// SPDX-License-Identifier: GPL-2.0

  #include <linux/types.h>
  #include <linux/atmmpc.h>

  #include <linux/slab.h>

  #include <linux/time.h>
  
  #include "mpoa_caches.h"
  #include "mpc.h"
  
  /*
   * mpoa_caches.c: Implementation of ingress and egress cache
   * handling functions
   */
  
  #if 0

  #define dprintk(format, args...)					\
  	printk(KERN_DEBUG "mpoa:%s: " format, __FILE__, ##args)  /* debug */

  #else

  #define dprintk(format, args...)					\
  	do { if (0)							\
  		printk(KERN_DEBUG "mpoa:%s: " format, __FILE__, ##args);\
  	} while (0)

  #endif
  
  #if 0

  #define ddprintk(format, args...)					\
  	printk(KERN_DEBUG "mpoa:%s: " format, __FILE__, ##args)  /* debug */

  #else

  #define ddprintk(format, args...)					\
  	do { if (0)							\
  		printk(KERN_DEBUG "mpoa:%s: " format, __FILE__, ##args);\
  	} while (0)

  #endif

  static in_cache_entry *in_cache_get(__be32 dst_ip,

  				    struct mpoa_client *client)
  {
  	in_cache_entry *entry;
  
  	read_lock_bh(&client->ingress_lock);
  	entry = client->in_cache;

  	while (entry != NULL) {
  		if (entry->ctrl_info.in_dst_ip == dst_ip) {

  			refcount_inc(&entry->use);

  			read_unlock_bh(&client->ingress_lock);
  			return entry;
  		}
  		entry = entry->next;
  	}
  	read_unlock_bh(&client->ingress_lock);
  
  	return NULL;
  }

  static in_cache_entry *in_cache_get_with_mask(__be32 dst_ip,

  					      struct mpoa_client *client,

  					      __be32 mask)

  {
  	in_cache_entry *entry;
  
  	read_lock_bh(&client->ingress_lock);
  	entry = client->in_cache;

  	while (entry != NULL) {
  		if ((entry->ctrl_info.in_dst_ip & mask) == (dst_ip & mask)) {

  			refcount_inc(&entry->use);

  			read_unlock_bh(&client->ingress_lock);
  			return entry;
  		}
  		entry = entry->next;
  	}
  	read_unlock_bh(&client->ingress_lock);
  
  	return NULL;
  
  }
  
  static in_cache_entry *in_cache_get_by_vcc(struct atm_vcc *vcc,

  					   struct mpoa_client *client)

  {
  	in_cache_entry *entry;
  
  	read_lock_bh(&client->ingress_lock);
  	entry = client->in_cache;

  	while (entry != NULL) {
  		if (entry->shortcut == vcc) {

  			refcount_inc(&entry->use);

  			read_unlock_bh(&client->ingress_lock);
  			return entry;
  		}
  		entry = entry->next;
  	}
  	read_unlock_bh(&client->ingress_lock);
  
  	return NULL;
  }

  static in_cache_entry *in_cache_add_entry(__be32 dst_ip,

  					  struct mpoa_client *client)
  {

  	in_cache_entry *entry = kzalloc(sizeof(in_cache_entry), GFP_KERNEL);

  
  	if (entry == NULL) {

  		pr_info("mpoa: mpoa_caches.c: new_in_cache_entry: out of memory
  ");

  		return NULL;
  	}

  	dprintk("adding an ingress entry, ip = %pI4
  ", &dst_ip);

  	refcount_set(&entry->use, 1);

  	dprintk("new_in_cache_entry: about to lock
  ");

  	write_lock_bh(&client->ingress_lock);
  	entry->next = client->in_cache;
  	entry->prev = NULL;
  	if (client->in_cache != NULL)
  		client->in_cache->prev = entry;
  	client->in_cache = entry;
  
  	memcpy(entry->MPS_ctrl_ATM_addr, client->mps_ctrl_addr, ATM_ESA_LEN);
  	entry->ctrl_info.in_dst_ip = dst_ip;
  	do_gettimeofday(&(entry->tv));
  	entry->retry_time = client->parameters.mpc_p4;
  	entry->count = 1;
  	entry->entry_state = INGRESS_INVALID;
  	entry->ctrl_info.holding_time = HOLDING_TIME_DEFAULT;

