iw: add MCS set parsing

This adds MCS set parsing to iw. When you can 'iw list' you can
now see the MCS set actually parsed, this can tell you information
such as all the RX/TX MCS indexes supported, max TX spatial streams,
if TX unequal modulation is supported and your max supported HT
RX data rate.

This is as per 802.11n Draft 7 on section 7.3.2.57.4 Supported MCS Set field.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>

diff --git a/info.c b/info.c
index bf3b8bd83363ee003ffa0ddc366982e43f8cad24..7ea8f999b39501c7424ccb5603a459f6f6e23005 100644 (file)
--- a/info.c
+++ b/info.c
@@ -1,3 +1,4 @@
+#include <stdbool.h>
 #include <errno.h>
 #include <net/if.h>
 
@@ -20,6 +21,24 @@ static void print_flag(const char *name, int *open)
        *open = 1;
 }
 
+static void print_mcs_index(unsigned char *mcs)
+{
+       unsigned int mcs_bit;
+
+       for (mcs_bit = 0; mcs_bit <= 76; mcs_bit++) {
+               unsigned int mcs_octet = mcs_bit/8;
+               unsigned int MCS_RATE_BIT = 1 << mcs_bit % 8;
+               bool mcs_rate_idx_set;
+
+               mcs_rate_idx_set = !!(mcs[mcs_octet] & MCS_RATE_BIT);
+
+               if (!mcs_rate_idx_set)
+                       continue;
+
+               printf("\t\t\tMCS index %d\n", mcs_bit);
+       }
+}
+
 static int print_phy_handler(struct nl_msg *msg, void *arg)
 {
        struct nlattr *tb_msg[NL80211_ATTR_MAX + 1];
@@ -128,10 +147,50 @@ static int print_phy_handler(struct nl_msg *msg, void *arg)
                }
                if (tb_band[NL80211_BAND_ATTR_HT_MCS_SET] &&
                    nla_len(tb_band[NL80211_BAND_ATTR_HT_MCS_SET]) == 16) {
+                       /* As defined in 7.3.2.57.4 Supported MCS Set field */
+                       unsigned int tx_max_num_spatial_streams, max_rx_supp_data_rate;
                        unsigned char *mcs = nla_data(tb_band[NL80211_BAND_ATTR_HT_MCS_SET]);
+                       bool tx_mcs_set_defined, tx_mcs_set_equal, tx_unequal_modulation;
+
                        printf("\t\tHT MCS set: %.2x %.2x %.2x %.2x %.2x %.2x %.2x %.2x %.2x %.2x %.2x %.2x %.2x %.2x %.2x %.2x\n",
                                mcs[0], mcs[1], mcs[2], mcs[3], mcs[4], mcs[5], mcs[6], mcs[7],
                                mcs[8], mcs[9], mcs[10], mcs[11], mcs[12], mcs[13], mcs[14], mcs[15]);
+
+                       max_rx_supp_data_rate = ((mcs[10] >> 8) & ((mcs[11] & 0x3) << 8));
+                       tx_mcs_set_defined = !!(mcs[12] & (1 << 0));
+                       tx_mcs_set_equal = !(mcs[12] & (1 << 1));
+                       tx_max_num_spatial_streams = (mcs[12] | ((1 << 3) | (1 << 4))) + 1;
+                       tx_unequal_modulation = !!(mcs[12] & (1 << 5));
+
+                       if (max_rx_supp_data_rate)
+                               printf("\t\tHT Max RX data rate: %d Mbps\n", max_rx_supp_data_rate);
+                       /* XXX: else see 9.6.0e.5.3 how to get this I think */
+
+                       if (tx_mcs_set_defined) {
+                               if (tx_mcs_set_equal) {
+                                       printf("\t\tHT TX/RX MCS rate indexes supported:\n");
+                                       print_mcs_index(&mcs[0]);
+                               } else {
+                                       printf("\t\tHT RX MCS rate indexes supported:\n");
+                                       print_mcs_index(&mcs[0]);
+
+                                       if (tx_unequal_modulation)
+                                               printf("TX unequal modulation supported\n");
+                                       else
+                                               printf("TX unequal modulation not supported\n");
+
+                                       printf("\t\tHT TX Max spatiel streams: %d\n",
+                                               tx_max_num_spatial_streams);
+
+                                       printf("\t\tHT TX MCS rate indexes supported may differ\n");
+                               }
+                       }
+                       else {
+                               printf("\t\tHT RX MCS rate indexes supported:\n");
+                               print_mcs_index(&mcs[0]);
+                               printf("\t\tHT TX MCS rates indexes are undefined\n");
+                       }
+
                }
 #endif