[PATCH v3 38/41] net: mac802154: Add support for active scans

[Miquel Raynal <miquel.raynal@bootlin.com>]

Active scan support is based on the current passive scan support,
cheered up with beacon requests sent after every channel change.

Co-developed-by: David Girault <david.girault@qorvo.com>
Signed-off-by: David Girault <david.girault@qorvo.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 include/net/ieee802154_netdev.h | 14 +++++++-
 net/ieee802154/header_ops.c     | 25 +++++++++++++++
 net/mac802154/ieee802154_i.h    |  1 +
 net/mac802154/scan.c            | 57 +++++++++++++++++++++++++++++++--
 4 files changed, 94 insertions(+), 3 deletions(-)

diff --git a/include/net/ieee802154_netdev.h b/include/net/ieee802154_netdev.h
index f7716aeec93b..1bf1a4e508a2 100644
--- a/include/net/ieee802154_netdev.h
+++ b/include/net/ieee802154_netdev.h
@@ -58,6 +58,11 @@ struct ieee802154_beacon_hdr {
 #endif
 } __packed;
 
+struct ieee802154_mac_cmd_pl {
+	u8  cmd_id;
+	/* TODO: content depending on the cmd_id */
+} __packed;
+
 struct ieee802154_sechdr {
 #if defined(__LITTLE_ENDIAN_BITFIELD)
 	u8 level:3,
@@ -139,6 +144,11 @@ struct ieee802154_hdr {
 	struct ieee802154_sechdr sec;
 };
 
+struct ieee802154_beacon_req_frame {
+	struct ieee802154_hdr mhr;
+	struct ieee802154_mac_cmd_pl mac_pl;
+};
+
 struct ieee802154_beacon_frame {
 	struct ieee802154_hdr mhr;
 	struct ieee802154_beacon_hdr mac_pl;
@@ -169,7 +179,9 @@ int ieee802154_hdr_peek_addrs(const struct sk_buff *skb,
  */
 int ieee802154_hdr_peek(const struct sk_buff *skb, struct ieee802154_hdr *hdr);
 
-/* pushes a beacon frame into an skb */
+/* pushes a beacon_req or a beacon frame into an skb */
+int ieee802154_beacon_req_push(struct sk_buff *skb,
+			       struct ieee802154_beacon_req_frame *breq);
 int ieee802154_beacon_push(struct sk_buff *skb,
 			   struct ieee802154_beacon_frame *beacon);
 
diff --git a/net/ieee802154/header_ops.c b/net/ieee802154/header_ops.c
index bab710aa36f9..c31a9e429a14 100644
--- a/net/ieee802154/header_ops.c
+++ b/net/ieee802154/header_ops.c
@@ -121,6 +121,31 @@ ieee802154_hdr_push(struct sk_buff *skb, struct ieee802154_hdr *hdr)
 }
 EXPORT_SYMBOL_GPL(ieee802154_hdr_push);
 
+int ieee802154_beacon_req_push(struct sk_buff *skb,
+			       struct ieee802154_beacon_req_frame *breq)
+{
+	struct ieee802154_mac_cmd_pl *mac_pl = &breq->mac_pl;
+	struct ieee802154_hdr *mhr = &breq->mhr;
+	u16 crc;
+	int ret;
+
+	skb_reserve(skb, sizeof(*mhr));
+	ret = ieee802154_hdr_push(skb, mhr);
+	if (ret < 0)
+		return ret;
+
+	skb_reset_mac_header(skb);
+	skb->mac_len = ret;
+
+	skb_put_data(skb, mac_pl, sizeof(*mac_pl));
+
+	crc = crc_ccitt(0, skb->data, skb->len);
+	put_unaligned_le16(crc, skb_put(skb, 2));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ieee802154_beacon_req_push);
+
 int ieee802154_beacon_push(struct sk_buff *skb,
 			   struct ieee802154_beacon_frame *beacon)
 {
diff --git a/net/mac802154/ieee802154_i.h b/net/mac802154/ieee802154_i.h
index 514446c1f815..0b1bcbab1ff3 100644
--- a/net/mac802154/ieee802154_i.h
+++ b/net/mac802154/ieee802154_i.h
@@ -56,6 +56,7 @@ struct ieee802154_local {
 	struct cfg802154_scan_request __rcu *scan_req;
 	struct ieee802154_sub_if_data __rcu *scan_sdata;
 	struct delayed_work scan_work;
+	struct ieee802154_beacon_req_frame beacon_req;
 
 	/* Beacons handling */
 	bool ongoing_beacons_request;
diff --git a/net/mac802154/scan.c b/net/mac802154/scan.c
index d9b54b35660a..71a845e3e76d 100644
--- a/net/mac802154/scan.c
+++ b/net/mac802154/scan.c
@@ -19,10 +19,15 @@
 
