ieee80211: add code to obtain and parse 6 GHz operation field

Add some code to obtain and parse the 6 GHz operation field
inside the HE operation element.

While at it, fix the required length using sizeof() the new
struct, which is 5 instead of 4 now.

Link: https://lore.kernel.org/r/20200528213443.42ca72c45ca9.Id74bc1b03da9ea6574f9bc70deeb60dfc1634359@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

include/linux/ieee80211.h

@@ -2209,6 +2209,28 @@ ieee80211_he_ppe_size(u8 ppe_thres_hdr, const u8 *phy_cap_info)
 #define IEEE80211_HE_OPERATION_PARTIAL_BSS_COLOR		0x40000000
 #define IEEE80211_HE_OPERATION_BSS_COLOR_DISABLED		0x80000000
 
+/**
+ * ieee80211_he_6ghz_oper - HE 6 GHz operation Information field
+ * @primary: primary channel
+ * @control: control flags
+ * @ccfs0: channel center frequency segment 0
+ * @ccfs1: channel center frequency segment 1
+ * @minrate: minimum rate (in 1 Mbps units)
+ */
+struct ieee80211_he_6ghz_oper {
+	u8 primary;
+#define IEEE80211_HE_6GHZ_OPER_CTRL_CHANWIDTH	0x3
+#define		IEEE80211_HE_6GHZ_OPER_CTRL_CHANWIDTH_20MHZ	0
+#define		IEEE80211_HE_6GHZ_OPER_CTRL_CHANWIDTH_40MHZ	1
+#define		IEEE80211_HE_6GHZ_OPER_CTRL_CHANWIDTH_80MHZ	2
+#define		IEEE80211_HE_6GHZ_OPER_CTRL_CHANWIDTH_160MHZ	3
+#define IEEE80211_HE_6GHZ_OPER_CTRL_DUP_BEACON	0x4
+	u8 control;
+	u8 ccfs0;
+	u8 ccfs1;
+	u8 minrate;
+} __packed;
+
 /*
  * ieee80211_he_oper_size - calculate 802.11ax HE Operations IE size
  * @he_oper_ie: byte data of the He Operations IE, stating from the byte
@@ -2235,7 +2257,7 @@ ieee80211_he_oper_size(const u8 *he_oper_ie)
 	if (he_oper_params & IEEE80211_HE_OPERATION_CO_HOSTED_BSS)
 		oper_len++;
 	if (he_oper_params & IEEE80211_HE_OPERATION_6GHZ_OP_INFO)
-		oper_len += 4;
+		oper_len += sizeof(struct ieee80211_he_6ghz_oper);
 
 	/* Add the first byte (extension ID) to the total length */
 	oper_len++;
@@ -2243,6 +2265,34 @@ ieee80211_he_oper_size(const u8 *he_oper_ie)
 	return oper_len;
 }
 
+/**
+ * ieee80211_he_6ghz_oper - obtain 6 GHz operation field
+ * @he_oper: HE operation element (must be pre-validated for size)
+ *	but may be %NULL
+ *
+ * Return: a pointer to the 6 GHz operation field, or %NULL
+ */
+static inline const struct ieee80211_he_6ghz_oper *
+ieee80211_he_6ghz_oper(const struct ieee80211_he_operation *he_oper)
+{
+	const u8 *ret = (void *)&he_oper->optional;
+	u32 he_oper_params;
+
+	if (!he_oper)
+		return NULL;
+
+	he_oper_params = le32_to_cpu(he_oper->he_oper_params);
+
+	if (!(he_oper_params & IEEE80211_HE_OPERATION_6GHZ_OP_INFO))
+		return NULL;
+	if (he_oper_params & IEEE80211_HE_OPERATION_VHT_OPER_INFO)
+		ret += 3;
+	if (he_oper_params & IEEE80211_HE_OPERATION_CO_HOSTED_BSS)
+		ret++;
+
+	return (void *)ret;
+}
+
 /* HE Spatial Reuse defines */
 #define IEEE80211_HE_SPR_NON_SRG_OFFSET_PRESENT			0x4
 #define IEEE80211_HE_SPR_SRG_INFORMATION_PRESENT		0x8