/*
   * Copyright Gavin Shan, IBM Corporation 2016.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>
  #include <linux/netlink.h>
  
  #include <net/ncsi.h>
  #include <net/net_namespace.h>
  #include <net/sock.h>

  #include <net/addrconf.h>
  #include <net/ipv6.h>
  #include <net/if_inet6.h>

  
  #include "internal.h"

  #include "ncsi-pkt.h"

  
  LIST_HEAD(ncsi_dev_list);
  DEFINE_SPINLOCK(ncsi_dev_lock);
  
  static inline int ncsi_filter_size(int table)
  {
  	int sizes[] = { 2, 6, 6, 6 };
  
  	BUILD_BUG_ON(ARRAY_SIZE(sizes) != NCSI_FILTER_MAX);
  	if (table < NCSI_FILTER_BASE || table >= NCSI_FILTER_MAX)
  		return -EINVAL;
  
  	return sizes[table];
  }
  
  int ncsi_find_filter(struct ncsi_channel *nc, int table, void *data)
  {
  	struct ncsi_channel_filter *ncf;
  	void *bitmap;
  	int index, size;
  	unsigned long flags;
  
  	ncf = nc->filters[table];
  	if (!ncf)
  		return -ENXIO;
  
  	size = ncsi_filter_size(table);
  	if (size < 0)
  		return size;
  
  	spin_lock_irqsave(&nc->lock, flags);
  	bitmap = (void *)&ncf->bitmap;
  	index = -1;
  	while ((index = find_next_bit(bitmap, ncf->total, index + 1))
  	       < ncf->total) {
  		if (!memcmp(ncf->data + size * index, data, size)) {
  			spin_unlock_irqrestore(&nc->lock, flags);
  			return index;
  		}
  	}
  	spin_unlock_irqrestore(&nc->lock, flags);
  
  	return -ENOENT;
  }
  
  int ncsi_add_filter(struct ncsi_channel *nc, int table, void *data)
  {
  	struct ncsi_channel_filter *ncf;
  	int index, size;
  	void *bitmap;
  	unsigned long flags;
  
  	size = ncsi_filter_size(table);
  	if (size < 0)
  		return size;
  
  	index = ncsi_find_filter(nc, table, data);
  	if (index >= 0)
  		return index;
  
  	ncf = nc->filters[table];
  	if (!ncf)
  		return -ENODEV;
  
  	spin_lock_irqsave(&nc->lock, flags);
  	bitmap = (void *)&ncf->bitmap;
  	do {
  		index = find_next_zero_bit(bitmap, ncf->total, 0);
  		if (index >= ncf->total) {
  			spin_unlock_irqrestore(&nc->lock, flags);
  			return -ENOSPC;
  		}
  	} while (test_and_set_bit(index, bitmap));
  
  	memcpy(ncf->data + size * index, data, size);
  	spin_unlock_irqrestore(&nc->lock, flags);
  
  	return index;
  }
  
  int ncsi_remove_filter(struct ncsi_channel *nc, int table, int index)
  {
  	struct ncsi_channel_filter *ncf;
  	int size;
  	void *bitmap;
  	unsigned long flags;
  
  	size = ncsi_filter_size(table);
  	if (size < 0)
  		return size;
  
  	ncf = nc->filters[table];
  	if (!ncf || index >= ncf->total)
  		return -ENODEV;
  
  	spin_lock_irqsave(&nc->lock, flags);
  	bitmap = (void *)&ncf->bitmap;
  	if (test_and_clear_bit(index, bitmap))
  		memset(ncf->data + size * index, 0, size);
  	spin_unlock_irqrestore(&nc->lock, flags);
  
  	return 0;
  }

  static void ncsi_report_link(struct ncsi_dev_priv *ndp, bool force_down)
  {
  	struct ncsi_dev *nd = &ndp->ndev;
  	struct ncsi_package *np;
  	struct ncsi_channel *nc;

  	unsigned long flags;

  
  	nd->state = ncsi_dev_state_functional;
  	if (force_down) {
  		nd->link_up = 0;
  		goto report;
  	}
  
  	nd->link_up = 0;
  	NCSI_FOR_EACH_PACKAGE(ndp, np) {
  		NCSI_FOR_EACH_CHANNEL(np, nc) {

  			spin_lock_irqsave(&nc->lock, flags);

  			if (!list_empty(&nc->link) ||

  			    nc->state != NCSI_CHANNEL_ACTIVE) {
  				spin_unlock_irqrestore(&nc->lock, flags);

  				continue;

  			}

  
  			if (nc->modes[NCSI_MODE_LINK].data[2] & 0x1) {

  				spin_unlock_irqrestore(&nc->lock, flags);

  				nd->link_up = 1;
  				goto report;
  			}

  
  			spin_unlock_irqrestore(&nc->lock, flags);

  		}
  	}
  
  report:
  	nd->handler(nd);
  }
  
  static void ncsi_channel_monitor(unsigned long data)
  {
  	struct ncsi_channel *nc = (struct ncsi_channel *)data;
  	struct ncsi_package *np = nc->package;
  	struct ncsi_dev_priv *ndp = np->ndp;
  	struct ncsi_cmd_arg nca;

  	bool enabled, chained;

  	unsigned int monitor_state;

  	unsigned long flags;

  	int state, ret;

  
  	spin_lock_irqsave(&nc->lock, flags);

  	state = nc->state;
  	chained = !list_empty(&nc->link);

  	enabled = nc->monitor.enabled;
  	monitor_state = nc->monitor.state;

  	spin_unlock_irqrestore(&nc->lock, flags);

  	if (!enabled || chained)

  		return;

  	if (state != NCSI_CHANNEL_INACTIVE &&
  	    state != NCSI_CHANNEL_ACTIVE)

  		return;

  	switch (monitor_state) {
  	case NCSI_CHANNEL_MONITOR_START:
  	case NCSI_CHANNEL_MONITOR_RETRY:

  		nca.ndp = ndp;
  		nca.package = np->id;
  		nca.channel = nc->id;
  		nca.type = NCSI_PKT_CMD_GLS;

  		nca.req_flags = 0;

  		ret = ncsi_xmit_cmd(&nca);
  		if (ret) {
  			netdev_err(ndp->ndev.dev, "Error %d sending GLS
  ",
  				   ret);
  			return;
  		}

  		break;
  	case NCSI_CHANNEL_MONITOR_WAIT ... NCSI_CHANNEL_MONITOR_WAIT_MAX:
  		break;
  	default:

  		if (!(ndp->flags & NCSI_DEV_HWA) &&

  		    state == NCSI_CHANNEL_ACTIVE) {

  			ncsi_report_link(ndp, true);

  			ndp->flags |= NCSI_DEV_RESHUFFLE;
  		}

  		spin_lock_irqsave(&nc->lock, flags);
  		nc->state = NCSI_CHANNEL_INVISIBLE;
  		spin_unlock_irqrestore(&nc->lock, flags);

  		spin_lock_irqsave(&ndp->lock, flags);

  		nc->state = NCSI_CHANNEL_INACTIVE;

  		list_add_tail_rcu(&nc->link, &ndp->channel_queue);
  		spin_unlock_irqrestore(&ndp->lock, flags);
  		ncsi_process_next_channel(ndp);
  		return;
  	}
  
  	spin_lock_irqsave(&nc->lock, flags);

  	nc->monitor.state++;

  	spin_unlock_irqrestore(&nc->lock, flags);

  	mod_timer(&nc->monitor.timer, jiffies + HZ);

  }
  
  void ncsi_start_channel_monitor(struct ncsi_channel *nc)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&nc->lock, flags);

  	WARN_ON_ONCE(nc->monitor.enabled);
  	nc->monitor.enabled = true;
  	nc->monitor.state = NCSI_CHANNEL_MONITOR_START;

  	spin_unlock_irqrestore(&nc->lock, flags);

  	mod_timer(&nc->monitor.timer, jiffies + HZ);

  }
  
  void ncsi_stop_channel_monitor(struct ncsi_channel *nc)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&nc->lock, flags);

  	if (!nc->monitor.enabled) {

  		spin_unlock_irqrestore(&nc->lock, flags);
  		return;
  	}

  	nc->monitor.enabled = false;

  	spin_unlock_irqrestore(&nc->lock, flags);

  	del_timer_sync(&nc->monitor.timer);

  }

  struct ncsi_channel *ncsi_find_channel(struct ncsi_package *np,
  				       unsigned char id)
  {
  	struct ncsi_channel *nc;
  
  	NCSI_FOR_EACH_CHANNEL(np, nc) {
  		if (nc->id == id)
  			return nc;
  	}
  
  	return NULL;
  }
  
  struct ncsi_channel *ncsi_add_channel(struct ncsi_package *np, unsigned char id)
  {
  	struct ncsi_channel *nc, *tmp;
  	int index;
  	unsigned long flags;
  
  	nc = kzalloc(sizeof(*nc), GFP_ATOMIC);
  	if (!nc)
  		return NULL;
  
  	nc->id = id;
  	nc->package = np;
  	nc->state = NCSI_CHANNEL_INACTIVE;

  	nc->monitor.enabled = false;
  	setup_timer(&nc->monitor.timer,
  		    ncsi_channel_monitor, (unsigned long)nc);

  	spin_lock_init(&nc->lock);

  	INIT_LIST_HEAD(&nc->link);

  	for (index = 0; index < NCSI_CAP_MAX; index++)
  		nc->caps[index].index = index;
  	for (index = 0; index < NCSI_MODE_MAX; index++)
  		nc->modes[index].index = index;
  
  	spin_lock_irqsave(&np->lock, flags);
  	tmp = ncsi_find_channel(np, id);
  	if (tmp) {
  		spin_unlock_irqrestore(&np->lock, flags);
  		kfree(nc);
  		return tmp;
  	}
  
  	list_add_tail_rcu(&nc->node, &np->channels);
  	np->channel_num++;
  	spin_unlock_irqrestore(&np->lock, flags);
  
  	return nc;
  }
  
  static void ncsi_remove_channel(struct ncsi_channel *nc)
  {
  	struct ncsi_package *np = nc->package;
  	struct ncsi_channel_filter *ncf;
  	unsigned long flags;
  	int i;
  
  	/* Release filters */
  	spin_lock_irqsave(&nc->lock, flags);
  	for (i = 0; i < NCSI_FILTER_MAX; i++) {
  		ncf = nc->filters[i];
  		if (!ncf)
  			continue;
  
  		nc->filters[i] = NULL;
  		kfree(ncf);
  	}
  
  	nc->state = NCSI_CHANNEL_INACTIVE;
  	spin_unlock_irqrestore(&nc->lock, flags);

  	ncsi_stop_channel_monitor(nc);

  
  	/* Remove and free channel */
  	spin_lock_irqsave(&np->lock, flags);
  	list_del_rcu(&nc->node);
  	np->channel_num--;
  	spin_unlock_irqrestore(&np->lock, flags);
  
  	kfree(nc);
  }
  
  struct ncsi_package *ncsi_find_package(struct ncsi_dev_priv *ndp,
  				       unsigned char id)
  {
  	struct ncsi_package *np;
  
  	NCSI_FOR_EACH_PACKAGE(ndp, np) {
  		if (np->id == id)
  			return np;
  	}
  
  	return NULL;
  }
  
  struct ncsi_package *ncsi_add_package(struct ncsi_dev_priv *ndp,
  				      unsigned char id)
  {
  	struct ncsi_package *np, *tmp;
  	unsigned long flags;
  
  	np = kzalloc(sizeof(*np), GFP_ATOMIC);
  	if (!np)
  		return NULL;
  
  	np->id = id;
  	np->ndp = ndp;
  	spin_lock_init(&np->lock);
  	INIT_LIST_HEAD(&np->channels);
  
  	spin_lock_irqsave(&ndp->lock, flags);
  	tmp = ncsi_find_package(ndp, id);
  	if (tmp) {
  		spin_unlock_irqrestore(&ndp->lock, flags);
  		kfree(np);
  		return tmp;
  	}
  
  	list_add_tail_rcu(&np->node, &ndp->packages);
  	ndp->package_num++;
  	spin_unlock_irqrestore(&ndp->lock, flags);
  
  	return np;
  }
  
  void ncsi_remove_package(struct ncsi_package *np)
  {
  	struct ncsi_dev_priv *ndp = np->ndp;
  	struct ncsi_channel *nc, *tmp;
  	unsigned long flags;
  
  	/* Release all child channels */
  	list_for_each_entry_safe(nc, tmp, &np->channels, node)
  		ncsi_remove_channel(nc);
  
  	/* Remove and free package */
  	spin_lock_irqsave(&ndp->lock, flags);
  	list_del_rcu(&np->node);
  	ndp->package_num--;
  	spin_unlock_irqrestore(&ndp->lock, flags);
  
  	kfree(np);
  }
  
  void ncsi_find_package_and_channel(struct ncsi_dev_priv *ndp,
  				   unsigned char id,
  				   struct ncsi_package **np,
  				   struct ncsi_channel **nc)
  {
  	struct ncsi_package *p;
  	struct ncsi_channel *c;
  
  	p = ncsi_find_package(ndp, NCSI_PACKAGE_INDEX(id));
  	c = p ? ncsi_find_channel(p, NCSI_CHANNEL_INDEX(id)) : NULL;
  
  	if (np)
  		*np = p;
  	if (nc)
  		*nc = c;
  }
  
  /* For two consecutive NCSI commands, the packet IDs shouldn't
   * be same. Otherwise, the bogus response might be replied. So
   * the available IDs are allocated in round-robin fashion.
   */

  struct ncsi_request *ncsi_alloc_request(struct ncsi_dev_priv *ndp,
  					unsigned int req_flags)

  {
  	struct ncsi_request *nr = NULL;
  	int i, limit = ARRAY_SIZE(ndp->requests);
  	unsigned long flags;
  
  	/* Check if there is one available request until the ceiling */
  	spin_lock_irqsave(&ndp->lock, flags);

  	for (i = ndp->request_id; i < limit; i++) {

  		if (ndp->requests[i].used)
  			continue;
  
  		nr = &ndp->requests[i];
  		nr->used = true;

  		nr->flags = req_flags;

  		ndp->request_id = i + 1;
  		goto found;

  	}
  
  	/* Fail back to check from the starting cursor */

  	for (i = NCSI_REQ_START_IDX; i < ndp->request_id; i++) {

  		if (ndp->requests[i].used)
  			continue;
  
  		nr = &ndp->requests[i];
  		nr->used = true;

  		nr->flags = req_flags;

  		ndp->request_id = i + 1;
  		goto found;

  	}

  found:
  	spin_unlock_irqrestore(&ndp->lock, flags);

  	return nr;
  }
  
  void ncsi_free_request(struct ncsi_request *nr)
  {
  	struct ncsi_dev_priv *ndp = nr->ndp;
  	struct sk_buff *cmd, *rsp;
  	unsigned long flags;

  	bool driven;

  
  	if (nr->enabled) {
  		nr->enabled = false;
  		del_timer_sync(&nr->timer);
  	}
  
  	spin_lock_irqsave(&ndp->lock, flags);
  	cmd = nr->cmd;
  	rsp = nr->rsp;
  	nr->cmd = NULL;
  	nr->rsp = NULL;
  	nr->used = false;

  	driven = !!(nr->flags & NCSI_REQ_FLAG_EVENT_DRIVEN);

  	spin_unlock_irqrestore(&ndp->lock, flags);

  	if (driven && cmd && --ndp->pending_req_num == 0)
  		schedule_work(&ndp->work);

  	/* Release command and response */
  	consume_skb(cmd);
  	consume_skb(rsp);
  }
  
  struct ncsi_dev *ncsi_find_dev(struct net_device *dev)
  {
  	struct ncsi_dev_priv *ndp;
  
  	NCSI_FOR_EACH_DEV(ndp) {
  		if (ndp->ndev.dev == dev)
  			return &ndp->ndev;
  	}
  
  	return NULL;
  }
  
  static void ncsi_request_timeout(unsigned long data)
  {
  	struct ncsi_request *nr = (struct ncsi_request *)data;
  	struct ncsi_dev_priv *ndp = nr->ndp;
  	unsigned long flags;
  
  	/* If the request already had associated response,
  	 * let the response handler to release it.
  	 */
  	spin_lock_irqsave(&ndp->lock, flags);
  	nr->enabled = false;
  	if (nr->rsp || !nr->cmd) {
  		spin_unlock_irqrestore(&ndp->lock, flags);
  		return;
  	}
  	spin_unlock_irqrestore(&ndp->lock, flags);
  
  	/* Release the request */
  	ncsi_free_request(nr);
  }

  static void ncsi_suspend_channel(struct ncsi_dev_priv *ndp)
  {
  	struct ncsi_dev *nd = &ndp->ndev;
  	struct ncsi_package *np = ndp->active_package;
  	struct ncsi_channel *nc = ndp->active_channel;
  	struct ncsi_cmd_arg nca;

  	unsigned long flags;

  	int ret;
  
  	nca.ndp = ndp;

  	nca.req_flags = NCSI_REQ_FLAG_EVENT_DRIVEN;

  	switch (nd->state) {
  	case ncsi_dev_state_suspend:
  		nd->state = ncsi_dev_state_suspend_select;
  		/* Fall through */
  	case ncsi_dev_state_suspend_select:

  		ndp->pending_req_num = 1;
  
  		nca.type = NCSI_PKT_CMD_SP;
  		nca.package = np->id;
  		nca.channel = NCSI_RESERVED_CHANNEL;
  		if (ndp->flags & NCSI_DEV_HWA)
  			nca.bytes[0] = 0;
  		else
  			nca.bytes[0] = 1;