 #define IEEE802154_BEACON_MHR_SZ 13
 #define IEEE802154_BEACON_PL_SZ 4
+#define IEEE802154_BEACON_REQ_MHR_SZ 7
+#define IEEE802154_BEACON_REQ_PL_SZ 1
 #define IEEE802154_CRC_SZ 2
 #define IEEE802154_BEACON_SKB_SZ (IEEE802154_BEACON_MHR_SZ + \
 				  IEEE802154_BEACON_PL_SZ + \
 				  IEEE802154_CRC_SZ)
+#define IEEE802154_BEACON_REQ_SKB_SZ (IEEE802154_BEACON_REQ_MHR_SZ + \
+				      IEEE802154_BEACON_REQ_PL_SZ +  \
+				      IEEE802154_CRC_SZ)
 
 static bool mac802154_check_promiscuous(struct ieee802154_local *local)
 {
@@ -112,6 +117,48 @@ static unsigned int mac802154_scan_get_channel_time(u8 duration_order,
 				(BIT(duration_order) + 1));
 }
 
+static int mac802154_scan_prepare_beacon_req(struct ieee802154_local *local)
+{
+	memset(&local->beacon_req, 0, sizeof(local->beacon_req));
+	local->beacon_req.mhr.fc.type = IEEE802154_FC_TYPE_MAC_CMD;
+	local->beacon_req.mhr.fc.dest_addr_mode = IEEE802154_SHORT_ADDRESSING;
+	local->beacon_req.mhr.fc.version = IEEE802154_2003_STD;
+	local->beacon_req.mhr.fc.source_addr_mode = IEEE802154_NO_ADDRESSING;
+	local->beacon_req.mhr.dest.mode = IEEE802154_ADDR_SHORT;
+	local->beacon_req.mhr.dest.pan_id = cpu_to_le16(IEEE802154_PANID_BROADCAST);
+	local->beacon_req.mhr.dest.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
+	local->beacon_req.mac_pl.cmd_id = IEEE802154_CMD_BEACON_REQ;
+
+	return 0;
+}
+
+static int mac802154_transmit_beacon_req_locked(struct ieee802154_local *local)
+{
+	struct ieee802154_sub_if_data *sdata;
+	struct sk_buff *skb;
+	int ret;
+
+	lockdep_assert_held(&local->scan_lock);
+
+	skb = alloc_skb(IEEE802154_BEACON_REQ_SKB_SZ, GFP_KERNEL);
+	if (!skb)
+		return -ENOBUFS;
+
+	sdata = rcu_dereference_protected(local->scan_sdata,
+					  lockdep_is_held(&local->scan_lock));
+	skb->dev = sdata->dev;
+
+	ret = ieee802154_beacon_req_push(skb, &local->beacon_req);
+	if (ret) {
+		kfree_skb(skb);
+		return ret;
+	}
+
+	ieee802154_mlme_tx(local, skb);
+
+	return 0;
+}
+
 void mac802154_scan_work(struct work_struct *work)
 {
 	struct ieee802154_local *local =
@@ -157,6 +204,9 @@ void mac802154_scan_work(struct work_struct *work)
 		ieee802154_configure_durations(local->phy);
 	} while (ret);
 
+	if (scan_req->type == NL802154_SCAN_ACTIVE)
+		mac802154_transmit_beacon_req_locked(local);
+
 queue_work:
 	scan_duration = mac802154_scan_get_channel_time(scan_req->duration,
 							local->phy->symbol_duration);
@@ -183,8 +233,8 @@ int mac802154_trigger_scan_locked(struct ieee802154_sub_if_data *sdata,
 	if (mac802154_scan_is_ongoing(local))
 		return -EBUSY;
 
-	/* TODO: support other scanning type */
-	if (request->type != NL802154_SCAN_PASSIVE)
+	if (request->type != NL802154_SCAN_PASSIVE &&
+	    request->type != NL802154_SCAN_ACTIVE)
 		return -EOPNOTSUPP;
 
 	/* Store scanning parameters */
@@ -197,6 +247,9 @@ int mac802154_trigger_scan_locked(struct ieee802154_sub_if_data *sdata,
 	else
 		local->scan_addr = cpu_to_le64(get_unaligned_be64(sdata->dev->dev_addr));
 
+	if (request->type == NL802154_SCAN_ACTIVE)
+		mac802154_scan_prepare_beacon_req(local);
+
 	local->scan_channel_idx = -1;
 	atomic_set(&local->scanning, 1);
 
-- 
2.27.0