/*
   * 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 <net/ncsi.h>
  #include <net/net_namespace.h>
  #include <net/sock.h>
  
  #include "internal.h"
  #include "ncsi-pkt.h"
  
  static int ncsi_validate_aen_pkt(struct ncsi_aen_pkt_hdr *h,
  				 const unsigned short payload)
  {
  	u32 checksum;
  	__be32 *pchecksum;
  
  	if (h->common.revision != NCSI_PKT_REVISION)
  		return -EINVAL;
  	if (ntohs(h->common.length) != payload)
  		return -EINVAL;
  
  	/* Validate checksum, which might be zeroes if the
  	 * sender doesn't support checksum according to NCSI
  	 * specification.
  	 */
  	pchecksum = (__be32 *)((void *)(h + 1) + payload - 4);
  	if (ntohl(*pchecksum) == 0)
  		return 0;
  
  	checksum = ncsi_calculate_checksum((unsigned char *)h,
  					   sizeof(*h) + payload - 4);
  	if (*pchecksum != htonl(checksum))
  		return -EINVAL;
  
  	return 0;
  }
  
  static int ncsi_aen_handler_lsc(struct ncsi_dev_priv *ndp,
  				struct ncsi_aen_pkt_hdr *h)
  {
  	struct ncsi_aen_lsc_pkt *lsc;
  	struct ncsi_channel *nc;
  	struct ncsi_channel_mode *ncm;

  	bool chained;
  	int state;
  	unsigned long old_data, data;

  	unsigned long flags;
  
  	/* Find the NCSI channel */
  	ncsi_find_package_and_channel(ndp, h->common.channel, NULL, &nc);
  	if (!nc)
  		return -ENODEV;
  
  	/* Update the link status */

  	lsc = (struct ncsi_aen_lsc_pkt *)h;

  
  	spin_lock_irqsave(&nc->lock, flags);
  	ncm = &nc->modes[NCSI_MODE_LINK];

  	old_data = ncm->data[2];

  	data = ntohl(lsc->status);
  	ncm->data[2] = data;

  	ncm->data[4] = ntohl(lsc->oem_status);

  
  	chained = !list_empty(&nc->link);
  	state = nc->state;
  	spin_unlock_irqrestore(&nc->lock, flags);
  
  	if (!((old_data ^ data) & 0x1) || chained)

  		return 0;

  	if (!(state == NCSI_CHANNEL_INACTIVE && (data & 0x1)) &&
  	    !(state == NCSI_CHANNEL_ACTIVE && !(data & 0x1)))

  		return 0;
  
  	if (!(ndp->flags & NCSI_DEV_HWA) &&

  	    state == NCSI_CHANNEL_ACTIVE)

  		ndp->flags |= NCSI_DEV_RESHUFFLE;
  
  	ncsi_stop_channel_monitor(nc);
  	spin_lock_irqsave(&ndp->lock, flags);
  	list_add_tail_rcu(&nc->link, &ndp->channel_queue);
  	spin_unlock_irqrestore(&ndp->lock, flags);
  
  	return ncsi_process_next_channel(ndp);
  }
  
  static int ncsi_aen_handler_cr(struct ncsi_dev_priv *ndp,
  			       struct ncsi_aen_pkt_hdr *h)
  {
  	struct ncsi_channel *nc;
  	unsigned long flags;
  
  	/* Find the NCSI channel */
  	ncsi_find_package_and_channel(ndp, h->common.channel, NULL, &nc);
  	if (!nc)
  		return -ENODEV;

  	spin_lock_irqsave(&nc->lock, flags);

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

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

  		return 0;

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

  
  	ncsi_stop_channel_monitor(nc);

  	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);
  
  	return ncsi_process_next_channel(ndp);
  }
  
  static int ncsi_aen_handler_hncdsc(struct ncsi_dev_priv *ndp,
  				   struct ncsi_aen_pkt_hdr *h)
  {
  	struct ncsi_channel *nc;
  	struct ncsi_channel_mode *ncm;
  	struct ncsi_aen_hncdsc_pkt *hncdsc;
  	unsigned long flags;
  
  	/* Find the NCSI channel */
  	ncsi_find_package_and_channel(ndp, h->common.channel, NULL, &nc);
  	if (!nc)
  		return -ENODEV;
  
  	/* If the channel is active one, we need reconfigure it */

  	spin_lock_irqsave(&nc->lock, flags);

  	ncm = &nc->modes[NCSI_MODE_LINK];
  	hncdsc = (struct ncsi_aen_hncdsc_pkt *)h;
  	ncm->data[3] = ntohl(hncdsc->status);
  	if (!list_empty(&nc->link) ||

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

  		return 0;

  	}

  	spin_unlock_irqrestore(&nc->lock, flags);
  	if (!(ndp->flags & NCSI_DEV_HWA) && !(ncm->data[3] & 0x1))

  		ndp->flags |= NCSI_DEV_RESHUFFLE;
  
  	/* If this channel is the active one and the link doesn't
  	 * work, we have to choose another channel to be active one.
  	 * The logic here is exactly similar to what we do when link
  	 * is down on the active channel.

  	 *
  	 * On the other hand, we need configure it when host driver
  	 * state on the active channel becomes ready.

  	 */
  	ncsi_stop_channel_monitor(nc);

  
  	spin_lock_irqsave(&nc->lock, flags);
  	nc->state = (ncm->data[3] & 0x1) ? NCSI_CHANNEL_INACTIVE :
  					   NCSI_CHANNEL_ACTIVE;
  	spin_unlock_irqrestore(&nc->lock, flags);

  	spin_lock_irqsave(&ndp->lock, flags);
  	list_add_tail_rcu(&nc->link, &ndp->channel_queue);
  	spin_unlock_irqrestore(&ndp->lock, flags);
  
  	ncsi_process_next_channel(ndp);
  
  	return 0;
  }
  
  static struct ncsi_aen_handler {
  	unsigned char type;
  	int           payload;
  	int           (*handler)(struct ncsi_dev_priv *ndp,
  				 struct ncsi_aen_pkt_hdr *h);
  } ncsi_aen_handlers[] = {
  	{ NCSI_PKT_AEN_LSC,    12, ncsi_aen_handler_lsc    },
  	{ NCSI_PKT_AEN_CR,      4, ncsi_aen_handler_cr     },

  	{ NCSI_PKT_AEN_HNCDSC,  8, ncsi_aen_handler_hncdsc }

  };
  
  int ncsi_aen_handler(struct ncsi_dev_priv *ndp, struct sk_buff *skb)
  {
  	struct ncsi_aen_pkt_hdr *h;
  	struct ncsi_aen_handler *nah = NULL;
  	int i, ret;
  
  	/* Find the handler */
  	h = (struct ncsi_aen_pkt_hdr *)skb_network_header(skb);
  	for (i = 0; i < ARRAY_SIZE(ncsi_aen_handlers); i++) {
  		if (ncsi_aen_handlers[i].type == h->type) {
  			nah = &ncsi_aen_handlers[i];
  			break;
  		}
  	}
  
  	if (!nah) {
  		netdev_warn(ndp->ndev.dev, "Invalid AEN (0x%x) received
  ",
  			    h->type);
  		return -ENOENT;
  	}
  
  	ret = ncsi_validate_aen_pkt(h, nah->payload);
  	if (ret)
  		goto out;
  
  	ret = nah->handler(ndp, h);
  out:
  	consume_skb(skb);
  	return ret;
  }