From: Johannes Berg <johannes.berg@xxxxxxxxx>
IEEE 802.11-2016 extended the VHT capability fields to allow
indicating the number of spatial streams depending on the
actually used bandwidth, add support for decoding this.
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
include/linux/ieee80211.h | 35 ++++++++++++++-
net/wireless/util.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 140 insertions(+), 2 deletions(-)
diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 22bf0676d928..522ba67027fc 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -1457,13 +1457,16 @@ struct ieee80211_ht_operation {
* STA can receive. Rate expressed in units of 1 Mbps.
* If this field is 0 this value should not be used to
* consider the highest RX data rate supported.
- * The top 3 bits of this field are reserved.
+ * The top 3 bits of this field indicate the Maximum NSTS,total
+ * (a beamformee capability.)
* @tx_mcs_map: TX MCS map 2 bits for each stream, total 8 streams
* @tx_highest: Indicates highest long GI VHT PPDU data rate
* STA can transmit. Rate expressed in units of 1 Mbps.
* If this field is 0 this value should not be used to
* consider the highest TX data rate supported.
- * The top 3 bits of this field are reserved.
+ * The top 2 bits of this field are reserved, the
+ * 3rd bit from the top indiciates VHT Extended NSS BW
+ * Capability.
*/
struct ieee80211_vht_mcs_info {
__le16 rx_mcs_map;
@@ -1472,6 +1475,13 @@ struct ieee80211_vht_mcs_info {
__le16 tx_highest;
} __packed;
+/* for rx_highest */
+#define IEEE80211_VHT_MAX_NSTS_TOTAL_SHIFT 13
+#define IEEE80211_VHT_MAX_NSTS_TOTAL_MASK (7 << IEEE80211_VHT_MAX_NSTS_TOTAL_SHIFT)
+
+/* for tx_highest */
+#define IEEE80211_VHT_EXT_NSS_BW_CAPABLE (1 << 13)
+
/**
* enum ieee80211_vht_mcs_support - VHT MCS support definitions
* @IEEE80211_VHT_MCS_SUPPORT_0_7: MCSes 0-7 are supported for the
@@ -1547,6 +1557,7 @@ struct ieee80211_vht_operation {
#define IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ 0x00000004
#define IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ 0x00000008
#define IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK 0x0000000C
+#define IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_SHIFT 2
#define IEEE80211_VHT_CAP_RXLDPC 0x00000010
#define IEEE80211_VHT_CAP_SHORT_GI_80 0x00000020
#define IEEE80211_VHT_CAP_SHORT_GI_160 0x00000040
@@ -1575,6 +1586,26 @@ struct ieee80211_vht_operation {
#define IEEE80211_VHT_CAP_VHT_LINK_ADAPTATION_VHT_MRQ_MFB 0x0c000000
#define IEEE80211_VHT_CAP_RX_ANTENNA_PATTERN 0x10000000
#define IEEE80211_VHT_CAP_TX_ANTENNA_PATTERN 0x20000000
+#define IEEE80211_VHT_CAP_EXT_NSS_BW_SHIFT 30
+#define IEEE80211_VHT_CAP_EXT_NSS_BW_MASK 0xc0000000
+
+/**
+ * ieee80211_get_vht_max_nss - return max NSS for a given bandwidth/MCS
+ * @cap: VHT capabilities of the peer
+ * @bw: bandwidth to use
+ * @mcs: MCS index to use
+ * @ext_nss_bw_capable: indicates whether or not the local transmitter
+ * (rate scaling algorithm) can deal with the new logic
+ * (dot11VHTExtendedNSSBWCapable)
+ *
+ * Due to the VHT Extended NSS Bandwidth Support, the maximum NSS can
+ * vary for a given BW/MCS. This function parses the data.
+ *
+ * Note: This function is exported by cfg80211.
