mac80211: introduce BSS color collision detection

Add ieee80211_rx_check_bss_color_collision routine in order to introduce
BSS color collision detection in mac80211 if it is not supported in HW/FW
(e.g. for mt7915 chipset).
Add IEEE80211_HW_DETECTS_COLOR_COLLISION flag to let the driver notify
BSS color collision detection is supported in HW/FW. Set this for ath11k
which apparently didn't need this code.

Tested-by: Peter Chiu <Chui-Hao.Chiu@mediatek.com>
Co-developed-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/a05eeeb1841a84560dc5aaec77894fcb69a54f27.1648204871.git.lorenzo@kernel.org
[clarify commit message a bit, move flag to mac80211]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/ath/ath11k/mac.c

@@ -8720,9 +8720,12 @@ static int __ath11k_mac_register(struct ath11k *ar)
 
 	wiphy_ext_feature_set(ar->hw->wiphy, NL80211_EXT_FEATURE_CQM_RSSI_LIST);
 	wiphy_ext_feature_set(ar->hw->wiphy, NL80211_EXT_FEATURE_STA_TX_PWR);
-	if (test_bit(WMI_TLV_SERVICE_BSS_COLOR_OFFLOAD, ar->ab->wmi_ab.svc_map))
+	if (test_bit(WMI_TLV_SERVICE_BSS_COLOR_OFFLOAD,
+		     ar->ab->wmi_ab.svc_map)) {
 		wiphy_ext_feature_set(ar->hw->wiphy,
 				      NL80211_EXT_FEATURE_BSS_COLOR);
+		ieee80211_hw_set(ar->hw, DETECTS_COLOR_COLLISION);
+	}
 
 	ar->hw->wiphy->cipher_suites = cipher_suites;
 	ar->hw->wiphy->n_cipher_suites = ARRAY_SIZE(cipher_suites);

include/net/mac80211.h

@@ -2434,6 +2434,9 @@ struct ieee80211_txq {
  *	usage and 802.11 frames with %RX_FLAG_ONLY_MONITOR set for monitor to
  *	the stack.
  *
+ * @IEEE80211_HW_DETECTS_COLOR_COLLISION: HW/driver has support for BSS color
+ *	collision detection and doesn't need it in software.
+ *
  * @NUM_IEEE80211_HW_FLAGS: number of hardware flags, used for sizing arrays
  */
 enum ieee80211_hw_flags {
@@ -2489,6 +2492,7 @@ enum ieee80211_hw_flags {
 	IEEE80211_HW_SUPPORTS_TX_ENCAP_OFFLOAD,
 	IEEE80211_HW_SUPPORTS_RX_DECAP_OFFLOAD,
 	IEEE80211_HW_SUPPORTS_CONC_MON_RX_DECAP,
+	IEEE80211_HW_DETECTS_COLOR_COLLISION,
 
 	/* keep last, obviously */
 	NUM_IEEE80211_HW_FLAGS

net/mac80211/debugfs.c

@@ -504,6 +504,7 @@ static const char *hw_flag_names[] = {
 	FLAG(SUPPORTS_TX_ENCAP_OFFLOAD),
 	FLAG(SUPPORTS_RX_DECAP_OFFLOAD),
 	FLAG(SUPPORTS_CONC_MON_RX_DECAP),
+	FLAG(DETECTS_COLOR_COLLISION),
 #undef FLAG
 };
 

net/mac80211/rx.c

@@ -3178,6 +3178,49 @@ static void ieee80211_process_sa_query_req(struct ieee80211_sub_if_data *sdata,
 	ieee80211_tx_skb(sdata, skb);
 }
 
+static void
+ieee80211_rx_check_bss_color_collision(struct ieee80211_rx_data *rx)
+{
+	struct ieee80211_mgmt *mgmt = (void *)rx->skb->data;
+	const struct element *ie;
+	size_t baselen;
+
+	if (!wiphy_ext_feature_isset(rx->local->hw.wiphy,
+				     NL80211_EXT_FEATURE_BSS_COLOR))
+		return;
+
+	if (ieee80211_hw_check(&rx->local->hw, DETECTS_COLOR_COLLISION))
+		return;
+
+	if (rx->sdata->vif.csa_active)
+		return;
+
+	baselen = mgmt->u.beacon.variable - rx->skb->data;
+	if (baselen > rx->skb->len)
+		return;
+
+	ie = cfg80211_find_ext_elem(WLAN_EID_EXT_HE_OPERATION,
+				    mgmt->u.beacon.variable,
+				    rx->skb->len - baselen);
+	if (ie && ie->datalen >= sizeof(struct ieee80211_he_operation) &&
+	    ie->datalen >= ieee80211_he_oper_size(ie->data + 1)) {
+		struct ieee80211_bss_conf *bss_conf = &rx->sdata->vif.bss_conf;
+		const struct ieee80211_he_operation *he_oper;
+		u8 color;
+
+		he_oper = (void *)(ie->data + 1);
+		if (le32_get_bits(he_oper->he_oper_params,
+				  IEEE80211_HE_OPERATION_BSS_COLOR_DISABLED))
+			return;
+
+		color = le32_get_bits(he_oper->he_oper_params,
+				      IEEE80211_HE_OPERATION_BSS_COLOR_MASK);
+		if (color == bss_conf->he_bss_color.color)
+			ieeee80211_obss_color_collision_notify(&rx->sdata->vif,
+							       BIT_ULL(color));
+	}
+}
+
 static ieee80211_rx_result debug_noinline
 ieee80211_rx_h_mgmt_check(struct ieee80211_rx_data *rx)
 {
@@ -3203,6 +3246,9 @@ ieee80211_rx_h_mgmt_check(struct ieee80211_rx_data *rx)
 	    !(rx->flags & IEEE80211_RX_BEACON_REPORTED)) {
 		int sig = 0;
 
+		/* sw bss color collision detection */
+		ieee80211_rx_check_bss_color_collision(rx);
+
 		if (ieee80211_hw_check(&rx->local->hw, SIGNAL_DBM) &&
 		    !(status->flag & RX_FLAG_NO_SIGNAL_VAL))
 			sig = status->signal;