  		/* To retrieve the last link states of channels in current
  		 * package when current active channel needs fail over to
  		 * another one. It means we will possibly select another
  		 * channel as next active one. The link states of channels
  		 * are most important factor of the selection. So we need
  		 * accurate link states. Unfortunately, the link states on
  		 * inactive channels can't be updated with LSC AEN in time.
  		 */
  		if (ndp->flags & NCSI_DEV_RESHUFFLE)
  			nd->state = ncsi_dev_state_suspend_gls;
  		else
  			nd->state = ncsi_dev_state_suspend_dcnt;

  		ret = ncsi_xmit_cmd(&nca);
  		if (ret)
  			goto error;
  
  		break;

  	case ncsi_dev_state_suspend_gls:
  		ndp->pending_req_num = np->channel_num;
  
  		nca.type = NCSI_PKT_CMD_GLS;
  		nca.package = np->id;
  
  		nd->state = ncsi_dev_state_suspend_dcnt;
  		NCSI_FOR_EACH_CHANNEL(np, nc) {
  			nca.channel = nc->id;
  			ret = ncsi_xmit_cmd(&nca);
  			if (ret)
  				goto error;
  		}
  
  		break;

  	case ncsi_dev_state_suspend_dcnt:

  		ndp->pending_req_num = 1;
  
  		nca.type = NCSI_PKT_CMD_DCNT;
  		nca.package = np->id;
  		nca.channel = nc->id;
  
  		nd->state = ncsi_dev_state_suspend_dc;
  		ret = ncsi_xmit_cmd(&nca);
  		if (ret)
  			goto error;
  
  		break;

  	case ncsi_dev_state_suspend_dc:

  		ndp->pending_req_num = 1;
  
  		nca.type = NCSI_PKT_CMD_DC;
  		nca.package = np->id;
  		nca.channel = nc->id;
  		nca.bytes[0] = 1;
  
  		nd->state = ncsi_dev_state_suspend_deselect;
  		ret = ncsi_xmit_cmd(&nca);
  		if (ret)
  			goto error;
  
  		break;

  	case ncsi_dev_state_suspend_deselect:
  		ndp->pending_req_num = 1;

  		nca.type = NCSI_PKT_CMD_DP;

  		nca.package = np->id;

  		nca.channel = NCSI_RESERVED_CHANNEL;

  		nd->state = ncsi_dev_state_suspend_done;

  		ret = ncsi_xmit_cmd(&nca);

  		if (ret)
  			goto error;

  
  		break;
  	case ncsi_dev_state_suspend_done:

  		spin_lock_irqsave(&nc->lock, flags);
  		nc->state = NCSI_CHANNEL_INACTIVE;
  		spin_unlock_irqrestore(&nc->lock, flags);

  		ncsi_process_next_channel(ndp);
  
  		break;
  	default:
  		netdev_warn(nd->dev, "Wrong NCSI state 0x%x in suspend
  ",
  			    nd->state);
  	}

  
  	return;
  error:
  	nd->state = ncsi_dev_state_functional;

  }
  
  static void ncsi_configure_channel(struct ncsi_dev_priv *ndp)
  {
  	struct ncsi_dev *nd = &ndp->ndev;
  	struct net_device *dev = nd->dev;
  	struct ncsi_package *np = ndp->active_package;
  	struct ncsi_channel *nc = ndp->active_channel;

  	struct ncsi_channel *hot_nc = NULL;

  	struct ncsi_cmd_arg nca;
  	unsigned char index;

  	unsigned long flags;

  	int ret;
  
  	nca.ndp = ndp;

  	nca.req_flags = NCSI_REQ_FLAG_EVENT_DRIVEN;

  	switch (nd->state) {
  	case ncsi_dev_state_config:
  	case ncsi_dev_state_config_sp:
  		ndp->pending_req_num = 1;
  
  		/* Select the specific package */
  		nca.type = NCSI_PKT_CMD_SP;
  		if (ndp->flags & NCSI_DEV_HWA)
  			nca.bytes[0] = 0;
  		else
  			nca.bytes[0] = 1;
  		nca.package = np->id;

  		nca.channel = NCSI_RESERVED_CHANNEL;

  		ret = ncsi_xmit_cmd(&nca);
  		if (ret)
  			goto error;
  
  		nd->state = ncsi_dev_state_config_cis;
  		break;
  	case ncsi_dev_state_config_cis:
  		ndp->pending_req_num = 1;
  
  		/* Clear initial state */
  		nca.type = NCSI_PKT_CMD_CIS;
  		nca.package = np->id;
  		nca.channel = nc->id;
  		ret = ncsi_xmit_cmd(&nca);
  		if (ret)
  			goto error;
  
  		nd->state = ncsi_dev_state_config_sma;
  		break;
  	case ncsi_dev_state_config_sma:
  	case ncsi_dev_state_config_ebf:
  #if IS_ENABLED(CONFIG_IPV6)
  	case ncsi_dev_state_config_egmf:
  #endif
  	case ncsi_dev_state_config_ecnt:
  	case ncsi_dev_state_config_ec:
  	case ncsi_dev_state_config_ae:
  	case ncsi_dev_state_config_gls:
  		ndp->pending_req_num = 1;
  
  		nca.package = np->id;
  		nca.channel = nc->id;
  