  	refcount_inc(&entry->use);

  
  	write_unlock_bh(&client->ingress_lock);

  	dprintk("new_in_cache_entry: unlocked
  ");

  
  	return entry;
  }
  
  static int cache_hit(in_cache_entry *entry, struct mpoa_client *mpc)
  {
  	struct atm_mpoa_qos *qos;
  	struct k_message msg;
  
  	entry->count++;

  	if (entry->entry_state == INGRESS_RESOLVED && entry->shortcut != NULL)

  		return OPEN;

  	if (entry->entry_state == INGRESS_REFRESHING) {
  		if (entry->count > mpc->parameters.mpc_p1) {

  			msg.type = SND_MPOA_RES_RQST;
  			msg.content.in_info = entry->ctrl_info;
  			memcpy(msg.MPS_ctrl, mpc->mps_ctrl_addr, ATM_ESA_LEN);
  			qos = atm_mpoa_search_qos(entry->ctrl_info.in_dst_ip);

  			if (qos != NULL)
  				msg.qos = qos->qos;

  			msg_to_mpoad(&msg, mpc);
  			do_gettimeofday(&(entry->reply_wait));
  			entry->entry_state = INGRESS_RESOLVING;
  		}

  		if (entry->shortcut != NULL)

  			return OPEN;
  		return CLOSED;
  	}

  	if (entry->entry_state == INGRESS_RESOLVING && entry->shortcut != NULL)

  		return OPEN;

  	if (entry->count > mpc->parameters.mpc_p1 &&
  	    entry->entry_state == INGRESS_INVALID) {

  		dprintk("(%s) threshold exceeded for ip %pI4, sending MPOA res req
  ",

  			mpc->dev->name, &entry->ctrl_info.in_dst_ip);

  		entry->entry_state = INGRESS_RESOLVING;

  		msg.type = SND_MPOA_RES_RQST;
  		memcpy(msg.MPS_ctrl, mpc->mps_ctrl_addr, ATM_ESA_LEN);

  		msg.content.in_info = entry->ctrl_info;
  		qos = atm_mpoa_search_qos(entry->ctrl_info.in_dst_ip);

  		if (qos != NULL)
  			msg.qos = qos->qos;
  		msg_to_mpoad(&msg, mpc);

  		do_gettimeofday(&(entry->reply_wait));
  	}
  
  	return CLOSED;
  }
  
  static void in_cache_put(in_cache_entry *entry)
  {

  	if (refcount_dec_and_test(&entry->use)) {

  		memset(entry, 0, sizeof(in_cache_entry));
  		kfree(entry);
  	}

  }
  
  /*
   * This should be called with write lock on
   */
  static void in_cache_remove_entry(in_cache_entry *entry,
  				  struct mpoa_client *client)
  {
  	struct atm_vcc *vcc;
  	struct k_message msg;

  
  	vcc = entry->shortcut;

  	dprintk("removing an ingress entry, ip = %pI4
  ",

  		&entry->ctrl_info.in_dst_ip);

  
  	if (entry->prev != NULL)
  		entry->prev->next = entry->next;
  	else
  		client->in_cache = entry->next;
  	if (entry->next != NULL)
  		entry->next->prev = entry->prev;
  	client->in_ops->put(entry);

  	if (client->in_cache == NULL && client->eg_cache == NULL) {

  		msg.type = STOP_KEEP_ALIVE_SM;

  		msg_to_mpoad(&msg, client);

  	}
  
  	/* Check if the egress side still uses this VCC */
  	if (vcc != NULL) {

  		eg_cache_entry *eg_entry = client->eg_ops->get_by_vcc(vcc,
  								      client);

  		if (eg_entry != NULL) {
  			client->eg_ops->put(eg_entry);
  			return;
  		}
  		vcc_release_async(vcc, -EPIPE);
  	}

