[PATCH v6 4/6] proximity: link loss: implement link loss server

Arik Nemtsov
2012-03-27T20:24:17Z

The profile is implemented in linkloss.[ch]. A GATT service is
registered with read/write callbacks on the link-loss alert level
attribute. The alert level is maintained per device. It is returned
on read and updated on write.

When the alert level is non-zero, a callback is registered on the
disconnection of the remote device. If a device with non-zero alert
state is disconnected, an appropriate PropertyChanged signal is emitted
with the alert level previously set by the device. We avoid emitting
a signal when the disconnection was requested by us.
---
Makefile.am | 3 +-
proximity/linkloss.c | 337 ++++++++++++++++++++++++++++++++++++++++++++++++++
proximity/linkloss.h | 26 ++++
proximity/reporter.c | 42 +------
4 files changed, 368 insertions(+), 40 deletions(-)
create mode 100644 proximity/linkloss.c
create mode 100644 proximity/linkloss.h

diff --git a/Makefile.am b/Makefile.am
index ddc28d2..12b3d81 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -222,7 +222,8 @@ builtin_sources += thermometer/main.c \
plugins/gatt-example.c \
proximity/main.c proximity/manager.h proximity/manager.c \
proximity/monitor.h proximity/monitor.c \
- proximity/reporter.h proximity/reporter.c
+ proximity/reporter.h proximity/reporter.c \
+ proximity/linkloss.h proximity/linkloss.c
endif

