drivers/staging/most/aim-network/networking.c - nest-learning-thermostat/6.0/linux-imx-4.9.88 - Git at Google

 /*
  * Networking AIM - Networking Application Interface Module for MostCore
  *
  * Copyright (C) 2015, Microchip Technology Germany II GmbH & Co. KG
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * This file is licensed under GPLv2.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/module.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/list.h>
 #include <linux/wait.h>
 #include <linux/kobject.h>
 #include "mostcore.h"
 #include "networking.h"

 #define MEP_HDR_LEN 8
 #define MDP_HDR_LEN 16
 #define MAMAC_DATA_LEN (1024 - MDP_HDR_LEN)

 #define PMHL 5

 #define PMS_TELID_UNSEGM_MAMAC	0x0A
 #define PMS_FIFONO_MDP		0x01
 #define PMS_FIFONO_MEP		0x04
 #define PMS_MSGTYPE_DATA	0x04
 #define PMS_DEF_PRIO		0
 #define MEP_DEF_RETRY		15

 #define PMS_FIFONO_MASK		0x07
 #define PMS_FIFONO_SHIFT	3
 #define PMS_RETRY_SHIFT		4
 #define PMS_TELID_MASK		0x0F
 #define PMS_TELID_SHIFT		4

 #define HB(value)		((u8)((u16)(value) >> 8))
 #define LB(value)		((u8)(value))

 #define EXTRACT_BIT_SET(bitset_name, value) \
 	(((value) >> bitset_name##_SHIFT) & bitset_name##_MASK)

 #define PMS_IS_MEP(buf, len) \
 	((len) > MEP_HDR_LEN && \
 	 EXTRACT_BIT_SET(PMS_FIFONO, (buf)[3]) == PMS_FIFONO_MEP)

 #define PMS_IS_MAMAC(buf, len) \
 	((len) > MDP_HDR_LEN && \
 	 EXTRACT_BIT_SET(PMS_FIFONO, (buf)[3]) == PMS_FIFONO_MDP && \
 	 EXTRACT_BIT_SET(PMS_TELID, (buf)[14]) == PMS_TELID_UNSEGM_MAMAC)

 struct net_dev_channel {
 	bool linked;
 	int ch_id;
 };

 struct net_dev_context {
 	struct most_interface *iface;
 	bool channels_opened;
 	bool is_mamac;
 	unsigned char link_stat;
 	struct net_device *dev;
 	struct net_dev_channel rx;
 	struct net_dev_channel tx;
 	struct list_head list;
 };

 static struct list_head net_devices = LIST_HEAD_INIT(net_devices);
 static struct spinlock list_lock;
 static struct most_aim aim;

 static int skb_to_mamac(const struct sk_buff *skb, struct mbo *mbo)
 {
 	u8 *buff = mbo->virt_address;
 	const u8 broadcast[] = { 0x03, 0xFF };
 	const u8 *dest_addr = skb->data + 4;
 	const u8 *eth_type = skb->data + 12;
 	unsigned int payload_len = skb->len - ETH_HLEN;
 	unsigned int mdp_len = payload_len + MDP_HDR_LEN;

 	if (mbo->buffer_length < mdp_len) {
 		pr_err("drop: too small buffer! (%d for %d)\n",
 		       mbo->buffer_length, mdp_len);
 		return -EINVAL;
 	}

 	if (skb->len < ETH_HLEN) {
 		pr_err("drop: too small packet! (%d)\n", skb->len);
 		return -EINVAL;
 	}

 	if (dest_addr[0] == 0xFF && dest_addr[1] == 0xFF)
 		dest_addr = broadcast;

 	*buff++ = HB(mdp_len - 2);
 	*buff++ = LB(mdp_len - 2);

 	*buff++ = PMHL;
 	*buff++ = (PMS_FIFONO_MDP << PMS_FIFONO_SHIFT) | PMS_MSGTYPE_DATA;
 	*buff++ = PMS_DEF_PRIO;
 	*buff++ = dest_addr[0];
 	*buff++ = dest_addr[1];
 	*buff++ = 0x00;

 	*buff++ = HB(payload_len + 6);
 	*buff++ = LB(payload_len + 6);

 	/* end of FPH here */

 	*buff++ = eth_type[0];
 	*buff++ = eth_type[1];
 	*buff++ = 0;
 	*buff++ = 0;