  }

  /* Call this every MPC-p2 seconds... Not exactly correct solution,
     but an easy one... */
  static void clear_count_and_expired(struct mpoa_client *client)
  {

  	in_cache_entry *entry, *next_entry;
  	struct timeval now;
  
  	do_gettimeofday(&now);
  
  	write_lock_bh(&client->ingress_lock);
  	entry = client->in_cache;

  	while (entry != NULL) {
  		entry->count = 0;

  		next_entry = entry->next;

  		if ((now.tv_sec - entry->tv.tv_sec)
  		   > entry->ctrl_info.holding_time) {

  			dprintk("holding time expired, ip = %pI4
  ",

  				&entry->ctrl_info.in_dst_ip);

  			client->in_ops->remove_entry(entry, client);
  		}
  		entry = next_entry;
  	}
  	write_unlock_bh(&client->ingress_lock);

  }
  
  /* Call this every MPC-p4 seconds. */
  static void check_resolving_entries(struct mpoa_client *client)
  {
  
  	struct atm_mpoa_qos *qos;
  	in_cache_entry *entry;
  	struct timeval now;
  	struct k_message msg;

  	do_gettimeofday(&now);

  
  	read_lock_bh(&client->ingress_lock);
  	entry = client->in_cache;

  	while (entry != NULL) {
  		if (entry->entry_state == INGRESS_RESOLVING) {
  			if ((now.tv_sec - entry->hold_down.tv_sec) <
  			    client->parameters.mpc_p6) {
  				entry = entry->next;	/* Entry in hold down */

  				continue;
  			}

  			if ((now.tv_sec - entry->reply_wait.tv_sec) >
  			    entry->retry_time) {
  				entry->retry_time = MPC_C1 * (entry->retry_time);
  				/*
  				 * Retry time maximum exceeded,
  				 * put entry in hold down.
  				 */
  				if (entry->retry_time > client->parameters.mpc_p5) {

  					do_gettimeofday(&(entry->hold_down));
  					entry->retry_time = client->parameters.mpc_p4;
  					entry = entry->next;
  					continue;
  				}
  				/* Ask daemon to send a resolution request. */

  				memset(&(entry->hold_down), 0, sizeof(struct timeval));

  				msg.type = SND_MPOA_RES_RTRY;
  				memcpy(msg.MPS_ctrl, client->mps_ctrl_addr, ATM_ESA_LEN);
  				msg.content.in_info = entry->ctrl_info;
  				qos = atm_mpoa_search_qos(entry->ctrl_info.in_dst_ip);

  				if (qos != NULL)
  					msg.qos = qos->qos;

  				msg_to_mpoad(&msg, client);
  				do_gettimeofday(&(entry->reply_wait));
  			}
  		}
  		entry = entry->next;
  	}
  	read_unlock_bh(&client->ingress_lock);
  }
  
  /* Call this every MPC-p5 seconds. */
  static void refresh_entries(struct mpoa_client *client)
  {
  	struct timeval now;
  	struct in_cache_entry *entry = client->in_cache;

  	ddprintk("refresh_entries
  ");

  	do_gettimeofday(&now);
  
  	read_lock_bh(&client->ingress_lock);

  	while (entry != NULL) {
  		if (entry->entry_state == INGRESS_RESOLVED) {
  			if (!(entry->refresh_time))
  				entry->refresh_time = (2 * (entry->ctrl_info.holding_time))/3;
  			if ((now.tv_sec - entry->reply_wait.tv_sec) >
  			    entry->refresh_time) {

  				dprintk("refreshing an entry.
  ");

  				entry->entry_state = INGRESS_REFRESHING;
  
  			}
  		}
  		entry = entry->next;
  	}
  	read_unlock_bh(&client->ingress_lock);
  }
  
  static void in_destroy_cache(struct mpoa_client *mpc)
  {
  	write_lock_irq(&mpc->ingress_lock);

  	while (mpc->in_cache != NULL)

  		mpc->in_ops->remove_entry(mpc->in_cache, mpc);
  	write_unlock_irq(&mpc->ingress_lock);

  }

  static eg_cache_entry *eg_cache_get_by_cache_id(__be32 cache_id,
  						struct mpoa_client *mpc)

