rt2x00: Implement HT protection for rt2800

Update the HT operation mode when mac80211 sends it to us and set
the different HT protection modes and rates accordingly. For now
only use CTS-to-self with OFDM 24M or CCK 11M when protection is
required.
Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2800lib.c

@@ -1169,6 +1169,102 @@ void rt2800_config_intf(struct rt2x00_dev *rt2x00dev, struct rt2x00_intf *intf,
 }
 EXPORT_SYMBOL_GPL(rt2800_config_intf);
 
+static void rt2800_config_ht_opmode(struct rt2x00_dev *rt2x00dev,
+				    struct rt2x00lib_erp *erp)
+{
+	bool any_sta_nongf = !!(erp->ht_opmode &
+				IEEE80211_HT_OP_MODE_NON_GF_STA_PRSNT);
+	u8 protection = erp->ht_opmode & IEEE80211_HT_OP_MODE_PROTECTION;
+	u8 mm20_mode, mm40_mode, gf20_mode, gf40_mode;
+	u16 mm20_rate, mm40_rate, gf20_rate, gf40_rate;
+	u32 reg;
+
+	/* default protection rate for HT20: OFDM 24M */
+	mm20_rate = gf20_rate = 0x4004;
+
+	/* default protection rate for HT40: duplicate OFDM 24M */
+	mm40_rate = gf40_rate = 0x4084;
+
+	switch (protection) {
+	case IEEE80211_HT_OP_MODE_PROTECTION_NONE:
+		/*
+		 * All STAs in this BSS are HT20/40 but there might be
+		 * STAs not supporting greenfield mode.
+		 * => Disable protection for HT transmissions.
+		 */
+		mm20_mode = mm40_mode = gf20_mode = gf40_mode = 0;
+
+		break;
+	case IEEE80211_HT_OP_MODE_PROTECTION_20MHZ:
+		/*
+		 * All STAs in this BSS are HT20 or HT20/40 but there
+		 * might be STAs not supporting greenfield mode.
+		 * => Protect all HT40 transmissions.
+		 */
+		mm20_mode = gf20_mode = 0;
+		mm40_mode = gf40_mode = 2;
+
+		break;
+	case IEEE80211_HT_OP_MODE_PROTECTION_NONMEMBER:
+		/*
+		 * Nonmember protection:
+		 * According to 802.11n we _should_ protect all
+		 * HT transmissions (but we don't have to).
+		 *
+		 * But if cts_protection is enabled we _shall_ protect
+		 * all HT transmissions using a CCK rate.
+		 *
+		 * And if any station is non GF we _shall_ protect
+		 * GF transmissions.
+		 *
+		 * We decide to protect everything
+		 * -> fall through to mixed mode.
+		 */
+	case IEEE80211_HT_OP_MODE_PROTECTION_NONHT_MIXED:
+		/*
+		 * Legacy STAs are present
+		 * => Protect all HT transmissions.
+		 */
+		mm20_mode = mm40_mode = gf20_mode = gf40_mode = 2;
+
+		/*
+		 * If erp protection is needed we have to protect HT
+		 * transmissions with CCK 11M long preamble.
+		 */
+		if (erp->cts_protection) {
+			/* don't duplicate RTS/CTS in CCK mode */
+			mm20_rate = mm40_rate = 0x0003;
+			gf20_rate = gf40_rate = 0x0003;
+		}
+		break;
+	};
+
+	/* check for STAs not supporting greenfield mode */
+	if (any_sta_nongf)
+		gf20_mode = gf40_mode = 2;
+
+	/* Update HT protection config */
+	rt2800_register_read(rt2x00dev, MM20_PROT_CFG, &reg);
+	rt2x00_set_field32(&reg, MM20_PROT_CFG_PROTECT_RATE, mm20_rate);
+	rt2x00_set_field32(&reg, MM20_PROT_CFG_PROTECT_CTRL, mm20_mode);
+	rt2800_register_write(rt2x00dev, MM20_PROT_CFG, reg);
+
+	rt2800_register_read(rt2x00dev, MM40_PROT_CFG, &reg);
+	rt2x00_set_field32(&reg, MM40_PROT_CFG_PROTECT_RATE, mm40_rate);
+	rt2x00_set_field32(&reg, MM40_PROT_CFG_PROTECT_CTRL, mm40_mode);
+	rt2800_register_write(rt2x00dev, MM40_PROT_CFG, reg);
+
+	rt2800_register_read(rt2x00dev, GF20_PROT_CFG, &reg);
+	rt2x00_set_field32(&reg, GF20_PROT_CFG_PROTECT_RATE, gf20_rate);
+	rt2x00_set_field32(&reg, GF20_PROT_CFG_PROTECT_CTRL, gf20_mode);
+	rt2800_register_write(rt2x00dev, GF20_PROT_CFG, reg);
+
+	rt2800_register_read(rt2x00dev, GF40_PROT_CFG, &reg);
+	rt2x00_set_field32(&reg, GF40_PROT_CFG_PROTECT_RATE, gf40_rate);
+	rt2x00_set_field32(&reg, GF40_PROT_CFG_PROTECT_CTRL, gf40_mode);
+	rt2800_register_write(rt2x00dev, GF40_PROT_CFG, reg);
+}
+
 void rt2800_config_erp(struct rt2x00_dev *rt2x00dev, struct rt2x00lib_erp *erp,
 		       u32 changed)
 {
@@ -1213,6 +1309,9 @@ void rt2800_config_erp(struct rt2x00_dev *rt2x00dev, struct rt2x00lib_erp *erp,
 				   erp->beacon_int * 16);
 		rt2800_register_write(rt2x00dev, BCN_TIME_CFG, reg);
 	}
+
+	if (changed & BSS_CHANGED_HT)
+		rt2800_config_ht_opmode(rt2x00dev, erp);
 }
 EXPORT_SYMBOL_GPL(rt2800_config_erp);
 

drivers/net/wireless/rt2x00/rt2x00.h

@@ -458,6 +458,7 @@ struct rt2x00lib_erp {
 	short eifs;
 
 	u16 beacon_int;
+	u16 ht_opmode;
 };
 
 /*

drivers/net/wireless/rt2x00/rt2x00config.c

@@ -103,6 +103,9 @@ void rt2x00lib_config_erp(struct rt2x00_dev *rt2x00dev,
 	/* Update global beacon interval time, this is needed for PS support */
 	rt2x00dev->beacon_int = bss_conf->beacon_int;
 
+	if (changed & BSS_CHANGED_HT)
+		erp.ht_opmode = bss_conf->ht_operation_mode;
+
 	rt2x00dev->ops->lib->config_erp(rt2x00dev, &erp, changed);
 }
 

drivers/net/wireless/rt2x00/rt2x00mac.c

@@ -671,7 +671,7 @@ void rt2x00mac_bss_info_changed(struct ieee80211_hw *hw,
 	 */
 	if (changes & (BSS_CHANGED_ERP_CTS_PROT | BSS_CHANGED_ERP_PREAMBLE |
 		       BSS_CHANGED_ERP_SLOT | BSS_CHANGED_BASIC_RATES |
-		       BSS_CHANGED_BEACON_INT))
+		       BSS_CHANGED_BEACON_INT | BSS_CHANGED_HT))
 		rt2x00lib_config_erp(rt2x00dev, intf, bss_conf, changes);
 }
 EXPORT_SYMBOL_GPL(rt2x00mac_bss_info_changed);