Expand MCS support manual 24–31 range for 4-stream

Update the vwifi_set_bitrate_mask callback to support the full range of MCS indices
24 through 31, aligning with the 4-spatial-stream configuration in nf_band_2ghz.
This change  enabling support for manual MCS from 24-31 coding schemes (1/2, 3/4, 2/3, 5/6)
and modulations (BPSK, QPSK,16-QAM, 64-QAM) as defined by the IEEE 802.11n specification.
The callback now rejects indices outside 24–31, ensuring compliance with 4-stream capabilities and
allowing comprehensive rate testing (26–260 Mbps).

The auto MCS selection ,due to this function is based on only signal strength,
while the MCS should construct with modulation and coding scheme ,which the coding
scheme is related with BER (bite error rate),previous vWiFI only implement
random signal strength,meaning that bit error rate should also based on the channel state info.

Author: dingsen-Greenhorn

vwifi.c

@@ -88,8 +88,8 @@ struct vwifi_vif {
     struct wireless_dev wdev;
     struct net_device *ndev;
     struct net_device_stats stats;
-    int manual_mcs;      
-    bool manual_mcs_set; 
+    int manual_mcs;
+    bool manual_mcs_set;
 
     size_t ssid_len;
     /* Currently connected BSS id */
@@ -1406,7 +1406,7 @@ static int vwifi_get_station(struct wiphy *wiphy,
     sinfo->tx_bytes = vif->stats.tx_bytes;
     sinfo->rx_bytes = vif->stats.rx_bytes;
 
-    /* Log byte counters for debugging */ 
+    /* Log byte counters for debugging */
     pr_info(
         "vwifi: Station %pM tx_bytes %llu, rx_bytes %llu, tx_packets %u, "
         "rx_packets %u, tx_failed %u\n",
@@ -1415,8 +1415,7 @@ static int vwifi_get_station(struct wiphy *wiphy,
 
     /* For CFG80211_SIGNAL_TYPE_MBM, value is expressed in dBm */
     sinfo->signal = rand_int_smooth(-100, -30, jiffies);
-    pr_info("vwifi: Station %pM signal %d dBm (raw)\n", mac,
-            sinfo->signal); 
+    pr_info("vwifi: Station %pM signal %d dBm (raw)\n", mac, sinfo->signal);
     sinfo->inactive_time = jiffies_to_msecs(jiffies - vif->active_time);
     /*
      * Using 802.11n (HT) as the PHY, configure as follows:
@@ -1437,52 +1436,79 @@ static int vwifi_get_station(struct wiphy *wiphy,
      * https://semfionetworks.com/blog/mcs-table-updated-with-80211ax-data-rates/
      * IEEE 802.11n : https://zh.wikipedia.org/zh-tw/IEEE_802.11n
      */
+    
     /* Check vif->manual_mcs_set to use vif->manual_mcs if set;
      * Assign modulation string for manual MCS ; else auto change based
      * on signal strength
      */
     int mcs_index;
     const char *modulation;
+    const char *coding_rate;
     if (vif->manual_mcs_set) {
         mcs_index = vif->manual_mcs;
         switch (mcs_index) {
-        case 7:
+        case 24:
             modulation = "BPSK";
+            coding_rate = "1/2";
             break;
-        case 15:
+        case 25:
             modulation = "QPSK";
+            coding_rate = "1/2";
             break;
-        case 23:
+        case 26:
+            modulation = "QPSK";
+            coding_rate = "3/4";
+            break;
+        case 27:
+            modulation = "16-QAM";
+            coding_rate = "1/2";
+            break;
+        case 28:
             modulation = "16-QAM";
+            coding_rate = "3/4";
+            break;
+        case 29:
+            modulation = "64-QAM";
+            coding_rate = "2/3";
+            break;
+        case 30:
+            modulation = "64-QAM";
+            coding_rate = "3/4";
             break;
         case 31:
             modulation = "64-QAM";
+            coding_rate = "5/6";
             break;
         default:
-            modulation = "Unknown";
+            pr_err("vwifi: Unsupported MCS index %d\n", mcs_index);
+            mcs_index = 24; /* Default to lowest 4-stream MCS */
+            modulation = "BPSK";
+            coding_rate = "1/2";
             break;
         }
-        pr_info("vwifi: Station %pM using manual MCS %d (%s)\n", mac, mcs_index,
-                modulation);
+        pr_info("vwifi: Station %pM using manual MCS %d (%s, %s)\n", mac,
+                mcs_index, modulation, coding_rate);
     } else {
         if (sinfo->signal > -50) {
             mcs_index = 31;
             modulation = "64-QAM";
+            coding_rate = "5/6";
         } else if (sinfo->signal > -70 && sinfo->signal <= -50) {
-            mcs_index = 23;
+            mcs_index = 28;
             modulation = "16-QAM";
+            coding_rate = "3/4";
         } else if (sinfo->signal > -90 && sinfo->signal <= -70) {
-            mcs_index = 15;
+            mcs_index = 25;
             modulation = "QPSK";
+            coding_rate = "1/2";
         } else {
-            mcs_index = 7;
+            mcs_index = 24;
             modulation = "BPSK";
+            coding_rate = "1/2";
         }
-        pr_info(
-            "vwifi: Station %pM signal %d dBm, using modulation %s (MCS %d)\n",
-            mac, sinfo->signal, modulation, mcs_index);
+        pr_info("vwifi: Station %pM signal %d dBm, using MCS %d (%s, %s)\n",
+                mac, sinfo->signal, mcs_index, modulation, coding_rate);
     }
-
     /* Configure RX and TX rates */
     sinfo->rxrate.flags = RATE_INFO_FLAGS_MCS;
     sinfo->rxrate.mcs = mcs_index;
@@ -1497,7 +1523,6 @@ static int vwifi_get_station(struct wiphy *wiphy,
     /* Log rate configuration for verification */
     pr_info("vwifi: Station %pM txrate MCS %d, rxrate MCS %d\n", mac,
             sinfo->txrate.mcs, sinfo->rxrate.mcs);
-
     return 0;
 }
 
@@ -2262,8 +2287,8 @@ static int vwifi_set_bitrate_mask(struct wiphy *wiphy,
         return -EINVAL;
     }
 
-    if (mcs_index != 7 && mcs_index != 15 && mcs_index != 23 &&
-        mcs_index != 31) {
+    /* Restrict to supported 4-stream MCS indices 24–31 */
+    if (mcs_index < 24 || mcs_index > 31) {
         pr_err("vwifi: Unsupported MCS index %d\n", mcs_index);
         return -EINVAL;
     }
@@ -2353,7 +2378,6 @@ static const struct ieee80211_rate vwifi_supported_rates[] = {
     RATE_ENT(360, 0x200), RATE_ENT(480, 0x400), RATE_ENT(540, 0x800),
 };
 
-/* Describes supported band of 2GHz. */
 static struct ieee80211_supported_band nf_band_2ghz = {
     .band = NL80211_BAND_2GHZ,
     .channels = vwifi_supported_channels_2ghz,