 	*buff++ = PMS_TELID_UNSEGM_MAMAC << 4 | HB(payload_len);
 	*buff++ = LB(payload_len);

 	memcpy(buff, skb->data + ETH_HLEN, payload_len);
 	mbo->buffer_length = mdp_len;
 	return 0;
 }

 static int skb_to_mep(const struct sk_buff *skb, struct mbo *mbo)
 {
 	u8 *buff = mbo->virt_address;
 	unsigned int mep_len = skb->len + MEP_HDR_LEN;

 	if (mbo->buffer_length < mep_len) {
 		pr_err("drop: too small buffer! (%d for %d)\n",
 		       mbo->buffer_length, mep_len);
 		return -EINVAL;
 	}

 	*buff++ = HB(mep_len - 2);
 	*buff++ = LB(mep_len - 2);

 	*buff++ = PMHL;
 	*buff++ = (PMS_FIFONO_MEP << PMS_FIFONO_SHIFT) | PMS_MSGTYPE_DATA;
 	*buff++ = (MEP_DEF_RETRY << PMS_RETRY_SHIFT) | PMS_DEF_PRIO;
 	*buff++ = 0;
 	*buff++ = 0;
 	*buff++ = 0;

 	memcpy(buff, skb->data, skb->len);
 	mbo->buffer_length = mep_len;
 	return 0;
 }

 static int most_nd_set_mac_address(struct net_device *dev, void *p)
 {
 	struct net_dev_context *nd = dev->ml_priv;
 	int err = eth_mac_addr(dev, p);

 	if (err)
 		return err;

 	BUG_ON(nd->dev != dev);

 	nd->is_mamac =
 		(dev->dev_addr[0] == 0 && dev->dev_addr[1] == 0 &&
 		 dev->dev_addr[2] == 0 && dev->dev_addr[3] == 0);

 	/*
 	 * Set default MTU for the given packet type.
 	 * It is still possible to change MTU using ip tools afterwards.
 	 */
 	dev->mtu = nd->is_mamac ? MAMAC_DATA_LEN : ETH_DATA_LEN;

 	return 0;
 }

 static int most_nd_open(struct net_device *dev)
 {
 	struct net_dev_context *nd = dev->ml_priv;

 	netdev_info(dev, "open net device\n");

 	BUG_ON(nd->dev != dev);

 	if (nd->channels_opened)
 		return -EFAULT;

 	BUG_ON(!nd->tx.linked || !nd->rx.linked);

 	if (most_start_channel(nd->iface, nd->rx.ch_id, &aim)) {
 		netdev_err(dev, "most_start_channel() failed\n");
 		return -EBUSY;
 	}

 	if (most_start_channel(nd->iface, nd->tx.ch_id, &aim)) {
 		netdev_err(dev, "most_start_channel() failed\n");
 		most_stop_channel(nd->iface, nd->rx.ch_id, &aim);
 		return -EBUSY;
 	}

 	nd->channels_opened = true;

 	if (nd->is_mamac) {
 		nd->link_stat = 1;
 		netif_wake_queue(dev);
 	} else {
 		nd->iface->request_netinfo(nd->iface, nd->tx.ch_id);
 	}

 	return 0;
 }

 static int most_nd_stop(struct net_device *dev)
 {
 	struct net_dev_context *nd = dev->ml_priv;

 	netdev_info(dev, "stop net device\n");

 	BUG_ON(nd->dev != dev);
 	netif_stop_queue(dev);

 	if (nd->channels_opened) {
 		most_stop_channel(nd->iface, nd->rx.ch_id, &aim);
 		most_stop_channel(nd->iface, nd->tx.ch_id, &aim);
 		nd->channels_opened = false;
 	}

 	return 0;
 }

 static netdev_tx_t most_nd_start_xmit(struct sk_buff *skb,
 				      struct net_device *dev)
 {
 	struct net_dev_context *nd = dev->ml_priv;
 	struct mbo *mbo;
 	int ret;

 	BUG_ON(nd->dev != dev);

 	mbo = most_get_mbo(nd->iface, nd->tx.ch_id, &aim);

 	if (!mbo) {
 		netif_stop_queue(dev);
 		dev->stats.tx_fifo_errors++;
 		return NETDEV_TX_BUSY;
 	}

 	if (nd->is_mamac)
 		ret = skb_to_mamac(skb, mbo);
 	else
 		ret = skb_to_mep(skb, mbo);

 	if (ret) {
 		most_put_mbo(mbo);
 		dev->stats.tx_dropped++;
 		kfree_skb(skb);
 		return NETDEV_TX_OK;
 	}

 	most_submit_mbo(mbo);
 	dev->stats.tx_packets++;
 	dev->stats.tx_bytes += skb->len;
 	kfree_skb(skb);
 	return NETDEV_TX_OK;
 }

 static const struct net_device_ops most_nd_ops = {
 	.ndo_open = most_nd_open,
 	.ndo_stop = most_nd_stop,
 	.ndo_start_xmit = most_nd_start_xmit,
 	.ndo_set_mac_address = most_nd_set_mac_address,
 };

 static void most_nd_setup(struct net_device *dev)
 {
 	netdev_info(dev, "setup net device\n");
 	ether_setup(dev);
 	dev->netdev_ops = &most_nd_ops;
 }

 static void most_net_rm_netdev_safe(struct net_dev_context *nd)
 {
 	if (!nd->dev)
 		return;

 	pr_info("remove net device %p\n", nd->dev);

 	unregister_netdev(nd->dev);
 	free_netdev(nd->dev);
 	nd->dev = NULL;
 }

 static struct net_dev_context *get_net_dev_context(
 	struct most_interface *iface)
 {
 	struct net_dev_context *nd, *tmp;
 	unsigned long flags;

 	spin_lock_irqsave(&list_lock, flags);
 	list_for_each_entry_safe(nd, tmp, &net_devices, list) {
 		if (nd->iface == iface) {
 			spin_unlock_irqrestore(&list_lock, flags);
 			return nd;
 		}
 	}
 	spin_unlock_irqrestore(&list_lock, flags);
 	return NULL;
 }

 static int aim_probe_channel(struct most_interface *iface, int channel_idx,
 			     struct most_channel_config *ccfg,
 			     struct kobject *parent, char *name)
 {
 	struct net_dev_context *nd;
 	struct net_dev_channel *ch;
 	unsigned long flags;

 	if (!iface)
 		return -EINVAL;

 	if (ccfg->data_type != MOST_CH_ASYNC)
 		return -EINVAL;

 	nd = get_net_dev_context(iface);

 	if (!nd) {
 		nd = kzalloc(sizeof(*nd), GFP_KERNEL);
 		if (!nd)
 			return -ENOMEM;

 		nd->iface = iface;

 		spin_lock_irqsave(&list_lock, flags);
 		list_add(&nd->list, &net_devices);
 		spin_unlock_irqrestore(&list_lock, flags);
 	}

 	ch = ccfg->direction == MOST_CH_TX ? &nd->tx : &nd->rx;
 	if (ch->linked) {
 		pr_err("only one channel per instance & direction allowed\n");
 		return -EINVAL;
 	}

 	if (nd->tx.linked || nd->rx.linked) {
 		struct net_device *dev =
 			alloc_netdev(0, "meth%d", NET_NAME_UNKNOWN,
 				     most_nd_setup);

 		if (!dev) {
 			pr_err("no memory for net_device\n");
 			return -ENOMEM;
 		}

 		nd->dev = dev;
 		ch->ch_id = channel_idx;
 		ch->linked = true;

 		dev->ml_priv = nd;
 		if (register_netdev(dev)) {
 			pr_err("registering net device failed\n");
 			ch->linked = false;
 			free_netdev(dev);
 			return -EINVAL;
 		}
 	}

 	ch->ch_id = channel_idx;
 	ch->linked = true;

 	return 0;
 }

 static int aim_disconnect_channel(struct most_interface *iface,
 				  int channel_idx)
 {
 	struct net_dev_context *nd;
 	struct net_dev_channel *ch;
 	unsigned long flags;

 	nd = get_net_dev_context(iface);
 	if (!nd)
 		return -EINVAL;

 	if (nd->rx.linked && channel_idx == nd->rx.ch_id)
 		ch = &nd->rx;
 	else if (nd->tx.linked && channel_idx == nd->tx.ch_id)
 		ch = &nd->tx;
 	else
 		return -EINVAL;

 	ch->linked = false;

 	/*
 	 * do not call most_stop_channel() here, because channels are
 	 * going to be closed in ndo_stop() after unregister_netdev()
 	 */
 	most_net_rm_netdev_safe(nd);

 	if (!nd->rx.linked && !nd->tx.linked) {
 		spin_lock_irqsave(&list_lock, flags);
 		list_del(&nd->list);
 		spin_unlock_irqrestore(&list_lock, flags);
 		kfree(nd);
 	}

 	return 0;
 }

 static int aim_resume_tx_channel(struct most_interface *iface,
 				 int channel_idx)
 {
 	struct net_dev_context *nd;

 	nd = get_net_dev_context(iface);
 	if (!nd || !nd->channels_opened || nd->tx.ch_id != channel_idx)
 		return 0;

