/*
 * Copyright (c) 2016, Mellanox Technologies. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/mlx5/driver.h>
#include <linux/mlx5/fs.h>
#include <linux/rbtree.h>
#include "mlx5_core.h"
#include "fs_core.h"
#include "fs_cmd.h"

#define MLX5_FC_STATS_PERIOD msecs_to_jiffies(1000)

/* locking scheme:
 *
 * It is the responsibility of the user to prevent concurrent calls or bad
 * ordering to mlx5_fc_create(), mlx5_fc_destroy() and accessing a reference
 * to struct mlx5_fc.
 * e.g en_tc.c is protected by RTNL lock of its caller, and will never call a
 * dump (access to struct mlx5_fc) after a counter is destroyed.
 *
 * access to counter list:
 * - create (user context)
 *   - mlx5_fc_create() only adds to an addlist to be used by
 *     mlx5_fc_stats_query_work(). addlist is protected by a spinlock.
 *   - spawn thread to do the actual destroy
 *
 * - destroy (user context)
 *   - mark a counter as deleted
 *   - spawn thread to do the actual del
 *
 * - dump (user context)
 *   user should not call dump after destroy
 *
 * - query (single thread workqueue context)
 *   destroy/dump - no conflict (see destroy)
 *   query/dump - packets and bytes might be inconsistent (since update is not
 *                atomic)
 *   query/create - no conflict (see create)
 *   since every create/destroy spawn the work, only after necessary time has
 *   elapsed, the thread will actually query the hardware.
 */

static void mlx5_fc_stats_insert(struct rb_root *root, struct mlx5_fc *counter)
{
        struct rb_node **new = &root->rb_node;
        struct rb_node *parent = NULL;

        while (*new) {
                struct mlx5_fc *this = container_of(*new, struct mlx5_fc, node);
                int result = counter->id - this->id;

                parent = *new;
                if (result < 0)
                        new = &((*new)->rb_left);
                else
                        new = &((*new)->rb_right);
        }

        /* Add new node and rebalance tree. */
        rb_link_node(&counter->node, parent, new);
        rb_insert_color(&counter->node, root);
}

static struct rb_node *mlx5_fc_stats_query(struct mlx5_core_dev *dev,
                                           struct mlx5_fc *first,
                                           u16 last_id)
{
        struct mlx5_cmd_fc_bulk *b;
        struct rb_node *node = NULL;
        u16 afirst_id;
        int num;
        int err;
        int max_bulk = 1 << MLX5_CAP_GEN(dev, log_max_flow_counter_bulk);

        /* first id must be aligned to 4 when using bulk query */
        afirst_id = first->id & ~0x3;

        /* number of counters to query inc. the last counter */
        num = ALIGN(last_id - afirst_id + 1, 4);
        if (num > max_bulk) {
                num = max_bulk;
                last_id = afirst_id + num - 1;
        }

        b = mlx5_cmd_fc_bulk_alloc(dev, afirst_id, num);
        if (!b) {
                mlx5_core_err(dev, "Error allocating resources for bulk query\n");
                return NULL;
        }

        err = mlx5_cmd_fc_bulk_query(dev, b);
        if (err) {
                mlx5_core_err(dev, "Error doing bulk query: %d\n", err);
                goto out;
        }

        for (node = &first->node; node; node = rb_next(node)) {
                struct mlx5_fc *counter = rb_entry(node, struct mlx5_fc, node);
                struct mlx5_fc_cache *c = &counter->cache;
                u64 packets;
                u64 bytes;

                if (counter->id > last_id)
                        break;

                mlx5_cmd_fc_bulk_get(dev, b,
                                     counter->id, &packets, &bytes);

                if (c->packets == packets)
                        continue;

                c->packets = packets;
                c->bytes = bytes;
                c->lastuse = jiffies;
        }

out:
        mlx5_cmd_fc_bulk_free(b);

        return node;
}

static void mlx5_fc_stats_work(struct work_struct *work)
{
        struct mlx5_core_dev *dev = container_of(work, struct mlx5_core_dev,
                                                 priv.fc_stats.work.work);
        struct mlx5_fc_stats *fc_stats = &dev->priv.fc_stats;
        unsigned long now = jiffies;
        struct mlx5_fc *counter = NULL;
        struct mlx5_fc *last = NULL;
        struct rb_node *node;
        LIST_HEAD(tmplist);

        spin_lock(&fc_stats->addlist_lock);

        list_splice_tail_init(&fc_stats->addlist, &tmplist);

        if (!list_empty(&tmplist) || !RB_EMPTY_ROOT(&fc_stats->counters))
                queue_delayed_work(fc_stats->wq, &fc_stats->work, MLX5_FC_STATS_PERIOD);

        spin_unlock(&fc_stats->addlist_lock);

        list_for_each_entry(counter, &tmplist, list)
                mlx5_fc_stats_insert(&fc_stats->counters, counter);

        node = rb_first(&fc_stats->counters);
        while (node) {
                counter = rb_entry(node, struct mlx5_fc, node);

                node = rb_next(node);

                if (counter->deleted) {
                        rb_erase(&counter->node, &fc_stats->counters);

                        mlx5_cmd_fc_free(dev, counter->id);

                        kfree(counter);
                        continue;
                }

                last = counter;
        }

        if (time_before(now, fc_stats->next_query) || !last)
                return;

        node = rb_first(&fc_stats->counters);
        while (node) {
                counter = rb_entry(node, struct mlx5_fc, node);

                node = mlx5_fc_stats_query(dev, counter, last->id);
        }

        fc_stats->next_query = now + MLX5_FC_STATS_PERIOD;
}

struct mlx5_fc *mlx5_fc_create(struct mlx5_core_dev *dev, bool aging)
{
        struct mlx5_fc_stats *fc_stats = &dev->priv.fc_stats;
        struct mlx5_fc *counter;
        int err;

        counter = kzalloc(sizeof(*counter), GFP_KERNEL);
        if (!counter)
                return ERR_PTR(-ENOMEM);

        err = mlx5_cmd_fc_alloc(dev, &counter->id);
        if (err)
                goto err_out;

        if (aging) {
                counter->cache.lastuse = jiffies;
                counter->aging = true;

                spin_lock(&fc_stats->addlist_lock);
                list_add(&counter->list, &fc_stats->addlist);
                spin_unlock(&fc_stats->addlist_lock);

                mod_delayed_work(fc_stats->wq, &fc_stats->work, 0);
        }

        return counter;

err_out:
        kfree(counter);

        return ERR_PTR(err);
}

void mlx5_fc_destroy(struct mlx5_core_dev *dev, struct mlx5_fc *counter)
{
        struct mlx5_fc_stats *fc_stats = &dev->priv.fc_stats;

        if (!counter)
                return;

        if (counter->aging) {
                counter->deleted = true;
                mod_delayed_work(fc_stats->wq, &fc_stats->work, 0);
                return;
        }

        mlx5_cmd_fc_free(dev, counter->id);
        kfree(counter);
}

int mlx5_init_fc_stats(struct mlx5_core_dev *dev)
{
        struct mlx5_fc_stats *fc_stats = &dev->priv.fc_stats;

        fc_stats->counters = RB_ROOT;
        INIT_LIST_HEAD(&fc_stats->addlist);
        spin_lock_init(&fc_stats->addlist_lock);

        fc_stats->wq = create_singlethread_workqueue("mlx5_fc");
        if (!fc_stats->wq)
                return -ENOMEM;

        INIT_DELAYED_WORK(&fc_stats->work, mlx5_fc_stats_work);

        return 0;
}

void mlx5_cleanup_fc_stats(struct mlx5_core_dev *dev)
{
        struct mlx5_fc_stats *fc_stats = &dev->priv.fc_stats;
        struct mlx5_fc *counter;
        struct mlx5_fc *tmp;
        struct rb_node *node;

        cancel_delayed_work_sync(&dev->priv.fc_stats.work);
        destroy_workqueue(dev->priv.fc_stats.wq);
        dev->priv.fc_stats.wq = NULL;

        list_for_each_entry_safe(counter, tmp, &fc_stats->addlist, list) {
                list_del(&counter->list);

                mlx5_cmd_fc_free(dev, counter->id);

                kfree(counter);
        }

        node = rb_first(&fc_stats->counters);
        while (node) {
                counter = rb_entry(node, struct mlx5_fc, node);

                node = rb_next(node);

                rb_erase(&counter->node, &fc_stats->counters);

                mlx5_cmd_fc_free(dev, counter->id);

                kfree(counter);
        }
}

void mlx5_fc_query_cached(struct mlx5_fc *counter,
                          u64 *bytes, u64 *packets, u64 *lastuse)
{
        struct mlx5_fc_cache c;

        c = counter->cache;

        *bytes = c.bytes - counter->lastbytes;
        *packets = c.packets - counter->lastpackets;
        *lastuse = c.lastuse;

        counter->lastbytes = c.bytes;
        counter->lastpackets = c.packets;
}