wcn36xx: Correct band/freq reporting on RX

For packets originating from hardware scan, the channel and band is
included in the buffer descriptor (bd->rf_band & bd->rx_ch).

For 2Ghz band the channel value is directly reported in the 4-bit
rx_ch field. For 5Ghz band, the rx_ch field contains a mapping
index (given the 4-bit limitation).

The reserved0 value field is also used to extend 4-bit mapping to
5-bit mapping to support more than 16 5Ghz channels.

This change adds correct reporting of the frequency/band, that is
used in scan mechanism. And is required for 5Ghz hardware scan
support.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1634554678-7993-1-git-send-email-loic.poulain@linaro.org

drivers/net/wireless/ath/wcn36xx/txrx.c

@@ -31,6 +31,13 @@ struct wcn36xx_rate {
 	enum rate_info_bw bw;
 };
 
+/* Buffer descriptor rx_ch field is limited to 5-bit (4+1), a mapping is used
+ * for 11A Channels.
+ */
+static const u8 ab_rx_ch_map[] = { 36, 40, 44, 48, 52, 56, 60, 64, 100, 104,
+				   108, 112, 116, 120, 124, 128, 132, 136, 140,
+				   149, 153, 157, 161, 165, 144 };
+
 static const struct wcn36xx_rate wcn36xx_rate_table[] = {
 	/* 11b rates */
 	{  10, 0, RX_ENC_LEGACY, 0, RATE_INFO_BW_20 },
@@ -291,6 +298,22 @@ int wcn36xx_rx_skb(struct wcn36xx *wcn, struct sk_buff *skb)
 	    ieee80211_is_probe_resp(hdr->frame_control))
 		status.boottime_ns = ktime_get_boottime_ns();
 
+	if (bd->scan_learn) {
+		/* If packet originates from hardware scanning, extract the
+		 * band/channel from bd descriptor.
+		 */
+		u8 hwch = (bd->reserved0 << 4) + bd->rx_ch;
+
+		if (bd->rf_band != 1 && hwch <= sizeof(ab_rx_ch_map) && hwch >= 1) {
+			status.band = NL80211_BAND_5GHZ;
+			status.freq = ieee80211_channel_to_frequency(ab_rx_ch_map[hwch - 1],
+								     status.band);
+		} else {
+			status.band = NL80211_BAND_2GHZ;
+			status.freq = ieee80211_channel_to_frequency(hwch, status.band);
+		}
+	}
+
 	memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
 
 	if (ieee80211_is_beacon(hdr->frame_control)) {

drivers/net/wireless/ath/wcn36xx/txrx.h

@@ -110,7 +110,8 @@ struct wcn36xx_rx_bd {
 	/* 0x44 */
 	u32	exp_seq_num:12;
 	u32	cur_seq_num:12;
-	u32	fr_type_subtype:8;
+	u32	rf_band:2;
+	u32	fr_type_subtype:6;
 
 	/* 0x48 */
 	u32	msdu_size:16;