Bluetooth: Add basic constants for L2CAP ERTM support and use them

This adds the basic constants required to add support for L2CAP Enhanced
Retransmission feature.

Based on a patch from Nathan Holstein <nathan@lampreynetworks.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/l2cap.h

@@ -27,7 +27,12 @@
 
 /* L2CAP defaults */
 #define L2CAP_DEFAULT_MTU		672
-#define L2CAP_DEFAULT_FLUSH_TO	0xFFFF
+#define L2CAP_DEFAULT_FLUSH_TO		0xffff
+#define L2CAP_DEFAULT_RX_WINDOW		1
+#define L2CAP_DEFAULT_MAX_RECEIVE	1
+#define L2CAP_DEFAULT_RETRANS_TO	300    /* 300 milliseconds */
+#define L2CAP_DEFAULT_MONITOR_TO	1000   /* 1 second */
+#define L2CAP_DEFAULT_MAX_RX_APDU	0xfff7
 
 #define L2CAP_CONN_TIMEOUT	(40000) /* 40 seconds */
 #define L2CAP_INFO_TIMEOUT	(4000)  /*  4 seconds */
@@ -76,6 +81,18 @@ struct l2cap_conninfo {
 #define L2CAP_INFO_REQ		0x0a
 #define L2CAP_INFO_RSP		0x0b
 
+/* L2CAP feature mask */
+#define L2CAP_FEAT_FLOWCTL	0x00000001
+#define L2CAP_FEAT_RETRANS	0x00000002
+#define L2CAP_FEAT_ERTM		0x00000008
+#define L2CAP_FEAT_STREAMING	0x00000010
+#define L2CAP_FEAT_FCS		0x00000020
+#define L2CAP_FEAT_FIXED_CHAN	0x00000080
+
+/* L2CAP checksum option */
+#define L2CAP_FCS_NONE		0x00
+#define L2CAP_FCS_CRC16		0x01
+
 /* L2CAP structures */
 struct l2cap_hdr {
 	__le16     len;
@@ -150,11 +167,13 @@ struct l2cap_conf_opt {
 #define L2CAP_CONF_OPT_SIZE	2
 
 #define L2CAP_CONF_HINT		0x80
+#define L2CAP_CONF_MASK		0x7f
 
 #define L2CAP_CONF_MTU		0x01
 #define L2CAP_CONF_FLUSH_TO	0x02
 #define L2CAP_CONF_QOS		0x03
 #define L2CAP_CONF_RFC		0x04
+#define L2CAP_CONF_FCS		0x05
 
 #define L2CAP_CONF_MAX_SIZE	22
 
@@ -170,6 +189,8 @@ struct l2cap_conf_rfc {
 #define L2CAP_MODE_BASIC	0x00
 #define L2CAP_MODE_RETRANS	0x01
 #define L2CAP_MODE_FLOWCTL	0x02
+#define L2CAP_MODE_ERTM		0x03
+#define L2CAP_MODE_STREAM	0x04
 
 struct l2cap_disconn_req {
 	__le16     dcid;

net/bluetooth/l2cap.c

@@ -52,7 +52,7 @@
 
 #define VERSION "2.13"
 
-static u32 l2cap_feat_mask = 0x0080;
+static u32 l2cap_feat_mask = L2CAP_FEAT_FIXED_CHAN;
 static u8 l2cap_fixed_chan[8] = { 0x02, };
 
 static const struct proto_ops l2cap_sock_ops;
@@ -1747,7 +1747,7 @@ static int l2cap_parse_conf_req(struct sock *sk, void *data)
 		len -= l2cap_get_conf_opt(&req, &type, &olen, &val);
 
 		hint  = type & L2CAP_CONF_HINT;
-		type &= 0x7f;
+		type &= L2CAP_CONF_MASK;
 
 		switch (type) {
 		case L2CAP_CONF_MTU:
@@ -2244,7 +2244,7 @@ static inline int l2cap_information_rsp(struct l2cap_conn *conn, struct l2cap_cm
 	if (type == L2CAP_IT_FEAT_MASK) {
 		conn->feat_mask = get_unaligned_le32(rsp->data);
 
-		if (conn->feat_mask & 0x0080) {
+		if (conn->feat_mask & L2CAP_FEAT_FIXED_CHAN) {
 			struct l2cap_info_req req;
 			req.type = cpu_to_le16(L2CAP_IT_FIXED_CHAN);