211_vif_inc_num_mcast(struct ieee80211_sub_if_data *sdata);
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -3665,6 +3665,7 @@ u64 ieee80211_calculate_rx_timestamp(str
 	u64 ts = status->mactime;
 	struct rate_info ri;
 	u16 rate;
+	u8 n_ltf;
 
 	if (WARN_ON(!ieee80211_have_rx_timestamp(status)))
 		return 0;
@@ -3675,11 +3676,58 @@ u64 ieee80211_calculate_rx_timestamp(str
 
 	/* Fill cfg80211 rate info */
 	switch (status->encoding) {
+	case RX_ENC_HE:
+		ri.flags |= RATE_INFO_FLAGS_HE_MCS;
+		ri.mcs = status->rate_idx;
+		ri.nss = status->nss;
+		ri.he_ru_alloc = status->he_ru;
+		if (status->enc_flags & RX_ENC_FLAG_SHORT_GI)
+			ri.flags |= RATE_INFO_FLAGS_SHORT_GI;
+
+		/*
+		 * See P802.11ax_D6.0, section 27.3.4 for
+		 * VHT PPDU format.
+		 */
+		if (status->flag & RX_FLAG_MACTIME_PLCP_START) {
+			mpdu_offset += 2;
+			ts += 36;
+
+			/*
+			 * TODO:
+			 * For HE MU PPDU, add the HE-SIG-B.
+			 * For HE ER PPDU, add 8us for the HE-SIG-A.
+			 * For HE TB PPDU, add 4us for the HE-STF.
+			 * Add the HE-LTF durations - variable.
+			 */
+		}
+
+		break;
 	case RX_ENC_HT:
 		ri.mcs = status->rate_idx;
 		ri.flags |= RATE_INFO_FLAGS_MCS;
 		if (status->enc_flags & RX_ENC_FLAG_SHORT_GI)
 			ri.flags |= RATE_INFO_FLAGS_SHORT_GI;
+
+		/*
+		 * See P802.11REVmd_D3.0, section 19.3.2 for
+		 * HT PPDU format.
+		 */
+		if (status->flag & RX_FLAG_MACTIME_PLCP_START) {
+			mpdu_offset += 2;
+			if (status->enc_flags & RX_ENC_FLAG_HT_GF)
+				ts += 24;
+			else
+				ts += 32;
+
+			/*
+			 * Add Data HT-LTFs per streams
+			 * TODO: add Extension HT-LTFs, 4us per LTF
+			 */
+			n_ltf = ((ri.mcs >> 3) & 3) + 1;
+			n_ltf = n_ltf == 3 ? 4 : n_ltf;
+			ts += n_ltf * 4;
+		}
+
 		break;
 	case RX_ENC_VHT:
 		ri.flags |= RATE_INFO_FLAGS_VHT_MCS;
@@ -3687,6 +3735,23 @@ u64 ieee80211_calculate_rx_timestamp(str
 		ri.nss = status->nss;
 		if (status->enc_flags & RX_ENC_FLAG_SHORT_GI)
 			ri.flags |= RATE_INFO_FLAGS_SHORT_GI;
+
+		/*
+		 * See P802.11REVmd_D3.0, section 21.3.2 for
+		 * VHT PPDU format.
+		 */
+		if (status->flag & RX_FLAG_MACTIME_PLCP_START) {
+			mpdu_offset += 2;
+			ts += 36;
+
+			/*
+			 * Add VHT-LTFs per streams
+			 */
+			n_ltf = (ri.nss != 1) && (ri.nss % 2) ?
+				ri.nss + 1 : ri.nss;
+			ts += 4 * n_ltf;
+		}
+
 		break;
 	default:
 		WARN_ON(1);
@@ -3710,7 +3775,6 @@ u64 ieee80211_calculate_rx_timestamp(str
 		ri.legacy = DIV_ROUND_UP(bitrate, (1 << shift));
 
 		if (status->flag & RX_FLAG_MACTIME_PLCP_START) {
-			/* TODO: handle HT/VHT preambles */
 			if (status->band == NL80211_BAND_5GHZ) {
 				ts += 20 << shift;
 				mpdu_offset += 2;