Bluetooth: L2CAP: Add initial code for Enhanced Credit Based Mode

This adds the initial code for Enhanced Credit Based Mode which
introduces a new socket mode called L2CAP_MODE_EXT_FLOWCTL, which for
the most part work the same as L2CAP_MODE_LE_FLOWCTL but uses different
PDUs to setup the connections and also works over BR/EDR.
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/l2cap.h

@@ -294,6 +294,8 @@ struct l2cap_conn_rsp {
 #define L2CAP_CR_LE_ENCRYPTION		0x0008
 #define L2CAP_CR_LE_INVALID_SCID	0x0009
 #define L2CAP_CR_LE_SCID_IN_USE		0X000A
+#define L2CAP_CR_LE_UNACCEPT_PARAMS	0X000B
+#define L2CAP_CR_LE_INVALID_PARAMS	0X000C
 
 /* connect/create channel status */
 #define L2CAP_CS_NO_INFO	0x0000
@@ -962,6 +964,7 @@ void l2cap_cleanup_sockets(void);
 bool l2cap_is_socket(struct socket *sock);
 
 void __l2cap_le_connect_rsp_defer(struct l2cap_chan *chan);
+void __l2cap_ecred_conn_rsp_defer(struct l2cap_chan *chan);
 void __l2cap_connect_rsp_defer(struct l2cap_chan *chan);
 
 int l2cap_add_psm(struct l2cap_chan *chan, bdaddr_t *src, __le16 psm);
@@ -971,6 +974,7 @@ struct l2cap_chan *l2cap_chan_create(void);
 void l2cap_chan_close(struct l2cap_chan *chan, int reason);
 int l2cap_chan_connect(struct l2cap_chan *chan, __le16 psm, u16 cid,
 		       bdaddr_t *dst, u8 dst_type);
+int l2cap_chan_reconfigure(struct l2cap_chan *chan, __u16 mtu);
 int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len);
 void l2cap_chan_busy(struct l2cap_chan *chan, int busy);
 int l2cap_chan_check_security(struct l2cap_chan *chan, bool initiator);

net/bluetooth/l2cap_sock.c

@@ -232,7 +232,7 @@ static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr,
 			return -EINVAL;
 	}
 
-	if (chan->psm && bdaddr_type_is_le(chan->src_type))
+	if (chan->psm && bdaddr_type_is_le(chan->src_type) && !chan->mode)
 		chan->mode = L2CAP_MODE_LE_FLOWCTL;
 
 	err = l2cap_chan_connect(chan, la.l2_psm, __le16_to_cpu(la.l2_cid),
@@ -273,6 +273,7 @@ static int l2cap_sock_listen(struct socket *sock, int backlog)
 	switch (chan->mode) {
 	case L2CAP_MODE_BASIC:
 	case L2CAP_MODE_LE_FLOWCTL:
+	case L2CAP_MODE_EXT_FLOWCTL:
 		break;
 	case L2CAP_MODE_ERTM:
 	case L2CAP_MODE_STREAMING:
@@ -427,6 +428,8 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname,
 		opts.max_tx   = chan->max_tx;
 		opts.txwin_size = chan->tx_win;
 
+		BT_DBG("mode 0x%2.2x", chan->mode);
+
 		len = min_t(unsigned int, len, sizeof(opts));
 		if (copy_to_user(optval, (char *) &opts, len))
 			err = -EFAULT;
@@ -707,6 +710,8 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname,
 			break;
 		}
 
+		BT_DBG("mode 0x%2.2x", chan->mode);
+
 		chan->imtu = opts.imtu;
 		chan->omtu = opts.omtu;
 		chan->fcs  = opts.fcs;
@@ -939,7 +944,8 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 			break;
 		}
 
-		if (sk->sk_state == BT_CONNECTED) {
+		if (chan->mode == L2CAP_MODE_LE_FLOWCTL &&
+		    sk->sk_state == BT_CONNECTED) {
 			err = -EISCONN;
 			break;
 		}
@@ -949,7 +955,12 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 			break;
 		}
 
-		chan->imtu = opt;
+		if (chan->mode == L2CAP_MODE_EXT_FLOWCTL &&
+		    sk->sk_state == BT_CONNECTED)
+			err = l2cap_chan_reconfigure(chan, opt);
+		else
+			chan->imtu = opt;
+
 		break;
 
 	default:
@@ -1004,7 +1015,11 @@ static int l2cap_sock_recvmsg(struct socket *sock, struct msghdr *msg,
 
 	if (sk->sk_state == BT_CONNECT2 && test_bit(BT_SK_DEFER_SETUP,
 						    &bt_sk(sk)->flags)) {
-		if (bdaddr_type_is_le(pi->chan->src_type)) {
+		if (pi->chan->mode == L2CAP_MODE_EXT_FLOWCTL) {
+			sk->sk_state = BT_CONNECTED;
+			pi->chan->state = BT_CONNECTED;
+			__l2cap_ecred_conn_rsp_defer(pi->chan);
+		} if (bdaddr_type_is_le(pi->chan->src_type)) {
 			sk->sk_state = BT_CONNECTED;
 			pi->chan->state = BT_CONNECTED;
 			__l2cap_le_connect_rsp_defer(pi->chan);