[PATCH iproute2-next v2 2/2] iplink: support for WWAN devices

[Sergey Ryazanov <ryazanov.s.a@gmail.com>]

The WWAN subsystem has been extended to generalize the per data channel
network interfaces management. This change implements support for WWAN
links handling. And actively uses the earlier introduced ip-link
capability to specify the parent by its device name.

The WWAN interface for a new data channel should be created with a
command like this:

ip link add dev wwan0-2 parentdev wwan0 type wwan linkid 2

Where: wwan0 is the modem HW device name (should be taken from
/sys/class/wwan) and linkid is an identifier of the opened data
channel.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
---
To compile this, a new uapi/linux/wwan.h header file should be copied
from the kernel sources.

Changes since v1:
* no changes

Changes since RFC:
* no changes

 ip/Makefile      |  2 +-
 ip/iplink.c      |  3 +-
 ip/iplink_wwan.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 75 insertions(+), 2 deletions(-)
 create mode 100644 ip/iplink_wwan.c

diff --git a/ip/Makefile b/ip/Makefile
index 4cad619c..b03af29b 100644
--- a/ip/Makefile
+++ b/ip/Makefile
@@ -11,7 +11,7 @@ IPOBJ=ip.o ipaddress.o ipaddrlabel.o iproute.o iprule.o ipnetns.o \
     iplink_bridge.o iplink_bridge_slave.o ipfou.o iplink_ipvlan.o \
     iplink_geneve.o iplink_vrf.o iproute_lwtunnel.o ipmacsec.o ipila.o \
     ipvrf.o iplink_xstats.o ipseg6.o iplink_netdevsim.o iplink_rmnet.o \
-    ipnexthop.o ipmptcp.o iplink_bareudp.o
+    ipnexthop.o ipmptcp.o iplink_bareudp.o iplink_wwan.o
 
 RTMONOBJ=rtmon.o
 
diff --git a/ip/iplink.c b/ip/iplink.c
index 33b7be30..18b2ea25 100644
--- a/ip/iplink.c
+++ b/ip/iplink.c
@@ -56,7 +56,8 @@ void iplink_types_usage(void)
 		"          ipip | ipoib | ipvlan | ipvtap |\n"
 		"          macsec | macvlan | macvtap |\n"
 		"          netdevsim | nlmon | rmnet | sit | team | team_slave |\n"
-		"          vcan | veth | vlan | vrf | vti | vxcan | vxlan | xfrm }\n");
+		"          vcan | veth | vlan | vrf | vti | vxcan | vxlan | wwan |\n"
+		"          xfrm }\n");
 }
 
 void iplink_usage(void)
diff --git a/ip/iplink_wwan.c b/ip/iplink_wwan.c
new file mode 100644
index 00000000..3510477a
--- /dev/null
+++ b/ip/iplink_wwan.c
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <stdio.h>
+#include <linux/netlink.h>
+#include <linux/wwan.h>
+
+#include "utils.h"
+#include "ip_common.h"
+
+static void print_explain(FILE *f)
+{
+	fprintf(f,
+		"Usage: ... wwan linkid LINKID\n"
+		"\n"
+		"Where: LINKID := 0-4294967295\n"
+	);
+}
+
+static void explain(void)
+{
+	print_explain(stderr);
+}
+
+static int wwan_parse_opt(struct link_util *lu, int argc, char **argv,
+			  struct nlmsghdr *n)
+{
+	while (argc > 0) {
+		if (matches(*argv, "linkid") == 0) {
+			__u32 linkid;
+
+			NEXT_ARG();
+			if (get_u32(&linkid, *argv, 0))
+				invarg("linkid", *argv);
+			addattr32(n, 1024, IFLA_WWAN_LINK_ID, linkid);
+		} else if (matches(*argv, "help") == 0) {
+			explain();
+			return -1;
+		} else {
+			fprintf(stderr, "wwan: unknown command \"%s\"?\n",
+				*argv);
+			explain();
+			return -1;
+		}
+		argc--, argv++;
+	}
+
+	return 0;
+}
+
+static void wwan_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
+{
+	if (!tb)
+		return;
+
+	if (tb[IFLA_WWAN_LINK_ID])
+		print_uint(PRINT_ANY, "linkid", "linkid %u ",
+			   rta_getattr_u32(tb[IFLA_WWAN_LINK_ID]));
+}
+
+static void wwan_print_help(struct link_util *lu, int argc, char **argv,
+			    FILE *f)
+{
+	print_explain(f);
+}
+
+struct link_util wwan_link_util = {
+	.id		= "wwan",
+	.maxattr	= IFLA_WWAN_MAX,
+	.parse_opt	= wwan_parse_opt,
+	.print_opt	= wwan_print_opt,
+	.print_help	= wwan_print_help,
+};
-- 
2.26.3