 	if (!nd->dev)
 		return 0;

 	netif_wake_queue(nd->dev);
 	return 0;
 }

 static int aim_rx_data(struct mbo *mbo)
 {
 	const u32 zero = 0;
 	struct net_dev_context *nd;
 	char *buf = mbo->virt_address;
 	u32 len = mbo->processed_length;
 	struct sk_buff *skb;
 	struct net_device *dev;
 	unsigned int skb_len;

 	nd = get_net_dev_context(mbo->ifp);
 	if (!nd || !nd->channels_opened || nd->rx.ch_id != mbo->hdm_channel_id)
 		return -EIO;

 	dev = nd->dev;
 	if (!dev) {
 		pr_err_once("drop packet: missing net_device\n");
 		return -EIO;
 	}

 	if (nd->is_mamac) {
 		if (!PMS_IS_MAMAC(buf, len))
 			return -EIO;

 		skb = dev_alloc_skb(len - MDP_HDR_LEN + 2 * ETH_ALEN + 2);
 	} else {
 		if (!PMS_IS_MEP(buf, len))
 			return -EIO;

 		skb = dev_alloc_skb(len - MEP_HDR_LEN);
 	}

 	if (!skb) {
 		dev->stats.rx_dropped++;
 		pr_err_once("drop packet: no memory for skb\n");
 		goto out;
 	}

 	skb->dev = dev;

 	if (nd->is_mamac) {
 		/* dest */
 		ether_addr_copy(skb_put(skb, ETH_ALEN), dev->dev_addr);

 		/* src */
 		memcpy(skb_put(skb, 4), &zero, 4);
 		memcpy(skb_put(skb, 2), buf + 5, 2);

 		/* eth type */
 		memcpy(skb_put(skb, 2), buf + 10, 2);

 		buf += MDP_HDR_LEN;
 		len -= MDP_HDR_LEN;
 	} else {
 		buf += MEP_HDR_LEN;
 		len -= MEP_HDR_LEN;
 	}

 	memcpy(skb_put(skb, len), buf, len);
 	skb->protocol = eth_type_trans(skb, dev);
 	skb_len = skb->len;
 	if (netif_rx(skb) == NET_RX_SUCCESS) {
 		dev->stats.rx_packets++;
 		dev->stats.rx_bytes += skb_len;
 	} else {
 		dev->stats.rx_dropped++;
 	}

 out:
 	most_put_mbo(mbo);
 	return 0;
 }

 static struct most_aim aim = {
 	.name = "networking",
 	.probe_channel = aim_probe_channel,
 	.disconnect_channel = aim_disconnect_channel,
 	.tx_completion = aim_resume_tx_channel,
 	.rx_completion = aim_rx_data,
 };

 static int __init most_net_init(void)
 {
 	pr_info("most_net_init()\n");
 	spin_lock_init(&list_lock);
 	return most_register_aim(&aim);
 }

 static void __exit most_net_exit(void)
 {
 	struct net_dev_context *nd, *tmp;
 	unsigned long flags;

 	spin_lock_irqsave(&list_lock, flags);
 	list_for_each_entry_safe(nd, tmp, &net_devices, list) {
 		list_del(&nd->list);
 		spin_unlock_irqrestore(&list_lock, flags);
 		/*
 		 * do not call most_stop_channel() here, because channels are
 		 * going to be closed in ndo_stop() after unregister_netdev()
 		 */
 		most_net_rm_netdev_safe(nd);
 		kfree(nd);
 		spin_lock_irqsave(&list_lock, flags);
 	}
 	spin_unlock_irqrestore(&list_lock, flags);

 	most_deregister_aim(&aim);
 	pr_info("most_net_exit()\n");
 }

 /**
  * most_deliver_netinfo - callback for HDM to be informed about HW's MAC
  * @param iface - most interface instance
  * @param link_stat - link status
  * @param mac_addr - MAC address
  */
 void most_deliver_netinfo(struct most_interface *iface,
 			  unsigned char link_stat, unsigned char *mac_addr)
 {
 	struct net_dev_context *nd;
 	struct net_device *dev;

 	pr_info("Received netinfo from %s\n", iface->description);

 	nd = get_net_dev_context(iface);
 	if (!nd)
 		return;

 	dev = nd->dev;
 	if (!dev)
 		return;

 	if (mac_addr)
 		ether_addr_copy(dev->dev_addr, mac_addr);

