/*
 * Copyright(c) 2016 Intel Corporation.
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * BSD LICENSE
 *
 * 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.
 *  - Neither the name of Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/kthread.h>
#include "cq.h"
#include "vt.h"

/**
 * rvt_cq_enter - add a new entry to the completion queue
 * @cq: completion queue
 * @entry: work completion entry to add
 * @sig: true if @entry is solicited
 *
 * This may be called with qp->s_lock held.
 */
void rvt_cq_enter(struct rvt_cq *cq, struct ib_wc *entry, bool solicited)
{
	struct rvt_cq_wc *wc;
	unsigned long flags;
	u32 head;
	u32 next;

	spin_lock_irqsave(&cq->lock, flags);

	/*
	 * Note that the head pointer might be writable by user processes.
	 * Take care to verify it is a sane value.
	 */
	wc = cq->queue;
	head = wc->head;
	if (head >= (unsigned)cq->ibcq.cqe) {
		head = cq->ibcq.cqe;
		next = 0;
	} else {
		next = head + 1;
	}

	if (unlikely(next == wc->tail)) {
		spin_unlock_irqrestore(&cq->lock, flags);
		if (cq->ibcq.event_handler) {
			struct ib_event ev;

			ev.device = cq->ibcq.device;
			ev.element.cq = &cq->ibcq;
			ev.event = IB_EVENT_CQ_ERR;
			cq->ibcq.event_handler(&ev, cq->ibcq.cq_context);
		}
		return;
	}
	if (cq->ip) {
		wc->uqueue[head].wr_id = entry->wr_id;
		wc->uqueue[head].status = entry->status;
		wc->uqueue[head].opcode = entry->opcode;
		wc->uqueue[head].vendor_err = entry->vendor_err;
		wc->uqueue[head].byte_len = entry->byte_len;
		wc->uqueue[head].ex.imm_data =
			(__u32 __force)entry->ex.imm_data;
		wc->uqueue[head].qp_num = entry->qp->qp_num;
		wc->uqueue[head].src_qp = entry->src_qp;
		wc->uqueue[head].wc_flags = entry->wc_flags;
		wc->uqueue[head].pkey_index = entry->pkey_index;
		wc->uqueue[head].slid = entry->slid;
		wc->uqueue[head].sl = entry->sl;
		wc->uqueue[head].dlid_path_bits = entry->dlid_path_bits;
		wc->uqueue[head].port_num = entry->port_num;
		/* Make sure entry is written before the head index. */
		smp_wmb();
	} else {
		wc->kqueue[head] = *entry;
	}
	wc->head = next;

	if (cq->notify == IB_CQ_NEXT_COMP ||
	    (cq->notify == IB_CQ_SOLICITED &&
	     (solicited || entry->status != IB_WC_SUCCESS))) {
		struct kthread_worker *worker;
		/*
		 * This will cause send_complete() to be called in
		 * another thread.
		 */
		smp_read_barrier_depends(); /* see rvt_cq_exit */
		worker = cq->rdi->worker;
		if (likely(worker)) {
			cq->notify = RVT_CQ_NONE;
			cq->triggered++;
			queue_kthread_work(worker, &cq->comptask);
		}
	}

	spin_unlock_irqrestore(&cq->lock, flags);
}
EXPORT_SYMBOL(rvt_cq_enter);

static void send_complete(struct kthread_work *work)
{
	struct rvt_cq *cq = container_of(work, struct rvt_cq, comptask);

	/*
	 * The completion handler will most likely rearm the notification
	 * and poll for all pending entries.  If a new completion entry
	 * is added while we are in this routine, queue_work()
	 * won't call us again until we return so we check triggered to
	 * see if we need to call the handler again.
	 */
	for (;;) {
		u8 triggered = cq->triggered;

