mac80211: Set basic rates while joining ibss network

This patch adds support to nl80211 and mac80211 to set basic rates when
joining/creating ibss network.

Original patch was posted by Johannes Berg on the linux-wireless posting list.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Teemu Paasikivi <ext-teemu.3.paasikivi@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index c65e67e..41529ac 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3955,6 +3955,55 @@
 		}
 	}
 
+	if (info->attrs[NL80211_ATTR_BSS_BASIC_RATES]) {
+		u8 *rates =
+			nla_data(info->attrs[NL80211_ATTR_BSS_BASIC_RATES]);
+		int n_rates =
+			nla_len(info->attrs[NL80211_ATTR_BSS_BASIC_RATES]);
+		struct ieee80211_supported_band *sband =
+			wiphy->bands[ibss.channel->band];
+		int i, j;
+
+		if (n_rates == 0) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		for (i = 0; i < n_rates; i++) {
+			int rate = (rates[i] & 0x7f) * 5;
+			bool found = false;
+
+			for (j = 0; j < sband->n_bitrates; j++) {
+				if (sband->bitrates[j].bitrate == rate) {
+					found = true;
+					ibss.basic_rates |= BIT(j);
+					break;
+				}
+			}
+			if (!found) {
+				err = -EINVAL;
+				goto out;
+			}
+		}
+	} else {
+		/*
+		* If no rates were explicitly configured,
+		* use the mandatory rate set for 11b or
+		* 11a for maximum compatibility.
+		*/
+		struct ieee80211_supported_band *sband =
+			wiphy->bands[ibss.channel->band];
+		int j;
+		u32 flag = ibss.channel->band == IEEE80211_BAND_5GHZ ?
+			IEEE80211_RATE_MANDATORY_A :
+			IEEE80211_RATE_MANDATORY_B;
+
+		for (j = 0; j < sband->n_bitrates; j++) {
+			if (sband->bitrates[j].flags & flag)
+				ibss.basic_rates |= BIT(j);
+		}
+	}
+
 	err = cfg80211_join_ibss(rdev, dev, &ibss, connkeys);
 
 out: