profiles/battery: Add Bluetooth LE Battery service

The Battery Level characteristic was tested with a
Microsoft Arc Touch Mouse SE.

The Battery1 interface is now exported for Bluetooth LE devices which
support the Battery Level characteristic, providing a single
"Percentage" value to other integration points in the OS, such as UPower
for consumption on most free desktops.

See https://bugs.freedesktop.org/show_bug.cgi?id=92370

3 files changed, 390 insertions, 0 deletions

diff --git a/Makefile.plugins b/Makefile.plugins
index 73377e532..1f3b5b552 100644
--- a/Makefile.plugins
+++ b/Makefile.plugins
@@ -100,6 +100,9 @@ builtin_sources += profiles/midi/midi.c \
 builtin_ldadd += @ALSA_LIBS@
 endif
 
+builtin_modules += battery
+builtin_sources += profiles/battery/battery.c
+
 if SIXAXIS
 plugin_LTLIBRARIES += plugins/sixaxis.la
 plugins_sixaxis_la_SOURCES = plugins/sixaxis.c
diff --git a/doc/battery-api.txt b/doc/battery-api.txt
new file mode 100644
index 000000000..dc7dbeda2
--- /dev/null
+++ b/doc/battery-api.txt
@@ -0,0 +1,14 @@
+BlueZ D-Bus Battery API description
+***********************************
+
+
+Battery hierarchy
+=================
+
+Service		org.bluez
+Interface	org.bluez.Battery1
+Object path	[variable prefix]/{hci0,hci1,...}/dev_XX_XX_XX_XX_XX_XX
+
+Properties	byte Percentage [readonly]
+
+			The percentage of battery left as an unsigned 8-bit integer.
diff --git a/profiles/battery/battery.c b/profiles/battery/battery.c
new file mode 100644
index 000000000..8cedfa250
--- /dev/null
+++ b/profiles/battery/battery.c
@@ -0,0 +1,373 @@
+/*
+ *
+ *  BlueZ - Bluetooth protocol stack for Linux
+ *
+ *  Copyright (C) 2012  Instituto Nokia de Tecnologia - INdT
+ *  Copyright (C) 2014  Google Inc.
+ *  Copyright (C) 2017  Red Hat Inc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <ctype.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include <glib.h>
+
+#include "gdbus/gdbus.h"
+
+#include "lib/bluetooth.h"
+#include "lib/hci.h"
+#include "lib/sdp.h"
+#include "lib/uuid.h"
+
+#include "src/dbus-common.h"
+#include "src/shared/util.h"
+#include "src/shared/att.h"
+#include "src/shared/queue.h"
+#include "src/shared/gatt-db.h"
+#include "src/shared/gatt-client.h"
+#include "src/plugin.h"
+#include "src/adapter.h"
+#include "src/device.h"
+#include "src/profile.h"
+#include "src/service.h"
+#include "src/log.h"
+#include "attrib/att.h"
+
+#define BATTERY_INTERFACE "org.bluez.Battery1"
+
+#define BATT_UUID16 0x180f
+
+/* Generic Attribute/Access Service */
+struct batt {
+	char *path; /* D-Bus path of device */
+	struct btd_device *device;
+	struct gatt_db *db;
+	struct bt_gatt_client *client;
+	struct gatt_db_attribute *attr;
+
+	unsigned int batt_level_cb_id;
+	uint16_t batt_level_io_handle;
+
+	uint8_t *initial_value;
+	uint8_t percentage;
+};
+
+static void batt_free(struct batt *batt)
+{
+	gatt_db_unref(batt->db);
+	bt_gatt_client_unref(batt->client);
+	btd_device_unref(batt->device);
+	g_free (batt->initial_value);
+	g_free(batt);
+}
+
+static void batt_reset(struct batt *batt)
+{
+	batt->attr = NULL;
+	gatt_db_unref(batt->db);
+	batt->db = NULL;
+	bt_gatt_client_unregister_notify(batt->client, batt->batt_level_cb_id);
+	bt_gatt_client_cancel_all(batt->client);
+	bt_gatt_client_unref(batt->client);
+	batt->client = NULL;
+	g_free (batt->initial_value);
+	batt->initial_value = NULL;
+	if (batt->path) {
+		g_dbus_unregister_interface(btd_get_dbus_connection(),
