[PATCH wireless-next v4 04/21] wifi: cfg80211: define layouts for SMD BSS Transition context

[Pooventhiran G]

IEEE P802.11bn/D2.0, Aug 2026, subclause 37.16.9, defines the context
data to be transported during SMD BSS Transition (ST) laid out in
subclause 37.16. The station's context data is attached to the ST
Preparation or Execution Request action frames so that userspace
receives the context along with the relevant frame.

Define the context data: per-TID sequence numbers (SN) in downlink (DL)
and uplink (UL) directions, packet number (PN) in DL, per-TID packet
numbers in UL, per-TID BlockAck session parameters in DL and UL,
management SN in DL and UL, and management PN in UL. This data is used
by drivers to report the context along with the frame SKB.

Signed-off-by: Pooventhiran G <pooventhiran.g@xxxxxxxxxxxxxxxx>
---
 include/net/cfg80211.h | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 54d549afd8e3..938fbfe0e71d 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -11147,4 +11147,86 @@ void cfg80211_incumbent_signal_notify(struct wiphy *wiphy,
 				      u32 signal_interference_bitmap,
 				      gfp_t gfp);
 
+/*
+ * Context information carried in SMD BSS Transition (refer IEEE P802.11bn/D2.0,
+ * Aug 2026, subclause 37.16.9.
+ */
+
+/*
+ * Data TIDs transported in the context, IEEE P802.11bn/D2.0, Aug 2026,
+ * subclause 9.4.2.364.
+ */
+#define IEEE80211_SMD_CTX_NUM_TIDS 8
+
+#define IEEE80211_SMD_CTX_MAX_PN_LEN 16
+
+/**
+ * struct ieee80211_smd_ctx_ba - BlockAck parameters for DL and UL
+ *
+ * @amsdu_supported: Peer's capability to support A-MSDU within A-MPDU.
+ * @ba_policy: BlockAck policy (0 = delayed BlockAck, 1 = immediate BlockAck)
+ * @buffer_size: Reorder buffer size from ADDBA Request (10-bit, max 1023)
+ * @timeout: BlockAck session timeout
+ * @ext_no_frag: ADDBA Extension fragmentation support
+ * @extfrag_level: ADDBA Extension HE fragmentation level
+ * @ext_buffer_size: ADDBA Extension buffer size; combined with @buffer_size as
+ *	(@ext_buffer_size << 10 | @buffer_size) to get the full reorder
+ *	buffer size
+ * @winstarto: WinStartO of the BA window
+ */
+struct ieee80211_smd_ctx_ba {
+	bool amsdu_supported;
+	u8 ba_policy;
+	u16 buffer_size;
+	u16 timeout;
+	bool ext_no_frag;
+	u8 extfrag_level;
+	u16 ext_buffer_size;
+	u16 winstarto;
+};
+
+/**
+ * struct ieee80211_smd_ctx - IEEE 802.11bn SMD Roaming Context (refer
+ *	IEEE P802.11bn/D2.0, Aug 2026, subclause 37.16.9)
+ *
+ * @dl_sn_valid: if downlink (DL) SN Transfer is requested or not
+ * @ul_sn_valid: if uplink (UL) SN Transfer is requested or not
+ * @pn_valid: if PN is transferred or not
+ * @ba_params_valid: if BlockAck parameters are transferred or not
+ * @mgmt_tid_valid: if management information is transferred or not.
+ *	@{d,u}l.mgmt_sn and @ul.mgmt_pn are still bounded by @{d,u}l_sn_valid
+ *	and @pn_valid fields.
+ * @pn_len: Length of PN in bytes; varies by cipher type
+ *	(e.g. CCMP (6), GCMP-256 (16))
+ * @dl: DL context data such as SN, PN, and BlockAck params.
+ *	SN and PN transferred are offset to reserve space for DL frames sent by
+ *	the current AP MLD so that the target AP MLD does not repeat them.
+ * @ul: UL context data such as SN, PN, and BlockAck params.
+ */
+struct ieee80211_smd_ctx {
+	u8 dl_sn_valid:1;
+	u8 ul_sn_valid:1;
+	u8 pn_valid:1;
+	u8 ba_params_valid:1;
+	u8 mgmt_tid_valid:1;
+
+	u8 pn_len;
+
+	struct {
+		u8 valid_tid_bmap;
+		u16 sn[IEEE80211_SMD_CTX_NUM_TIDS];
+		u8 pn[IEEE80211_SMD_CTX_MAX_PN_LEN];
+		struct ieee80211_smd_ctx_ba ba[IEEE80211_SMD_CTX_NUM_TIDS];
+		u16 mgmt_sn;
+	} dl;
+	struct {
+		u8 valid_tid_bmap;
+		u16 sn[IEEE80211_SMD_CTX_NUM_TIDS];
+		u8 pn[IEEE80211_SMD_CTX_NUM_TIDS][IEEE80211_SMD_CTX_MAX_PN_LEN];
+		struct ieee80211_smd_ctx_ba ba[IEEE80211_SMD_CTX_NUM_TIDS];
+		u16 mgmt_sn;
+		u8 mgmt_pn[IEEE80211_SMD_CTX_MAX_PN_LEN];
+	} ul;
+};
+
 #endif /* __NET_CFG80211_H */

-- 
2.34.1