mac80211: add support for mcs masks

* Handle MCS masks set by the user.
* Match rates provided by the rate control algorithm to the mask set,
  also in HT mode, and switch back to legacy mode if necessary.
* add debugfs files to observate the rate selection

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

6 files changed, 167 insertions, 9 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index dc7420441574..d15ba0d0de94 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1902,8 +1902,11 @@ static int ieee80211_set_bitrate_mask(struct wiphy *wiphy,
                         return ret;
         }
 
-        for (i = 0; i < IEEE80211_NUM_BANDS; i++)
+        for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
                 sdata->rc_rateidx_mask[i] = mask->control[i].legacy;
+                memcpy(sdata->rc_rateidx_mcs_mask[i], mask->control[i].mcs,
+                       sizeof(mask->control[i].mcs));
+        }
 
         return 0;
 }
diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 81d12e65a23c..510ed1dab3c7 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -87,6 +87,21 @@ static ssize_t ieee80211_if_fmt_##name(					\
 #define IEEE80211_IF_FMT_SIZE(name, field)                              \
                 IEEE80211_IF_FMT(name, field, "%zd\n")
 
+#define IEEE80211_IF_FMT_HEXARRAY(name, field)                          \
+static ssize_t ieee80211_if_fmt_##name(                                 \
+        const struct ieee80211_sub_if_data *sdata,                      \
+        char *buf, int buflen)                                          \
+{                                                                       \
+        char *p = buf;                                                  \
+        int i;                                                          \
+        for (i = 0; i < sizeof(sdata->field); i++) {                    \
+                p += scnprintf(p, buflen + buf - p, "%.2x ",            \
+                                 sdata->field[i]);                      \
+        }                                                               \
+        p += scnprintf(p, buflen + buf - p, "\n");                      \
+        return p - buf;                                                 \
+}
+
 #define IEEE80211_IF_FMT_ATOMIC(name, field)                            \
 static ssize_t ieee80211_if_fmt_##name(                                 \
         const struct ieee80211_sub_if_data *sdata,                      \
@@ -148,6 +163,11 @@ IEEE80211_IF_FILE(rc_rateidx_mask_2ghz, rc_rateidx_mask[IEEE80211_BAND_2GHZ],
                   HEX);
 IEEE80211_IF_FILE(rc_rateidx_mask_5ghz, rc_rateidx_mask[IEEE80211_BAND_5GHZ],
                   HEX);
+IEEE80211_IF_FILE(rc_rateidx_mcs_mask_2ghz,
+                  rc_rateidx_mcs_mask[IEEE80211_BAND_2GHZ], HEXARRAY);
+IEEE80211_IF_FILE(rc_rateidx_mcs_mask_5ghz,
+                  rc_rateidx_mcs_mask[IEEE80211_BAND_5GHZ], HEXARRAY);
+
 IEEE80211_IF_FILE(flags, flags, HEX);
 IEEE80211_IF_FILE(state, state, LHEX);
 IEEE80211_IF_FILE(channel_type, vif.bss_conf.channel_type, DEC);
@@ -442,6 +462,8 @@ static void add_sta_files(struct ieee80211_sub_if_data *sdata)
         DEBUGFS_ADD(channel_type);
         DEBUGFS_ADD(rc_rateidx_mask_2ghz);
         DEBUGFS_ADD(rc_rateidx_mask_5ghz);
+        DEBUGFS_ADD(rc_rateidx_mcs_mask_2ghz);
+        DEBUGFS_ADD(rc_rateidx_mcs_mask_5ghz);
 
         DEBUGFS_ADD(bssid);
         DEBUGFS_ADD(aid);
@@ -459,6 +481,8 @@ static void add_ap_files(struct ieee80211_sub_if_data *sdata)
         DEBUGFS_ADD(channel_type);
         DEBUGFS_ADD(rc_rateidx_mask_2ghz);
         DEBUGFS_ADD(rc_rateidx_mask_5ghz);
+        DEBUGFS_ADD(rc_rateidx_mcs_mask_2ghz);
+        DEBUGFS_ADD(rc_rateidx_mcs_mask_5ghz);
 
         DEBUGFS_ADD(num_sta_authorized);
         DEBUGFS_ADD(num_sta_ps);
@@ -469,6 +493,12 @@ static void add_ap_files(struct ieee80211_sub_if_data *sdata)
 
 static void add_ibss_files(struct ieee80211_sub_if_data *sdata)
 {
+        DEBUGFS_ADD(channel_type);
+        DEBUGFS_ADD(rc_rateidx_mask_2ghz);
+        DEBUGFS_ADD(rc_rateidx_mask_5ghz);
+        DEBUGFS_ADD(rc_rateidx_mcs_mask_2ghz);
+        DEBUGFS_ADD(rc_rateidx_mcs_mask_5ghz);
+
         DEBUGFS_ADD_MODE(tsf, 0600);
 }
 
