Bluetooth: Add __hci_cmd_sync() helper function

This patch adds a helper function for sending a single HCI command
waiting for its completion and then returning back the parameters in the
resulting command complete event (if there was one).

The implementation is very similar to that of hci_req_sync() except that
instead of invocing a callback for sending HCI commands the function
constructs and sends one itself and after being woken up picks the last
received event from hdev->recv_evt (if it matches the right criteria)
and returns it.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci_core.h

@@ -1057,6 +1057,9 @@ int hci_req_run(struct hci_request *req, hci_req_complete_t complete);
 void hci_req_add(struct hci_request *req, u16 opcode, u32 plen, void *param);
 void hci_req_cmd_complete(struct hci_dev *hdev, u16 opcode, u8 status);
 
+struct sk_buff *__hci_cmd_sync(struct hci_dev *hdev, u16 opcode, u32 plen,
+			       void *param, u32 timeout);
+
 int hci_send_cmd(struct hci_dev *hdev, __u16 opcode, __u32 plen, void *param);
 void hci_send_acl(struct hci_chan *chan, struct sk_buff *skb, __u16 flags);
 void hci_send_sco(struct hci_conn *conn, struct sk_buff *skb);

net/bluetooth/hci_core.c

@@ -79,6 +79,108 @@ static void hci_req_cancel(struct hci_dev *hdev, int err)
 	}
 }
 
+struct sk_buff *hci_get_cmd_complete(struct hci_dev *hdev, u16 opcode)
+{
+	struct hci_ev_cmd_complete *ev;
+	struct hci_event_hdr *hdr;
+	struct sk_buff *skb;
+
+	hci_dev_lock(hdev);
+
+	skb = hdev->recv_evt;
+	hdev->recv_evt = NULL;
+
+	hci_dev_unlock(hdev);
+
+	if (!skb)
+		return ERR_PTR(-ENODATA);
+
+	if (skb->len < sizeof(*hdr)) {
+		BT_ERR("Too short HCI event");
+		goto failed;
+	}
+
+	hdr = (void *) skb->data;
+	skb_pull(skb, HCI_EVENT_HDR_SIZE);
+
+	if (hdr->evt != HCI_EV_CMD_COMPLETE) {
+		BT_DBG("Last event is not cmd complete (0x%2.2x)", hdr->evt);
+		goto failed;
+	}
+
+	if (skb->len < sizeof(*ev)) {
+		BT_ERR("Too short cmd_complete event");
+		goto failed;
+	}
+
+	ev = (void *) skb->data;
+	skb_pull(skb, sizeof(*ev));
+
+	if (opcode == __le16_to_cpu(ev->opcode))
+		return skb;
+
+	BT_DBG("opcode doesn't match (0x%2.2x != 0x%2.2x)", opcode,
+	       __le16_to_cpu(ev->opcode));
+
+failed:
+	kfree_skb(skb);
+	return ERR_PTR(-ENODATA);
+}
+
+struct sk_buff *__hci_cmd_sync(struct hci_dev *hdev, u16 opcode, u32 plen,
+			       void *param, u32 timeout)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	struct hci_request req;
+	int err = 0;
+
+	BT_DBG("%s", hdev->name);
+
+	hci_req_init(&req, hdev);
+
+	hci_req_add(&req, opcode, plen, param);
+
+	hdev->req_status = HCI_REQ_PEND;
+
+	err = hci_req_run(&req, hci_req_sync_complete);
+	if (err < 0)
+		return ERR_PTR(err);
+
+	add_wait_queue(&hdev->req_wait_q, &wait);
+	set_current_state(TASK_INTERRUPTIBLE);
+
+	schedule_timeout(timeout);
+
+	remove_wait_queue(&hdev->req_wait_q, &wait);
+
+	if (signal_pending(current))
+		return ERR_PTR(-EINTR);
+
+	switch (hdev->req_status) {
+	case HCI_REQ_DONE:
+		err = -bt_to_errno(hdev->req_result);
+		break;
+
+	case HCI_REQ_CANCELED:
+		err = -hdev->req_result;
+		break;
+
+	default:
+		err = -ETIMEDOUT;
+		break;
+	}
+
+	hdev->req_status = hdev->req_result = 0;
+
+	BT_DBG("%s end: err %d", hdev->name, err);
+
+	if (err < 0)
+		return ERR_PTR(err);
+
+	return hci_get_cmd_complete(hdev, opcode);
+}
+EXPORT_SYMBOL(__hci_cmd_sync);
+
 /* Execute request and wait for completion. */
 static int __hci_req_sync(struct hci_dev *hdev,
 			  void (*func)(struct hci_request *req,