 	if (nd->link_stat != link_stat) {
 		nd->link_stat = link_stat;
 		if (nd->link_stat)
 			netif_wake_queue(dev);
 		else
 			netif_stop_queue(dev);
 	}
 }
 EXPORT_SYMBOL(most_deliver_netinfo);

 module_init(most_net_init);
 module_exit(most_net_exit);
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Andrey Shvetsov <andrey.shvetsov@k2l.de>");
 MODULE_DESCRIPTION("Networking Application Interface Module for MostCore");
	/*
	* Networking AIM - Networking Application Interface Module for MostCore
	*
	* Copyright (C) 2015, Microchip Technology Germany II GmbH & Co. KG
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* This file is licensed under GPLv2.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/module.h>
	#include <linux/netdevice.h>
	#include <linux/etherdevice.h>
	#include <linux/slab.h>
	#include <linux/init.h>
	#include <linux/list.h>
	#include <linux/wait.h>
	#include <linux/kobject.h>
	#include "mostcore.h"
	#include "networking.h"

	#define MEP_HDR_LEN 8
	#define MDP_HDR_LEN 16
	#define MAMAC_DATA_LEN (1024 - MDP_HDR_LEN)

	#define PMHL 5

	#define PMS_TELID_UNSEGM_MAMAC 0x0A
	#define PMS_FIFONO_MDP 0x01
	#define PMS_FIFONO_MEP 0x04
	#define PMS_MSGTYPE_DATA 0x04
	#define PMS_DEF_PRIO 0
	#define MEP_DEF_RETRY 15

	#define PMS_FIFONO_MASK 0x07
	#define PMS_FIFONO_SHIFT 3
	#define PMS_RETRY_SHIFT 4
	#define PMS_TELID_MASK 0x0F
	#define PMS_TELID_SHIFT 4

	#define HB(value) ((u8)((u16)(value) >> 8))
	#define LB(value) ((u8)(value))

	#define EXTRACT_BIT_SET(bitset_name, value) \
	(((value) >> bitset_name##_SHIFT) & bitset_name##_MASK)

	#define PMS_IS_MEP(buf, len) \
	((len) > MEP_HDR_LEN && \
	EXTRACT_BIT_SET(PMS_FIFONO, (buf)[3]) == PMS_FIFONO_MEP)

	#define PMS_IS_MAMAC(buf, len) \
	((len) > MDP_HDR_LEN && \
	EXTRACT_BIT_SET(PMS_FIFONO, (buf)[3]) == PMS_FIFONO_MDP && \
	EXTRACT_BIT_SET(PMS_TELID, (buf)[14]) == PMS_TELID_UNSEGM_MAMAC)

	struct net_dev_channel {
	bool linked;
	int ch_id;
	};

	struct net_dev_context {
	struct most_interface *iface;
	bool channels_opened;
	bool is_mamac;
	unsigned char link_stat;
	struct net_device *dev;
	struct net_dev_channel rx;
	struct net_dev_channel tx;
	struct list_head list;
	};

	static struct list_head net_devices = LIST_HEAD_INIT(net_devices);
	static struct spinlock list_lock;
	static struct most_aim aim;

	static int skb_to_mamac(const struct sk_buff skb, struct mbo mbo)
	{
	u8 *buff = mbo->virt_address;
	const u8 broadcast[] = { 0x03, 0xFF };
	const u8 *dest_addr = skb->data + 4;
	const u8 *eth_type = skb->data + 12;
	unsigned int payload_len = skb->len - ETH_HLEN;
	unsigned int mdp_len = payload_len + MDP_HDR_LEN;

	if (mbo->buffer_length < mdp_len) {
	pr_err("drop: too small buffer! (%d for %d)\n",
	mbo->buffer_length, mdp_len);
	return -EINVAL;
	}

	if (skb->len < ETH_HLEN) {
	pr_err("drop: too small packet! (%d)\n", skb->len);
	return -EINVAL;
	}

	if (dest_addr[0] == 0xFF && dest_addr[1] == 0xFF)
	dest_addr = broadcast;

	*buff++ = HB(mdp_len - 2);
	*buff++ = LB(mdp_len - 2);

	*buff++ = PMHL;
	*buff++ = (PMS_FIFONO_MDP << PMS_FIFONO_SHIFT) \| PMS_MSGTYPE_DATA;
	*buff++ = PMS_DEF_PRIO;
	*buff++ = dest_addr[0];
	*buff++ = dest_addr[1];
	*buff++ = 0x00;

	*buff++ = HB(payload_len + 6);
	*buff++ = LB(payload_len + 6);