+					    batt->path, BATTERY_INTERFACE);
+		g_free(batt->path);
+		batt->path = NULL;
+	}
+	btd_device_unref(batt->device);
+}
+
+static void parse_battery_level(struct batt *batt,
+				const uint8_t *value)
+{
+	uint8_t percentage;
+
+	percentage = value[0];
+	if (batt->percentage != percentage) {
+		batt->percentage = percentage;
+		DBG("Battery Level updated: %d%%", percentage);
+		g_dbus_emit_property_changed(btd_get_dbus_connection(), batt->path,
+						BATTERY_INTERFACE, "Percentage");
+	}
+}
+
+static void batt_io_value_cb(uint16_t value_handle, const uint8_t *value,
+                             uint16_t length, void *user_data)
+{
+	struct batt *batt = user_data;
+
+	if (value_handle == batt->batt_level_io_handle) {
+		parse_battery_level(batt, value);
+	} else {
+		g_assert_not_reached();
+	}
+}
+
+static gboolean property_get_percentage(
+					const GDBusPropertyTable *property,
+					DBusMessageIter *iter, void *data)
+{
+	struct batt *batt = data;
+
+	dbus_message_iter_append_basic(iter, DBUS_TYPE_BYTE, &batt->percentage);
+
+	return TRUE;
+}
+
+static const GDBusPropertyTable battery_properties[] = {
+	{ "Percentage", "y", property_get_percentage },
+	{ }
+};
+
+static void batt_io_ccc_written_cb(uint16_t att_ecode, void *user_data)
+{
+	struct batt *batt = user_data;
+
+	if (att_ecode != 0) {
+		error("Battery Level: notifications not enabled %s",
+		      att_ecode2str(att_ecode));
+		return;
+	}
+
+	if (g_dbus_register_interface(btd_get_dbus_connection(),
+					batt->path, BATTERY_INTERFACE,
+					NULL, NULL,
+					battery_properties, batt,
+					NULL) == FALSE) {
+		error("Unable to register %s interface for %s",
+			BATTERY_INTERFACE, batt->path);
+		batt_reset(batt);
+		return;
+	}
+
+	parse_battery_level(batt, batt->initial_value);
+	g_free (batt->initial_value);
+	batt->initial_value = NULL;
+
+	DBG("Battery Level: notification enabled");
+}
+
+static void read_initial_battery_level_cb(bool success,
+						uint8_t att_ecode,
+						const uint8_t *value,
+						uint16_t length,
+						void *user_data)
+{
+	struct batt *batt = user_data;
+
+	if (!success) {
+		DBG("Reading battery level failed with ATT errror: %u",
+								att_ecode);
+		return;
+	}
+
+	if (!length)
+		return;
+
+	batt->initial_value = g_memdup(value, length);
+
+	/* request notify */
+	batt->batt_level_cb_id =
+		bt_gatt_client_register_notify(batt->client,
+		                               batt->batt_level_io_handle,
+		                               batt_io_ccc_written_cb,
+		                               batt_io_value_cb,
+		                               batt,
+		                               NULL);
+}
+
+static void handle_battery_level(struct batt *batt, uint16_t value_handle)
+{
+	batt->batt_level_io_handle = value_handle;
+
+	if (!bt_gatt_client_read_value(batt->client, batt->batt_level_io_handle,
+						read_initial_battery_level_cb, batt, NULL))
+		DBG("Failed to send request to read battery level");
+}
+
+static bool uuid_cmp(uint16_t u16, const bt_uuid_t *uuid)
+{
+	bt_uuid_t lhs;
+
+	bt_uuid16_create(&lhs, u16);
+
+	return bt_uuid_cmp(&lhs, uuid) == 0;
+}
+
+static void handle_characteristic(struct gatt_db_attribute *attr,
+								void *user_data)
+{
+	struct batt *batt = user_data;
+	uint16_t value_handle;
+	bt_uuid_t uuid;
+
+	if (!gatt_db_attribute_get_char_data(attr, NULL, &value_handle, NULL,
+								NULL, &uuid)) {