  		/* Use first entry in unicast filter table. Note that
  		 * the MAC filter table starts from entry 1 instead of
  		 * 0.
  		 */
  		if (nd->state == ncsi_dev_state_config_sma) {
  			nca.type = NCSI_PKT_CMD_SMA;
  			for (index = 0; index < 6; index++)
  				nca.bytes[index] = dev->dev_addr[index];
  			nca.bytes[6] = 0x1;
  			nca.bytes[7] = 0x1;
  			nd->state = ncsi_dev_state_config_ebf;
  		} else if (nd->state == ncsi_dev_state_config_ebf) {
  			nca.type = NCSI_PKT_CMD_EBF;
  			nca.dwords[0] = nc->caps[NCSI_CAP_BC].cap;
  			nd->state = ncsi_dev_state_config_ecnt;
  #if IS_ENABLED(CONFIG_IPV6)
  			if (ndp->inet6_addr_num > 0 &&
  			    (nc->caps[NCSI_CAP_GENERIC].cap &
  			     NCSI_CAP_GENERIC_MC))
  				nd->state = ncsi_dev_state_config_egmf;
  			else
  				nd->state = ncsi_dev_state_config_ecnt;
  		} else if (nd->state == ncsi_dev_state_config_egmf) {
  			nca.type = NCSI_PKT_CMD_EGMF;
  			nca.dwords[0] = nc->caps[NCSI_CAP_MC].cap;
  			nd->state = ncsi_dev_state_config_ecnt;
  #endif /* CONFIG_IPV6 */
  		} else if (nd->state == ncsi_dev_state_config_ecnt) {
  			nca.type = NCSI_PKT_CMD_ECNT;
  			nd->state = ncsi_dev_state_config_ec;
  		} else if (nd->state == ncsi_dev_state_config_ec) {
  			/* Enable AEN if it's supported */
  			nca.type = NCSI_PKT_CMD_EC;
  			nd->state = ncsi_dev_state_config_ae;
  			if (!(nc->caps[NCSI_CAP_AEN].cap & NCSI_CAP_AEN_MASK))
  				nd->state = ncsi_dev_state_config_gls;
  		} else if (nd->state == ncsi_dev_state_config_ae) {
  			nca.type = NCSI_PKT_CMD_AE;
  			nca.bytes[0] = 0;
  			nca.dwords[1] = nc->caps[NCSI_CAP_AEN].cap;
  			nd->state = ncsi_dev_state_config_gls;
  		} else if (nd->state == ncsi_dev_state_config_gls) {
  			nca.type = NCSI_PKT_CMD_GLS;
  			nd->state = ncsi_dev_state_config_done;
  		}
  
  		ret = ncsi_xmit_cmd(&nca);
  		if (ret)
  			goto error;
  		break;
  	case ncsi_dev_state_config_done:

  		spin_lock_irqsave(&nc->lock, flags);

  		if (nc->modes[NCSI_MODE_LINK].data[2] & 0x1) {
  			hot_nc = nc;

  			nc->state = NCSI_CHANNEL_ACTIVE;

  		} else {
  			hot_nc = NULL;

  			nc->state = NCSI_CHANNEL_INACTIVE;

  		}

  		spin_unlock_irqrestore(&nc->lock, flags);

  		/* Update the hot channel */
  		spin_lock_irqsave(&ndp->lock, flags);
  		ndp->hot_channel = hot_nc;
  		spin_unlock_irqrestore(&ndp->lock, flags);

  		ncsi_start_channel_monitor(nc);
  		ncsi_process_next_channel(ndp);
  		break;
  	default:
  		netdev_warn(dev, "Wrong NCSI state 0x%x in config
  ",
  			    nd->state);
  	}
  
  	return;
  
  error:
  	ncsi_report_link(ndp, true);
  }
  
  static int ncsi_choose_active_channel(struct ncsi_dev_priv *ndp)
  {
  	struct ncsi_package *np;

  	struct ncsi_channel *nc, *found, *hot_nc;

  	struct ncsi_channel_mode *ncm;
  	unsigned long flags;

  	spin_lock_irqsave(&ndp->lock, flags);
  	hot_nc = ndp->hot_channel;
  	spin_unlock_irqrestore(&ndp->lock, flags);

  	/* The search is done once an inactive channel with up
  	 * link is found.
  	 */
  	found = NULL;
  	NCSI_FOR_EACH_PACKAGE(ndp, np) {
  		NCSI_FOR_EACH_CHANNEL(np, nc) {

  			spin_lock_irqsave(&nc->lock, flags);

  			if (!list_empty(&nc->link) ||

  			    nc->state != NCSI_CHANNEL_INACTIVE) {
  				spin_unlock_irqrestore(&nc->lock, flags);

  				continue;

  			}

  
  			if (!found)
  				found = nc;

  			if (nc == hot_nc)
  				found = nc;

  			ncm = &nc->modes[NCSI_MODE_LINK];
  			if (ncm->data[2] & 0x1) {

  				spin_unlock_irqrestore(&nc->lock, flags);

  				found = nc;
  				goto out;
  			}

  
  			spin_unlock_irqrestore(&nc->lock, flags);

  		}
  	}
  
  	if (!found) {
  		ncsi_report_link(ndp, true);
  		return -ENODEV;
  	}
  
  out:
  	spin_lock_irqsave(&ndp->lock, flags);
  	list_add_tail_rcu(&found->link, &ndp->channel_queue);
  	spin_unlock_irqrestore(&ndp->lock, flags);
  
  	return ncsi_process_next_channel(ndp);
  }
  
  static bool ncsi_check_hwa(struct ncsi_dev_priv *ndp)
  {
  	struct ncsi_package *np;
  	struct ncsi_channel *nc;
  	unsigned int cap;
  