	/* end of FPH here */

	*buff++ = eth_type[0];
	*buff++ = eth_type[1];
	*buff++ = 0;
	*buff++ = 0;

	*buff++ = PMS_TELID_UNSEGM_MAMAC << 4 \| HB(payload_len);
	*buff++ = LB(payload_len);

	memcpy(buff, skb->data + ETH_HLEN, payload_len);
	mbo->buffer_length = mdp_len;
	return 0;
	}

	static int skb_to_mep(const struct sk_buff skb, struct mbo mbo)
	{
	u8 *buff = mbo->virt_address;
	unsigned int mep_len = skb->len + MEP_HDR_LEN;

	if (mbo->buffer_length < mep_len) {
	pr_err("drop: too small buffer! (%d for %d)\n",
	mbo->buffer_length, mep_len);
	return -EINVAL;
	}

	*buff++ = HB(mep_len - 2);
	*buff++ = LB(mep_len - 2);

	*buff++ = PMHL;
	*buff++ = (PMS_FIFONO_MEP << PMS_FIFONO_SHIFT) \| PMS_MSGTYPE_DATA;
	*buff++ = (MEP_DEF_RETRY << PMS_RETRY_SHIFT) \| PMS_DEF_PRIO;
	*buff++ = 0;
	*buff++ = 0;
	*buff++ = 0;

	memcpy(buff, skb->data, skb->len);
	mbo->buffer_length = mep_len;
	return 0;
	}

	static int most_nd_set_mac_address(struct net_device dev, void p)
	{
	struct net_dev_context *nd = dev->ml_priv;
	int err = eth_mac_addr(dev, p);

	if (err)
	return err;

	BUG_ON(nd->dev != dev);

	nd->is_mamac =
	(dev->dev_addr[0] == 0 && dev->dev_addr[1] == 0 &&
	dev->dev_addr[2] == 0 && dev->dev_addr[3] == 0);

	/*
	* Set default MTU for the given packet type.
	* It is still possible to change MTU using ip tools afterwards.
	*/
	dev->mtu = nd->is_mamac ? MAMAC_DATA_LEN : ETH_DATA_LEN;

	return 0;
	}

	static int most_nd_open(struct net_device *dev)
	{
	struct net_dev_context *nd = dev->ml_priv;

	netdev_info(dev, "open net device\n");

	BUG_ON(nd->dev != dev);

	if (nd->channels_opened)
	return -EFAULT;

	BUG_ON(!nd->tx.linked \|\| !nd->rx.linked);

	if (most_start_channel(nd->iface, nd->rx.ch_id, &aim)) {
	netdev_err(dev, "most_start_channel() failed\n");
	return -EBUSY;
	}

	if (most_start_channel(nd->iface, nd->tx.ch_id, &aim)) {
	netdev_err(dev, "most_start_channel() failed\n");
	most_stop_channel(nd->iface, nd->rx.ch_id, &aim);
	return -EBUSY;
	}

	nd->channels_opened = true;

	if (nd->is_mamac) {
	nd->link_stat = 1;
	netif_wake_queue(dev);
	} else {
	nd->iface->request_netinfo(nd->iface, nd->tx.ch_id);
	}

	return 0;
	}

	static int most_nd_stop(struct net_device *dev)
	{
	struct net_dev_context *nd = dev->ml_priv;

	netdev_info(dev, "stop net device\n");

	BUG_ON(nd->dev != dev);
	netif_stop_queue(dev);

	if (nd->channels_opened) {
	most_stop_channel(nd->iface, nd->rx.ch_id, &aim);
	most_stop_channel(nd->iface, nd->tx.ch_id, &aim);
	nd->channels_opened = false;
	}

	return 0;
	}

	static netdev_tx_t most_nd_start_xmit(struct sk_buff *skb,
	struct net_device *dev)
	{
	struct net_dev_context *nd = dev->ml_priv;
	struct mbo *mbo;
	int ret;

