Bluetooth: audio: has: Add non-volatile settings

This adds non-volatile settings for the HAS Server. Those are needed to
restore the client awareness of preset list entries exposed by the
server. Based on the settings, the implementation determines how to
notify the client about the HAS related characteristic value changes.

Signed-off-by: Mariusz Skamra <mariusz.skamra@codecoup.pl>

subsys/bluetooth/audio/has.c

@@ -15,6 +15,7 @@
 #include <zephyr/sys/slist.h>
 
 #include "../bluetooth/host/hci_core.h"
+#include "../bluetooth/host/settings.h"
 #include "audio_internal.h"
 #include "has_internal.h"
 
@@ -298,8 +299,6 @@ static struct has_client *client_alloc(struct bt_conn *conn)
 		}
 
 		LOG_DBG("New client_context for %s", bt_addr_le_str(info.le.dst));
-	} else {
-		LOG_DBG("Restored client_context for %s", bt_addr_le_str(info.le.dst));
 	}
 
 	return client;
@@ -508,26 +507,15 @@ static void bond_deleted_cb(uint8_t id, const bt_addr_le_t *addr)
 	if (context != NULL) {
 		context_free(context);
 	}
+
+	if (IS_ENABLED(CONFIG_BT_SETTINGS)) {
+		bt_settings_delete("has", 0, addr);
+	}
 }
 
 static struct bt_conn_auth_info_cb auth_info_cb = {
 	.bond_deleted = bond_deleted_cb,
 };
-
-static void restore_client_context(const struct bt_bond_info *info, void *user_data)
-{
-	struct client_context *context;
-
-	context = context_alloc(&info->addr);
-	if (context == NULL) {
-		LOG_ERR("Failed to allocate client_context for %s", bt_addr_le_str(&info->addr));
-		return;
-	}
-
-	/* Notify all the characteristics values after reboot */
-	atomic_set(context->flags, BONDED_CLIENT_INIT_FLAGS);
-}
-
 #endif /* CONFIG_BT_HAS_PRESET_SUPPORT || CONFIG_BT_HAS_FEATURES_NOTIFIABLE */
 
 #if defined(CONFIG_BT_HAS_PRESET_SUPPORT)
@@ -868,19 +856,102 @@ static int bt_has_cp_generic_update(struct has_client *client, uint8_t prev_inde
 	}
 }
 
+#if defined(CONFIG_BT_SETTINGS)
+struct client_context_store {
+	/* Last notified preset index */
+	uint8_t last_preset_index_known;
+};
+
+static int settings_set_cb(const char *name, size_t len_rd, settings_read_cb read_cb, void *cb_arg)
+{
+	struct client_context_store store;
+	struct client_context *context;
+	bt_addr_le_t addr;
+	const char *next;
+	ssize_t len;
+	int err;
+
+	LOG_DBG("%s", name);
+
+	if (!name) {
+		LOG_ERR("Insufficient number of arguments");
+		return -EINVAL;
+	}
+
+	err = bt_settings_decode_key(name, &addr);
+	if (err) {
+		LOG_ERR("Unable to decode address %s", name);
+		return -EINVAL;
+	}
+
+	settings_name_next(name, &next);
+
+	context = context_find(&addr);
+	if (context == NULL && len_rd) {
+		/* Find and initialize a free entry */
+		context = context_alloc(&addr);
+		if (context == NULL) {
+			LOG_ERR("Failed to allocate client_context for %s", bt_addr_le_str(&addr));
+			return -ENOMEM;
+		}
+
+		/* Notify all the characteristics values after reboot */
+		atomic_set(context->flags, BONDED_CLIENT_INIT_FLAGS);
+	}
+
+	if (len_rd) {
+		len = read_cb(cb_arg, &store, sizeof(store));
+		if (len < 0) {
+			LOG_ERR("Failed to decode value (err %zd)", len);
+			return len;
+		}
+
+		context->last_preset_index_known = store.last_preset_index_known;
+
+		LOG_DBG("Restored client_context for %s len %zd", bt_addr_le_str(&addr), len);
+	}
+
+	return 0;
+}
+
+BT_SETTINGS_DEFINE(has, "has", settings_set_cb, NULL);
+
+static void store_client_context(struct client_context *context)
+{
+	struct client_context_store store = {
+		.last_preset_index_known = context->last_preset_index_known,
+	};
+	int err;
+
+	LOG_DBG("%s last_preset_index_known 0x%02x",
+		bt_addr_le_str(&context->addr), store.last_preset_index_known);
+
+	err = bt_settings_store("has", 0, &context->addr, &store, sizeof(store));
+	if (err != 0) {
+		LOG_ERR("Failed to store err %d", err);
+	}
+}
+#else
+#define store_client_context(...)
+#endif /* CONFIG_BT_SETTINGS */
+
 static void update_last_preset_index_known(struct has_client *client, uint8_t index)
 {
-	if (client != NULL) {
+	if (client != NULL && client->context != NULL &&
+	    client->context->last_preset_index_known != index) {
 		client->context->last_preset_index_known = index;
+		store_client_context(client->context);
 		return;
 	}
 
 	for (size_t i = 0; i < ARRAY_SIZE(has_client_list); i++) {
 		client = &has_client_list[i];
 
 		/* For each connected client */
-		if (client->conn != NULL && client->context != NULL) {
+		if (client->conn != NULL && client->context != NULL &&
+		    client->context->last_preset_index_known != index) {
 			client->context->last_preset_index_known = index;
+			store_client_context(client->context);
 		}
 	}
 }
@@ -1709,8 +1780,6 @@ int bt_has_register(const struct bt_has_features_param *features)
 
 #if defined(CONFIG_BT_HAS_PRESET_SUPPORT) || defined(CONFIG_BT_HAS_FEATURES_NOTIFIABLE)
 	bt_conn_auth_info_cb_register(&auth_info_cb);
-
-	bt_foreach_bond(BT_ID_DEFAULT, restore_client_context, NULL);
 #endif /* CONFIG_BT_HAS_PRESET_SUPPORT || CONFIG_BT_HAS_FEATURES_NOTIFIABLE */
 
 	has.registered = true;