@@ -480,6 +510,8 @@ static void add_wds_files(struct ieee80211_sub_if_data *sdata)
         DEBUGFS_ADD(channel_type);
         DEBUGFS_ADD(rc_rateidx_mask_2ghz);
         DEBUGFS_ADD(rc_rateidx_mask_5ghz);
+        DEBUGFS_ADD(rc_rateidx_mcs_mask_2ghz);
+        DEBUGFS_ADD(rc_rateidx_mcs_mask_5ghz);
 
         DEBUGFS_ADD(peer);
 }
@@ -492,6 +524,8 @@ static void add_vlan_files(struct ieee80211_sub_if_data *sdata)
         DEBUGFS_ADD(channel_type);
         DEBUGFS_ADD(rc_rateidx_mask_2ghz);
         DEBUGFS_ADD(rc_rateidx_mask_5ghz);
+        DEBUGFS_ADD(rc_rateidx_mcs_mask_2ghz);
+        DEBUGFS_ADD(rc_rateidx_mcs_mask_5ghz);
 }
 
 static void add_monitor_files(struct ieee80211_sub_if_data *sdata)
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index ca6486b941b6..d47e8c110b16 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -646,6 +646,7 @@ struct ieee80211_sub_if_data {
 
         /* bitmap of allowed (non-MCS) rate indexes for rate control */
         u32 rc_rateidx_mask[IEEE80211_NUM_BANDS];
+        u8  rc_rateidx_mcs_mask[IEEE80211_NUM_BANDS][IEEE80211_HT_MCS_MASK_LEN];
 
         union {
                 struct ieee80211_if_ap ap;
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 6b0d70e960d4..c33feede5dca 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1181,6 +1181,13 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
                 sband = local->hw.wiphy->bands[i];
                 sdata->rc_rateidx_mask[i] =
                         sband ? (1 << sband->n_bitrates) - 1 : 0;
+                if (sband)
+                        memcpy(sdata->rc_rateidx_mcs_mask[i],
+                               sband->ht_cap.mcs.rx_mask,
+                               sizeof(sdata->rc_rateidx_mcs_mask[i]));
+                else
+                        memset(sdata->rc_rateidx_mcs_mask[i], 0,
+                               sizeof(sdata->rc_rateidx_mcs_mask[i]));
         }
 
         /* setup type-dependent data */
diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c
index a21110aecd1a..3fef26d8898a 100644
--- a/net/mac80211/rate.c
+++ b/net/mac80211/rate.c
@@ -289,8 +289,8 @@ bool rate_control_send_low(struct ieee80211_sta *sta,
 }
 EXPORT_SYMBOL(rate_control_send_low);
 
-static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
-                                int n_bitrates, u32 mask)
+static bool rate_idx_match_legacy_mask(struct ieee80211_tx_rate *rate,
+                                       int n_bitrates, u32 mask)
 {
         int j;
 
@@ -299,7 +299,7 @@ static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
                 if (mask & (1 << j)) {
                         /* Okay, found a suitable rate. Use it. */
                         rate->idx = j;
-                        return;
+                        return true;
                 }
         }
 