  {
  	eg_cache_entry *entry;
  
  	read_lock_irq(&mpc->egress_lock);
  	entry = mpc->eg_cache;

  	while (entry != NULL) {
  		if (entry->ctrl_info.cache_id == cache_id) {

  			refcount_inc(&entry->use);

  			read_unlock_irq(&mpc->egress_lock);
  			return entry;
  		}
  		entry = entry->next;
  	}
  	read_unlock_irq(&mpc->egress_lock);
  
  	return NULL;
  }
  
  /* This can be called from any context since it saves CPU flags */

  static eg_cache_entry *eg_cache_get_by_tag(__be32 tag, struct mpoa_client *mpc)

  {
  	unsigned long flags;
  	eg_cache_entry *entry;
  
  	read_lock_irqsave(&mpc->egress_lock, flags);
  	entry = mpc->eg_cache;

  	while (entry != NULL) {

  		if (entry->ctrl_info.tag == tag) {

  			refcount_inc(&entry->use);

  			read_unlock_irqrestore(&mpc->egress_lock, flags);
  			return entry;
  		}
  		entry = entry->next;
  	}
  	read_unlock_irqrestore(&mpc->egress_lock, flags);
  
  	return NULL;
  }
  
  /* This can be called from any context since it saves CPU flags */

  static eg_cache_entry *eg_cache_get_by_vcc(struct atm_vcc *vcc,
  					   struct mpoa_client *mpc)

  {
  	unsigned long flags;
  	eg_cache_entry *entry;
  
  	read_lock_irqsave(&mpc->egress_lock, flags);
  	entry = mpc->eg_cache;

  	while (entry != NULL) {

  		if (entry->shortcut == vcc) {

  			refcount_inc(&entry->use);

  			read_unlock_irqrestore(&mpc->egress_lock, flags);

  			return entry;
  		}
  		entry = entry->next;
  	}
  	read_unlock_irqrestore(&mpc->egress_lock, flags);
  
  	return NULL;
  }

  static eg_cache_entry *eg_cache_get_by_src_ip(__be32 ipaddr,
  					      struct mpoa_client *mpc)

  {
  	eg_cache_entry *entry;
  
  	read_lock_irq(&mpc->egress_lock);
  	entry = mpc->eg_cache;

  	while (entry != NULL) {
  		if (entry->latest_ip_addr == ipaddr) {

  			refcount_inc(&entry->use);

  			read_unlock_irq(&mpc->egress_lock);

  			return entry;
  		}
  		entry = entry->next;
  	}
  	read_unlock_irq(&mpc->egress_lock);
  
  	return NULL;
  }
  
  static void eg_cache_put(eg_cache_entry *entry)
  {

  	if (refcount_dec_and_test(&entry->use)) {

  		memset(entry, 0, sizeof(eg_cache_entry));
  		kfree(entry);
  	}

  }
  
  /*
   * This should be called with write lock on
   */
  static void eg_cache_remove_entry(eg_cache_entry *entry,
  				  struct mpoa_client *client)
  {
  	struct atm_vcc *vcc;
  	struct k_message msg;
  
  	vcc = entry->shortcut;

  	dprintk("removing an egress entry.
  ");

  	if (entry->prev != NULL)
  		entry->prev->next = entry->next;
  	else
  		client->eg_cache = entry->next;
  	if (entry->next != NULL)
  		entry->next->prev = entry->prev;
  	client->eg_ops->put(entry);

  	if (client->in_cache == NULL && client->eg_cache == NULL) {

  		msg.type = STOP_KEEP_ALIVE_SM;

  		msg_to_mpoad(&msg, client);

  	}
  
  	/* Check if the ingress side still uses this VCC */
  	if (vcc != NULL) {
  		in_cache_entry *in_entry = client->in_ops->get_by_vcc(vcc, client);
  		if (in_entry != NULL) {
  			client->in_ops->put(in_entry);
  			return;
  		}
  		vcc_release_async(vcc, -EPIPE);
  	}

  }

  static eg_cache_entry *eg_cache_add_entry(struct k_message *msg,
  					  struct mpoa_client *client)

