Bluetooth: Stop scanning on LE connection

Some LE controllers don't support scanning and creating a connection
at the same time. So we should always stop scanning in order to
establish the connection.

Since we may prematurely stop the discovery procedure in favor of
the connection establishment, we should also cancel hdev->le_scan_
disable delayed work and set the discovery state to DISCOVERY_STOPPED.

This change does a small improvement since it is not mandatory the
user stops scanning before connecting anymore. Moreover, this change
is required by upcoming LE auto connection mechanism in order to work
properly with controllers that don't support background scanning and
connection establishment at the same time.

In future, we might want to do a small optimization by checking if
controller is able to scan and connect at the same time. For now,
we want the simplest approach so we always stop scanning (even if
the controller is able to carry out both operations).

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Remove unused function

This patch removes hci_create_le_conn() since it is not used anymore.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Refactor HCI connection code

hci_connect() is a very simple and useless wrapper of hci_connect_acl
and hci_connect_le functions. Addtionally, all places where hci_connect
is called the link type value is passed explicitly. This way, we can
safely delete hci_connect, declare hci_connect_acl and hci_connect_le
in hci_core.h and call them directly.

No functionality is changed by this patch.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Move address type conversion to outside hci_connect_le

This patch moves address type conversion (L2CAP address type to HCI
address type) to outside hci_connect_le. This way, we avoid back and
forth address type conversion in a comming patch.

So hci_connect_le() now expects 'dst_type' parameter in HCI address
type convention.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Introduce hdev->pend_le_conn list

This patch introduces the hdev->pend_le_conn list which holds the
device addresses the kernel should autonomously connect. It also
introduces some helper functions to manipulate the list.

The list and helper functions will be used by the next patch which
implements the LE auto connection infrastructure.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Introduce LE auto connection infrastructure

This patch introduces the LE auto connection infrastructure which
will be used to implement the LE auto connection options.

In summary, the auto connection mechanism works as follows: Once the
first pending LE connection is created, the background scanning is
started. When the target device is found in range, the kernel
autonomously starts the connection attempt. If connection is
established successfully, that pending LE connection is deleted and
the background is stopped.

To achieve that, this patch introduces the hci_update_background_scan()
which controls the background scanning state. This function starts or
stops the background scanning based on the hdev->pend_le_conns list. If
there is no pending LE connection, the background scanning is stopped.
Otherwise, we start the background scanning.

Then, every time a pending LE connection is added we call hci_update_
background_scan() so the background scanning is started (in case it is
not already running). Likewise, every time a pending LE connection is
deleted we call hci_update_background_scan() so the background scanning
is stopped (in case this was the last pending LE connection) or it is
started again (in case we have more pending LE connections). Finally,
we also call hci_update_background_scan() in hci_le_conn_failed() so
the background scan is restarted in case the connection establishment
fails. This way the background scanning keeps running until all pending
LE connection are established.

At this point, resolvable addresses are not support by this
infrastructure. The proper support is added in upcoming patches.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Introduce LE auto connect options

This patch introduces the LE auto connection options: HCI_AUTO_CONN_
ALWAYS and HCI_AUTO_CONN_LINK_LOSS. Their working mechanism are
described as follows:

The HCI_AUTO_CONN_ALWAYS option configures the kernel to always re-
establish the connection, no matter the reason the connection was
terminated. This feature is required by some LE profiles such as
HID over GATT, Health Thermometer and Blood Pressure. These profiles
require the host autonomously connect to the device as soon as it
enters in connectable mode (start advertising) so the device is able
to delivery notifications or indications.

The BT_AUTO_CONN_LINK_LOSS option configures the kernel to re-
establish the connection in case the connection was terminated due
to a link loss. This feature is required by the majority of LE
profiles such as Proximity, Find Me, Cycling Speed and Cadence and
Time.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Connection parameters and auto connection

This patch modifies hci_conn_params_add() and hci_conn_params_del() so
they also add/delete pending LE connections according to the auto_
connect option. This way, background scan is automatically triggered/
untriggered when connection parameters are added/removed.

For instance, when a new connection parameters with HCI_AUTO_CONN_ALWAYS
option is added and we are not connected to the device, we add a pending
LE connection for that device.

Likewise, when the connection parameters are updated we add or delete
a pending LE connection according to its new auto_connect option.

Finally, when the connection parameter is deleted we also delete the
pending LE connection (if any).

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Temporarily stop background scanning on discovery

If the user sends a mgmt start discovery command while the background
scanning is running, we should temporarily stop it. Once the discovery
finishes, we start the background scanning again.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Auto connection and power on

When hdev is closed (e.g. Mgmt power off command, RFKILL or controller
is reset), the ongoing active connections are silently dropped by the
controller (no Disconnection Complete Event is sent to host). For that
reason, the devices that require HCI_AUTO_CONN_ALWAYS are not added to
hdev->pend_le_conns list and they won't auto connect.

So to fix this issue, during hdev closing, we remove all pending LE
connections. After adapter is powered on, we add a pending LE connection
for each HCI_AUTO_CONN_ALWAYS address.

This way, the auto connection mechanism works propely after a power
off and power on sequence as well as RFKILL block/unblock.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Connection parameters and resolvable address

We should only add connection parameters for public, random static and
random private resolvable with IRK. If we allow non-resolvable or
resolvable without IRK, the background scan may run indefinitely. So, to
avoid this undesired behavior, we should check the address type in
hci_conn_params_add().

Additionally, since the IRK is removed during unpair, we should also
remove the connection parameters from that device.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Support resolvable private addresses

Only identity addresses are inserted into hdev->pend_le_conns. So,
in order to support resolvable private addresses in auto connection
mechanism, we should resolve the address before checking for pending
connections.

Thus, this patch adds an extra check in check_pending_le_conn() and
updates 'addr' and 'addr_type' variables before hci_pend_le_conn_
lookup().

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Add le_auto_conn file on debugfs

This patch adds to debugfs the le_auto_conn file. This file will be
used to test LE auto connection infrastructure.

This file accept writes in the following format:
  "add <address> <address_type> [auto_connect]"
  "del <address> <address_type>"
  "clr"

The <address type> values are:
  * 0 for public address
  * 1 for random address

The [auto_connect] values are (for more details see struct hci_
conn_params):
  * 0 for disabled (default)
  * 1 for always
  * 2 for link loss

So for instance, if you want the kernel autonomously establishes
connections with device AA:BB:CC:DD:EE:FF (public address) every
time the device enters in connectable mode (starts advertising),
you should run the command:
$ echo "add AA:BB:CC:DD:EE:FF 0 1" > /sys/kernel/debug/bluetooth/hci0/le_auto_conn

To delete the connection parameters for that device, run the command:
$ echo "del AA:BB:CC:DD:EE:FF 0" > /sys/kernel/debug/bluetooth/hci0/le_auto_conn

To clear the connection parameters list, run the command:
$ echo "clr" > /sys/kernel/debug/bluetooth/hci0/le_auto_conn

Finally. to get the list of connection parameters configured in kernel,
read the le_auto_conn file:
$ cat /sys/kernel/debug/bluetooth/hci0/le_auto_conn

This file is created only if LE is enabled.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Create hci_req_add_le_passive_scan helper

This patches creates the hci_req_add_le_passive_scan helper so it can
be re-used in the next patch.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Update background scan parameters

If new scanning parameters are set while background scan is running,
we should restart background scanning so these parameters are updated.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>