@@ -308,6 +308,112 @@ static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
                 if (mask & (1 << j)) {
                         /* Okay, found a suitable rate. Use it. */
                         rate->idx = j;
+                        return true;
+                }
+        }
+        return false;
+}
+
+static bool rate_idx_match_mcs_mask(struct ieee80211_tx_rate *rate,
+                                    u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN])
+{
+        int i, j;
+        int ridx, rbit;
+
+        ridx = rate->idx / 8;
+        rbit = rate->idx % 8;
+
+        /* sanity check */
+        if (ridx < 0 || ridx > IEEE80211_HT_MCS_MASK_LEN)
+                return false;
+
+        /* See whether the selected rate or anything below it is allowed. */
+        for (i = ridx; i >= 0; i--) {
+                for (j = rbit; j >= 0; j--)
+                        if (mcs_mask[i] & BIT(j)) {
+                                rate->idx = i * 8 + j;
+                                return true;
+                        }
+                rbit = 7;
+        }
+
+        /* Try to find a higher rate that would be allowed */
+        ridx = (rate->idx + 1) / 8;
+        rbit = (rate->idx + 1) % 8;
+
+        for (i = ridx; i < IEEE80211_HT_MCS_MASK_LEN; i++) {
+                for (j = rbit; j < 8; j++)
+                        if (mcs_mask[i] & BIT(j)) {
+                                rate->idx = i * 8 + j;
+                                return true;
+                        }
+                rbit = 0;
+        }
+        return false;
+}
+
+
+
+static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
+                                struct ieee80211_tx_rate_control *txrc,
+                                u32 mask,
+                                u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN])
+{
+        struct ieee80211_tx_rate alt_rate;
+
+        /* handle HT rates */
+        if (rate->flags & IEEE80211_TX_RC_MCS) {
+                if (rate_idx_match_mcs_mask(rate, mcs_mask))
+                        return;
+
+                /* also try the legacy rates. */
+                alt_rate.idx = 0;
+                /* keep protection flags */
+                alt_rate.flags = rate->flags &
+                                 (IEEE80211_TX_RC_USE_RTS_CTS |
+                                  IEEE80211_TX_RC_USE_CTS_PROTECT |
+                                  IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
+                alt_rate.count = rate->count;
+                if (rate_idx_match_legacy_mask(&alt_rate,
+                                               txrc->sband->n_bitrates,
+                                               mask)) {
+                        *rate = alt_rate;
+                        return;
+                }
+        } else {
+                struct sk_buff *skb = txrc->skb;
+                struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+                __le16 fc;
+
+                /* handle legacy rates */
+                if (rate_idx_match_legacy_mask(rate, txrc->sband->n_bitrates,
+                                               mask))
+                        return;
+
+                /* if HT BSS, and we handle a data frame, also try HT rates */
+                if (txrc->bss_conf->channel_type == NL80211_CHAN_NO_HT)
+                        return;
+
+                fc = hdr->frame_control;
+                if (!ieee80211_is_data(fc))
+                        return;
+
+                alt_rate.idx = 0;
+                /* keep protection flags */
+                alt_rate.flags = rate->flags &
+                                 (IEEE80211_TX_RC_USE_RTS_CTS |
+                                  IEEE80211_TX_RC_USE_CTS_PROTECT |
+                                  IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
+                alt_rate.count = rate->count;
+
+                alt_rate.flags |= IEEE80211_TX_RC_MCS;
+
+                if ((txrc->bss_conf->channel_type == NL80211_CHAN_HT40MINUS) ||
+                    (txrc->bss_conf->channel_type == NL80211_CHAN_HT40PLUS))
+                        alt_rate.flags |= IEEE80211_TX_RC_40_MHZ_WIDTH;
+
+                if (rate_idx_match_mcs_mask(&alt_rate, mcs_mask)) {
+                        *rate = alt_rate;
                         return;
                 }
         }
@@ -331,6 +437,7 @@ void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
         int i;
         u32 mask;
+        u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN];
 
         if (sta) {
                 ista = &sta->sta;
@@ -354,10 +461,14 @@ void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
          * the common case.
          */
         mask = sdata->rc_rateidx_mask[info->band];
+        memcpy(mcs_mask, sdata->rc_rateidx_mcs_mask[info->band],
+               sizeof(mcs_mask));
         if (mask != (1 << txrc->sband->n_bitrates) - 1) {
                 if (sta) {
                         /* Filter out rates that the STA does not support */
                         mask &= sta->sta.supp_rates[info->band];
+                        for (i = 0; i < sizeof(mcs_mask); i++)
+                                mcs_mask[i] &= sta->sta.ht_cap.mcs.rx_mask[i];
                 }
                 /*
                  * Make sure the rate index selected for each TX rate is
@@ -368,11 +479,8 @@ void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
                         /* Skip invalid rates */
                         if (info->control.rates[i].idx < 0)
                                 break;
-                        /* Rate masking supports only legacy rates for now */
-                        if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS)
-                                continue;
-                        rate_idx_match_mask(&info->control.rates[i],
-                                            txrc->sband->n_bitrates, mask);
+                        rate_idx_match_mask(&info->control.rates[i], txrc,
+                                            mask, mcs_mask);
                 }
         }
 
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index e05667cd5e76..1be0ca2b5936 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -635,6 +635,9 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
                 txrc.max_rate_idx = -1;
         else
                 txrc.max_rate_idx = fls(txrc.rate_idx_mask) - 1;
+        memcpy(txrc.rate_idx_mcs_mask,
+               tx->sdata->rc_rateidx_mcs_mask[tx->channel->band],
+               sizeof(txrc.rate_idx_mcs_mask));
         txrc.bss = (tx->sdata->vif.type == NL80211_IFTYPE_AP ||
                     tx->sdata->vif.type == NL80211_IFTYPE_MESH_POINT ||
                     tx->sdata->vif.type == NL80211_IFTYPE_ADHOC);
@@ -2431,6 +2434,8 @@ struct sk_buff *ieee80211_beacon_get_tim(struct ieee80211_hw *hw,
                 txrc.max_rate_idx = -1;
         else
                 txrc.max_rate_idx = fls(txrc.rate_idx_mask) - 1;
+        memcpy(txrc.rate_idx_mcs_mask, sdata->rc_rateidx_mcs_mask[band],
+               sizeof(txrc.rate_idx_mcs_mask));
         txrc.bss = true;
         rate_control_get_rate(sdata, NULL, &txrc);