mac80211: add radiotap flag and handling for 5/10 MHz

Wireshark already defines radiotap channel flags for 5 and 10 MHz, so
just use them in Linux radiotap too. Furthermore, add rx status flags to
allow drivers to report when they received data on 5 or 10 MHz channels.

Signed-off-by: Simon Wunderlich <[e-mail]>
Signed-off-by: Mathias Kretschmer <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

include/net/ieee80211_radiotap.h

···
 #define	IEEE80211_CHAN_PASSIVE	0x0200	/* Only passive scan allowed */
 #define	IEEE80211_CHAN_DYN	0x0400	/* Dynamic CCK-OFDM channel */
 #define	IEEE80211_CHAN_GFSK	0x0800	/* GFSK channel (FHSS PHY) */
+#define	IEEE80211_CHAN_GSM	0x1000	/* GSM (900 MHz) */
+#define	IEEE80211_CHAN_STURBO	0x2000	/* Static Turbo */
+#define	IEEE80211_CHAN_HALF	0x4000	/* Half channel (10 MHz wide) */
+#define	IEEE80211_CHAN_QUARTER	0x8000	/* Quarter channel (5 MHz wide) */
 
 /* For IEEE80211_RADIOTAP_FLAGS */
 #define	IEEE80211_RADIOTAP_F_CFP	0x01	/* sent/received

include/net/mac80211.h

···
  * @RX_FLAG_AMPDU_DELIM_CRC_KNOWN: The delimiter CRC field is known (the CRC
  *	is stored in the @ampdu_delimiter_crc field)
  * @RX_FLAG_STBC_MASK: STBC 2 bit bitmask. 1 - Nss=1, 2 - Nss=2, 3 - Nss=3
+ * @RX_FLAG_10MHZ: 10 MHz (half channel) was used
+ * @RX_FLAG_5MHZ: 5 MHz (quarter channel) was used
  */
 enum mac80211_rx_flags {
 	RX_FLAG_MMIC_ERROR		= BIT(0),
···
 	RX_FLAG_80P80MHZ		= BIT(24),
 	RX_FLAG_160MHZ			= BIT(25),
 	RX_FLAG_STBC_MASK		= BIT(26) | BIT(27),
+	RX_FLAG_10MHZ			= BIT(28),
+	RX_FLAG_5MHZ			= BIT(29),
 };
 
 #define RX_FLAG_STBC_SHIFT		26

net/mac80211/rx.c

···
 	__le32 *it_present;
 	u32 it_present_val;
 	u16 rx_flags = 0;
+	u16 channel_flags = 0;
 	int mpdulen, chain;
 	unsigned long chains = status->chains;
 
···
 	/* IEEE80211_RADIOTAP_CHANNEL */
 	put_unaligned_le16(status->freq, pos);
 	pos += 2;
+	if (status->flag & RX_FLAG_10MHZ)
+		channel_flags |= IEEE80211_CHAN_HALF;
+	else if (status->flag & RX_FLAG_5MHZ)
+		channel_flags |= IEEE80211_CHAN_QUARTER;
+
 	if (status->band == IEEE80211_BAND_5GHZ)
-		put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_5GHZ,
-				   pos);
+		channel_flags |= IEEE80211_CHAN_OFDM | IEEE80211_CHAN_5GHZ;
 	else if (status->flag & (RX_FLAG_HT | RX_FLAG_VHT))
-		put_unaligned_le16(IEEE80211_CHAN_DYN | IEEE80211_CHAN_2GHZ,
-				   pos);
+		channel_flags |= IEEE80211_CHAN_DYN | IEEE80211_CHAN_2GHZ;
 	else if (rate && rate->flags & IEEE80211_RATE_ERP_G)
-		put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_2GHZ,
-				   pos);
+		channel_flags |= IEEE80211_CHAN_OFDM | IEEE80211_CHAN_2GHZ;
 	else if (rate)
-		put_unaligned_le16(IEEE80211_CHAN_CCK | IEEE80211_CHAN_2GHZ,
-				   pos);
+		channel_flags |= IEEE80211_CHAN_OFDM | IEEE80211_CHAN_2GHZ;
 	else
-		put_unaligned_le16(IEEE80211_CHAN_2GHZ, pos);
+		channel_flags |= IEEE80211_CHAN_2GHZ;
+	put_unaligned_le16(channel_flags, pos);
 	pos += 2;
 
 	/* IEEE80211_RADIOTAP_DBM_ANTSIGNAL */