net/vlan: add some macro for vlan

Refer：
https://github.com/torvalds/linux/blob/v6.8/include/linux/if_vlan.h#L73-L76

Signed-off-by: gaohedong <gaohedong@xiaomi.com>

Documentation/components/drivers/special/net/vlan.rst

@@ -13,5 +13,81 @@ Vlan Device Drivers
 -  Supporting ADD_VLAN_CMD and DEL_VLAN_CMD of SIOCSIFVLAN.
 -  We add default PCP because some of our apps may not want to set
    PCP manually
+-  ``include/nuttx/net/ethernet.h``. Some definitions for 802.1Q VLAN
+
+   .. code-block:: c
+
+      #define VLAN_PRIO_MASK   0xe000 /* Priority Code Point */
+      #define VLAN_PRIO_SHIFT  13
+      #define VLAN_CFI_MASK    0x1000 /* Canonical Format Indicator / Drop Eligible Indicator */
+      #define VLAN_VID_MASK    0x0fff /* VLAN Identifier */
+      #define VLAN_N_VID       4096
 
 -  **Driver**: ``drivers/net/vlan.c``
+
+Configuration Options
+=====================
+
+``CONFIG_NET_VLAN``
+  Enable 802.1Q VLAN interface support.
+``CONFIG_NET_VLAN_COUNT``
+  Maximum number of VLAN interfaces per physical Ethernet interface.
+
+Usage
+=====
+
+.. code-block:: c
+
+  #include <nuttx/net/vlan.h>
+  #include "netutils/netlib.h"
+
+  /* Create a VLAN interface (eth0.100, VLAN ID 100) */
+
+  FAR const char *ifname = "eth0";
+  uint16_t vlanid = 100;
+  uint8_t priority = 0; /* Default PCP */
+
+  int sockfd = socket(NET_SOCK_FAMILY, NET_SOCK_TYPE, NET_SOCK_PROTOCOL);
+
+  if (sockfd >= 0)
+   {
+      struct vlan_ioctl_args ifv;
+
+      strncpy(ifv.vlan_devname, ifname, sizeof(ifv.device1));
+      ifv.u.VID  = vlanid;
+      ifv.vlan_qos = priority;
+      ifv.cmd = ADD_VLAN_CMD;
+      if (ioctl(sockfd, SIOCSIFVLAN, (unsigned long)&ifv) < 0)
+        {
+          /* Handle error */
+        }
+      close(sockfd);
+   }
+
+  /* Enable the VLAN interface */
+
+  netdev_ifup("eth0.100");
+
+.. code-block:: c
+
+  #include <nuttx/net/vlan.h>
+  #include "netutils/netlib.h"
+
+  /* Delete a VLAN interface (eth0.100, VLAN ID 100) */
+
+  FAR const char *ifname = "eth0.100";
+
+  int sockfd = socket(NET_SOCK_FAMILY, NET_SOCK_TYPE, NET_SOCK_PROTOCOL);
+
+  if (sockfd >= 0)
+   {
+      struct vlan_ioctl_args ifv;
+
+      strncpy(ifv.vlan_devname, ifname, sizeof(ifv.device1));
+      ifv.cmd = DEL_VLAN_CMD;
+      if (ioctl(sockfd, SIOCSIFVLAN, (unsigned long)&ifv) < 0)
+        {
+          /* Handle error */
+        }
+      close(sockfd);
+   }

include/nuttx/net/ethernet.h

@@ -2,7 +2,8 @@
  * include/nuttx/net/ethernet.h
  *
  * SPDX-License-Identifier: BSD-3-Clause
- * SPDX-FileCopyrightText: 2007, 2009-2012, 2015 Gregory Nutt. All rights reserved.
+ * SPDX-FileCopyrightText: 2007, 2009-2012, 2015 Gregory Nutt. All rights
+ *                         reserved.
  * SPDX-FileCopyrightText: 2001-2003, Adam Dunkels. All rights reserved.
  * SPDX-FileContributor: Gregory Nutt <gnutt@nuttx.org>
  * SPDX-FileContributor: Adam Dunkels <adam@dunkels.com>
@@ -63,6 +64,16 @@
 
 #define TPID_8021QVLAN   ETHERTYPE_VLAN
 
+/* These are some control information associated with QVLAN tagged
+ * Ethernet packets.
+ */
+
+#define VLAN_PRIO_MASK   0xe000 /* Priority Code Point */
+#define VLAN_PRIO_SHIFT  13
+#define VLAN_CFI_MASK    0x1000 /* Canonical Format Indicator / Drop Eligible Indicator */
+#define VLAN_VID_MASK    0x0fff /* VLAN Identifier */
+#define VLAN_N_VID       4096
+
 /* These are some of the types associated with QVLAN tagged
  * Ethernet packets.
  */