[Bluetooth] Add automatic sniff mode support

This patch introduces the automatic sniff mode feature. This allows
the host to switch idle connections into sniff mode to safe power.

Signed-off-by: Ulisses Furquim <ulissesf@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/hci_conn.c

@@ -115,8 +115,8 @@ void hci_add_sco(struct hci_conn *conn, __u16 handle)
 
 static void hci_conn_timeout(unsigned long arg)
 {
-	struct hci_conn *conn = (void *)arg;
-	struct hci_dev  *hdev = conn->hdev;
+	struct hci_conn *conn = (void *) arg;
+	struct hci_dev *hdev = conn->hdev;
 
 	BT_DBG("conn %p state %d", conn, conn->state);
 
@@ -132,11 +132,13 @@ static void hci_conn_timeout(unsigned long arg)
 	return;
 }
 
-static void hci_conn_init_timer(struct hci_conn *conn)
+static void hci_conn_idle(unsigned long arg)
 {
-	init_timer(&conn->timer);
-	conn->timer.function = hci_conn_timeout;
-	conn->timer.data = (unsigned long)conn;
+	struct hci_conn *conn = (void *) arg;
+
+	BT_DBG("conn %p mode %d", conn, conn->mode);
+
+	hci_conn_enter_sniff_mode(conn);
 }
 
 struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst)
@@ -145,17 +147,27 @@ struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst)
 
 	BT_DBG("%s dst %s", hdev->name, batostr(dst));
 
-	if (!(conn = kmalloc(sizeof(struct hci_conn), GFP_ATOMIC)))
+	conn = kzalloc(sizeof(struct hci_conn), GFP_ATOMIC);
+	if (!conn)
 		return NULL;
-	memset(conn, 0, sizeof(struct hci_conn));
 
 	bacpy(&conn->dst, dst);
-	conn->type   = type;
 	conn->hdev   = hdev;
+	conn->type   = type;
+	conn->mode   = HCI_CM_ACTIVE;
 	conn->state  = BT_OPEN;
 
+	conn->power_save = 1;
+
 	skb_queue_head_init(&conn->data_q);
-	hci_conn_init_timer(conn);
+
+	init_timer(&conn->disc_timer);
+	conn->disc_timer.function = hci_conn_timeout;
+	conn->disc_timer.data = (unsigned long) conn;
+
+	init_timer(&conn->idle_timer);
+	conn->idle_timer.function = hci_conn_idle;
+	conn->idle_timer.data = (unsigned long) conn;
 
 	atomic_set(&conn->refcnt, 0);
 
@@ -178,7 +190,9 @@ int hci_conn_del(struct hci_conn *conn)
 
 	BT_DBG("%s conn %p handle %d", hdev->name, conn, conn->handle);
 
-	hci_conn_del_timer(conn);
+	del_timer(&conn->idle_timer);
+
+	del_timer(&conn->disc_timer);
 
 	if (conn->type == SCO_LINK) {
 		struct hci_conn *acl = conn->link;
@@ -364,6 +378,70 @@ int hci_conn_switch_role(struct hci_conn *conn, uint8_t role)
 }
 EXPORT_SYMBOL(hci_conn_switch_role);
 
+/* Enter active mode */
+void hci_conn_enter_active_mode(struct hci_conn *conn)
+{
+	struct hci_dev *hdev = conn->hdev;
+
+	BT_DBG("conn %p mode %d", conn, conn->mode);
+
+	if (test_bit(HCI_RAW, &hdev->flags))
+		return;
+
+	if (conn->mode != HCI_CM_SNIFF || !conn->power_save)
+		goto timer;
+
+	if (!test_and_set_bit(HCI_CONN_MODE_CHANGE_PEND, &conn->pend)) {
+		struct hci_cp_exit_sniff_mode cp;
+		cp.handle = __cpu_to_le16(conn->handle);
+		hci_send_cmd(hdev, OGF_LINK_POLICY,
+				OCF_EXIT_SNIFF_MODE, sizeof(cp), &cp);
+	}
+
+timer:
+	if (hdev->idle_timeout > 0)
+		mod_timer(&conn->idle_timer,
+			jiffies + msecs_to_jiffies(hdev->idle_timeout));
+}
+
+/* Enter sniff mode */
+void hci_conn_enter_sniff_mode(struct hci_conn *conn)
+{
+	struct hci_dev *hdev = conn->hdev;
+
+	BT_DBG("conn %p mode %d", conn, conn->mode);
+
+	if (test_bit(HCI_RAW, &hdev->flags))
+		return;
+
+	if (!lmp_sniff_capable(hdev) || !lmp_sniff_capable(conn))
+		return;
+
+	if (conn->mode != HCI_CM_ACTIVE || !(conn->link_policy & HCI_LP_SNIFF))
+		return;
+
+	if (lmp_sniffsubr_capable(hdev) && lmp_sniffsubr_capable(conn)) {
+		struct hci_cp_sniff_subrate cp;
+		cp.handle             = __cpu_to_le16(conn->handle);
+		cp.max_latency        = __constant_cpu_to_le16(0);
+		cp.min_remote_timeout = __constant_cpu_to_le16(0);
+		cp.min_local_timeout  = __constant_cpu_to_le16(0);
+		hci_send_cmd(hdev, OGF_LINK_POLICY,
+				OCF_SNIFF_SUBRATE, sizeof(cp), &cp);
+	}
+
+	if (!test_and_set_bit(HCI_CONN_MODE_CHANGE_PEND, &conn->pend)) {
+		struct hci_cp_sniff_mode cp;
+		cp.handle       = __cpu_to_le16(conn->handle);
+		cp.max_interval = __cpu_to_le16(hdev->sniff_max_interval);
+		cp.min_interval = __cpu_to_le16(hdev->sniff_min_interval);
+		cp.attempt      = __constant_cpu_to_le16(4);
+		cp.timeout      = __constant_cpu_to_le16(1);
+		hci_send_cmd(hdev, OGF_LINK_POLICY,
+				OCF_SNIFF_MODE, sizeof(cp), &cp);
+	}
+}
+
 /* Drop all connection on the device */
 void hci_conn_hash_flush(struct hci_dev *hdev)
 {