Bluetooth: settings: Add support for per-submodule handlers

Add a new linker section for a list of submodule settings handlers,
and iterate the list from the various settings callbacks.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

include/linker/common-rom.ld

@@ -50,3 +50,12 @@
 		KEEP(*(SORT_BY_NAME(".net_l2.init*")))
 		__net_l2_end = .;
 	} GROUP_LINK_IN(ROMABLE_REGION)
+
+#if defined(CONFIG_BT_SETTINGS)
+	SECTION_DATA_PROLOGUE(_bt_settings_area, (OPTIONAL), SUBALIGN(4))
+	{
+		_bt_settings_start = .;
+		KEEP(*(SORT_BY_NAME("._bt_settings.static.*")))
+		_bt_settings_end = .;
+	} GROUP_LINK_IN(ROMABLE_REGION)
+#endif

subsys/bluetooth/host/settings.c

@@ -18,13 +18,28 @@
 #include "hci_core.h"
 #include "settings.h"
 
+/* Linker-defined symbols bound to the bt_settings_handler structs */
+extern const struct bt_settings_handler _bt_settings_start[];
+extern const struct bt_settings_handler _bt_settings_end[];
+
 static int set(int argc, char **argv, char *val)
 {
 	int len;
 
 	BT_DBG("argc %d argv[0] %s val %s", argc, argv[0], val);
 
-	if (argc != 1) {
+	if (argc > 1) {
+		const struct bt_settings_handler *h;
+
+		for (h = _bt_settings_start; h < _bt_settings_end; h++) {
+			if (!strcmp(argv[0], h->name)) {
+				argc--;
+				argv++;
+
+				return h->set(argc, argv, val);
+			}
+		}
+
 		return -ENOENT;
 	}
 
@@ -102,6 +117,8 @@ static void generate_irk(void)
 
 static int commit(void)
 {
+	const struct bt_settings_handler *h;
+
 	BT_DBG("");
 
 	if (!bt_addr_le_cmp(&bt_dev.id_addr, BT_ADDR_LE_ANY) ||
@@ -119,15 +136,41 @@ static int commit(void)
 	}
 #endif /* CONFIG_BT_PRIVACY */
 
+	for (h = _bt_settings_start; h < _bt_settings_end; h++) {
+		if (h->commit) {
+			h->commit();
+		}
+	}
+
 	bt_dev_show_info();
 
 	return 0;
 }
 
+static int export(int (*func)(const char *name, char *val),
+		  enum settings_export_tgt tgt)
+{
+	const struct bt_settings_handler *h;
+
+	if (tgt != SETTINGS_EXPORT_PERSIST) {
+		BT_WARN("Only persist target supported");
+		return -ENOTSUP;
+	}
+
+	for (h = _bt_settings_start; h < _bt_settings_end; h++) {
+		if (h->export) {
+			h->export(func);
+		}
+	}
+
+	return 0;
+}
+
 static struct settings_handler bt_settings = {
 	.name = "bt",
 	.h_set = set,
 	.h_commit = commit,
+	.h_export = export,
 };
 
 int bt_settings_init(void)

subsys/bluetooth/host/settings.h

@@ -4,4 +4,20 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+struct bt_settings_handler {
+	const char *name;
+	int (*set)(int argc, char **argv, char *val);
+	int (*commit)(void);
+	int (*export)(int (*func)(const char *name, char *val));
+};
+
+#define BT_SETTINGS_DEFINE(_name, _set, _commit, _export)               \
+	const struct bt_settings_handler _name __aligned(4)             \
+			__in_section(_bt_settings, static, _name) = {   \
+				.name = STRINGIFY(_name),               \
+				.set = _set,                            \
+				.commit = _commit,                      \
+				.export = _export,                      \
+			}
+
 int bt_settings_init(void);