+ */
+int ieee80211_get_vht_max_nss(struct ieee80211_vht_cap *cap,
+ enum ieee80211_vht_chanwidth bw,
+ int mcs, bool ext_nss_bw_capable);
/* Authentication algorithms */
#define WLAN_AUTH_OPEN 0
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 737c9c2c9cc9..313485d505c8 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -8,6 +8,7 @@
#include <linux/bitops.h>
#include <linux/etherdevice.h>
#include <linux/slab.h>
+#include <linux/ieee80211.h>
#include <net/cfg80211.h>
#include <net/ip.h>
#include <net/dsfield.h>
@@ -1874,3 +1875,109 @@ EXPORT_SYMBOL(rfc1042_header);
const unsigned char bridge_tunnel_header[] __aligned(2) =
{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
EXPORT_SYMBOL(bridge_tunnel_header);
+
+int ieee80211_get_vht_max_nss(struct ieee80211_vht_cap *cap,
+ enum ieee80211_vht_chanwidth bw,
+ int mcs, bool ext_nss_bw_capable)
+{
+ u16 map = le16_to_cpu(cap->supp_mcs.rx_mcs_map);
+ int max_vht_nss = 0;
+ int ext_nss_bw;
+ int supp_width;
+ int i, mcs_encoding;
+
+ if (map == 0xffff)
+ return 0;
+
+ if (WARN_ON(mcs > 9))
+ return 0;
+ if (mcs <= 7)
+ mcs_encoding = 0;
+ else if (mcs == 8)
+ mcs_encoding = 1;
+ else
+ mcs_encoding = 2;
+
+ /* find max_vht_nss for the given MCS */
+ for (i = 7; i >= 0; i--) {
+ int supp = (map >> (2*i)) & 3;
+
+ if (supp == 3)
+ continue;
+
+ if (supp >= mcs_encoding) {
+ max_vht_nss = i;
+ break;
+ }
+ }
+
+ if (!(cap->supp_mcs.tx_mcs_map & cpu_to_le16(IEEE80211_VHT_EXT_NSS_BW_CAPABLE)))
+ return max_vht_nss;
+
+ ext_nss_bw = (le32_to_cpu(cap->vht_cap_info) &
+ IEEE80211_VHT_CAP_EXT_NSS_BW_MASK)
+ >> IEEE80211_VHT_CAP_EXT_NSS_BW_SHIFT;
+ supp_width = (le32_to_cpu(cap->vht_cap_info) &
+ IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK)
+ >> IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_SHIFT;
+
+ /* if not capable, treat ext_nss_bw as 0 */
+ if (!ext_nss_bw_capable)
+ ext_nss_bw = 0;
+
+ /* This is invalid */
+ if (supp_width == 3)
+ return 0;
+
+ /* This is an invalid combination so pretend nothing is supported */
+ if (supp_width == 2 && (ext_nss_bw == 1 || ext_nss_bw == 2))
+ return 0;
+
+ /*
+ * Cover all the special cases according to IEEE 802.11-2016 Table 9-250.
+ * All other cases are either factor of 1 or not valid/supported.
+ */
+ switch (bw) {
+ case IEEE80211_VHT_CHANWIDTH_USE_HT:
+ case IEEE80211_VHT_CHANWIDTH_80MHZ:
+ if ((supp_width == 1 || supp_width == 2) &&
+ ext_nss_bw == 3)
+ return 2 * max_vht_nss;
+ break;
+ case IEEE80211_VHT_CHANWIDTH_160MHZ:
+ if (supp_width == 0 &&
+ (ext_nss_bw == 1 || ext_nss_bw == 2))
+ return DIV_ROUND_UP(max_vht_nss, 2);
+ if (supp_width == 0 &&
+ ext_nss_bw == 3)
+ return DIV_ROUND_UP(3 * max_vht_nss, 4);
+ if (supp_width == 1 &&
+ ext_nss_bw == 3)
+ return 2 * max_vht_nss;
+ break;
+ case IEEE80211_VHT_CHANWIDTH_80P80MHZ:
+ if (supp_width == 0 &&
+ (ext_nss_bw == 1 || ext_nss_bw == 2))
+ return 0; /* not possible */
+ if (supp_width == 0 &&
+ ext_nss_bw == 2)
+ return DIV_ROUND_UP(max_vht_nss, 2);
+ if (supp_width == 0 &&
+ ext_nss_bw == 3)
+ return DIV_ROUND_UP(3 * max_vht_nss, 4);
+ if (supp_width == 1 &&
+ ext_nss_bw == 0)
+ return 0; /* not possible */
+ if (supp_width == 1 &&
+ ext_nss_bw == 1)
+ return DIV_ROUND_UP(max_vht_nss, 2);
+ if (supp_width == 1 &&
+ ext_nss_bw == 2)
+ return DIV_ROUND_UP(3 * max_vht_nss, 4);
+ break;
+ }
+
+ /* not covered or invalid combination received */
+ return max_vht_nss;
+}
+EXPORT_SYMBOL(ieee80211_get_vht_max_nss);
--
2.11.0