diff --git a/proximity/linkloss.c b/proximity/linkloss.c
new file mode 100644
index 0000000..2e37574
--- /dev/null
+++ b/proximity/linkloss.c
@@ -0,0 +1,337 @@
+/*
+ *
+ * BlueZ - Bluetooth protocol stack for Linux
+ *
+ * Copyright (C) 2012 Texas Instruments Corporation
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <glib.h>
+#include <bluetooth/uuid.h>
+#include <adapter.h>
+
+#include <dbus/dbus.h>
+#include <gdbus.h>
+
+#include "log.h"
+#include "att.h"
+#include "att-database.h"
+#include "gattrib.h"
+#include "gatt-service.h"
+#include "attrib-server.h"
+#include "device.h"
+#include "attio.h"
+#include "dbus-common.h"
+#include "reporter.h"
+#include "linkloss.h"
+
+#define BLUEZ_SERVICE "org.bluez"
+
+struct link_loss_adapter {
+ struct btd_adapter *adapter;
+ uint16_t alert_lvl_value_handle;
+ DBusConnection *conn;
+ GSList *connected_devices;
+};
+
+struct connected_device {
+ struct btd_device *device;
+ struct link_loss_adapter *adapter;
+ uint8_t alert_level;
+ guint callback_id;
+ guint local_disc_id;
+};
+
+static GSList *link_loss_adapters;
+
+static int lldevice_cmp(gconstpointer a, gconstpointer b)
+{
+ const struct connected_device *llcondev = a;
+ const struct btd_device *device = b;
+
+ if (llcondev->device == device)
+ return 0;
+
+ return -1;
+}
+
+static struct connected_device *
+find_connected_device(struct link_loss_adapter *la, struct btd_device *device)
+{
+ GSList *l = g_slist_find_custom(la->connected_devices, device,
+ lldevice_cmp);
+ if (!l)
+ return NULL;
+
+ return l->data;
+}
+
+static int lladapter_cmp(gconstpointer a, gconstpointer b)
+{
+ const struct link_loss_adapter *lladapter = a;
+ const struct btd_adapter *adapter = b;
+
+ if (lladapter->adapter == adapter)
+ return 0;
+
+ return -1;
+}
+
+static struct link_loss_adapter *
+find_link_loss_adapter(struct btd_adapter *adapter)
+{
+ GSList *l = g_slist_find_custom(link_loss_adapters, adapter,
+ lladapter_cmp);
+ if (!l)
+ return NULL;
+
+ return l->data;
+}
+
+const char *link_loss_get_alert_level(struct btd_device *device)
+{
+ struct link_loss_adapter *lladapter;
+ struct connected_device *condev;
+
+ if (!device)
+ return get_alert_level_string(NO_ALERT);
+
+ lladapter = find_link_loss_adapter(device_get_adapter(device));
+ if (!lladapter)
+ return get_alert_level_string(NO_ALERT);
+
+ condev = find_connected_device(lladapter, device);
+ if (!condev)
+ return get_alert_level_string(NO_ALERT);
+
+ return get_alert_level_string(condev->alert_level);
+}
+
+static void link_loss_emit_alert_signal(struct connected_device *condev)
+{
+ struct link_loss_adapter *adapter = condev->adapter;
+ const char *alert_level_str, *path;
+
+ if (!condev->device)
+ return;
+
+ path = device_get_path(condev->device);
+ alert_level_str = get_alert_level_string(condev->alert_level);
+
+ DBG("alert %s remote %s", alert_level_str, path);
+
+ emit_property_changed(adapter->conn, path,
+ PROXIMITY_REPORTER_INTERFACE, "LinkLossAlertLevel",
+ DBUS_TYPE_STRING, &alert_level_str);
+}
+
+static uint8_t link_loss_alert_lvl_read(struct attribute *a,
+ struct btd_device *device, gpointer user_data)
+{
+ struct link_loss_adapter *la = user_data;
+ struct connected_device *condev;
+ uint8_t alert_level = NO_ALERT;
+
+ if (!device)
+ goto out;
+
+ condev = find_connected_device(la, device);
+ if (!condev)
+ goto out;
+
+ alert_level = condev->alert_level;
+
+out:
+ DBG("return alert level %d for dev %p", alert_level, device);
+
+ /* update the alert level according to the requesting device */
+ attrib_db_update(la->adapter, a->handle, NULL, &alert_level,
+ sizeof(alert_level), NULL);
+
+ return 0;
+}
+
+/* condev can be NULL */
+static void link_loss_remove_condev(struct connected_device *condev)
+{
+ struct link_loss_adapter *la;
+
+ if (!condev)
+ return;
+
+ la = condev->adapter;
+
+ if (condev->callback_id && condev->device)
+ btd_device_remove_attio_callback(condev->device,
+ condev->callback_id);
+
+ if (condev->local_disc_id && condev->device)
+ device_remove_disconnect_watch(condev->device,
+ condev->local_disc_id);
+
+ if (condev->device)
+ btd_device_unref(condev->device);
+
+ la->connected_devices = g_slist_remove(la->connected_devices, condev);
+ g_free(condev);
+}
+
+static void link_loss_disc_cb(gpointer user_data)
+{
+ struct connected_device *condev = user_data;
+
+ DBG("alert loss disconnect device %p", condev->device);
+
+ /* if an alert-level is set, emit a signal */
+ if (condev->alert_level != NO_ALERT)
+ link_loss_emit_alert_signal(condev);
+
+ /* we are open for more changes now */
+ link_loss_remove_condev(condev);
+}
+
+static void link_loss_local_disc(struct btd_device *device, gboolean removal,
+ void *user_data)
+{
+ struct connected_device *condev = user_data;
+
+ /* no need to alert on this device - we requested disconnection */
+ link_loss_remove_condev(condev);
+
+ DBG("alert level zeroed for locally disconnecting dev %p", device);
+}
+
+static uint8_t link_loss_alert_lvl_write(struct attribute *a,
+ struct btd_device *device, gpointer user_data)
+{
+ uint8_t value;
+ struct link_loss_adapter *la = user_data;
+ struct connected_device *condev = NULL;
+
+ if (!device)
+ goto set_error;
+
+ /* condev might remain NULL here if nothing is found */
+ condev = find_connected_device(la, device);
+
+ if (a->len == 0) {
+ DBG("Illegal alert level length");
+ goto set_error;
+ }
+
+ value = a->data[0];
+ if (value != NO_ALERT && value != MILD_ALERT && value != HIGH_ALERT) {
+ DBG("Illegal alert value");
+ goto set_error;
+ }
+
+ /* Register a disconnect cb if the alert level is non-zero */
+ if (value != NO_ALERT && !condev) {
+ condev = g_new0(struct connected_device, 1);
+ condev->device = btd_device_ref(device);
+ condev->adapter = la;
+ condev->callback_id = btd_device_add_attio_callback(device,
+ NULL, link_loss_disc_cb, condev);
+ condev->local_disc_id = device_add_disconnect_watch(device,
+ link_loss_local_disc, condev, NULL);
+
+ la->connected_devices = g_slist_append(la->connected_devices,
+ condev);
+ } else if (value == NO_ALERT && condev) {
+ link_loss_remove_condev(condev);
+ condev = NULL;
+ }
+
+ DBG("alert level set to %d by device %p", value, device);
+
+ if (condev)
+ condev->alert_level = value;
+
+ return 0;
+
+set_error:
+ error("Set link loss alert level for dev %p", device);
+ /* reset alert level on erroneous devices */
+ link_loss_remove_condev(condev);
+ return ATT_ECODE_IO;
+}
+
+void link_loss_register(struct btd_adapter *adapter, DBusConnection *conn)
+{
+ gboolean svc_added;
+ bt_uuid_t uuid;
+ struct link_loss_adapter *lladapter;
+
+ bt_uuid16_create(&uuid, LINK_LOSS_SVC_UUID);
+
+ lladapter = g_new0(struct link_loss_adapter, 1);
+ lladapter->adapter = adapter;
+ lladapter->conn = dbus_connection_ref(conn);
+
+ link_loss_adapters = g_slist_append(link_loss_adapters, lladapter);
+
+ /* Link Loss Service */
+ svc_added = gatt_service_add(adapter,
+ GATT_PRIM_SVC_UUID, &uuid,
+ /* Alert level characteristic */
+ GATT_OPT_CHR_UUID, ALERT_LEVEL_CHR_UUID,
+ GATT_OPT_CHR_PROPS,
+ ATT_CHAR_PROPER_READ | ATT_CHAR_PROPER_WRITE,
+ GATT_OPT_CHR_VALUE_CB, ATTRIB_READ,
+ link_loss_alert_lvl_read, lladapter,
+ GATT_OPT_CHR_VALUE_CB, ATTRIB_WRITE,
+ link_loss_alert_lvl_write, lladapter,
+ GATT_OPT_CHR_VALUE_GET_HANDLE,
+ &lladapter->alert_lvl_value_handle,
+ GATT_OPT_INVALID);
+
+ if (!svc_added)
+ goto err;
+
+ DBG("Link Loss service added");
+ return;
+
+err:
+ error("Error adding Link Loss service");
+ link_loss_unregister(adapter);
+}
+
+static void remove_condev_list_item(gpointer data, gpointer user_data)
+{
+ struct connected_device *condev = data;
+
+ link_loss_remove_condev(condev);
+}
+
+void link_loss_unregister(struct btd_adapter *adapter)
+{
+ struct link_loss_adapter *lladapter;
+ lladapter = find_link_loss_adapter(adapter);
+ if (!lladapter)
+ return;
+
+ g_slist_foreach(lladapter->connected_devices, remove_condev_list_item,
+ NULL);
+ dbus_connection_unref(lladapter->conn);
+
+ link_loss_adapters = g_slist_remove(link_loss_adapters, lladapter);
+ g_free(lladapter);
+}
diff --git a/proximity/linkloss.h b/proximity/linkloss.h
new file mode 100644
index 0000000..a7d83d0
--- /dev/null
+++ b/proximity/linkloss.h
@@ -0,0 +1,26 @@
+/*
+ *
+ * BlueZ - Bluetooth protocol stack for Linux
+ *
+ * Copyright (C) 2012 Texas Instruments Corporation
+ *
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+void link_loss_register(struct btd_adapter *adapter, DBusConnection *conn);
+void link_loss_unregister(struct btd_adapter *adapter);
+const char *link_loss_get_alert_level(struct btd_device *device);
diff --git a/proximity/reporter.c b/proximity/reporter.c
index 2474fea..cc371f2 100644
--- a/proximity/reporter.c
+++ b/proximity/reporter.c
@@ -39,6 +39,7 @@
#include "gattrib.h"
#include "attrib-server.h"
#include "reporter.h"
+#include "linkloss.h"

