ieee80211: add new VHT capability fields/parsing

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@intel.com>

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 17ea51d088aef3b2156ce0c77b771dcb3746b36f..280600a1011178c451a93bca884be9b3097cd8c9 100644 (file)
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -1460,13 +1460,16 @@ 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;
@@ -1475,6 +1478,13 @@ 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
@@ -1650,6 +1660,7 @@ struct ieee80211_mu_edca_param_set {
 #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
@@ -1678,6 +1689,26 @@ struct ieee80211_mu_edca_param_set {
 #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);
 
 /* 802.11ax HE MAC capabilities */
 #define IEEE80211_HE_MAC_CAP0_HTC_HE                           0x01

diff --git a/net/wireless/util.c b/net/wireless/util.c
index 4293f980e9c44b69b76280f33e8c27a198e2ce4e..ef14d80ca03ee22c5568933e1ff3d970557e59ea 100644 (file)
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -5,17 +5,20 @@
  * Copyright 2007-2009 Johannes Berg <johannes@sipsolutions.net>
  * Copyright 2013-2014  Intel Mobile Communications GmbH
  * Copyright 2017      Intel Deutschland GmbH
+ * Copyright (C) 2018 Intel Corporation
  */
 #include <linux/export.h>
 #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>
 #include <linux/if_vlan.h>
 #include <linux/mpls.h>
 #include <linux/gcd.h>
+#include <linux/bitfield.h>
 #include "core.h"
 #include "rdev-ops.h"
 
@@ -1938,3 +1941,109 @@ void cfg80211_send_layer2_update(struct net_device *dev, const u8 *addr)
        netif_rx_ni(skb);
 }
 EXPORT_SYMBOL(cfg80211_send_layer2_update);
+
+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_get_bits(cap->vht_cap_info,
+                                  IEEE80211_VHT_CAP_EXT_NSS_BW_MASK);
+       supp_width = le32_get_bits(cap->vht_cap_info,
+                                  IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK);
+
+       /* 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);