qtnfmac: validate interface combinations on changes

Validate new interface combinations using wireless core checks when new
interface is added or when the type of existing interface is modified.
This is performed to make sure that new interface combination is supported
by hardware. As a result, invalid interface combinations are rejected early,
rather than passed to hardware with sometimes unpredictable results.

Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/quantenna/qtnfmac/cfg80211.c

@@ -80,6 +80,41 @@ qtnf_mgmt_stypes[NUM_NL80211_IFTYPES] = {
 	},
 };
 
+static int
+qtnf_validate_iface_combinations(struct wiphy *wiphy,
+				 struct qtnf_vif *change_vif,
+				 enum nl80211_iftype new_type)
+{
+	struct qtnf_wmac *mac;
+	struct qtnf_vif *vif;
+	int i;
+	int ret = 0;
+	struct iface_combination_params params = {
+		.num_different_channels = 1,
+	};
+
+	mac = wiphy_priv(wiphy);
+	if (!mac)
+		return -EFAULT;
+
+	for (i = 0; i < QTNF_MAX_INTF; i++) {
+		vif = &mac->iflist[i];
+		if (vif->wdev.iftype != NL80211_IFTYPE_UNSPECIFIED)
+			params.iftype_num[vif->wdev.iftype]++;
+	}
+
+	if (change_vif) {
+		params.iftype_num[new_type]++;
+		params.iftype_num[change_vif->wdev.iftype]--;
+	} else {
+		params.iftype_num[new_type]++;
+	}
+
+	ret = cfg80211_check_combinations(wiphy, &params);
+
+	return ret;
+}
+
 static int
 qtnf_change_virtual_intf(struct wiphy *wiphy,
 			 struct net_device *dev,
@@ -90,6 +125,13 @@ qtnf_change_virtual_intf(struct wiphy *wiphy,
 	u8 *mac_addr;
 	int ret;
 
+	ret = qtnf_validate_iface_combinations(wiphy, vif, type);
+	if (ret) {
+		pr_err("VIF%u.%u combination check: failed to set type %d\n",
+		       vif->mac->macid, vif->vifid, type);
+		return ret;
+	}
+
 	if (params)
 		mac_addr = params->macaddr;
 	else
@@ -150,12 +192,20 @@ static struct wireless_dev *qtnf_add_virtual_intf(struct wiphy *wiphy,
 	struct qtnf_wmac *mac;
 	struct qtnf_vif *vif;
 	u8 *mac_addr = NULL;
+	int ret;
 
 	mac = wiphy_priv(wiphy);
 
 	if (!mac)
 		return ERR_PTR(-EFAULT);
 
+	ret = qtnf_validate_iface_combinations(wiphy, NULL, type);
+	if (ret) {
+		pr_err("MAC%u invalid combination: failed to add type %d\n",
+		       mac->macid, type);
+		return ERR_PTR(ret);
+	}
+
 	switch (type) {
 	case NL80211_IFTYPE_STATION:
 	case NL80211_IFTYPE_AP: