samples/bluetooth/broadcast_audio_sink/src/main.c

/*
 * Copyright (c) 2022-2023 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/bluetooth/bluetooth.h>
#include <zephyr/bluetooth/audio/audio.h>
#include <zephyr/bluetooth/audio/bap.h>
#include <zephyr/bluetooth/audio/pacs.h>

BUILD_ASSERT(IS_ENABLED(CONFIG_SCAN_SELF) || IS_ENABLED(CONFIG_SCAN_OFFLOAD),
	     "Either SCAN_SELF or SCAN_OFFLOAD must be enabled");

#define SEM_TIMEOUT K_SECONDS(10)
#define BROADCAST_ASSISTANT_TIMEOUT K_SECONDS(120) /* 2 minutes */

#if defined(CONFIG_SCAN_SELF)
#define ADV_TIMEOUT K_SECONDS(CONFIG_SCAN_DELAY)
#else /* !CONFIG_SCAN_SELF */
#define ADV_TIMEOUT K_FOREVER
#endif /* CONFIG_SCAN_SELF */

#define SYNC_RETRY_COUNT          6 /* similar to retries for connections */
#define PA_SYNC_SKIP              5

static K_SEM_DEFINE(sem_connected, 0U, 1U);
static K_SEM_DEFINE(sem_disconnected, 0U, 1U);
static K_SEM_DEFINE(sem_broadcaster_found, 0U, 1U);
static K_SEM_DEFINE(sem_pa_synced, 0U, 1U);
static K_SEM_DEFINE(sem_base_received, 0U, 1U);
static K_SEM_DEFINE(sem_syncable, 0U, 1U);
static K_SEM_DEFINE(sem_pa_sync_lost, 0U, 1U);
static K_SEM_DEFINE(sem_broadcast_code_received, 0U, 1U);
static K_SEM_DEFINE(sem_pa_request, 0U, 1U);
static K_SEM_DEFINE(sem_past_request, 0U, 1U);
static K_SEM_DEFINE(sem_bis_sync_requested, 0U, 1U);
static K_SEM_DEFINE(sem_bis_synced, 0U, CONFIG_BT_BAP_BROADCAST_SNK_STREAM_COUNT);

/* Sample assumes that we only have a single Scan Delegator receive state */
static const struct bt_bap_scan_delegator_recv_state *sink_recv_state;
static struct bt_bap_broadcast_sink *broadcast_sink;
static struct bt_bap_stream streams[CONFIG_BT_BAP_BROADCAST_SNK_STREAM_COUNT];
static struct bt_bap_stream *streams_p[ARRAY_SIZE(streams)];
static struct bt_conn *broadcast_assistant_conn;
static struct bt_le_ext_adv *ext_adv;

static struct bt_codec codec = BT_CODEC_LC3_CONFIG_16_2(BT_AUDIO_LOCATION_FRONT_LEFT,
							BT_AUDIO_CONTEXT_TYPE_UNSPECIFIED);

/* Create a mask for the maximum BIS we can sync to using the number of streams
 * we have. We add an additional 1 since the bis indexes start from 1 and not
 * 0.
 */
static const uint32_t bis_index_mask = BIT_MASK(ARRAY_SIZE(streams) + 1U);
static uint32_t requested_bis_sync;
static uint32_t bis_index_bitfield;
static uint8_t sink_broadcast_code[BT_AUDIO_BROADCAST_CODE_SIZE];

static void stream_started_cb(struct bt_bap_stream *stream)
{
	printk("Stream %p started\n", stream);

	k_sem_give(&sem_bis_synced);
}

static void stream_stopped_cb(struct bt_bap_stream *stream, uint8_t reason)
{
	int err;

	printk("Stream %p stopped with reason 0x%02X\n", stream, reason);

	err = k_sem_take(&sem_bis_synced, K_NO_WAIT);
	if (err != 0) {
		printk("Failed to take sem_bis_synced: %d\n", err);
	}
}

static void stream_recv_cb(struct bt_bap_stream *stream,
			   const struct bt_iso_recv_info *info,
			   struct net_buf *buf)
{
	static uint32_t recv_cnt;

	recv_cnt++;
	if ((recv_cnt % 1000U) == 0U) {
		printk("Received %u total ISO packets\n", recv_cnt);
	}
}

static struct bt_bap_stream_ops stream_ops = {
	.started = stream_started_cb,
	.stopped = stream_stopped_cb,
	.recv = stream_recv_cb
};

static bool scan_recv_cb(const struct bt_le_scan_recv_info *info,
			 struct net_buf_simple *ad,
			 uint32_t broadcast_id)
{
	if (broadcast_assistant_conn == NULL) {
		/* Not requested by Broadcast Assistant */
		k_sem_give(&sem_broadcaster_found);

		return true;
	} else if (sink_recv_state != NULL &&
		   bt_addr_le_eq(info->addr, &sink_recv_state->addr) &&
		   info->sid == sink_recv_state->adv_sid &&
		   broadcast_id == sink_recv_state->broadcast_id) {
		k_sem_give(&sem_broadcaster_found);

		return true;
	}

	return false;
}

static void scan_term_cb(int err)
{
	if (err != 0) {
		printk("Scan terminated with error: %d\n", err);
	}
}

static void pa_synced_cb(struct bt_bap_broadcast_sink *sink,
			 struct bt_le_per_adv_sync *sync,
			 uint32_t broadcast_id)
{
	if (broadcast_sink != NULL) {
		printk("Unexpected PA sync\n");
		return;
	}

	printk("PA synced for broadcast sink %p with broadcast ID 0x%06X\n",
	       sink, broadcast_id);

	broadcast_sink = sink;

	k_sem_give(&sem_pa_synced);
}

static void base_recv_cb(struct bt_bap_broadcast_sink *sink, const struct bt_bap_base *base)
{
	uint32_t base_bis_index_bitfield = 0U;

	if (k_sem_count_get(&sem_base_received) != 0U) {
		return;
	}

	printk("Received BASE with %u subgroups from broadcast sink %p\n",
	       base->subgroup_count, sink);

	for (size_t i = 0U; i < base->subgroup_count; i++) {
		for (size_t j = 0U; j < base->subgroups[i].bis_count; j++) {
			const uint8_t index = base->subgroups[i].bis_data[j].index;

			base_bis_index_bitfield |= BIT(index);
		}
	}

	bis_index_bitfield = base_bis_index_bitfield & bis_index_mask;

	if (broadcast_assistant_conn == NULL) {
		/* No broadcast assistant requesting anything */
		requested_bis_sync = BT_BAP_BIS_SYNC_NO_PREF;
		k_sem_give(&sem_bis_sync_requested);
	}

	k_sem_give(&sem_base_received);
}

static void syncable_cb(struct bt_bap_broadcast_sink *sink, bool encrypted)
{
	k_sem_give(&sem_syncable);

	if (!encrypted) {
		/* Use the semaphore as a boolean */
		k_sem_reset(&sem_broadcast_code_received);
		k_sem_give(&sem_broadcast_code_received);
	}
}

static void pa_sync_lost_cb(struct bt_bap_broadcast_sink *sink)
{
	if (broadcast_sink == NULL) {
		printk("Unexpected PA sync lost\n");
		return;
	}

	printk("Sink %p disconnected\n", sink);

	broadcast_sink = NULL;

	k_sem_give(&sem_pa_sync_lost);
}

static struct bt_bap_broadcast_sink_cb broadcast_sink_cbs = {
	.scan_recv = scan_recv_cb,
	.scan_term = scan_term_cb,
	.base_recv = base_recv_cb,
	.syncable = syncable_cb,
	.pa_synced = pa_synced_cb,
	.pa_sync_lost = pa_sync_lost_cb
};

const struct bt_bap_scan_delegator_recv_state *broadcast_recv_state;

static void pa_timer_handler(struct k_work *work)
{
	if (broadcast_recv_state != NULL) {
		enum bt_bap_pa_state pa_state;

		if (broadcast_recv_state->pa_sync_state == BT_BAP_PA_STATE_INFO_REQ) {
			pa_state = BT_BAP_PA_STATE_NO_PAST;
		} else {
			pa_state = BT_BAP_PA_STATE_FAILED;
		}

		bt_bap_scan_delegator_set_pa_state(broadcast_recv_state->src_id,
						   pa_state);
	}

	printk("PA timeout\n");
}

static K_WORK_DELAYABLE_DEFINE(pa_timer, pa_timer_handler);

static uint16_t interval_to_sync_timeout(uint16_t pa_interval)
{
	uint16_t pa_timeout;

	if (pa_interval == BT_BAP_PA_INTERVAL_UNKNOWN) {
		/* Use maximum value to maximize chance of success */
		pa_timeout = BT_GAP_PER_ADV_MAX_TIMEOUT;
	} else {
		/* Ensure that the following calculation does not overflow silently */
		__ASSERT(SYNC_RETRY_COUNT < 10,
			 "SYNC_RETRY_COUNT shall be less than 10");