  	/* The hardware arbitration is disabled if any one channel
  	 * doesn't support explicitly.
  	 */
  	NCSI_FOR_EACH_PACKAGE(ndp, np) {
  		NCSI_FOR_EACH_CHANNEL(np, nc) {
  			cap = nc->caps[NCSI_CAP_GENERIC].cap;
  			if (!(cap & NCSI_CAP_GENERIC_HWA) ||
  			    (cap & NCSI_CAP_GENERIC_HWA_MASK) !=
  			    NCSI_CAP_GENERIC_HWA_SUPPORT) {
  				ndp->flags &= ~NCSI_DEV_HWA;
  				return false;
  			}
  		}
  	}
  
  	ndp->flags |= NCSI_DEV_HWA;
  	return true;
  }
  
  static int ncsi_enable_hwa(struct ncsi_dev_priv *ndp)
  {
  	struct ncsi_package *np;
  	struct ncsi_channel *nc;
  	unsigned long flags;
  
  	/* Move all available channels to processing queue */
  	spin_lock_irqsave(&ndp->lock, flags);
  	NCSI_FOR_EACH_PACKAGE(ndp, np) {
  		NCSI_FOR_EACH_CHANNEL(np, nc) {
  			WARN_ON_ONCE(nc->state != NCSI_CHANNEL_INACTIVE ||
  				     !list_empty(&nc->link));
  			ncsi_stop_channel_monitor(nc);
  			list_add_tail_rcu(&nc->link, &ndp->channel_queue);
  		}
  	}
  	spin_unlock_irqrestore(&ndp->lock, flags);
  
  	/* We can have no channels in extremely case */
  	if (list_empty(&ndp->channel_queue)) {
  		ncsi_report_link(ndp, false);
  		return -ENOENT;
  	}
  
  	return ncsi_process_next_channel(ndp);
  }
  
  static void ncsi_probe_channel(struct ncsi_dev_priv *ndp)
  {
  	struct ncsi_dev *nd = &ndp->ndev;
  	struct ncsi_package *np;
  	struct ncsi_channel *nc;
  	struct ncsi_cmd_arg nca;
  	unsigned char index;
  	int ret;
  
  	nca.ndp = ndp;

  	nca.req_flags = NCSI_REQ_FLAG_EVENT_DRIVEN;

  	switch (nd->state) {
  	case ncsi_dev_state_probe:
  		nd->state = ncsi_dev_state_probe_deselect;
  		/* Fall through */
  	case ncsi_dev_state_probe_deselect:
  		ndp->pending_req_num = 8;
  
  		/* Deselect all possible packages */
  		nca.type = NCSI_PKT_CMD_DP;

  		nca.channel = NCSI_RESERVED_CHANNEL;

  		for (index = 0; index < 8; index++) {
  			nca.package = index;
  			ret = ncsi_xmit_cmd(&nca);
  			if (ret)
  				goto error;
  		}
  
  		nd->state = ncsi_dev_state_probe_package;
  		break;
  	case ncsi_dev_state_probe_package:
  		ndp->pending_req_num = 16;
  
  		/* Select all possible packages */
  		nca.type = NCSI_PKT_CMD_SP;
  		nca.bytes[0] = 1;

  		nca.channel = NCSI_RESERVED_CHANNEL;

  		for (index = 0; index < 8; index++) {
  			nca.package = index;
  			ret = ncsi_xmit_cmd(&nca);
  			if (ret)
  				goto error;
  		}
  
  		/* Disable all possible packages */
  		nca.type = NCSI_PKT_CMD_DP;
  		for (index = 0; index < 8; index++) {
  			nca.package = index;
  			ret = ncsi_xmit_cmd(&nca);
  			if (ret)
  				goto error;
  		}
  
  		nd->state = ncsi_dev_state_probe_channel;
  		break;
  	case ncsi_dev_state_probe_channel:
  		if (!ndp->active_package)
  			ndp->active_package = list_first_or_null_rcu(
  				&ndp->packages, struct ncsi_package, node);
  		else if (list_is_last(&ndp->active_package->node,
  				      &ndp->packages))
  			ndp->active_package = NULL;
  		else
  			ndp->active_package = list_next_entry(
  				ndp->active_package, node);
  
  		/* All available packages and channels are enumerated. The
  		 * enumeration happens for once when the NCSI interface is
  		 * started. So we need continue to start the interface after
  		 * the enumeration.
  		 *
  		 * We have to choose an active channel before configuring it.
  		 * Note that we possibly don't have active channel in extreme
  		 * situation.
  		 */
  		if (!ndp->active_package) {
  			ndp->flags |= NCSI_DEV_PROBED;
  			if (ncsi_check_hwa(ndp))
  				ncsi_enable_hwa(ndp);
  			else
  				ncsi_choose_active_channel(ndp);
  			return;
  		}
  
  		/* Select the active package */
  		ndp->pending_req_num = 1;
  		nca.type = NCSI_PKT_CMD_SP;
  		nca.bytes[0] = 1;
  		nca.package = ndp->active_package->id;

  		nca.channel = NCSI_RESERVED_CHANNEL;

  		ret = ncsi_xmit_cmd(&nca);
  		if (ret)
  			goto error;
  
  		nd->state = ncsi_dev_state_probe_cis;
  		break;
  	case ncsi_dev_state_probe_cis:

  		ndp->pending_req_num = NCSI_RESERVED_CHANNEL;

  
  		/* Clear initial state */
  		nca.type = NCSI_PKT_CMD_CIS;
  		nca.package = ndp->active_package->id;

  		for (index = 0; index < NCSI_RESERVED_CHANNEL; index++) {

  			nca.channel = index;
  			ret = ncsi_xmit_cmd(&nca);
  			if (ret)
  				goto error;
  		}
  
  		nd->state = ncsi_dev_state_probe_gvi;
  		break;
  	case ncsi_dev_state_probe_gvi:
  	case ncsi_dev_state_probe_gc:
  	case ncsi_dev_state_probe_gls:
  		np = ndp->active_package;
  		ndp->pending_req_num = np->channel_num;
  
