Bluetooth: Classic: HFP_AG: Compatible old version HF

In current implementation, the HF with old version cannot be
supported properly.
Such as, if the AG is version 0.96, the AT command `AT+BRSF` will not
be sent. It causes the AG cannot know the features of HF.

Compatible old version with the following changes,

Discover the HF SDP record to get the profile version and HF features.
If the SDP discovery is failed, break the RFCOMM DLC connection.

If the AG version is v0.96, update the HF features according to the
discovered HF features.

Signed-off-by: Lyle Zhu <lyle.zhu@nxp.com>

Author: lylezhu2012

subsys/bluetooth/host/classic/hfp_ag.c

@@ -83,6 +83,8 @@ static struct bt_ag_tx ag_tx[CONFIG_BT_HFP_AG_TX_BUF_COUNT * 2];
 static K_FIFO_DEFINE(ag_tx_free);
 static K_FIFO_DEFINE(ag_tx_notify);
 
+#define BT_HFP_AG_VERSION BT_HFP_VERSION_1_9
+
 /* HFP Gateway SDP record */
 static struct bt_sdp_attribute hfp_ag_attrs[] = {
 	BT_SDP_NEW_SERVICE,
@@ -141,7 +143,7 @@ static struct bt_sdp_attribute hfp_ag_attrs[] = {
 			},
 			{
 				BT_SDP_TYPE_SIZE(BT_SDP_UINT16),
-				BT_SDP_ARRAY_16(0x0109)
+				BT_SDP_ARRAY_16(BT_HFP_AG_VERSION)
 			},
 			)
 		},
@@ -3727,12 +3729,30 @@ static void hfp_ag_postprocess_at_cmd(struct bt_hfp_ag *ag)
 	k_work_reschedule(&ag->tx_work, K_NO_WAIT);
 }
 
+static int hfp_ag_at_cmd_ack(struct bt_hfp_ag *ag, int err)
+{
+	enum at_cme cme_err;
+
+	if ((err != 0) && atomic_test_bit(ag->flags, BT_HFP_AG_CMEE_ENABLE)) {
+		cme_err = bt_hfp_ag_get_cme_err(err);
+		err = hfp_ag_send_data(ag, NULL, NULL, "\r\n+CME ERROR:%d\r\n", (uint32_t)cme_err);
+	} else {
+		bt_hfp_ag_tx_cb_t cb;
+
+		cb = atomic_test_and_clear_bit(ag->flags, BT_HFP_AG_SLC_CONNECTED)
+			     ? bt_hfp_ag_slc_connected
+			     : NULL;
+		err = hfp_ag_send_data(ag, cb, NULL, "\r\n%s\r\n", (err == 0) ? "OK" : "ERROR");
+	}
+
+	return err;
+}
+
 static void hfp_ag_recv(struct bt_rfcomm_dlc *dlc, struct net_buf *buf)
 {
 	struct bt_hfp_ag *ag = CONTAINER_OF(dlc, struct bt_hfp_ag, rfcomm_dlc);
 	uint8_t *data = buf->data;
 	uint16_t len = buf->len;
-	enum at_cme cme_err;
 	int err = -ENOEXEC;
 
 	LOG_HEXDUMP_DBG(data, len, "Received:");
@@ -3760,18 +3780,15 @@ static void hfp_ag_recv(struct bt_rfcomm_dlc *dlc, struct net_buf *buf)
 		return;
 	}
 
-	if ((err != 0) && atomic_test_bit(ag->flags, BT_HFP_AG_CMEE_ENABLE)) {
-		cme_err = bt_hfp_ag_get_cme_err(err);
-		err = hfp_ag_send_data(ag, NULL, NULL, "\r\n+CME ERROR:%d\r\n", (uint32_t)cme_err);
-	} else {
-		bt_hfp_ag_tx_cb_t cb;
-
-		cb = atomic_test_and_clear_bit(ag->flags, BT_HFP_AG_SLC_CONNECTED)
-			     ? bt_hfp_ag_slc_connected
-			     : NULL;
-		err = hfp_ag_send_data(ag, cb, NULL, "\r\n%s\r\n", (err == 0) ? "OK" : "ERROR");
+	if (!atomic_test_and_set_bit(ag->flags, BT_HFP_AG_1ST_AT_RECV)) {
+		LOG_DBG("First AT command ack will be replied later");
+		ag->ack_err = err;
+		k_work_submit(&ag->slc_work);
+		return;
 	}
 
+	err = hfp_ag_at_cmd_ack(ag, err);
+
 	hfp_ag_postprocess_at_cmd(ag);
 
 	if (err != 0) {
@@ -4004,16 +4021,123 @@ static void bt_ag_ongoing_call_work(struct k_work *work)
 	bt_ag_send_ok_code(ag);
 }
 
+static void bt_ag_slc_work(struct k_work *work)
+{
+	struct bt_hfp_ag *ag = CONTAINER_OF(work, struct bt_hfp_ag, slc_work);
+	int err;
+
+	if (!atomic_test_bit(ag->flags, BT_HFP_AG_DISCOVER_DONE)) {
+		return;
+	}
+
+	if (!atomic_test_bit(ag->flags, BT_HFP_AG_1ST_AT_RECV)) {
+		return;
+	}
+
+	if (atomic_test_and_set_bit(ag->flags, BT_HFP_AG_FEAT_UPDATED)) {
+		return;
+	}
+
+	if (atomic_test_bit(ag->flags, BT_HFP_AG_RECORD_FOUND)) {
+		err = hfp_ag_at_cmd_ack(ag, ag->ack_err);
+		hfp_ag_postprocess_at_cmd(ag);
+		if (err != 0) {
+			LOG_ERR("Failed to send AT command ACK: %d", err);
+		}
+		return;
+	}
+
+	err = bt_hfp_ag_disconnect(ag);
+	if (err != 0) {
+		LOG_ERR("Failed to disconnect HF: %d", err);
+	}
+}
+
+#define HFP_SDP_FEAT_MASK GENMASK(4, 0)
+
+static uint8_t bt_hfp_ag_discover_cb(struct bt_conn *conn, struct bt_sdp_client_result *result,
+				     const struct bt_sdp_discover_params *params)
+{
+	size_t index;
+	struct bt_hfp_ag *ag;
+	int err;
+
+	index = (size_t)bt_conn_index(conn);
+	__ASSERT(index < ARRAY_SIZE(bt_hfp_ag_pool), "Index is out of bounds");
+
+	ag = &bt_hfp_ag_pool[index];
+
+	if ((result == NULL) || (result->resp_buf == NULL)) {
+		LOG_ERR("SDP discovery failed");
+		goto failed;
+	}
+
+	err = bt_sdp_get_profile_version(result->resp_buf, BT_SDP_HANDSFREE_SVCLASS,
+					 &ag->hf_sdp_version);
+	if (err != 0) {
+		LOG_ERR("Failed to get HF profile version");
+		goto failed;
+	}
+	err = bt_sdp_get_features(result->resp_buf, &ag->hf_sdp_features);
+	if (err != 0) {
+		LOG_ERR("Failed to get HF feature");
+		goto failed;
+	}
+
+	if ((ag->hf_sdp_version <= BT_HFP_VERSION_1_5) ||
+	    (BT_HFP_AG_VERSION <= BT_HFP_VERSION_1_5)) {
+		if (ag->hf_sdp_features & BT_HFP_HF_SDP_FEATURE_WBS) {
+			LOG_WRN("Unsupported SDP feature (WBS) is enabled.");
+			ag->hf_sdp_features &= ~BT_HFP_HF_SDP_FEATURE_WBS;
+		}
+
+		if (ag->hf_sdp_features & BT_HFP_HF_SDP_FEATURE_SUPER_WBS) {
+			LOG_WRN("Unsupported SDP feature (Super WBS) is enabled.");
+			ag->hf_sdp_features &= ~BT_HFP_HF_SDP_FEATURE_SUPER_WBS;
+		}
+	}
+
+	if ((ag->hf_sdp_version <= BT_HFP_VERSION_0_96) ||
+	    (BT_HFP_AG_VERSION <= BT_HFP_VERSION_0_96)) {
+		/* Update the AG features according to the SDP features for HFP version 0.96.
+		 *
+		 * Hands-Free Profile Specification V1.9, 6.3 SDP Interoperability Requirements
+		 * The values of the “SupportedFeatures” bitmap given in Table 6.6 shall be the
+		 * same as the values of the Bits 0 to 4 of the unsolicited result code +BRSF.
+		 */
+		ag->hf_features = ag->hf_sdp_features & HFP_SDP_FEAT_MASK;
+	}
+
+	atomic_set_bit(ag->flags, BT_HFP_AG_RECORD_FOUND);
+failed:
+	atomic_set_bit(ag->flags, BT_HFP_AG_DISCOVER_DONE);
+	k_work_submit(&ag->slc_work);
+
+	return BT_SDP_DISCOVER_UUID_STOP;
+}
+
 static struct bt_hfp_ag *hfp_ag_create(struct bt_conn *conn)
 {
+	size_t index;
+	struct bt_hfp_ag *ag;
+	int err;
+
 	static struct bt_rfcomm_dlc_ops ops = {
 		.connected = hfp_ag_connected,
 		.disconnected = hfp_ag_disconnected,
 		.recv = hfp_ag_recv,
 		.sent = hfp_ag_sent,
 	};
-	size_t index;
-	struct bt_hfp_ag *ag;
+	static struct bt_sdp_attribute_id_range id_range[] = {
+		{ BT_SDP_ATTR_PROTO_DESC_LIST, BT_SDP_ATTR_PROTO_DESC_LIST },
+		{ BT_SDP_ATTR_PROFILE_DESC_LIST, BT_SDP_ATTR_PROFILE_DESC_LIST },
+		{ BT_SDP_ATTR_SUPPORTED_FEATURES, BT_SDP_ATTR_SUPPORTED_FEATURES },
+	};
+	static struct bt_sdp_attribute_id_list id_list = {
+		.count = ARRAY_SIZE(id_range),
+		.ranges = id_range,
+	};
+	static struct bt_uuid_16 uuid;
 
