Some chips can tell us if received frame was
encoded with STBC or not. To make this information available
in user space we can use updated radiotap specification:
http://www.radiotap.org/defined-fields/MCS
This patch add HAVE_STBC flag and provide number
of STBC encoded spatial streams (Nss).
Signed-off-by: Oleksij Rempel <li...@rempel-privat.de>
---
include/net/ieee80211_radiotap.h | 7 +++++++
include/net/mac80211.h | 4 ++++
net/mac80211/rx.c | 13 ++++++++++++-
3 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/include/net/ieee80211_radiotap.h b/include/net/ieee80211_radiotap.h
index c399963..c6d07cb 100644
--- a/include/net/ieee80211_radiotap.h
+++ b/include/net/ieee80211_radiotap.h
@@ -269,6 +269,7 @@ enum ieee80211_radiotap_type {
#define IEEE80211_RADIOTAP_MCS_HAVE_GI 0x04
#define IEEE80211_RADIOTAP_MCS_HAVE_FMT 0x08
#define IEEE80211_RADIOTAP_MCS_HAVE_FEC 0x10
+#define IEEE80211_RADIOTAP_MCS_HAVE_STBC 0x20
#define IEEE80211_RADIOTAP_MCS_BW_MASK 0x03
#define IEEE80211_RADIOTAP_MCS_BW_20 0
@@ -278,6 +279,12 @@ enum ieee80211_radiotap_type {
#define IEEE80211_RADIOTAP_MCS_SGI 0x04
#define IEEE80211_RADIOTAP_MCS_FMT_GF 0x08
#define IEEE80211_RADIOTAP_MCS_FEC_LDPC 0x10
+#define IEEE80211_RADIOTAP_MCS_STBC_MASK 0x60
+#define IEEE80211_RADIOTAP_MCS_STBC_1 1
+#define IEEE80211_RADIOTAP_MCS_STBC_2 2
+#define IEEE80211_RADIOTAP_MCS_STBC_3 3
+
+#define IEEE80211_RADIOTAP_MCS_STBC_SHIFT 5
/* For IEEE80211_RADIOTAP_AMPDU_STATUS */
#define IEEE80211_RADIOTAP_AMPDU_REPORT_ZEROLEN 0x0001
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 885898a..16705a9 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -805,6 +805,7 @@ ieee80211_tx_info_clear_status(struct ieee80211_tx_info
*info)
* on this subframe
* @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
*/
enum mac80211_rx_flags {
RX_FLAG_MMIC_ERROR = BIT(0),
@@ -832,8 +833,11 @@ enum mac80211_rx_flags {
RX_FLAG_80MHZ = BIT(23),
RX_FLAG_80P80MHZ = BIT(24),
RX_FLAG_160MHZ = BIT(25),
+ RX_FLAG_STBC_MASK = BIT(26) | BIT(27),
};
+#define RX_FLAG_STBC_SHIFT 26
+
/**
* struct ieee80211_rx_status - receive status
*
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 8e29526..db7c68a 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -258,8 +258,16 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local
*local,
pos += 2;
if (status->flag & RX_FLAG_HT) {
+ unsigned int stbc = status->flag & RX_FLAG_STBC_MASK;
rthdr->it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_MCS);
- *pos++ = local->hw.radiotap_mcs_details;
+
+ /* MCS known field */
+ *pos = local->hw.radiotap_mcs_details;
+ if (stbc)
+ *pos |= IEEE80211_RADIOTAP_MCS_HAVE_STBC;
+ *pos++;
+
+ /* MCS flags field */
*pos = 0;
if (status->flag & RX_FLAG_SHORT_GI)
*pos |= IEEE80211_RADIOTAP_MCS_SGI;
@@ -267,6 +275,9 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local
*local,
*pos |= IEEE80211_RADIOTAP_MCS_BW_40;
if (status->flag & RX_FLAG_HT_GF)
*pos |= IEEE80211_RADIOTAP_MCS_FMT_GF;
+ if (stbc)
+ *pos |= (stbc >> RX_FLAG_STBC_SHIFT)
+ << IEEE80211_RADIOTAP_MCS_STBC_SHIFT;
pos++;
*pos++ = status->rate_idx;
}
--
1.8.1.2
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