  		/* Retrieve version, capability or link status */
  		if (nd->state == ncsi_dev_state_probe_gvi)
  			nca.type = NCSI_PKT_CMD_GVI;
  		else if (nd->state == ncsi_dev_state_probe_gc)
  			nca.type = NCSI_PKT_CMD_GC;
  		else
  			nca.type = NCSI_PKT_CMD_GLS;
  
  		nca.package = np->id;
  		NCSI_FOR_EACH_CHANNEL(np, nc) {
  			nca.channel = nc->id;
  			ret = ncsi_xmit_cmd(&nca);
  			if (ret)
  				goto error;
  		}
  
  		if (nd->state == ncsi_dev_state_probe_gvi)
  			nd->state = ncsi_dev_state_probe_gc;
  		else if (nd->state == ncsi_dev_state_probe_gc)
  			nd->state = ncsi_dev_state_probe_gls;
  		else
  			nd->state = ncsi_dev_state_probe_dp;
  		break;
  	case ncsi_dev_state_probe_dp:
  		ndp->pending_req_num = 1;
  
  		/* Deselect the active package */
  		nca.type = NCSI_PKT_CMD_DP;
  		nca.package = ndp->active_package->id;

  		nca.channel = NCSI_RESERVED_CHANNEL;

  		ret = ncsi_xmit_cmd(&nca);
  		if (ret)
  			goto error;
  
  		/* Scan channels in next package */
  		nd->state = ncsi_dev_state_probe_channel;
  		break;
  	default:
  		netdev_warn(nd->dev, "Wrong NCSI state 0x%0x in enumeration
  ",
  			    nd->state);
  	}
  
  	return;
  error:
  	ncsi_report_link(ndp, true);
  }
  
  static void ncsi_dev_work(struct work_struct *work)
  {
  	struct ncsi_dev_priv *ndp = container_of(work,
  			struct ncsi_dev_priv, work);
  	struct ncsi_dev *nd = &ndp->ndev;
  
  	switch (nd->state & ncsi_dev_state_major) {
  	case ncsi_dev_state_probe:
  		ncsi_probe_channel(ndp);
  		break;
  	case ncsi_dev_state_suspend:
  		ncsi_suspend_channel(ndp);
  		break;
  	case ncsi_dev_state_config:
  		ncsi_configure_channel(ndp);
  		break;
  	default:
  		netdev_warn(nd->dev, "Wrong NCSI state 0x%x in workqueue
  ",
  			    nd->state);
  	}
  }
  
  int ncsi_process_next_channel(struct ncsi_dev_priv *ndp)
  {
  	struct ncsi_channel *nc;
  	int old_state;
  	unsigned long flags;
  
  	spin_lock_irqsave(&ndp->lock, flags);
  	nc = list_first_or_null_rcu(&ndp->channel_queue,
  				    struct ncsi_channel, link);

  	if (!nc) {
  		spin_unlock_irqrestore(&ndp->lock, flags);
  		goto out;

  	}

  	list_del_init(&nc->link);

  	spin_unlock_irqrestore(&ndp->lock, flags);

  	spin_lock_irqsave(&nc->lock, flags);
  	old_state = nc->state;
  	nc->state = NCSI_CHANNEL_INVISIBLE;
  	spin_unlock_irqrestore(&nc->lock, flags);

  	ndp->active_channel = nc;

  	ndp->active_package = nc->package;

  
  	switch (old_state) {
  	case NCSI_CHANNEL_INACTIVE:
  		ndp->ndev.state = ncsi_dev_state_config;
  		ncsi_configure_channel(ndp);
  		break;
  	case NCSI_CHANNEL_ACTIVE:
  		ndp->ndev.state = ncsi_dev_state_suspend;
  		ncsi_suspend_channel(ndp);
  		break;
  	default:
  		netdev_err(ndp->ndev.dev, "Invalid state 0x%x on %d:%d
  ",

  			   old_state, nc->package->id, nc->id);

  		ncsi_report_link(ndp, false);
  		return -EINVAL;
  	}
  
  	return 0;

  
  out:
  	ndp->active_channel = NULL;
  	ndp->active_package = NULL;
  	if (ndp->flags & NCSI_DEV_RESHUFFLE) {
  		ndp->flags &= ~NCSI_DEV_RESHUFFLE;
  		return ncsi_choose_active_channel(ndp);
  	}
  
  	ncsi_report_link(ndp, false);
  	return -ENODEV;

  }
  
  #if IS_ENABLED(CONFIG_IPV6)
  static int ncsi_inet6addr_event(struct notifier_block *this,
  				unsigned long event, void *data)
  {
  	struct inet6_ifaddr *ifa = data;
  	struct net_device *dev = ifa->idev->dev;
  	struct ncsi_dev *nd = ncsi_find_dev(dev);
  	struct ncsi_dev_priv *ndp = nd ? TO_NCSI_DEV_PRIV(nd) : NULL;
  	struct ncsi_package *np;
  	struct ncsi_channel *nc;
  	struct ncsi_cmd_arg nca;
  	bool action;
  	int ret;
  
  	if (!ndp || (ipv6_addr_type(&ifa->addr) &
  	    (IPV6_ADDR_LINKLOCAL | IPV6_ADDR_LOOPBACK)))
  		return NOTIFY_OK;
  
  	switch (event) {
  	case NETDEV_UP:
  		action = (++ndp->inet6_addr_num) == 1;
  		nca.type = NCSI_PKT_CMD_EGMF;
  		break;
  	case NETDEV_DOWN:
  		action = (--ndp->inet6_addr_num == 0);
  		nca.type = NCSI_PKT_CMD_DGMF;
  		break;
  	default:
  		return NOTIFY_OK;
  	}
  
  	/* We might not have active channel or packages. The IPv6
  	 * required multicast will be enabled when active channel
  	 * or packages are chosen.
  	 */
  	np = ndp->active_package;
  	nc = ndp->active_channel;
  	if (!action || !np || !nc)
  		return NOTIFY_OK;
  
