cfg80211/mac80211: Use more generic bitrate mask for rate control

Extend struct cfg80211_bitrate_mask to actually use a bitfield mask
instead of just a single fixed or maximum rate index. This change
itself does not modify the behavior (except for debugfs files), but it
prepares cfg80211 and mac80211 for a new nl80211 command for setting
which rates can be used in TX rate control.

Since frames are now going through the rate control algorithm
unconditionally, the internal IEEE80211_TX_INTFL_RCALGO flag can now
be removed. The RC implementations can use the rate_idx_mask value to
optimize their behavior if only a single rate is enabled.

The old max_rate_idx in struct ieee80211_tx_rate_control is maintained
(but commented as deprecated) for backwards compatibility with existing
RC implementations. Once these implementations have been updated to
use the more generic rate_idx_mask, the max_rate_idx value can be
removed.

Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 976014c..e5dda6f 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1406,8 +1406,6 @@
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
 	int i;
-	u32 target_rate;
-	struct ieee80211_supported_band *sband;
 
 	/*
 	 * This _could_ be supported by providing a hook for
@@ -1417,35 +1415,11 @@
 	if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
 		return -EOPNOTSUPP;
 
-	sband = local->hw.wiphy->bands[local->hw.conf.channel->band];
 
-	/*
-	 * target_rate = -1, rate->fixed = 0 means auto only, so use all rates
-	 * target_rate = X, rate->fixed = 1 means only rate X
-	 * target_rate = X, rate->fixed = 0 means all rates <= X
-	 */
-	sdata->max_ratectrl_rateidx = -1;
-	sdata->force_unicast_rateidx = -1;
+	for (i = 0; i < IEEE80211_NUM_BANDS; i++)
+		sdata->rc_rateidx_mask[i] = mask->control[i].legacy;
 
-	if (mask->fixed)
-		target_rate = mask->fixed / 100;
-	else if (mask->maxrate)
-		target_rate = mask->maxrate / 100;
-	else
-		return 0;
-
-	for (i = 0; i< sband->n_bitrates; i++) {
-		if (target_rate != sband->bitrates[i].bitrate)
-			continue;
-
-		/* requested bitrate found */
-		sdata->max_ratectrl_rateidx = i;
-		if (mask->fixed)
-			sdata->force_unicast_rateidx = i;
-		return 0;
-	}
-
-	return -EINVAL;
+	return 0;
 }
 
 static int ieee80211_remain_on_channel(struct wiphy *wiphy,