  {

  	eg_cache_entry *entry = kzalloc(sizeof(eg_cache_entry), GFP_KERNEL);

  
  	if (entry == NULL) {

  		pr_info("out of memory
  ");

  		return NULL;
  	}

  	dprintk("adding an egress entry, ip = %pI4, this should be our IP
  ",

  		&msg->content.eg_info.eg_dst_ip);

  	refcount_set(&entry->use, 1);

  	dprintk("new_eg_cache_entry: about to lock
  ");

  	write_lock_irq(&client->egress_lock);
  	entry->next = client->eg_cache;
  	entry->prev = NULL;
  	if (client->eg_cache != NULL)
  		client->eg_cache->prev = entry;
  	client->eg_cache = entry;
  
  	memcpy(entry->MPS_ctrl_ATM_addr, client->mps_ctrl_addr, ATM_ESA_LEN);
  	entry->ctrl_info = msg->content.eg_info;
  	do_gettimeofday(&(entry->tv));
  	entry->entry_state = EGRESS_RESOLVED;

  	dprintk("new_eg_cache_entry cache_id %u
  ",

  		ntohl(entry->ctrl_info.cache_id));

  	dprintk("mps_ip = %pI4
  ", &entry->ctrl_info.mps_ip);

  	refcount_inc(&entry->use);

  
  	write_unlock_irq(&client->egress_lock);

  	dprintk("new_eg_cache_entry: unlocked
  ");

  
  	return entry;
  }

  static void update_eg_cache_entry(eg_cache_entry *entry, uint16_t holding_time)

  {
  	do_gettimeofday(&(entry->tv));
  	entry->entry_state = EGRESS_RESOLVED;
  	entry->ctrl_info.holding_time = holding_time;

  }
  
  static void clear_expired(struct mpoa_client *client)
  {
  	eg_cache_entry *entry, *next_entry;
  	struct timeval now;
  	struct k_message msg;
  
  	do_gettimeofday(&now);
  
  	write_lock_irq(&client->egress_lock);
  	entry = client->eg_cache;

  	while (entry != NULL) {

  		next_entry = entry->next;

  		if ((now.tv_sec - entry->tv.tv_sec)
  		   > entry->ctrl_info.holding_time) {

  			msg.type = SND_EGRESS_PURGE;
  			msg.content.eg_info = entry->ctrl_info;

  			dprintk("egress_cache: holding time expired, cache_id = %u.
  ",

  				ntohl(entry->ctrl_info.cache_id));

  			msg_to_mpoad(&msg, client);
  			client->eg_ops->remove_entry(entry, client);
  		}
  		entry = next_entry;
  	}
  	write_unlock_irq(&client->egress_lock);

  }
  
  static void eg_destroy_cache(struct mpoa_client *mpc)
  {
  	write_lock_irq(&mpc->egress_lock);

  	while (mpc->eg_cache != NULL)

  		mpc->eg_ops->remove_entry(mpc->eg_cache, mpc);
  	write_unlock_irq(&mpc->egress_lock);

  }

  static const struct in_cache_ops ingress_ops = {

  	.add_entry = in_cache_add_entry,
  	.get = in_cache_get,
  	.get_with_mask = in_cache_get_with_mask,
  	.get_by_vcc = in_cache_get_by_vcc,
  	.put = in_cache_put,
  	.remove_entry = in_cache_remove_entry,
  	.cache_hit = cache_hit,
  	.clear_count = clear_count_and_expired,
  	.check_resolving = check_resolving_entries,
  	.refresh = refresh_entries,
  	.destroy_cache = in_destroy_cache

  };

  static const struct eg_cache_ops egress_ops = {

  	.add_entry = eg_cache_add_entry,
  	.get_by_cache_id = eg_cache_get_by_cache_id,
  	.get_by_tag = eg_cache_get_by_tag,
  	.get_by_vcc = eg_cache_get_by_vcc,
  	.get_by_src_ip = eg_cache_get_by_src_ip,
  	.put = eg_cache_put,
  	.remove_entry = eg_cache_remove_entry,
  	.update = update_eg_cache_entry,
  	.clear_expired = clear_expired,
  	.destroy_cache = eg_destroy_cache

  };

  void atm_mpoa_init_cache(struct mpoa_client *mpc)
  {
  	mpc->in_ops = &ingress_ops;
  	mpc->eg_ops = &egress_ops;

  }