		/* Add retries and convert to unit in 10's of ms */
		pa_timeout = ((uint32_t)pa_interval * SYNC_RETRY_COUNT) / 10;

		/* Enforce restraints */
		pa_timeout = CLAMP(pa_timeout, BT_GAP_PER_ADV_MIN_TIMEOUT,
				   BT_GAP_PER_ADV_MAX_TIMEOUT);
	}

	return pa_timeout;
}

static int pa_sync_past(struct bt_conn *conn, uint16_t pa_interval)
{
	struct bt_le_per_adv_sync_transfer_param param = { 0 };
	int err;

	param.skip = PA_SYNC_SKIP;
	param.timeout = interval_to_sync_timeout(pa_interval);

	err = bt_le_per_adv_sync_transfer_subscribe(conn, &param);
	if (err != 0) {
		printk("Could not do PAST subscribe: %d\n", err);
	} else {
		printk("Syncing with PAST: %d\n", err);
		(void)k_work_reschedule(&pa_timer, K_MSEC(param.timeout * 10));
	}

	return err;
}

static int pa_sync_req_cb(struct bt_conn *conn,
			  const struct bt_bap_scan_delegator_recv_state *recv_state,
			  bool past_avail, uint16_t pa_interval)
{
	int err;

	sink_recv_state = recv_state;

	broadcast_recv_state = recv_state;

	if (recv_state->pa_sync_state == BT_BAP_PA_STATE_SYNCED ||
	    recv_state->pa_sync_state == BT_BAP_PA_STATE_INFO_REQ) {
		/* Already syncing */
		/* TODO: Terminate existing sync and then sync to new?*/
		return -1;
	}

	if (IS_ENABLED(CONFIG_BT_PER_ADV_SYNC_TRANSFER_RECEIVER) && past_avail) {
		err = pa_sync_past(conn, pa_interval);
		k_sem_give(&sem_past_request);
	} else {
		/* start scan */
		err = 0;
	}

	k_sem_give(&sem_pa_request);

	return err;
}

static int pa_sync_term_req_cb(struct bt_conn *conn,
			       const struct bt_bap_scan_delegator_recv_state *recv_state)
{
	int err;

	sink_recv_state = recv_state;

	err = bt_bap_broadcast_sink_delete(broadcast_sink);
	if (err != 0) {
		return err;
	}

	broadcast_sink = NULL;

	return 0;
}

static void broadcast_code_cb(struct bt_conn *conn,
			      const struct bt_bap_scan_delegator_recv_state *recv_state,
			      const uint8_t broadcast_code[BT_AUDIO_BROADCAST_CODE_SIZE])
{
	printk("Broadcast code received for %p\n", recv_state);

	sink_recv_state = recv_state;

	(void)memcpy(sink_broadcast_code, broadcast_code, BT_AUDIO_BROADCAST_CODE_SIZE);

	/* Use the semaphore as a boolean */
	k_sem_reset(&sem_broadcast_code_received);
	k_sem_give(&sem_broadcast_code_received);
}

static int bis_sync_req_cb(struct bt_conn *conn,
			   const struct bt_bap_scan_delegator_recv_state *recv_state,
			   const uint32_t bis_sync_req[BT_BAP_SCAN_DELEGATOR_MAX_SUBGROUPS])
{
	const bool bis_synced = k_sem_count_get(&sem_bis_synced) > 0U;

	printk("BIS sync request received for %p: 0x%08x\n",
	       recv_state, bis_sync_req[0]);

	/* We only care about a single subgroup in this sample */
	if (bis_synced && requested_bis_sync != bis_sync_req[0]) {
		/* If the BIS sync request is received while we are already
		 * synced, it means that the requested BIS sync has changed.
		 */
		int err;

		/* The stream stopped callback will be called as part of this,
		 * and we do not need to wait for any events from the
		 * controller. Thus, when this returns, the `sem_bis_synced`
		 * is back to  0.
		 */
		err = bt_bap_broadcast_sink_stop(broadcast_sink);
		if (err != 0) {
			printk("Failed to stop Broadcast Sink: %d\n", err);

			return err;
		}
	}

	requested_bis_sync = bis_sync_req[0];
	if (bis_sync_req[0] != 0) {
		k_sem_give(&sem_bis_sync_requested);
	}

	return 0;
}

static struct bt_bap_scan_delegator_cb scan_delegator_cbs = {
	.pa_sync_req = pa_sync_req_cb,
	.pa_sync_term_req = pa_sync_term_req_cb,
	.broadcast_code = broadcast_code_cb,
	.bis_sync_req = bis_sync_req_cb,
};

static void connected(struct bt_conn *conn, uint8_t err)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	if (err != 0U) {
		printk("Failed to connect to %s (%u)\n", addr, err);

		broadcast_assistant_conn = NULL;
		return;
	}

	printk("Connected: %s\n", addr);
	broadcast_assistant_conn = bt_conn_ref(conn);

	k_sem_give(&sem_connected);
}

static void disconnected(struct bt_conn *conn, uint8_t reason)
{
	char addr[BT_ADDR_LE_STR_LEN];

	if (conn != broadcast_assistant_conn) {
		return;
	}

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);

	bt_conn_unref(broadcast_assistant_conn);
	broadcast_assistant_conn = NULL;

	k_sem_give(&sem_disconnected);
}

BT_CONN_CB_DEFINE(conn_callbacks) = {
	.connected = connected,
	.disconnected = disconnected,
};

static struct bt_pacs_cap cap = {
	.codec = &codec,
};

static int init(void)
{
	int err;

	err = bt_enable(NULL);
	if (err) {
		printk("Bluetooth enable failed (err %d)\n", err);
		return err;
	}

	printk("Bluetooth initialized\n");

	err = bt_pacs_cap_register(BT_AUDIO_DIR_SINK, &cap);
	if (err) {
		printk("Capability register failed (err %d)\n", err);
		return err;
	}

	bt_bap_broadcast_sink_register_cb(&broadcast_sink_cbs);
	bt_bap_scan_delegator_register_cb(&scan_delegator_cbs);

	for (size_t i = 0U; i < ARRAY_SIZE(streams); i++) {
		streams[i].ops = &stream_ops;
	}

	return 0;
}

static int reset(void)
{
	int err;

	bis_index_bitfield = 0U;
	requested_bis_sync = 0U;
	sink_recv_state = NULL;
	(void)memset(sink_broadcast_code, 0, sizeof(sink_broadcast_code));

	if (broadcast_sink != NULL) {
		err = bt_bap_broadcast_sink_delete(broadcast_sink);
		if (err) {
			printk("Deleting broadcast sink failed (err %d)\n", err);

			return err;
		}

		broadcast_sink = NULL;
	}

	if (IS_ENABLED(CONFIG_SCAN_OFFLOAD)) {
		if (broadcast_assistant_conn != NULL) {
			err = bt_conn_disconnect(broadcast_assistant_conn,
						 BT_HCI_ERR_REMOTE_USER_TERM_CONN);
			if (err) {
				printk("Disconnecting Broadcast Assistant failed (err %d)\n",
				       err);

				return err;
			}

			err = k_sem_take(&sem_disconnected, SEM_TIMEOUT);
			if (err != 0) {
				printk("Failed to take sem_disconnected: %d\n", err);

				return err;
			}
		} else if (ext_adv != NULL) { /* advertising still running */
			err = bt_le_ext_adv_stop(ext_adv);
			if (err) {
				printk("Stopping advertising set failed (err %d)\n",
				       err);

				return err;
			}

			err = bt_le_ext_adv_delete(ext_adv);
			if (err) {
				printk("Deleting advertising set failed (err %d)\n",
				       err);

				return err;
			}

			ext_adv = NULL;
		}

		k_sem_reset(&sem_connected);
		k_sem_reset(&sem_disconnected);
		k_sem_reset(&sem_pa_request);
		k_sem_reset(&sem_past_request);
	}

	k_sem_reset(&sem_broadcaster_found);
	k_sem_reset(&sem_pa_synced);
	k_sem_reset(&sem_base_received);
	k_sem_reset(&sem_syncable);
	k_sem_reset(&sem_pa_sync_lost);
	k_sem_reset(&sem_broadcast_code_received);
	k_sem_reset(&sem_bis_sync_requested);
	k_sem_reset(&sem_bis_synced);

	return 0;
}

static int start_adv(void)
{
	const struct bt_data ad[] = {
		BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
		BT_DATA_BYTES(BT_DATA_UUID16_ALL,
			      BT_UUID_16_ENCODE(BT_UUID_BASS_VAL),
			      BT_UUID_16_ENCODE(BT_UUID_PACS_VAL)),
	};
	int err;

	/* Create a non-connectable non-scannable advertising set */
	err = bt_le_ext_adv_create(BT_LE_EXT_ADV_CONN_NAME, NULL, &ext_adv);
	if (err != 0) {
		printk("Failed to create advertising set (err %d)\n", err);

		return err;
	}

	err = bt_le_ext_adv_set_data(ext_adv, ad, ARRAY_SIZE(ad), NULL, 0);
	if (err != 0) {
		printk("Failed to set advertising data (err %d)\n", err);

		return err;
	}

	err = bt_le_ext_adv_start(ext_adv, BT_LE_EXT_ADV_START_DEFAULT);
	if (err != 0) {
		printk("Failed to start advertising set (err %d)\n", err);

		return err;
	}

	return 0;
}

static int stop_adv(void)
{
	int err;

	err = bt_le_ext_adv_stop(ext_adv);
	if (err != 0) {
		printk("Failed to stop advertising set (err %d)\n", err);

		return err;
	}

	err = bt_le_ext_adv_delete(ext_adv);
	if (err != 0) {
		printk("Failed to delete advertising set (err %d)\n", err);

		return err;
	}

	ext_adv = NULL;

	return 0;
}

int main(void)
{
	int err;

	err = init();
	if (err) {
		printk("Init failed (err %d)\n", err);
		return 0;
	}

	for (size_t i = 0U; i < ARRAY_SIZE(streams_p); i++) {
		streams_p[i] = &streams[i];
	}

	while (true) {
		err = reset();
		if (err != 0) {
			printk("Resetting failed: %d - Aborting\n", err);

			return 0;
		}

		if (IS_ENABLED(CONFIG_SCAN_OFFLOAD)) {
			printk("Starting advertising\n");
			err = start_adv();
			if (err != 0) {
				printk("Unable to start advertising connectable: %d\n",
				       err);

				return 0;
			}

			printk("Waiting for Broadcast Assistant\n");
			err = k_sem_take(&sem_connected, ADV_TIMEOUT);
			if (err != 0) {
				printk("No Broadcast Assistant connected\n");

				err = stop_adv();
				if (err != 0) {
					printk("Unable to stop advertising: %d\n",
					       err);

					return 0;
				}
			} else {
				/* Wait for the PA request to determine if we
				 * should start scanning, or wait for PAST
				 */
				err = k_sem_take(&sem_pa_request,
						 BROADCAST_ASSISTANT_TIMEOUT);
				if (err != 0) {
					printk("sem_pa_request timed out, resetting\n");
					continue;
				}

				if (k_sem_take(&sem_past_request, K_NO_WAIT) == 0) {
					goto wait_for_pa_sync;
				} /* else continue with scanning below */
			}
		}

		printk("Scanning for broadcast sources\n");
		err = bt_bap_broadcast_sink_scan_start(BT_LE_SCAN_ACTIVE);
		if (err != 0 && err != -EALREADY) {
			printk("Unable to start scan for broadcast sources: %d\n",
			       err);
			return 0;
		}

		err = k_sem_take(&sem_broadcaster_found, SEM_TIMEOUT);
		if (err != 0) {
			printk("sem_broadcaster_found timed out, resetting\n");
			continue;
		}
		printk("Broadcast source found, waiting for PA sync\n");

wait_for_pa_sync:
		err = k_sem_take(&sem_pa_synced, SEM_TIMEOUT);
		if (err != 0) {
			printk("sem_pa_synced timed out, resetting\n");
			continue;
		}
		printk("Broadcast source PA synced, waiting for BASE\n");

		err = k_sem_take(&sem_base_received, SEM_TIMEOUT);
		if (err != 0) {
			printk("sem_base_received timed out, resetting\n");
			continue;
		}
		printk("BASE received, waiting for syncable\n");

		err = k_sem_take(&sem_syncable, SEM_TIMEOUT);
		if (err != 0) {
			printk("sem_syncable timed out, resetting\n");
			continue;
		}

		/* sem_broadcast_code_received is also given if the
		 * broadcast is not encrypted
		 */
		printk("Waiting for broadcast code OK\n");
		err = k_sem_take(&sem_broadcast_code_received, SEM_TIMEOUT);
		if (err != 0) {
			printk("sem_syncable timed out, resetting\n");
			continue;
		}

		printk("Waiting for BIS sync request\n");
		err = k_sem_take(&sem_bis_sync_requested, SEM_TIMEOUT);
		if (err != 0) {
			printk("sem_syncable timed out, resetting\n");
			continue;
		}

		printk("Syncing to broadcast\n");
		err = bt_bap_broadcast_sink_sync(broadcast_sink,
						 bis_index_bitfield & requested_bis_sync,
						 streams_p, sink_broadcast_code);
		if (err != 0) {
			printk("Unable to sync to broadcast source: %d\n", err);
			return 0;
		}

		printk("Waiting for PA disconnected\n");
		k_sem_take(&sem_pa_sync_lost, K_FOREVER);
	}
	return 0;
}