	BUG_ON(nd->dev != dev);

	mbo = most_get_mbo(nd->iface, nd->tx.ch_id, &aim);

	if (!mbo) {
	netif_stop_queue(dev);
	dev->stats.tx_fifo_errors++;
	return NETDEV_TX_BUSY;
	}

	if (nd->is_mamac)
	ret = skb_to_mamac(skb, mbo);
	else
	ret = skb_to_mep(skb, mbo);

	if (ret) {
	most_put_mbo(mbo);
	dev->stats.tx_dropped++;
	kfree_skb(skb);
	return NETDEV_TX_OK;
	}

	most_submit_mbo(mbo);
	dev->stats.tx_packets++;
	dev->stats.tx_bytes += skb->len;
	kfree_skb(skb);
	return NETDEV_TX_OK;
	}

	static const struct net_device_ops most_nd_ops = {
	.ndo_open = most_nd_open,
	.ndo_stop = most_nd_stop,
	.ndo_start_xmit = most_nd_start_xmit,
	.ndo_set_mac_address = most_nd_set_mac_address,
	};

	static void most_nd_setup(struct net_device *dev)
	{
	netdev_info(dev, "setup net device\n");
	ether_setup(dev);
	dev->netdev_ops = &most_nd_ops;
	}

	static void most_net_rm_netdev_safe(struct net_dev_context *nd)
	{
	if (!nd->dev)
	return;

	pr_info("remove net device %p\n", nd->dev);

	unregister_netdev(nd->dev);
	free_netdev(nd->dev);
	nd->dev = NULL;
	}

	static struct net_dev_context *get_net_dev_context(
	struct most_interface *iface)
	{
	struct net_dev_context nd, tmp;
	unsigned long flags;

	spin_lock_irqsave(&list_lock, flags);
	list_for_each_entry_safe(nd, tmp, &net_devices, list) {
	if (nd->iface == iface) {
	spin_unlock_irqrestore(&list_lock, flags);
	return nd;
	}
	}
	spin_unlock_irqrestore(&list_lock, flags);
	return NULL;
	}

	static int aim_probe_channel(struct most_interface *iface, int channel_idx,
	struct most_channel_config *ccfg,
	struct kobject parent, char name)
	{
	struct net_dev_context *nd;
	struct net_dev_channel *ch;
	unsigned long flags;

	if (!iface)
	return -EINVAL;

	if (ccfg->data_type != MOST_CH_ASYNC)
	return -EINVAL;

	nd = get_net_dev_context(iface);

	if (!nd) {
	nd = kzalloc(sizeof(*nd), GFP_KERNEL);
	if (!nd)
	return -ENOMEM;

	nd->iface = iface;

	spin_lock_irqsave(&list_lock, flags);
	list_add(&nd->list, &net_devices);
	spin_unlock_irqrestore(&list_lock, flags);
	}

	ch = ccfg->direction == MOST_CH_TX ? &nd->tx : &nd->rx;
	if (ch->linked) {
	pr_err("only one channel per instance & direction allowed\n");
	return -EINVAL;
	}

	if (nd->tx.linked \|\| nd->rx.linked) {
	struct net_device *dev =
	alloc_netdev(0, "meth%d", NET_NAME_UNKNOWN,
	most_nd_setup);

	if (!dev) {
	pr_err("no memory for net_device\n");
	return -ENOMEM;
	}

	nd->dev = dev;
	ch->ch_id = channel_idx;
	ch->linked = true;

	dev->ml_priv = nd;
	if (register_netdev(dev)) {
	pr_err("registering net device failed\n");
	ch->linked = false;
	free_netdev(dev);
	return -EINVAL;
	}
	}

	ch->ch_id = channel_idx;
	ch->linked = true;

	return 0;
	}

	static int aim_disconnect_channel(struct most_interface *iface,
	int channel_idx)
	{
	struct net_dev_context *nd;
	struct net_dev_channel *ch;
	unsigned long flags;

	nd = get_net_dev_context(iface);
	if (!nd)
	return -EINVAL;

	if (nd->rx.linked && channel_idx == nd->rx.ch_id)
	ch = &nd->rx;
	else if (nd->tx.linked && channel_idx == nd->tx.ch_id)
	ch = &nd->tx;
	else
	return -EINVAL;

	ch->linked = false;

	/*
	* do not call most_stop_channel() here, because channels are
	* going to be closed in ndo_stop() after unregister_netdev()
	*/
	most_net_rm_netdev_safe(nd);

	if (!nd->rx.linked && !nd->tx.linked) {
	spin_lock_irqsave(&list_lock, flags);
	list_del(&nd->list);
	spin_unlock_irqrestore(&list_lock, flags);
	kfree(nd);
	}

	return 0;
	}

	static int aim_resume_tx_channel(struct most_interface *iface,
	int channel_idx)
	{
	struct net_dev_context *nd;

	nd = get_net_dev_context(iface);
	if (!nd \|\| !nd->channels_opened \|\| nd->tx.ch_id != channel_idx)
	return 0;

	if (!nd->dev)
	return 0;

