diff --git a/Makefile.am b/Makefile.am
index 69b9582..95917f6 100644
--- a/Makefile.am
+++ b/Makefile.am
src/device.h src/device.c \
src/dbus-common.c src/dbus-common.h \
src/eir.h src/eir.c \
- src/adv_monitor.h src/adv_monitor.c
+ src/adv_monitor.h src/adv_monitor.c \
+ src/battery.h src/battery.c
src_bluetoothd_LDADD = lib/libbluetooth-internal.la \
gdbus/libgdbus-internal.la \
src/libshared-glib.la \
diff --git a/src/battery.c b/src/battery.c
new file mode 100644
index 0000000..87a6b91
--- /dev/null
+++ b/src/battery.c
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * BlueZ - Bluetooth protocol stack for Linux
+ *
+ * Copyright (C) 2020 Google LLC
+ *
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#define _GNU_SOURCE
+#include <stdbool.h>
+#include <stdint.h>
+#include <glib.h>
+
+#include "gdbus/gdbus.h"
+#include "lib/bluetooth.h"
+#include "src/shared/queue.h"
+#include "src/shared/util.h"
+#include "battery.h"
+#include "dbus-common.h"
+#include "adapter.h"
+#include "log.h"
+
+#define BATTERY_INTERFACE "org.bluez.Battery1"
+
+#define BATTERY_MAX_PERCENTAGE 100
+
+struct btd_battery {
+ char *path; /* D-Bus object path, owns pointer */
+ uint8_t percentage; /* valid between 0 to 100 inclusively */
+};
+
+static struct queue *batteries = NULL;
+
+static void battery_add(struct btd_battery *battery)
+{
+ if (!batteries)
+ batteries = queue_new();
+
+ queue_push_head(batteries, battery);
+}
+
+static void battery_remove(struct btd_battery *battery)
+{
+ queue_remove(batteries, battery);
+ if (queue_isempty(batteries)) {
+ queue_destroy(batteries, NULL);
+ batteries = NULL;
+ }
+}
+
+static bool match_path(const void *data, const void *user_data)
+{
+ const struct btd_battery *battery = data;
+ const char *path = user_data;
+
+ return g_strcmp0(battery->path, path) == 0;
+}
+
+static struct btd_battery *battery_new(const char *path)
+{
+ struct btd_battery *battery;
+
+ battery = new0(struct btd_battery, 1);
+ battery->path = g_strdup(path);
+ battery->percentage = UINT8_MAX;
+
+ return battery;
+}
+
+static void battery_free(struct btd_battery *battery)
+{
+ if (battery->path)
+ g_free(battery->path);
+
+ free(battery);
+}
+
+static gboolean property_percentage_get(const GDBusPropertyTable *property,
+ DBusMessageIter *iter, void *data)
+{
+ struct btd_battery *battery = data;
+
+ dbus_message_iter_append_basic(iter, DBUS_TYPE_BYTE,
+ &battery->percentage);
+
+ return TRUE;
+}
+
+static gboolean property_percentage_exists(const GDBusPropertyTable *property,
+ void *data)
+{
+ struct btd_battery *battery = data;
+
+ return battery->percentage <= BATTERY_MAX_PERCENTAGE;
+}
+
+static const GDBusPropertyTable battery_properties[] = {
+ { "Percentage", "y", property_percentage_get, NULL,
+ property_percentage_exists },
+ {}
+};
+
+struct btd_battery *btd_battery_register(const char *path)
+{
+ struct btd_battery *battery;
+
+ DBG("path = %s", path);
+
+ if (queue_find(batteries, match_path, path)) {
+ error("error registering battery: path exists");
+ return NULL;
+ }
+
+ if (!g_str_has_prefix(path, "/")) {
+ error("error registering battery: invalid D-Bus object path");
+ return NULL;
+ }
+
+ battery = battery_new(path);
+ battery_add(battery);
+
+ if (!g_dbus_register_interface(btd_get_dbus_connection(), battery->path,
+ BATTERY_INTERFACE, NULL, NULL,
+ battery_properties, battery, NULL)) {
+ error("error registering D-Bus interface for %s",
+ battery->path);
+
+ battery_remove(battery);
+ battery_free(battery);
+
+ return NULL;
+ }
+
+ DBG("registered Battery object: %s", battery->path);
+
+ return battery;
+}
+
+bool btd_battery_unregister(struct btd_battery *battery)
+{
+ DBG("path = %s", battery->path);
+
+ if (!queue_find(batteries, NULL, battery)) {
+ error("error unregistering battery: "
+ "battery %s is not registered",
+ battery->path);
+ return false;
+ }
+
+ if (!g_dbus_unregister_interface(btd_get_dbus_connection(),
+ battery->path, BATTERY_INTERFACE)) {
+ error("error unregistering battery %s from D-Bus interface",
+ battery->path);
+ return false;
+ }
+
+ battery_remove(battery);
+ battery_free(battery);
+
+ return true;
+}
+
+bool btd_battery_update(struct btd_battery *battery, uint8_t percentage)
+{
+ DBG("path = %s", battery->path);
+
+ if (!queue_find(batteries, NULL, battery)) {
+ error("error updating battery: battery is not registered");
+ return false;
+ }
+
+ if (percentage > BATTERY_MAX_PERCENTAGE) {
+ error("error updating battery: percentage is not valid");
+ return false;
+ }
+
+ if (battery->percentage == percentage)
+ return true;
+
+ battery->percentage = percentage;
+ g_dbus_emit_property_changed(btd_get_dbus_connection(), battery->path,
+ BATTERY_INTERFACE, "Percentage");
+
+ return true;
+}
diff --git a/src/battery.h b/src/battery.h
new file mode 100644
index 0000000..9c69b7a
--- /dev/null
+++ b/src/battery.h
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *
+ * BlueZ - Bluetooth protocol stack for Linux
+ *
+ * Copyright (C) 2020 Google LLC
+ *
+ *
+ */
+
+struct btd_battery;
+
+struct btd_battery *btd_battery_register(const char *path);
+bool btd_battery_unregister(struct btd_battery *battery);
+bool btd_battery_update(struct btd_battery *battery, uint8_t percentage);