static DBusConnection *connection;

@@ -56,44 +57,6 @@ const char *get_alert_level_string(uint8_t level)
return "unknown";
}

-static void register_link_loss(struct btd_adapter *adapter)
-{
- uint16_t start_handle, h;
- const int svc_size = 3;
- uint8_t atval[256];
- bt_uuid_t uuid;
-
- bt_uuid16_create(&uuid, LINK_LOSS_SVC_UUID);
- start_handle = attrib_db_find_avail(adapter, &uuid, svc_size);
- if (start_handle == 0) {
- error("Not enough free handles to register service");
- return;
- }
-
- DBG("start_handle=0x%04x", start_handle);
-
- h = start_handle;
-
- /* Primary service definition */
- bt_uuid16_create(&uuid, GATT_PRIM_SVC_UUID);
- att_put_u16(LINK_LOSS_SVC_UUID, &atval[0]);
- attrib_db_add(adapter, h++, &uuid, ATT_NONE, ATT_NOT_PERMITTED, atval, 2);
-
- /* Alert level characteristic */
- bt_uuid16_create(&uuid, GATT_CHARAC_UUID);
- atval[0] = ATT_CHAR_PROPER_READ | ATT_CHAR_PROPER_WRITE;
- att_put_u16(h + 1, &atval[1]);
- att_put_u16(ALERT_LEVEL_CHR_UUID, &atval[3]);
- attrib_db_add(adapter, h++, &uuid, ATT_NONE, ATT_NOT_PERMITTED, atval, 5);
-
- /* Alert level value */
- bt_uuid16_create(&uuid, ALERT_LEVEL_CHR_UUID);
- att_put_u8(NO_ALERT, &atval[0]);
- attrib_db_add(adapter, h++, &uuid, ATT_NONE, ATT_NONE, atval, 1);
-
- g_assert(h - start_handle == svc_size);
-}
-
static void register_tx_power(struct btd_adapter *adapter)
{
uint16_t start_handle, h;
@@ -188,7 +151,7 @@ int reporter_init(struct btd_adapter *adapter)
return -EIO;
DBG("Proximity Reporter for adapter %p", adapter);

- register_link_loss(adapter);
+ link_loss_register(adapter, connection);
register_tx_power(adapter);
register_immediate_alert(adapter);

@@ -197,5 +160,6 @@ int reporter_init(struct btd_adapter *adapter)

void reporter_exit(struct btd_adapter *adapter)
{
+ link_loss_unregister(adapter);
dbus_connection_unref(connection);
}
--
1.7.5.4