	netif_wake_queue(nd->dev);
	return 0;
	}

	static int aim_rx_data(struct mbo *mbo)
	{
	const u32 zero = 0;
	struct net_dev_context *nd;
	char *buf = mbo->virt_address;
	u32 len = mbo->processed_length;
	struct sk_buff *skb;
	struct net_device *dev;
	unsigned int skb_len;

	nd = get_net_dev_context(mbo->ifp);
	if (!nd \|\| !nd->channels_opened \|\| nd->rx.ch_id != mbo->hdm_channel_id)
	return -EIO;

	dev = nd->dev;
	if (!dev) {
	pr_err_once("drop packet: missing net_device\n");
	return -EIO;
	}

	if (nd->is_mamac) {
	if (!PMS_IS_MAMAC(buf, len))
	return -EIO;

	skb = dev_alloc_skb(len - MDP_HDR_LEN + 2 * ETH_ALEN + 2);
	} else {
	if (!PMS_IS_MEP(buf, len))
	return -EIO;

	skb = dev_alloc_skb(len - MEP_HDR_LEN);
	}

	if (!skb) {
	dev->stats.rx_dropped++;
	pr_err_once("drop packet: no memory for skb\n");
	goto out;
	}

	skb->dev = dev;

	if (nd->is_mamac) {
	/* dest */
	ether_addr_copy(skb_put(skb, ETH_ALEN), dev->dev_addr);

	/* src */
	memcpy(skb_put(skb, 4), &zero, 4);
	memcpy(skb_put(skb, 2), buf + 5, 2);

	/* eth type */
	memcpy(skb_put(skb, 2), buf + 10, 2);

	buf += MDP_HDR_LEN;
	len -= MDP_HDR_LEN;
	} else {
	buf += MEP_HDR_LEN;
	len -= MEP_HDR_LEN;
	}

	memcpy(skb_put(skb, len), buf, len);
	skb->protocol = eth_type_trans(skb, dev);
	skb_len = skb->len;
	if (netif_rx(skb) == NET_RX_SUCCESS) {
	dev->stats.rx_packets++;
	dev->stats.rx_bytes += skb_len;
	} else {
	dev->stats.rx_dropped++;
	}

	out:
	most_put_mbo(mbo);
	return 0;
	}

	static struct most_aim aim = {
	.name = "networking",
	.probe_channel = aim_probe_channel,
	.disconnect_channel = aim_disconnect_channel,
	.tx_completion = aim_resume_tx_channel,
	.rx_completion = aim_rx_data,
	};

	static int __init most_net_init(void)
	{
	pr_info("most_net_init()\n");
	spin_lock_init(&list_lock);
	return most_register_aim(&aim);
	}

	static void __exit most_net_exit(void)
	{
	struct net_dev_context nd, tmp;
	unsigned long flags;

	spin_lock_irqsave(&list_lock, flags);
	list_for_each_entry_safe(nd, tmp, &net_devices, list) {
	list_del(&nd->list);
	spin_unlock_irqrestore(&list_lock, flags);
	/*
	* do not call most_stop_channel() here, because channels are
	* going to be closed in ndo_stop() after unregister_netdev()
	*/
	most_net_rm_netdev_safe(nd);
	kfree(nd);
	spin_lock_irqsave(&list_lock, flags);
	}
	spin_unlock_irqrestore(&list_lock, flags);

	most_deregister_aim(&aim);
	pr_info("most_net_exit()\n");
	}

	/**
	* most_deliver_netinfo - callback for HDM to be informed about HW's MAC
	* @param iface - most interface instance
	* @param link_stat - link status
	* @param mac_addr - MAC address
	*/
	void most_deliver_netinfo(struct most_interface *iface,
	unsigned char link_stat, unsigned char *mac_addr)
	{
	struct net_dev_context *nd;
	struct net_device *dev;

	pr_info("Received netinfo from %s\n", iface->description);

	nd = get_net_dev_context(iface);
	if (!nd)
	return;

	dev = nd->dev;
	if (!dev)
	return;

	if (mac_addr)
	ether_addr_copy(dev->dev_addr, mac_addr);

	if (nd->link_stat != link_stat) {
	nd->link_stat = link_stat;
	if (nd->link_stat)
	netif_wake_queue(dev);
	else
	netif_stop_queue(dev);
	}
	}
	EXPORT_SYMBOL(most_deliver_netinfo);

	module_init(most_net_init);
	module_exit(most_net_exit);
	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Andrey Shvetsov <andrey.shvetsov@k2l.de>");
	MODULE_DESCRIPTION("Networking Application Interface Module for MostCore");