Bluetooth: Connection Parameter Update Procedure

This patch adds support for LE Connection Parameters Request Link
Layer control procedure introduced in Core spec 4.1. This procedure
allows a Peripheral or Central to update the Link Layer connection
parameters of an established connection.

Regarding the acceptance of connection parameters, the LL procedure
follows the same approach of L2CAP procedure (see l2cap_conn_param_
update_req function). We accept any connection parameters values as
long as they are within the valid range.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci.h

@@ -355,6 +355,7 @@ enum {
 #define HCI_LK_AUTH_COMBINATION_P256	0x08
 
 /* ---- HCI Error Codes ---- */
+#define HCI_ERROR_UNKNOWN_CONN_ID	0x02
 #define HCI_ERROR_AUTH_FAILURE		0x05
 #define HCI_ERROR_MEMORY_EXCEEDED	0x07
 #define HCI_ERROR_CONNECTION_TIMEOUT	0x08
@@ -364,6 +365,7 @@ enum {
 #define HCI_ERROR_REMOTE_POWER_OFF	0x15
 #define HCI_ERROR_LOCAL_HOST_TERM	0x16
 #define HCI_ERROR_PAIRING_NOT_ALLOWED	0x18
+#define HCI_ERROR_INVALID_LL_PARAMS	0x1E
 #define HCI_ERROR_ADVERTISING_TIMEOUT	0x3c
 
 /* Flow control modes */
@@ -1305,6 +1307,23 @@ struct hci_rp_le_read_supported_states {
 	__u8	le_states[8];
 } __packed;
 
+#define HCI_OP_LE_CONN_PARAM_REQ_REPLY	0x2020
+struct hci_cp_le_conn_param_req_reply {
+	__le16	handle;
+	__le16	interval_min;
+	__le16	interval_max;
+	__le16	latency;
+	__le16	timeout;
+	__le16	min_ce_len;
+	__le16	max_ce_len;
+} __packed;
+
+#define HCI_OP_LE_CONN_PARAM_REQ_NEG_REPLY	0x2021
+struct hci_cp_le_conn_param_req_neg_reply {
+	__le16	handle;
+	__u8	reason;
+} __packed;
+
 /* ---- HCI Events ---- */
 #define HCI_EV_INQUIRY_COMPLETE		0x01
 
@@ -1700,6 +1719,15 @@ struct hci_ev_le_ltk_req {
 	__le16	ediv;
 } __packed;
 
+#define HCI_EV_LE_REMOTE_CONN_PARAM_REQ	0x06
+struct hci_ev_le_remote_conn_param_req {
+	__le16 handle;
+	__le16 interval_min;
+	__le16 interval_max;
+	__le16 latency;
+	__le16 timeout;
+} __packed;
+
 /* Advertising report event types */
 #define LE_ADV_IND		0x00
 #define LE_ADV_DIRECT_IND	0x01

net/bluetooth/hci_event.c

@@ -4382,6 +4382,52 @@ not_found:
 	hci_dev_unlock(hdev);
 }
 
+static void send_conn_param_neg_reply(struct hci_dev *hdev, u16 handle,
+				      u8 reason)
+{
+	struct hci_cp_le_conn_param_req_neg_reply cp;
+
+	cp.handle = cpu_to_le16(handle);
+	cp.reason = reason;
+
+	hci_send_cmd(hdev, HCI_OP_LE_CONN_PARAM_REQ_NEG_REPLY, sizeof(cp),
+		     &cp);
+}
+
+static void hci_le_remote_conn_param_req_evt(struct hci_dev *hdev,
+					     struct sk_buff *skb)
+{
+	struct hci_ev_le_remote_conn_param_req *ev = (void *) skb->data;
+	struct hci_cp_le_conn_param_req_reply cp;
+	struct hci_conn *hcon;
+	u16 handle, min, max, latency, timeout;
+
+	handle = le16_to_cpu(ev->handle);
+	min = le16_to_cpu(ev->interval_min);
+	max = le16_to_cpu(ev->interval_max);
+	latency = le16_to_cpu(ev->latency);
+	timeout = le16_to_cpu(ev->timeout);
+
+	hcon = hci_conn_hash_lookup_handle(hdev, handle);
+	if (!hcon || hcon->state != BT_CONNECTED)
+		return send_conn_param_neg_reply(hdev, handle,
+						 HCI_ERROR_UNKNOWN_CONN_ID);
+
+	if (hci_check_conn_params(min, max, latency, timeout))
+		return send_conn_param_neg_reply(hdev, handle,
+						 HCI_ERROR_INVALID_LL_PARAMS);
+
+	cp.handle = ev->handle;
+	cp.interval_min = ev->interval_min;
+	cp.interval_max = ev->interval_max;
+	cp.latency = ev->latency;
+	cp.timeout = ev->timeout;
+	cp.min_ce_len = 0;
+	cp.max_ce_len = 0;
+
+	hci_send_cmd(hdev, HCI_OP_LE_CONN_PARAM_REQ_REPLY, sizeof(cp), &cp);
+}
+
 static void hci_le_meta_evt(struct hci_dev *hdev, struct sk_buff *skb)
 {
 	struct hci_ev_le_meta *le_ev = (void *) skb->data;
@@ -4405,6 +4451,10 @@ static void hci_le_meta_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		hci_le_ltk_request_evt(hdev, skb);
 		break;
 
+	case HCI_EV_LE_REMOTE_CONN_PARAM_REQ:
+		hci_le_remote_conn_param_req_evt(hdev, skb);
+		break;
+
 	default:
 		break;
 	}