// 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\n");
		return NULL;
	}

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

	refcount_set(&entry->use, 1);
	dprintk("new_in_cache_entry: about to lock\n");
	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;
	entry->time = ktime_get_seconds();
	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\n");

	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);
			entry->reply_wait = ktime_get_seconds();
			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\n",
			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);
		entry->reply_wait = ktime_get_seconds();
	}

	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\n",
		&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;
	time64_t now;

	now = ktime_get_seconds();

	write_lock_bh(&client->ingress_lock);
	entry = client->in_cache;
	while (entry != NULL) {
		entry->count = 0;
		next_entry = entry->next;
		if ((now - entry->time) > entry->ctrl_info.holding_time) {
			dprintk("holding time expired, ip = %pI4\n",
				&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;
	time64_t now;
	struct k_message msg;

	now = ktime_get_seconds();

	read_lock_bh(&client->ingress_lock);
	entry = client->in_cache;
	while (entry != NULL) {
		if (entry->entry_state == INGRESS_RESOLVING) {

			if ((now - entry->hold_down)
					< client->parameters.mpc_p6) {
				entry = entry->next;	/* Entry in hold down */
				continue;
			}
			if ((now - entry->reply_wait) > 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) {
					entry->hold_down = ktime_get_seconds();
					entry->retry_time = client->parameters.mpc_p4;
					entry = entry->next;
					continue;
				}
				/* Ask daemon to send a resolution request. */
				memset(&entry->hold_down, 0, sizeof(time64_t));
				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);
				entry->reply_wait = ktime_get_seconds();
			}
		}
		entry = entry->next;
	}
	read_unlock_bh(&client->ingress_lock);
}

/* Call this every MPC-p5 seconds. */
static void refresh_entries(struct mpoa_client *client)
{
	time64_t now;
	struct in_cache_entry *entry = client->in_cache;

	ddprintk("refresh_entries\n");
	now = ktime_get_seconds();

	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 - entry->reply_wait) >
			    entry->refresh_time) {
				dprintk("refreshing an entry.\n");
				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.\n");
	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\n");
		return NULL;
	}

	dprintk("adding an egress entry, ip = %pI4, this should be our IP\n",
		&msg->content.eg_info.eg_dst_ip);

	refcount_set(&entry->use, 1);
	dprintk("new_eg_cache_entry: about to lock\n");
	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;
	entry->time = ktime_get_seconds();
	entry->entry_state = EGRESS_RESOLVED;
	dprintk("new_eg_cache_entry cache_id %u\n",
		ntohl(entry->ctrl_info.cache_id));
	dprintk("mps_ip = %pI4\n", &entry->ctrl_info.mps_ip);
	refcount_inc(&entry->use);

	write_unlock_irq(&client->egress_lock);
	dprintk("new_eg_cache_entry: unlocked\n");

	return entry;
}

static void update_eg_cache_entry(eg_cache_entry *entry, uint16_t holding_time)
{
	entry->time = ktime_get_seconds();
	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;
	time64_t now;
	struct k_message msg;

	now = ktime_get_seconds();

	write_lock_irq(&client->egress_lock);
	entry = client->eg_cache;
	while (entry != NULL) {
		next_entry = entry->next;
		if ((now - entry->time) > 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.\n",
				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;
}