+		error("Failed to obtain characteristic data");
+		return;
+	}
+
+	if (uuid_cmp(GATT_CHARAC_BATTERY_LEVEL, &uuid)) {
+		handle_battery_level(batt, value_handle);
+	} else {
+		char uuid_str[MAX_LEN_UUID_STR];
+
+		bt_uuid_to_string(&uuid, uuid_str, sizeof(uuid_str));
+		DBG("Unsupported characteristic: %s", uuid_str);
+	}
+}
+
+static void handle_batt_service(struct batt *batt)
+{
+	gatt_db_service_foreach_char(batt->attr, handle_characteristic, batt);
+}
+
+static int batt_probe(struct btd_service *service)
+{
+	struct btd_device *device = btd_service_get_device(service);
+	struct batt *batt = btd_service_get_user_data(service);
+	char addr[18];
+
+	ba2str(device_get_address(device), addr);
+	DBG("BATT profile probe (%s)", addr);
+
+	/* Ignore, if we were probed for this device already */
+	if (batt) {
+		error("Profile probed twice for the same device!");
+		return -1;
+	}
+
+	batt = g_new0(struct batt, 1);
+	if (!batt)
+		return -1;
+
+	batt->percentage = -1;
+	batt->device = btd_device_ref(device);
+	btd_service_set_user_data(service, batt);
+
+	return 0;
+}
+
+static void batt_remove(struct btd_service *service)
+{
+	struct btd_device *device = btd_service_get_device(service);
+	struct batt *batt;
+	char addr[18];
+
+	ba2str(device_get_address(device), addr);
+	DBG("BATT profile remove (%s)", addr);
+
+	batt = btd_service_get_user_data(service);
+	if (!batt) {
+		error("BATT service not handled by profile");
+		return;
+	}
+
+	batt_free(batt);
+}
+
+static void foreach_batt_service(struct gatt_db_attribute *attr, void *user_data)
+{
+	struct batt *batt = user_data;
+
+	if (batt->attr) {
+		error("More than one BATT service exists for this device");
+		return;
+	}
+
+	batt->attr = attr;
+	handle_batt_service(batt);
+}
+
+static int batt_accept(struct btd_service *service)
+{
+	struct btd_device *device = btd_service_get_device(service);
+	struct gatt_db *db = btd_device_get_gatt_db(device);
+	struct bt_gatt_client *client = btd_device_get_gatt_client(device);
+	struct batt *batt = btd_service_get_user_data(service);
+	char addr[18];
+	bt_uuid_t batt_uuid;
+
+	ba2str(device_get_address(device), addr);
+	DBG("BATT profile accept (%s)", addr);
+
+	if (!batt) {
+		error("BATT service not handled by profile");
+		return -1;
+	}
+
+	batt->db = gatt_db_ref(db);
+	batt->client = bt_gatt_client_clone(client);
+
+	/* Handle the BATT services */
+	bt_uuid16_create(&batt_uuid, BATT_UUID16);
+	gatt_db_foreach_service(db, &batt_uuid, foreach_batt_service, batt);
+
+	if (!batt->attr) {
+		error("BATT attribute not found");
+		batt_reset(batt);
+		return -1;
+	}
+
+	batt->path = g_strdup (device_get_path(device));
+
+	btd_service_connecting_complete(service, 0);
+
+	return 0;
+}
+
+static int batt_disconnect(struct btd_service *service)
+{
+	struct batt *batt = btd_service_get_user_data(service);
+
+	batt_reset(batt);
+
+	btd_service_disconnecting_complete(service, 0);
+
+	return 0;
+}
+
+static struct btd_profile batt_profile = {
+	.name		= "batt-profile",
+	.remote_uuid	= BATTERY_UUID,
+	.device_probe	= batt_probe,
+	.device_remove	= batt_remove,
+	.accept		= batt_accept,
+	.disconnect	= batt_disconnect,
+};
+
+static int batt_init(void)
+{
+	return btd_profile_register(&batt_profile);
+}
+
+static void batt_exit(void)
+{
+	btd_profile_unregister(&batt_profile);
+}
+
+BLUETOOTH_PLUGIN_DEFINE(battery, VERSION, BLUETOOTH_PLUGIN_PRIORITY_DEFAULT,
+							batt_init, batt_exit)