mac80211: HE: add Spatial Reuse element parsing support

Add support to mac80211 for parsing SPR elements as per
P802.11ax_D4.0 section 9.4.2.241.

Signed-off-by: Shashidhar Lakkavalli <slakkavalli@datto.com>
Signed-off-by: John Crispin <john@phrozen.org>
Link: https://lore.kernel.org/r/20190618061915.7102-2-john@phrozen.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/linux/ieee80211.h

@@ -1633,6 +1633,18 @@ struct ieee80211_he_operation {
 	u8 optional[0];
 } __packed;
 
+/**
+ * struct ieee80211_he_spr - HE spatial reuse element
+ *
+ * This structure is the "HE spatial reuse element" element as
+ * described in P802.11ax_D4.0 section 9.4.2.241
+ */
+struct ieee80211_he_spr {
+	u8 he_sr_control;
+	/* Optional 0 to 19 bytes: depends on @he_sr_control */
+	u8 optional[0];
+} __packed;
+
 /**
  * struct ieee80211_he_mu_edca_param_ac_rec - MU AC Parameter Record field
  *
@@ -2071,6 +2083,42 @@ ieee80211_he_oper_size(const u8 *he_oper_ie)
 	return oper_len;
 }
 
+/* HE Spatial Reuse defines */
+#define IEEE80211_HE_SPR_NON_SRG_OFFSET_PRESENT			0x4
+#define IEEE80211_HE_SPR_SRG_INFORMATION_PRESENT		0x8
+
+/*
+ * ieee80211_he_spr_size - calculate 802.11ax HE Spatial Reuse IE size
+ * @he_spr_ie: byte data of the He Spatial Reuse IE, stating from the the byte
+ *	after the ext ID byte. It is assumed that he_spr_ie has at least
+ *	sizeof(struct ieee80211_he_spr) bytes, the caller must have validated
+ *	this
+ * @return the actual size of the IE data (not including header), or 0 on error
+ */
+static inline u8
+ieee80211_he_spr_size(const u8 *he_spr_ie)
+{
+	struct ieee80211_he_spr *he_spr = (void *)he_spr_ie;
+	u8 spr_len = sizeof(struct ieee80211_he_spr);
+	u32 he_spr_params;
+
+	/* Make sure the input is not NULL */
+	if (!he_spr_ie)
+		return 0;
+
+	/* Calc required length */
+	he_spr_params = le32_to_cpu(he_spr->he_sr_control);
+	if (he_spr_params & IEEE80211_HE_SPR_NON_SRG_OFFSET_PRESENT)
+		spr_len++;
+	if (he_spr_params & IEEE80211_HE_SPR_SRG_INFORMATION_PRESENT)
+		spr_len += 18;
+
+	/* Add the first byte (extension ID) to the total length */
+	spr_len++;
+
+	return spr_len;
+}
+
 /* Authentication algorithms */
 #define WLAN_AUTH_OPEN 0
 #define WLAN_AUTH_SHARED_KEY 1
@@ -2493,6 +2541,7 @@ enum ieee80211_eid_ext {
 	WLAN_EID_EXT_HE_OPERATION = 36,
 	WLAN_EID_EXT_UORA = 37,
 	WLAN_EID_EXT_HE_MU_EDCA = 38,
+	WLAN_EID_EXT_HE_SPR = 39,
 	WLAN_EID_EXT_MAX_CHANNEL_SWITCH_TIME = 52,
 	WLAN_EID_EXT_MULTIPLE_BSSID_CONFIGURATION = 55,
 	WLAN_EID_EXT_NON_INHERITANCE = 56,

net/mac80211/ieee80211_i.h

@@ -1480,6 +1480,7 @@ struct ieee802_11_elems {
 	const struct ieee80211_meshconf_ie *mesh_config;
 	const u8 *he_cap;
 	const struct ieee80211_he_operation *he_operation;
+	const struct ieee80211_he_spr *he_spr;
 	const struct ieee80211_mu_edca_param_set *mu_edca_param_set;
 	const u8 *uora_element;
 	const u8 *mesh_id;

net/mac80211/util.c

@@ -1240,6 +1240,10 @@ _ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
 				   WLAN_EID_EXT_MULTIPLE_BSSID_CONFIGURATION &&
 				   elen == 3) {
 				elems->mbssid_config_ie = (void *)&pos[1];
+			} else if (pos[0] == WLAN_EID_EXT_HE_SPR &&
+				   elen >= sizeof(*elems->he_spr) &&
+				   elen >= ieee80211_he_spr_size(&pos[1])) {
+				elems->he_spr = (void *)&pos[1];
 			}
 			break;
 		default: