/*-
 * SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0
 *
 * Copyright (c) 2017 Mellanox Technologies Ltd.  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 <sys/cdefs.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>

#include <rdma/ib_verbs.h>

/* # of WCs to poll for with a single call to ib_poll_cq */
#define IB_POLL_BATCH                   16
#define IB_POLL_BATCH_DIRECT            8

/* # of WCs to iterate over before yielding */
#define IB_POLL_BUDGET_WORKQUEUE        65536

#define IB_POLL_FLAGS \
        (IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS)

static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *wcs,
                           int batch)
{
        int i, n, completed = 0;

        /*
         * budget might be (-1) if the caller does not
         * want to bound this call, thus we need unsigned
         * minimum here.
         */
        while ((n = ib_poll_cq(cq, min_t(u32, batch,
                                         budget - completed), wcs)) > 0) {
                for (i = 0; i < n; i++) {
                        struct ib_wc *wc = &wcs[i];

                        if (wc->wr_cqe)
                                wc->wr_cqe->done(cq, wc);
                        else
                                WARN_ON_ONCE(wc->status == IB_WC_SUCCESS);
                }

                completed += n;

                if (n != batch || (budget != -1 && completed >= budget))
                        break;
        }

        return completed;
}

/**
 * ib_process_direct_cq - process a CQ in caller context
 * @cq:         CQ to process
 * @budget:     number of CQEs to poll for
 *
 * This function is used to process all outstanding CQ entries.
 * It does not offload CQ processing to a different context and does
 * not ask for completion interrupts from the HCA.
 * Using direct processing on CQ with non IB_POLL_DIRECT type may trigger
 * concurrent processing.
 *
 * Note: do not pass -1 as %budget unless it is guaranteed that the number
 * of completions that will be processed is small.
 */
int ib_process_cq_direct(struct ib_cq *cq, int budget)
{
        struct ib_wc wcs[IB_POLL_BATCH_DIRECT];

        return __ib_process_cq(cq, budget, wcs, IB_POLL_BATCH_DIRECT);
}
EXPORT_SYMBOL(ib_process_cq_direct);

static void ib_cq_completion_direct(struct ib_cq *cq, void *private)
{
        WARN_ONCE(1, "got unsolicited completion for CQ 0x%p\n", cq);
}

static void ib_cq_poll_work(struct work_struct *work)
{
        struct ib_cq *cq = container_of(work, struct ib_cq, work);
        int completed;

        completed = __ib_process_cq(cq, IB_POLL_BUDGET_WORKQUEUE, cq->wc,
                                    IB_POLL_BATCH);
        if (completed >= IB_POLL_BUDGET_WORKQUEUE ||
            ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
                queue_work(ib_comp_wq, &cq->work);
}

static void
ib_cq_completion_workqueue(struct ib_cq *cq, void *private)
{
        queue_work(ib_comp_wq, &cq->work);
}

struct ib_cq *
__ib_alloc_cq_user(struct ib_device *dev, void *private,
                   int nr_cqe, int comp_vector,
                   enum ib_poll_context poll_ctx,
                   const char *caller, struct ib_udata *udata)
{
        struct ib_cq_init_attr cq_attr = {
                .cqe = nr_cqe,
                .comp_vector = comp_vector,
        };
        struct ib_cq *cq;
        int ret = -ENOMEM;

        /*
         * Check for invalid parameters early on to avoid
         * extra error handling code:
         */
        switch (poll_ctx) {
        case IB_POLL_DIRECT:
        case IB_POLL_SOFTIRQ:
        case IB_POLL_WORKQUEUE:
                break;
        default:
                return (ERR_PTR(-EINVAL));
        }

        cq = rdma_zalloc_drv_obj(dev, ib_cq);
        if (!cq)
                return ERR_PTR(-ENOMEM);

        cq->device = dev;
        cq->cq_context = private;
        cq->poll_ctx = poll_ctx;
        atomic_set(&cq->usecnt, 0);

        cq->wc = kmalloc_array(IB_POLL_BATCH, sizeof(*cq->wc), GFP_KERNEL);
        if (!cq->wc)
                goto out_free_cq;

        ret = dev->create_cq(cq, &cq_attr, NULL);
        if (ret)
                goto out_free_wc;

        switch (cq->poll_ctx) {
        case IB_POLL_DIRECT:
                cq->comp_handler = ib_cq_completion_direct;
                break;
        case IB_POLL_SOFTIRQ:
        case IB_POLL_WORKQUEUE:
                cq->comp_handler = ib_cq_completion_workqueue;
                INIT_WORK(&cq->work, ib_cq_poll_work);
                ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
                break;
        default:
                break;
        }
        return (cq);

out_free_wc:
        kfree(cq->wc);
out_free_cq:
        kfree(cq);
        return (ERR_PTR(ret));
}
EXPORT_SYMBOL(__ib_alloc_cq_user);

void
ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata)
{

        if (WARN_ON_ONCE(atomic_read(&cq->usecnt) != 0))
                return;

        switch (cq->poll_ctx) {
        case IB_POLL_DIRECT:
                break;
        case IB_POLL_SOFTIRQ:
        case IB_POLL_WORKQUEUE:
                flush_work(&cq->work);
                break;
        default:
                break;
        }

        kfree(cq->wc);
        cq->device->destroy_cq(cq, udata);
        kfree(cq);
}
EXPORT_SYMBOL(ib_free_cq_user);