  	/* We needn't enable or disable it if the function isn't supported */
  	if (!(nc->caps[NCSI_CAP_GENERIC].cap & NCSI_CAP_GENERIC_MC))
  		return NOTIFY_OK;
  
  	nca.ndp = ndp;

  	nca.req_flags = 0;

  	nca.package = np->id;
  	nca.channel = nc->id;
  	nca.dwords[0] = nc->caps[NCSI_CAP_MC].cap;
  	ret = ncsi_xmit_cmd(&nca);
  	if (ret) {
  		netdev_warn(dev, "Fail to %s global multicast filter (%d)
  ",
  			    (event == NETDEV_UP) ? "enable" : "disable", ret);
  		return NOTIFY_DONE;
  	}
  
  	return NOTIFY_OK;
  }
  
  static struct notifier_block ncsi_inet6addr_notifier = {
  	.notifier_call = ncsi_inet6addr_event,
  };
  #endif /* CONFIG_IPV6 */

  struct ncsi_dev *ncsi_register_dev(struct net_device *dev,
  				   void (*handler)(struct ncsi_dev *ndev))
  {
  	struct ncsi_dev_priv *ndp;
  	struct ncsi_dev *nd;
  	unsigned long flags;
  	int i;
  
  	/* Check if the device has been registered or not */
  	nd = ncsi_find_dev(dev);
  	if (nd)
  		return nd;
  
  	/* Create NCSI device */
  	ndp = kzalloc(sizeof(*ndp), GFP_ATOMIC);
  	if (!ndp)
  		return NULL;
  
  	nd = &ndp->ndev;
  	nd->state = ncsi_dev_state_registered;
  	nd->dev = dev;
  	nd->handler = handler;

  	ndp->pending_req_num = 0;
  	INIT_LIST_HEAD(&ndp->channel_queue);
  	INIT_WORK(&ndp->work, ncsi_dev_work);

  
  	/* Initialize private NCSI device */
  	spin_lock_init(&ndp->lock);
  	INIT_LIST_HEAD(&ndp->packages);

  	ndp->request_id = NCSI_REQ_START_IDX;

  	for (i = 0; i < ARRAY_SIZE(ndp->requests); i++) {
  		ndp->requests[i].id = i;
  		ndp->requests[i].ndp = ndp;
  		setup_timer(&ndp->requests[i].timer,
  			    ncsi_request_timeout,
  			    (unsigned long)&ndp->requests[i]);
  	}
  
  	spin_lock_irqsave(&ncsi_dev_lock, flags);

  #if IS_ENABLED(CONFIG_IPV6)
  	ndp->inet6_addr_num = 0;
  	if (list_empty(&ncsi_dev_list))
  		register_inet6addr_notifier(&ncsi_inet6addr_notifier);
  #endif

  	list_add_tail_rcu(&ndp->node, &ncsi_dev_list);
  	spin_unlock_irqrestore(&ncsi_dev_lock, flags);

  	/* Register NCSI packet Rx handler */
  	ndp->ptype.type = cpu_to_be16(ETH_P_NCSI);
  	ndp->ptype.func = ncsi_rcv_rsp;
  	ndp->ptype.dev = dev;
  	dev_add_pack(&ndp->ptype);

  	return nd;
  }
  EXPORT_SYMBOL_GPL(ncsi_register_dev);

  int ncsi_start_dev(struct ncsi_dev *nd)
  {
  	struct ncsi_dev_priv *ndp = TO_NCSI_DEV_PRIV(nd);

  	int ret;

  
  	if (nd->state != ncsi_dev_state_registered &&
  	    nd->state != ncsi_dev_state_functional)
  		return -ENOTTY;
  
  	if (!(ndp->flags & NCSI_DEV_PROBED)) {
  		nd->state = ncsi_dev_state_probe;
  		schedule_work(&ndp->work);
  		return 0;
  	}

  	if (ndp->flags & NCSI_DEV_HWA)
  		ret = ncsi_enable_hwa(ndp);
  	else
  		ret = ncsi_choose_active_channel(ndp);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(ncsi_start_dev);
  
  void ncsi_stop_dev(struct ncsi_dev *nd)
  {
  	struct ncsi_dev_priv *ndp = TO_NCSI_DEV_PRIV(nd);
  	struct ncsi_package *np;
  	struct ncsi_channel *nc;
  	bool chained;
  	int old_state;
  	unsigned long flags;
  
  	/* Stop the channel monitor and reset channel's state */

  	NCSI_FOR_EACH_PACKAGE(ndp, np) {
  		NCSI_FOR_EACH_CHANNEL(np, nc) {

  			ncsi_stop_channel_monitor(nc);

  			spin_lock_irqsave(&nc->lock, flags);
  			chained = !list_empty(&nc->link);
  			old_state = nc->state;
  			nc->state = NCSI_CHANNEL_INACTIVE;
  			spin_unlock_irqrestore(&nc->lock, flags);
  
  			WARN_ON_ONCE(chained ||

  				     old_state == NCSI_CHANNEL_INVISIBLE);
  		}
  	}

  	ncsi_report_link(ndp, true);

  }

  EXPORT_SYMBOL_GPL(ncsi_stop_dev);

  void ncsi_unregister_dev(struct ncsi_dev *nd)
  {
  	struct ncsi_dev_priv *ndp = TO_NCSI_DEV_PRIV(nd);
  	struct ncsi_package *np, *tmp;
  	unsigned long flags;

  	dev_remove_pack(&ndp->ptype);

  	list_for_each_entry_safe(np, tmp, &ndp->packages, node)
  		ncsi_remove_package(np);
  
  	spin_lock_irqsave(&ncsi_dev_lock, flags);
  	list_del_rcu(&ndp->node);

  #if IS_ENABLED(CONFIG_IPV6)
  	if (list_empty(&ncsi_dev_list))
  		unregister_inet6addr_notifier(&ncsi_inet6addr_notifier);
  #endif

  	spin_unlock_irqrestore(&ncsi_dev_lock, flags);
  
  	kfree(ndp);
  }
  EXPORT_SYMBOL_GPL(ncsi_unregister_dev);