 	LOG_DBG("conn %p", conn);
 
@@ -4028,6 +4152,20 @@ static struct bt_hfp_ag *hfp_ag_create(struct bt_conn *conn)
 
 	(void)memset(ag, 0, sizeof(struct bt_hfp_ag));
 
+	uuid.uuid.type = BT_UUID_TYPE_16;
+	uuid.val = BT_SDP_HANDSFREE_SVCLASS;
+
+	ag->sdp_param.func = bt_hfp_ag_discover_cb;
+	ag->sdp_param.type = BT_SDP_DISCOVER_SERVICE_SEARCH_ATTR;
+	ag->sdp_param.uuid = &uuid.uuid;
+	ag->sdp_param.pool = &ag_pool;
+	ag->sdp_param.ids  = &id_list;
+
+	err = bt_sdp_discover(conn, &ag->sdp_param);
+	if (err != 0) {
+		return NULL;
+	}
+
 	sys_slist_init(&ag->tx_pending);
 	sys_slist_init(&ag->tx_submit_pending);
 
@@ -4040,6 +4178,10 @@ static struct bt_hfp_ag *hfp_ag_create(struct bt_conn *conn)
 	ag->ag_features = BT_HFP_AG_SUPPORTED_FEATURES;
 	ag->ag_features |= BT_FEAT_SC(bt_dev.features) ? BT_HFP_AG_FEATURE_ESCO_S4 : 0;
 
+	/* Set the default HF infrmation */
+	ag->hf_sdp_features = 0;
+	ag->hf_sdp_version = BT_HFP_VERSION_0_96;
+
 	/* Support HF indicators */
 	if (IS_ENABLED(CONFIG_BT_HFP_AG_HF_INDICATOR_ENH_SAFETY)) {
 		ag->hf_indicators_of_ag |= BIT(HFP_HF_ENHANCED_SAFETY_IND);
@@ -4082,6 +4224,8 @@ static struct bt_hfp_ag *hfp_ag_create(struct bt_conn *conn)
 	/* Set Codec ID*/
 	ag->selected_codec_id = BT_HFP_AG_CODEC_CVSD;
 
+	k_work_init(&ag->slc_work, bt_ag_slc_work);
+
 	/* Init delay work */
 	k_work_init_delayable(&ag->tx_work, bt_ag_tx_work);
 	/* Init delay work */

subsys/bluetooth/host/classic/hfp_ag_internal.h

@@ -173,6 +173,10 @@ enum {
 	BT_HGP_AG_ONGOING_CALLS, /* Waiting ongoing calls */
 	BT_HFP_AG_SLC_CONNECTED, /* SLC connected event needs to be notified */
 	BT_HFP_AG_AT_PROCESS,    /* AT command is in processing */
+	BT_HFP_AG_DISCOVER_DONE, /* SDP Record discovered done */
+	BT_HFP_AG_RECORD_FOUND,  /* SDP HF Record found */
+	BT_HFP_AG_1ST_AT_RECV,   /* 1st AT is received */
+	BT_HFP_AG_FEAT_UPDATED,  /* Remote feature has been updated */
 
 	/* Total number of flags - must be at the end of the enum */
 	BT_HFP_AG_NUM_FLAGS,
@@ -266,6 +270,10 @@ struct bt_hfp_ag {
 	uint32_t hf_indicators_of_hf;
 	uint32_t hf_indicators;
 
+	/* AG profile information */
+	uint16_t hf_sdp_version;
+	uint16_t hf_sdp_features;
+
 	/* operator */
 	uint8_t mode;
 	char operator[AT_COPS_OPERATOR_MAX_LEN + 1];
@@ -285,6 +293,13 @@ struct bt_hfp_ag {
 	/* SCO connect */
 	struct bt_conn *sco_conn;
 
+	/* SDP discover params */
+	struct bt_sdp_discover_params sdp_param;
+
+	/* SCL work */
+	struct k_work slc_work;
+	int ack_err;
+
 	/* HFP TX pending */
 	sys_slist_t tx_pending;
 	sys_slist_t tx_submit_pending;