[PATCH v3 1/2] wan/hdlc_x25: make lapb params configurable

[Martin Schiller <ms@dev.tdt.de>]

This enables you to configure mode (DTE/DCE), Modulo, Window, T1, T2, N2 via
sethdlc (which needs to be patched as well).

Signed-off-by: Martin Schiller <ms@dev.tdt.de>
---
 drivers/net/wan/hdlc_x25.c      | 80 +++++++++++++++++++++++++++++++--
 include/uapi/linux/hdlc/ioctl.h |  9 ++++
 include/uapi/linux/if.h         |  1 +
 3 files changed, 87 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wan/hdlc_x25.c b/drivers/net/wan/hdlc_x25.c
index 5643675ff724..b0252b600ae2 100644
--- a/drivers/net/wan/hdlc_x25.c
+++ b/drivers/net/wan/hdlc_x25.c
@@ -21,8 +21,17 @@
 #include <linux/skbuff.h>
 #include <net/x25device.h>
 
+struct x25_state {
+	x25_hdlc_proto settings;
+};
+
 static int x25_ioctl(struct net_device *dev, struct ifreq *ifr);
 
+static struct x25_state *state(hdlc_device *hdlc)
+{
+	return (struct x25_state *)hdlc->state;
+}
+
 /* These functions are callbacks called by LAPB layer */
 
 static void x25_connect_disconnect(struct net_device *dev, int reason, int code)
@@ -131,7 +140,6 @@ static netdev_tx_t x25_xmit(struct sk_buff *skb, struct net_device *dev)
 
 static int x25_open(struct net_device *dev)
 {
-	int result;
 	static const struct lapb_register_struct cb = {
 		.connect_confirmation = x25_connected,
 		.connect_indication = x25_connected,
@@ -140,10 +148,33 @@ static int x25_open(struct net_device *dev)
 		.data_indication = x25_data_indication,
 		.data_transmit = x25_data_transmit,
 	};
+	hdlc_device *hdlc = dev_to_hdlc(dev);
+	struct lapb_parms_struct params;
+	int result;
 
 	result = lapb_register(dev, &cb);
 	if (result != LAPB_OK)
 		return result;
+
+	result = lapb_getparms(dev, &params);
+	if (result != LAPB_OK)
+		return result;
+
+	if (state(hdlc)->settings.dce)
+		params.mode = params.mode | LAPB_DCE;
+
+	if (state(hdlc)->settings.modulo == 128)
+		params.mode = params.mode | LAPB_EXTENDED;
+
+	params.window = state(hdlc)->settings.window;
+	params.t1 = state(hdlc)->settings.t1;
+	params.t2 = state(hdlc)->settings.t2;
+	params.n2 = state(hdlc)->settings.n2;
+
+	result = lapb_setparms(dev, &params);
+	if (result != LAPB_OK)
+		return result;
+
 	return 0;
 }
 
@@ -186,7 +217,10 @@ static struct hdlc_proto proto = {
 
 static int x25_ioctl(struct net_device *dev, struct ifreq *ifr)
 {
+	x25_hdlc_proto __user *x25_s = ifr->ifr_settings.ifs_ifsu.x25;
+	const size_t size = sizeof(x25_hdlc_proto);
 	hdlc_device *hdlc = dev_to_hdlc(dev);
+	x25_hdlc_proto new_settings;
 	int result;
 
 	switch (ifr->ifr_settings.type) {
@@ -194,7 +228,13 @@ static int x25_ioctl(struct net_device *dev, struct ifreq *ifr)
 		if (dev_to_hdlc(dev)->proto != &proto)
 			return -EINVAL;
 		ifr->ifr_settings.type = IF_PROTO_X25;
-		return 0; /* return protocol only, no settable parameters */
+		if (ifr->ifr_settings.size < size) {
+			ifr->ifr_settings.size = size; /* data size wanted */
+			return -ENOBUFS;
+		}
+		if (copy_to_user(x25_s, &state(hdlc)->settings, size))
+			return -EFAULT;
+		return 0;
 
 	case IF_PROTO_X25:
 		if (!capable(CAP_NET_ADMIN))
@@ -203,12 +243,46 @@ static int x25_ioctl(struct net_device *dev, struct ifreq *ifr)
 		if (dev->flags & IFF_UP)
 			return -EBUSY;
 
+		/* backward compatibility */
+		if (ifr->ifr_settings.size = 0) {
+			new_settings.dce = 0;
+			new_settings.modulo = 8;
+			new_settings.window = 7;
+			new_settings.t1 = 3;
+			new_settings.t2 = 1;
+			new_settings.n2 = 10;
+		}
+		else {
+			if (copy_from_user(&new_settings, x25_s, size))
+				return -EFAULT;
+
+			if ((new_settings.dce != 0 &&
+			new_settings.dce != 1) ||
+			(new_settings.modulo != 8 &&
+			new_settings.modulo != 128) ||
+			new_settings.window < 1 ||
+			(new_settings.modulo == 8 &&
+			new_settings.window > 7) ||
+			(new_settings.modulo == 128 &&
+			new_settings.window > 127) ||
+			new_settings.t1 < 1 ||
+			new_settings.t1 > 255 ||
+			new_settings.t2 < 1 ||
+			new_settings.t2 > 255 ||
+			new_settings.n2 < 1 ||
+			new_settings.n2 > 255)
+				return -EINVAL;
+		}
+
 		result=hdlc->attach(dev, ENCODING_NRZ,PARITY_CRC16_PR1_CCITT);
 		if (result)
 			return result;
 
-		if ((result = attach_hdlc_protocol(dev, &proto, 0)))
+		if ((result = attach_hdlc_protocol(dev, &proto,
+						   sizeof(struct x25_state))))
 			return result;
+
+		memcpy(&state(hdlc)->settings, &new_settings, size);
 		dev->type = ARPHRD_X25;
 		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
 		netif_dormant_off(dev);
diff --git a/include/uapi/linux/hdlc/ioctl.h b/include/uapi/linux/hdlc/ioctl.h
index 0fe4238e8246..b06341acab5e 100644
--- a/include/uapi/linux/hdlc/ioctl.h
+++ b/include/uapi/linux/hdlc/ioctl.h
@@ -79,6 +79,15 @@ typedef struct {
     unsigned int timeout;
 } cisco_proto;
 
+typedef struct {
+	unsigned short dce; /* 1 for DCE (network side) operation */
+	unsigned int modulo; /* modulo (8 = basic / 128 = extended) */
+	unsigned int window; /* frame window size */
+	unsigned int t1; /* timeout t1 */
+	unsigned int t2; /* timeout t2 */
+	unsigned int n2; /* frame retry counter */
+} x25_hdlc_proto;
+
 /* PPP doesn't need any info now - supply length = 0 to ioctl */
 
 #endif /* __ASSEMBLY__ */
diff --git a/include/uapi/linux/if.h b/include/uapi/linux/if.h
index 4bf33344aab1..be714cd8c826 100644
--- a/include/uapi/linux/if.h
+++ b/include/uapi/linux/if.h
@@ -213,6 +213,7 @@ struct if_settings {
 		fr_proto		__user *fr;
 		fr_proto_pvc		__user *fr_pvc;
 		fr_proto_pvc_info	__user *fr_pvc_info;
+		x25_hdlc_proto		__user *x25;
 
 		/* interface settings */
 		sync_serial_settings	__user *sync;
-- 
2.20.1