cfg80211: enable dynack through nl80211

Enable ACK timeout estimation algorithm (dynack) using mac80211
set_coverage_class API. Dynack is activated passing coverage class equals to -1
to lower drivers and it is automatically disabled setting valid value for
coverage class.
Define NL80211_ATTR_WIPHY_DYN_ACK flag attribute to enable dynack from
userspace. In order to activate dynack NL80211_FEATURE_ACKTO_ESTIMATION feature
flag must be set by lower drivers to indicate dynack capability.

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -1805,6 +1805,7 @@ struct cfg80211_connect_params {
  * @WIPHY_PARAM_FRAG_THRESHOLD: wiphy->frag_threshold has changed
  * @WIPHY_PARAM_RTS_THRESHOLD: wiphy->rts_threshold has changed
  * @WIPHY_PARAM_COVERAGE_CLASS: coverage class changed
+ * @WIPHY_PARAM_DYN_ACK: dynack has been enabled
  */
 enum wiphy_params_flags {
 	WIPHY_PARAM_RETRY_SHORT		= 1 << 0,
@@ -1812,6 +1813,7 @@ enum wiphy_params_flags {
 	WIPHY_PARAM_FRAG_THRESHOLD	= 1 << 2,
 	WIPHY_PARAM_RTS_THRESHOLD	= 1 << 3,
 	WIPHY_PARAM_COVERAGE_CLASS	= 1 << 4,
+	WIPHY_PARAM_DYN_ACK		= 1 << 5,
 };
 
 /*

include/uapi/linux/nl80211.h

@@ -1605,6 +1605,12 @@ enum nl80211_commands {
  *	association request. In addition, it must also set the RRM capability
  *	flag in the association request's Capability Info field.
  *
+ * @NL80211_ATTR_WIPHY_DYN_ACK: flag attribute used to enable ACK timeout
+ *	estimation algorithm (dynack). In order to activate dynack
+ *	%NL80211_FEATURE_ACKTO_ESTIMATION feature flag must be set by lower
+ *	drivers to indicate dynack capability. Dynack is automatically disabled
+ *	setting valid value for coverage class.
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
@@ -1949,6 +1955,8 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_USE_RRM,
 
+	NL80211_ATTR_WIPHY_DYN_ACK,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
@@ -3991,6 +3999,9 @@ enum nl80211_ap_sme_features {
  *	current tx power value into the TPC Report IE in the spectrum
  *	management TPC Report action frame, and in the Radio Measurement Link
  *	Measurement Report action frame.
+ * @NL80211_FEATURE_ACKTO_ESTIMATION: This driver supports dynamic ACK timeout
+ *	estimation (dynack). %NL80211_ATTR_WIPHY_DYN_ACK flag attribute is used
+ *	to enable dynack.
  */
 enum nl80211_feature_flags {
 	NL80211_FEATURE_SK_TX_STATUS			= 1 << 0,
@@ -4016,6 +4027,7 @@ enum nl80211_feature_flags {
 	NL80211_FEATURE_WFA_TPC_IE_IN_PROBES		= 1 << 20,
 	NL80211_FEATURE_QUIET				= 1 << 21,
 	NL80211_FEATURE_TX_POWER_INSERTION		= 1 << 22,
+	NL80211_FEATURE_ACKTO_ESTIMATION		= 1 << 23,
 };
 
 /**

net/wireless/nl80211.c

@@ -226,6 +226,7 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
 	[NL80211_ATTR_WIPHY_FRAG_THRESHOLD] = { .type = NLA_U32 },
 	[NL80211_ATTR_WIPHY_RTS_THRESHOLD] = { .type = NLA_U32 },
 	[NL80211_ATTR_WIPHY_COVERAGE_CLASS] = { .type = NLA_U8 },
+	[NL80211_ATTR_WIPHY_DYN_ACK] = { .type = NLA_FLAG },
 
 	[NL80211_ATTR_IFTYPE] = { .type = NLA_U32 },
 	[NL80211_ATTR_IFINDEX] = { .type = NLA_U32 },
@@ -2239,11 +2240,21 @@ static int nl80211_set_wiphy(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	if (info->attrs[NL80211_ATTR_WIPHY_COVERAGE_CLASS]) {
+		if (info->attrs[NL80211_ATTR_WIPHY_DYN_ACK])
+			return -EINVAL;
+
 		coverage_class = nla_get_u8(
 			info->attrs[NL80211_ATTR_WIPHY_COVERAGE_CLASS]);
 		changed |= WIPHY_PARAM_COVERAGE_CLASS;
 	}
 
+	if (info->attrs[NL80211_ATTR_WIPHY_DYN_ACK]) {
+		if (!(rdev->wiphy.features & NL80211_FEATURE_ACKTO_ESTIMATION))
+			return -EOPNOTSUPP;
+
+		changed |= WIPHY_PARAM_DYN_ACK;
+	}
+
 	if (changed) {
 		u8 old_retry_short, old_retry_long;
 		u32 old_frag_threshold, old_rts_threshold;