net/netdev/netdev_register.c - nuttx - Git at Google

 /****************************************************************************
  * net/netdev/netdev_register.c
  *
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.  The
  * ASF licenses this file to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance with the
  * License.  You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
  * License for the specific language governing permissions and limitations
  * under the License.
  *
  ****************************************************************************/

 /****************************************************************************
  * Included Files
  ****************************************************************************/

 #include <nuttx/config.h>

 #include <sys/socket.h>
 #include <stdio.h>
 #include <assert.h>
 #include <string.h>
 #include <errno.h>
 #include <debug.h>

 #include <net/if.h>
 #include <net/ethernet.h>
 #include <nuttx/net/netconfig.h>
 #include <nuttx/net/netdev.h>
 #include <nuttx/net/ethernet.h>
 #include <nuttx/net/bluetooth.h>
 #include <nuttx/net/can.h>

 #include "utils/utils.h"
 #include "icmpv6/icmpv6.h"
 #include "igmp/igmp.h"
 #include "mld/mld.h"
 #include "netdev/netdev.h"

 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/

 #define NETDEV_ETH_FORMAT   "eth%d"
 #define NETDEV_LO_FORMAT    "lo"
 #define NETDEV_SLIP_FORMAT  "sl%d"
 #define NETDEV_TUN_FORMAT   "tun%d"
 #define NETDEV_BNEP_FORMAT  "bnep%d"
 #define NETDEV_PAN_FORMAT   "pan%d"
 #define NETDEV_WLAN_FORMAT  "wlan%d"
 #define NETDEV_WPAN_FORMAT  "wpan%d"
 #define NETDEV_WWAN_FORMAT  "wwan%d"
 #define NETDEV_CAN_FORMAT   "can%d"
 #define NETDEV_CELL_FORMAT  "cell%d"

 #if defined(CONFIG_DRIVERS_IEEE80211) /* Usually also has CONFIG_NET_ETHERNET */
 #  define NETDEV_DEFAULT_FORMAT NETDEV_WLAN_FORMAT
 #elif defined(CONFIG_NET_ETHERNET)
 #  define NETDEV_DEFAULT_FORMAT NETDEV_ETH_FORMAT
 #elif defined(CONFIG_NET_6LOWPAN)
 #  define NETDEV_DEFAULT_FORMAT NETDEV_WPAN_FORMAT
 #elif defined(CONFIG_NET_SLIP)
 #  define NETDEV_DEFAULT_FORMAT NETDEV_SLIP_FORMAT
 #elif defined(CONFIG_NET_TUN)
 #  define NETDEV_DEFAULT_FORMAT NETDEV_TUN_FORMAT
 #elif defined(CONFIG_NET_CAN)
 #  define NETDEV_DEFAULT_FORMAT NETDEV_CAN_FORMAT
 #else /* if defined(CONFIG_NET_LOOPBACK) */
 #  define NETDEV_DEFAULT_FORMAT NETDEV_LO_FORMAT
 #endif

 /****************************************************************************
  * Public Data
  ****************************************************************************/

 /* List of registered Ethernet device drivers */

 struct net_driver_s *g_netdevices = NULL;

 #ifdef CONFIG_NETDEV_IFINDEX
 /* The set of network devices that have been registered.  This is used to
  * assign a unique device index to the newly registered device.
  *
  * REVISIT:  The width of g_nassigned limits the number of registered
  * devices to 32 (MAX_IFINDEX).
  */

 uint32_t g_devset;

 /* The set of network devices that have been freed.  The purpose of this
  * set is to postpone reuse of a interface index for as long as possible,
  * i.e., don't reuse an interface index until all of the possible indices
  * have been used.
  */

 uint32_t g_devfreed;
 #endif

 /****************************************************************************
  * Private Data
  ****************************************************************************/

 static mutex_t g_netdevices_lock = NXMUTEX_INITIALIZER;

 /****************************************************************************
  * Private Functions
  ****************************************************************************/

 /****************************************************************************
  * Name: find_devnum
  *
  * Description:
  *   Given a device name format string, find the next device number for the
  *   class of device represented by that format string.
  *
  * Input Parameters:
  *   devfmt - The device format string
  *
  * Returned Value:
  *   The next device number for that device class
  *
  ****************************************************************************/

 static int find_devnum(FAR const char *devfmt)
 {
   FAR struct net_driver_s *curr;
   size_t fmt_size;
   int result = 0;

   fmt_size = strlen(devfmt);

   /* Assumed that devfmt is xxx%d */

   DEBUGASSERT(fmt_size > 2);
   fmt_size -= 2;

   /* Search the list of currently registered network devices */

   for (curr = g_netdevices; curr; curr = curr->flink )
     {
       /* Does this device name match the format we were given? */

       if (strncmp(curr->d_ifname, devfmt, fmt_size) == 0)
         {
           /* Yes.. increment the candidate device number */

           result++;
         }
     }

   /* Return this next device number for this format */

   return result;
 }

 /****************************************************************************
  * Name: get_ifindex
  *
  * Description:
  *   Assign a unique interface index to the device.
  *
  * Input Parameters:
  *   None
  *
  * Returned Value:
  *   The interface index assigned to the device.  -ENOSPC is returned if
  *   more the MAX_IFINDEX names have been assigned.
  *
  ****************************************************************************/

 #ifdef CONFIG_NETDEV_IFINDEX
 static int get_ifindex(void)
 {
   uint32_t devset;
   int ndx;

   /* Try to postpone reusing interface indices as long as possible */

   devset = g_devset | g_devfreed;
   if (devset == 0xffffffff)
     {
       /* Time start reusing interface indices */

       devset     = g_devset;
       g_devfreed = 0;
     }

   /* Search for an unused index */

   for (ndx = 0; ndx < MAX_IFINDEX; ndx++)
     {
       uint32_t bit = 1UL << ndx;
       if ((devset & bit) == 0)
         {
           /* Indicate that this index is in use */

           g_devset |= bit;

           /* NOTE that the index + 1 is returned.  Zero is reserved to
            * mean no-index in the POSIX standards.
            */

           return ndx + 1;
         }
     }

   return -ENOSPC;
 }
 #endif

 /****************************************************************************
  * Public Functions
  ****************************************************************************/

 /****************************************************************************
  * Name: netdev_list_lock
  *
  * Description:
  *   Lock the network device list.  This is used to protect the network
  *   device list from concurrent access.
  *
  ****************************************************************************/

 void netdev_list_lock(void)
 {
   nxmutex_lock(&g_netdevices_lock);
 }

 /****************************************************************************
  * Name: netdev_list_unlock
  *
  * Description:
  *   Unlock the network device list.
  *
  ****************************************************************************/

 void netdev_list_unlock(void)
 {
   nxmutex_unlock(&g_netdevices_lock);
 }

 /****************************************************************************
  * Name: netdev_register
  *
  * Description:
  *   Register a network device driver and assign a name to it so that it can
  *   be found in subsequent network ioctl operations on the device.
  *
  *   A custom, device-specific interface name format string may be selected
  *   by putting that format string into the device structure's d_ifname[]
  *   array before calling netdev_register().  Otherwise, the d_ifname[] must
  *   be zeroed on entry.
  *
  * Input Parameters:
  *   dev    - The device driver structure to be registered.
  *   lltype - Link level protocol used by the driver (Ethernet, SLIP, TUN,
  *            ...)
  *
  * Returned Value:
  *   0:Success; negated errno on failure
  *
  * Assumptions:
  *   Called during system bring-up, but also when a removable network
  *   device is installed.
  *
  ****************************************************************************/

 int netdev_register(FAR struct net_driver_s *dev, enum net_lltype_e lltype)
 {
   FAR struct net_driver_s **last;
   FAR char devfmt_str[IFNAMSIZ];
   FAR const char *devfmt;
   uint32_t flags   = 0;
   uint16_t pktsize = 0;
   uint8_t llhdrlen = 0;
   int devnum;
 #ifdef CONFIG_NETDEV_IFINDEX
   int ifindex;
 #endif

   if (dev != NULL)
     {
       /* Set the protocol used by the device and the size of the link
        * header used by this protocol.
        */

       switch (lltype)
         {
 #ifdef CONFIG_NET_LOOPBACK
           case NET_LL_LOOPBACK:   /* Local loopback */
             llhdrlen = 0;
             pktsize  = NET_LO_PKTSIZE;
             devfmt   = NETDEV_LO_FORMAT;
             flags    = IFF_LOOPBACK;
             break;
 #endif

 #ifdef CONFIG_NET_ETHERNET
           case NET_LL_ETHERNET:   /* Ethernet */
             llhdrlen = ETH_HDRLEN;
             pktsize  = CONFIG_NET_ETH_PKTSIZE;
             devfmt   = NETDEV_ETH_FORMAT;
             flags    = IFF_BROADCAST | IFF_MULTICAST;
             break;
 #endif

 #ifdef CONFIG_DRIVERS_IEEE80211
           case NET_LL_IEEE80211:  /* IEEE 802.11 */
             llhdrlen = ETH_HDRLEN;
             pktsize  = CONFIG_NET_ETH_PKTSIZE;
             devfmt   = NETDEV_WLAN_FORMAT;
             flags    = IFF_BROADCAST | IFF_MULTICAST;
             break;
 #endif

 #ifdef CONFIG_NET_CAN
           case NET_LL_CAN:  /* CAN bus */
             dev->d_llhdrlen = 0;
             dev->d_pktsize  = NET_CAN_PKTSIZE;
             devfmt          = NETDEV_CAN_FORMAT;
             flags           = IFF_NOARP;
             break;
 #endif

 #ifdef CONFIG_NET_BLUETOOTH
           case NET_LL_BLUETOOTH:              /* Bluetooth */
             llhdrlen = BLUETOOTH_MAX_HDRLEN;  /* Determined at runtime */
 #ifdef CONFIG_NET_6LOWPAN
             pktsize  = CONFIG_NET_6LOWPAN_PKTSIZE;
 #endif
             devfmt   = NETDEV_BNEP_FORMAT;
             flags    = IFF_BROADCAST | IFF_MULTICAST;
             break;
 #endif

 #if defined(CONFIG_NET_6LOWPAN) || defined(CONFIG_NET_IEEE802154)
           case NET_LL_IEEE802154: /* IEEE 802.15.4 MAC */
           case NET_LL_PKTRADIO:   /* Non-IEEE 802.15.4 packet radio */
             llhdrlen = 0;         /* Determined at runtime */
 #ifdef CONFIG_NET_6LOWPAN
             pktsize  = CONFIG_NET_6LOWPAN_PKTSIZE;
 #endif
             devfmt   = NETDEV_WPAN_FORMAT;
             flags    = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
             break;
 #endif

 #ifdef CONFIG_NET_SLIP
           case NET_LL_SLIP:       /* Serial Line Internet Protocol (SLIP) */
             llhdrlen = 0;
             pktsize  = CONFIG_NET_SLIP_PKTSIZE;
             devfmt   = NETDEV_SLIP_FORMAT;
             flags    = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
             break;
 #endif

 #ifdef CONFIG_NET_TUN
           case NET_LL_TUN:        /* Virtual Network Device (TUN) */
             llhdrlen = 0;         /* This will be overwritten by tun_ioctl
                                    * if used as a TAP (layer 2) device */
             pktsize  = CONFIG_NET_TUN_PKTSIZE;
             devfmt   = NETDEV_TUN_FORMAT;
             flags    = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
             break;
 #endif

 #ifdef CONFIG_NET_MBIM
           case NET_LL_MBIM:
             llhdrlen = 0;
             pktsize  = 1200;
             devfmt   = NETDEV_WWAN_FORMAT;
             flags    = IFF_BROADCAST | IFF_NOARP | IFF_MULTICAST;
             break;
 #endif

 #ifdef CONFIG_NET_CELLULAR
           case NET_LL_CELL:
             llhdrlen = 0;
             pktsize  = CONFIG_NET_ETH_PKTSIZE;
             devfmt   = NETDEV_CELL_FORMAT;
             flags    = IFF_NOARP;
             break;
 #endif

           default:
             nerr("ERROR: Unrecognized link type: %d\n", lltype);
             return -EINVAL;
         }

       /* Update the package length.  A network driver may provide custom
        * values for MAC header length and for the maximum packet size.  Some
        * driver implementations (for example, the simulator) will require
        * dynamic MTU calculations to support tunneling (as an example).
        */

       if (dev->d_llhdrlen == 0)
         {
           dev->d_llhdrlen = llhdrlen;
         }

       if (dev->d_pktsize == 0)
         {
           dev->d_pktsize = pktsize;
         }

       dev->d_flags |= flags;

       /* Remember the verified link type */

       dev->d_lltype = (uint8_t)lltype;

       /* There are no clients of the device yet */

       dev->d_conncb = NULL;
       dev->d_conncb_tail = NULL;
       dev->d_devcb = NULL;

       dev->d_polltype = 0;

       nxrmutex_init(&dev->d_lock);

       /* We need exclusive access for the following operations */

       netdev_list_lock();

 #ifdef CONFIG_NETDEV_IFINDEX
       ifindex = get_ifindex();
       if (ifindex < 0)
         {
           netdev_list_unlock();
           return ifindex;
         }

       dev->d_ifindex = (uint8_t)ifindex;
 #endif

       /* Get the next available device number and assign a device name to
        * the interface
        */

       /* Check if the caller has provided a user device-specific interface
        * name format string (in d_ifname).
        */

       if (dev->d_ifname[0] != '\0')
         {
           /* Copy the string in a temporary buffer.  How do we know that the
            * string is valid and not just uninitialized memory?  We don't.
            * Let's at least make certain that the format string is NUL
            * terminated.
            */

           dev->d_ifname[IFNAMSIZ - 1] = '\0';
           strlcpy(devfmt_str, dev->d_ifname, IFNAMSIZ);

           /* Then use the content of the temporary buffer as the format
            * string.
            */

           devfmt = (FAR const char *)devfmt_str;
         }

 #ifdef CONFIG_NET_LOOPBACK
       /* The local loopback device is a special case:  There can be only one
        * local loopback device so it is unnumbered.
        */

       if (lltype == NET_LL_LOOPBACK)
         {
           devnum = 0;
         }
       else
 #endif
         {
           devnum = find_devnum(devfmt);
         }

       /* Complete the device name by including the device number (if
        * included in the format).
        */

       snprintf(dev->d_ifname, IFNAMSIZ, devfmt, devnum);

       /* Add the device to the list of known network devices */

       last = &g_netdevices;
       while (*last)
         {
           last = &((*last)->flink);
         }

       *last = dev;

       dev->flink = NULL;

 #ifdef CONFIG_NET_IGMP
       /* Configure the device for IGMP support */

       igmp_devinit(dev);
 #endif

 #ifdef CONFIG_NET_MLD
       /* Configure the device for MLD support */

       if ((flags & IFF_MULTICAST) != 0)
         {
           /* MLD is only supported on multicast capable devices */

           mld_devinit(dev);
         }
 #endif

 #ifdef NET_ICMPv6_HAVE_STACK
       /* Configure the device for ICMPv6 support */

       icmpv6_devinit(dev);
 #endif

       netdev_list_unlock();

 #if defined(CONFIG_NET_ETHERNET) || defined(CONFIG_DRIVERS_IEEE80211)
       ninfo("Registered MAC: %02x:%02x:%02x:%02x:%02x:%02x as dev: %s\n",
             dev->d_mac.ether.ether_addr_octet[0],
             dev->d_mac.ether.ether_addr_octet[1],
             dev->d_mac.ether.ether_addr_octet[2],
             dev->d_mac.ether.ether_addr_octet[3],
             dev->d_mac.ether.ether_addr_octet[4],
             dev->d_mac.ether.ether_addr_octet[5],
             dev->d_ifname);
 #else
       ninfo("Registered dev: %s\n", dev->d_ifname);
 #endif
       return OK;
     }

   return -EINVAL;
 }
	/****************************************************************************
	* net/netdev/netdev_register.c
	*
	* SPDX-License-Identifier: Apache-2.0
	*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership. The
	* ASF licenses this file to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance with the
	* License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	* License for the specific language governing permissions and limitations
	* under the License.
	*
	****************************************************************************/

	/****************************************************************************
	* Included Files
	****************************************************************************/

	#include <nuttx/config.h>

	#include <sys/socket.h>
	#include <stdio.h>
	#include <assert.h>
	#include <string.h>
	#include <errno.h>
	#include <debug.h>

	#include <net/if.h>
	#include <net/ethernet.h>
	#include <nuttx/net/netconfig.h>
	#include <nuttx/net/netdev.h>
	#include <nuttx/net/ethernet.h>
	#include <nuttx/net/bluetooth.h>
	#include <nuttx/net/can.h>

	#include "utils/utils.h"
	#include "icmpv6/icmpv6.h"
	#include "igmp/igmp.h"
	#include "mld/mld.h"
	#include "netdev/netdev.h"

	/****************************************************************************
	* Pre-processor Definitions
	****************************************************************************/

	#define NETDEV_ETH_FORMAT "eth%d"
	#define NETDEV_LO_FORMAT "lo"
	#define NETDEV_SLIP_FORMAT "sl%d"
	#define NETDEV_TUN_FORMAT "tun%d"
	#define NETDEV_BNEP_FORMAT "bnep%d"
	#define NETDEV_PAN_FORMAT "pan%d"
	#define NETDEV_WLAN_FORMAT "wlan%d"
	#define NETDEV_WPAN_FORMAT "wpan%d"
	#define NETDEV_WWAN_FORMAT "wwan%d"
	#define NETDEV_CAN_FORMAT "can%d"
	#define NETDEV_CELL_FORMAT "cell%d"

	#if defined(CONFIG_DRIVERS_IEEE80211) /* Usually also has CONFIG_NET_ETHERNET */
	# define NETDEV_DEFAULT_FORMAT NETDEV_WLAN_FORMAT
	#elif defined(CONFIG_NET_ETHERNET)
	# define NETDEV_DEFAULT_FORMAT NETDEV_ETH_FORMAT
	#elif defined(CONFIG_NET_6LOWPAN)
	# define NETDEV_DEFAULT_FORMAT NETDEV_WPAN_FORMAT
	#elif defined(CONFIG_NET_SLIP)
	# define NETDEV_DEFAULT_FORMAT NETDEV_SLIP_FORMAT
	#elif defined(CONFIG_NET_TUN)
	# define NETDEV_DEFAULT_FORMAT NETDEV_TUN_FORMAT
	#elif defined(CONFIG_NET_CAN)
	# define NETDEV_DEFAULT_FORMAT NETDEV_CAN_FORMAT
	#else /* if defined(CONFIG_NET_LOOPBACK) */
	# define NETDEV_DEFAULT_FORMAT NETDEV_LO_FORMAT
	#endif

	/****************************************************************************
	* Public Data
	****************************************************************************/

	/* List of registered Ethernet device drivers */

	struct net_driver_s *g_netdevices = NULL;

	#ifdef CONFIG_NETDEV_IFINDEX
	/* The set of network devices that have been registered. This is used to
	* assign a unique device index to the newly registered device.
	*
	* REVISIT: The width of g_nassigned limits the number of registered
	* devices to 32 (MAX_IFINDEX).
	*/

	uint32_t g_devset;

	/* The set of network devices that have been freed. The purpose of this
	* set is to postpone reuse of a interface index for as long as possible,
	* i.e., don't reuse an interface index until all of the possible indices
	* have been used.
	*/

	uint32_t g_devfreed;
	#endif

	/****************************************************************************
	* Private Data
	****************************************************************************/

	static mutex_t g_netdevices_lock = NXMUTEX_INITIALIZER;

	/****************************************************************************
	* Private Functions
	****************************************************************************/

	/****************************************************************************
	* Name: find_devnum
	*
	* Description:
	* Given a device name format string, find the next device number for the
	* class of device represented by that format string.
	*
	* Input Parameters:
	* devfmt - The device format string
	*
	* Returned Value:
	* The next device number for that device class
	*
	****************************************************************************/

	static int find_devnum(FAR const char *devfmt)
	{
	FAR struct net_driver_s *curr;
	size_t fmt_size;
	int result = 0;

	fmt_size = strlen(devfmt);

	/* Assumed that devfmt is xxx%d */

	DEBUGASSERT(fmt_size > 2);
	fmt_size -= 2;

	/* Search the list of currently registered network devices */

	for (curr = g_netdevices; curr; curr = curr->flink )
	{
	/* Does this device name match the format we were given? */

	if (strncmp(curr->d_ifname, devfmt, fmt_size) == 0)
	{
	/* Yes.. increment the candidate device number */

	result++;
	}
	}

	/* Return this next device number for this format */

	return result;
	}

	/****************************************************************************
	* Name: get_ifindex
	*
	* Description:
	* Assign a unique interface index to the device.
	*
	* Input Parameters:
	* None
	*
	* Returned Value:
	* The interface index assigned to the device. -ENOSPC is returned if
	* more the MAX_IFINDEX names have been assigned.
	*
	****************************************************************************/

	#ifdef CONFIG_NETDEV_IFINDEX
	static int get_ifindex(void)
	{
	uint32_t devset;
	int ndx;

	/* Try to postpone reusing interface indices as long as possible */

	devset = g_devset \| g_devfreed;
	if (devset == 0xffffffff)
	{
	/* Time start reusing interface indices */

	devset = g_devset;
	g_devfreed = 0;
	}

	/* Search for an unused index */

	for (ndx = 0; ndx < MAX_IFINDEX; ndx++)
	{
	uint32_t bit = 1UL << ndx;
	if ((devset & bit) == 0)
	{
	/* Indicate that this index is in use */

	g_devset \|= bit;

	/* NOTE that the index + 1 is returned. Zero is reserved to
	* mean no-index in the POSIX standards.
	*/

	return ndx + 1;
	}
	}

	return -ENOSPC;
	}
	#endif

	/****************************************************************************
	* Public Functions
	****************************************************************************/

	/****************************************************************************
	* Name: netdev_list_lock
	*
	* Description:
	* Lock the network device list. This is used to protect the network
	* device list from concurrent access.
	*
	****************************************************************************/

	void netdev_list_lock(void)
	{
	nxmutex_lock(&g_netdevices_lock);
	}

	/****************************************************************************
	* Name: netdev_list_unlock
	*
	* Description:
	* Unlock the network device list.
	*
	****************************************************************************/

	void netdev_list_unlock(void)
	{
	nxmutex_unlock(&g_netdevices_lock);
	}

	/****************************************************************************
	* Name: netdev_register
	*
	* Description:
	* Register a network device driver and assign a name to it so that it can
	* be found in subsequent network ioctl operations on the device.
	*
	* A custom, device-specific interface name format string may be selected
	* by putting that format string into the device structure's d_ifname[]
	* array before calling netdev_register(). Otherwise, the d_ifname[] must
	* be zeroed on entry.
	*
	* Input Parameters:
	* dev - The device driver structure to be registered.
	* lltype - Link level protocol used by the driver (Ethernet, SLIP, TUN,
	* ...)
	*
	* Returned Value:
	* 0:Success; negated errno on failure
	*
	* Assumptions:
	* Called during system bring-up, but also when a removable network
	* device is installed.
	*
	****************************************************************************/

	int netdev_register(FAR struct net_driver_s *dev, enum net_lltype_e lltype)
	{
	FAR struct net_driver_s **last;
	FAR char devfmt_str[IFNAMSIZ];
	FAR const char *devfmt;
	uint32_t flags = 0;
	uint16_t pktsize = 0;
	uint8_t llhdrlen = 0;
	int devnum;
	#ifdef CONFIG_NETDEV_IFINDEX
	int ifindex;
	#endif

	if (dev != NULL)
	{
	/* Set the protocol used by the device and the size of the link
	* header used by this protocol.
	*/

	switch (lltype)
	{
	#ifdef CONFIG_NET_LOOPBACK
	case NET_LL_LOOPBACK: /* Local loopback */
	llhdrlen = 0;
	pktsize = NET_LO_PKTSIZE;
	devfmt = NETDEV_LO_FORMAT;
	flags = IFF_LOOPBACK;
	break;
	#endif

	#ifdef CONFIG_NET_ETHERNET
	case NET_LL_ETHERNET: /* Ethernet */
	llhdrlen = ETH_HDRLEN;
	pktsize = CONFIG_NET_ETH_PKTSIZE;
	devfmt = NETDEV_ETH_FORMAT;
	flags = IFF_BROADCAST \| IFF_MULTICAST;
	break;
	#endif

	#ifdef CONFIG_DRIVERS_IEEE80211
	case NET_LL_IEEE80211: /* IEEE 802.11 */
	llhdrlen = ETH_HDRLEN;
	pktsize = CONFIG_NET_ETH_PKTSIZE;
	devfmt = NETDEV_WLAN_FORMAT;
	flags = IFF_BROADCAST \| IFF_MULTICAST;
	break;
	#endif

	#ifdef CONFIG_NET_CAN
	case NET_LL_CAN: /* CAN bus */
	dev->d_llhdrlen = 0;
	dev->d_pktsize = NET_CAN_PKTSIZE;
	devfmt = NETDEV_CAN_FORMAT;
	flags = IFF_NOARP;
	break;
	#endif

	#ifdef CONFIG_NET_BLUETOOTH
	case NET_LL_BLUETOOTH: /* Bluetooth */
	llhdrlen = BLUETOOTH_MAX_HDRLEN; /* Determined at runtime */
	#ifdef CONFIG_NET_6LOWPAN
	pktsize = CONFIG_NET_6LOWPAN_PKTSIZE;
	#endif
	devfmt = NETDEV_BNEP_FORMAT;
	flags = IFF_BROADCAST \| IFF_MULTICAST;
	break;
	#endif

	#if defined(CONFIG_NET_6LOWPAN) \|\| defined(CONFIG_NET_IEEE802154)
	case NET_LL_IEEE802154: /* IEEE 802.15.4 MAC */
	case NET_LL_PKTRADIO: /* Non-IEEE 802.15.4 packet radio */
	llhdrlen = 0; /* Determined at runtime */
	#ifdef CONFIG_NET_6LOWPAN
	pktsize = CONFIG_NET_6LOWPAN_PKTSIZE;
	#endif
	devfmt = NETDEV_WPAN_FORMAT;
	flags = IFF_POINTOPOINT \| IFF_NOARP \| IFF_MULTICAST;
	break;
	#endif

	#ifdef CONFIG_NET_SLIP
	case NET_LL_SLIP: /* Serial Line Internet Protocol (SLIP) */
	llhdrlen = 0;
	pktsize = CONFIG_NET_SLIP_PKTSIZE;
	devfmt = NETDEV_SLIP_FORMAT;
	flags = IFF_POINTOPOINT \| IFF_NOARP \| IFF_MULTICAST;
	break;
	#endif

	#ifdef CONFIG_NET_TUN
	case NET_LL_TUN: /* Virtual Network Device (TUN) */
	llhdrlen = 0; /* This will be overwritten by tun_ioctl
	* if used as a TAP (layer 2) device */
	pktsize = CONFIG_NET_TUN_PKTSIZE;
	devfmt = NETDEV_TUN_FORMAT;
	flags = IFF_POINTOPOINT \| IFF_NOARP \| IFF_MULTICAST;
	break;
	#endif

	#ifdef CONFIG_NET_MBIM
	case NET_LL_MBIM:
	llhdrlen = 0;
	pktsize = 1200;
	devfmt = NETDEV_WWAN_FORMAT;
	flags = IFF_BROADCAST \| IFF_NOARP \| IFF_MULTICAST;
	break;
	#endif

	#ifdef CONFIG_NET_CELLULAR
	case NET_LL_CELL:
	llhdrlen = 0;
	pktsize = CONFIG_NET_ETH_PKTSIZE;
	devfmt = NETDEV_CELL_FORMAT;
	flags = IFF_NOARP;
	break;
	#endif

	default:
	nerr("ERROR: Unrecognized link type: %d\n", lltype);
	return -EINVAL;
	}

	/* Update the package length. A network driver may provide custom
	* values for MAC header length and for the maximum packet size. Some
	* driver implementations (for example, the simulator) will require
	* dynamic MTU calculations to support tunneling (as an example).
	*/

	if (dev->d_llhdrlen == 0)
	{
	dev->d_llhdrlen = llhdrlen;
	}

	if (dev->d_pktsize == 0)
	{
	dev->d_pktsize = pktsize;
	}

	dev->d_flags \|= flags;

	/* Remember the verified link type */

	dev->d_lltype = (uint8_t)lltype;

	/* There are no clients of the device yet */

	dev->d_conncb = NULL;
	dev->d_conncb_tail = NULL;
	dev->d_devcb = NULL;

	dev->d_polltype = 0;

	nxrmutex_init(&dev->d_lock);

	/* We need exclusive access for the following operations */

	netdev_list_lock();

	#ifdef CONFIG_NETDEV_IFINDEX
	ifindex = get_ifindex();
	if (ifindex < 0)
	{
	netdev_list_unlock();
	return ifindex;
	}

	dev->d_ifindex = (uint8_t)ifindex;
	#endif

	/* Get the next available device number and assign a device name to
	* the interface
	*/

	/* Check if the caller has provided a user device-specific interface
	* name format string (in d_ifname).
	*/

	if (dev->d_ifname[0] != '\0')
	{
	/* Copy the string in a temporary buffer. How do we know that the
	* string is valid and not just uninitialized memory? We don't.
	* Let's at least make certain that the format string is NUL
	* terminated.
	*/

	dev->d_ifname[IFNAMSIZ - 1] = '\0';
	strlcpy(devfmt_str, dev->d_ifname, IFNAMSIZ);

	/* Then use the content of the temporary buffer as the format
	* string.
	*/

	devfmt = (FAR const char *)devfmt_str;
	}

	#ifdef CONFIG_NET_LOOPBACK
	/* The local loopback device is a special case: There can be only one
	* local loopback device so it is unnumbered.
	*/

	if (lltype == NET_LL_LOOPBACK)
	{
	devnum = 0;
	}
	else
	#endif
	{
	devnum = find_devnum(devfmt);
	}

	/* Complete the device name by including the device number (if
	* included in the format).
	*/

	snprintf(dev->d_ifname, IFNAMSIZ, devfmt, devnum);

	/* Add the device to the list of known network devices */

	last = &g_netdevices;
	while (*last)
	{
	last = &((*last)->flink);
	}

	*last = dev;

	dev->flink = NULL;

	#ifdef CONFIG_NET_IGMP
	/* Configure the device for IGMP support */

	igmp_devinit(dev);
	#endif

	#ifdef CONFIG_NET_MLD
	/* Configure the device for MLD support */

	if ((flags & IFF_MULTICAST) != 0)
	{
	/* MLD is only supported on multicast capable devices */

	mld_devinit(dev);
	}
	#endif

	#ifdef NET_ICMPv6_HAVE_STACK
	/* Configure the device for ICMPv6 support */

	icmpv6_devinit(dev);
	#endif

	netdev_list_unlock();

	#if defined(CONFIG_NET_ETHERNET) \|\| defined(CONFIG_DRIVERS_IEEE80211)
	ninfo("Registered MAC: %02x:%02x:%02x:%02x:%02x:%02x as dev: %s\n",
	dev->d_mac.ether.ether_addr_octet[0],
	dev->d_mac.ether.ether_addr_octet[1],
	dev->d_mac.ether.ether_addr_octet[2],
	dev->d_mac.ether.ether_addr_octet[3],
	dev->d_mac.ether.ether_addr_octet[4],
	dev->d_mac.ether.ether_addr_octet[5],
	dev->d_ifname);
	#else
	ninfo("Registered dev: %s\n", dev->d_ifname);
	#endif
	return OK;
	}

	return -EINVAL;
	}