		/*
		 * IPoIB connected mode assumes the callback is from a
		 * soft IRQ. We simulate this by blocking "bottom halves".
		 * See the implementation for ipoib_cm_handle_tx_wc(),
		 * netif_tx_lock_bh() and netif_tx_lock().
		 */
		local_bh_disable();
		cq->ibcq.comp_handler(&cq->ibcq, cq->ibcq.cq_context);
		local_bh_enable();

		if (cq->triggered == triggered)
			return;
	}
}

/**
 * rvt_create_cq - create a completion queue
 * @ibdev: the device this completion queue is attached to
 * @attr: creation attributes
 * @context: unused by the QLogic_IB driver
 * @udata: user data for libibverbs.so
 *
 * Called by ib_create_cq() in the generic verbs code.
 *
 * Return: pointer to the completion queue or negative errno values
 * for failure.
 */
struct ib_cq *rvt_create_cq(struct ib_device *ibdev,
			    const struct ib_cq_init_attr *attr,
			    struct ib_ucontext *context,
			    struct ib_udata *udata)
{
	struct rvt_dev_info *rdi = ib_to_rvt(ibdev);
	struct rvt_cq *cq;
	struct rvt_cq_wc *wc;
	struct ib_cq *ret;
	u32 sz;
	unsigned int entries = attr->cqe;

	if (attr->flags)
		return ERR_PTR(-EINVAL);

	if (entries < 1 || entries > rdi->dparms.props.max_cqe)
		return ERR_PTR(-EINVAL);

	/* Allocate the completion queue structure. */
	cq = kzalloc(sizeof(*cq), GFP_KERNEL);
	if (!cq)
		return ERR_PTR(-ENOMEM);

	/*
	 * Allocate the completion queue entries and head/tail pointers.
	 * This is allocated separately so that it can be resized and
	 * also mapped into user space.
	 * We need to use vmalloc() in order to support mmap and large
	 * numbers of entries.
	 */
	sz = sizeof(*wc);
	if (udata && udata->outlen >= sizeof(__u64))
		sz += sizeof(struct ib_uverbs_wc) * (entries + 1);
	else
		sz += sizeof(struct ib_wc) * (entries + 1);
	wc = vmalloc_user(sz);
	if (!wc) {
		ret = ERR_PTR(-ENOMEM);
		goto bail_cq;
	}

	/*
	 * Return the address of the WC as the offset to mmap.
	 * See rvt_mmap() for details.
	 */
	if (udata && udata->outlen >= sizeof(__u64)) {
		int err;

		cq->ip = rvt_create_mmap_info(rdi, sz, context, wc);
		if (!cq->ip) {
			ret = ERR_PTR(-ENOMEM);
			goto bail_wc;
		}

		err = ib_copy_to_udata(udata, &cq->ip->offset,
				       sizeof(cq->ip->offset));
		if (err) {
			ret = ERR_PTR(err);
			goto bail_ip;
		}
	}

	spin_lock(&rdi->n_cqs_lock);
	if (rdi->n_cqs_allocated == rdi->dparms.props.max_cq) {
		spin_unlock(&rdi->n_cqs_lock);
		ret = ERR_PTR(-ENOMEM);
		goto bail_ip;
	}

	rdi->n_cqs_allocated++;
	spin_unlock(&rdi->n_cqs_lock);

	if (cq->ip) {
		spin_lock_irq(&rdi->pending_lock);
		list_add(&cq->ip->pending_mmaps, &rdi->pending_mmaps);
		spin_unlock_irq(&rdi->pending_lock);
	}

	/*
	 * ib_create_cq() will initialize cq->ibcq except for cq->ibcq.cqe.
	 * The number of entries should be >= the number requested or return
	 * an error.
	 */
	cq->rdi = rdi;
	cq->ibcq.cqe = entries;
	cq->notify = RVT_CQ_NONE;
	spin_lock_init(&cq->lock);
	init_kthread_work(&cq->comptask, send_complete);
	cq->queue = wc;

	ret = &cq->ibcq;

	goto done;

bail_ip:
	kfree(cq->ip);
bail_wc:
	vfree(wc);
bail_cq:
	kfree(cq);
done:
	return ret;
}

/**
 * rvt_destroy_cq - destroy a completion queue
 * @ibcq: the completion queue to destroy.
 *
 * Called by ib_destroy_cq() in the generic verbs code.
 *
 * Return: always 0
 */
int rvt_destroy_cq(struct ib_cq *ibcq)
{
	struct rvt_cq *cq = ibcq_to_rvtcq(ibcq);
	struct rvt_dev_info *rdi = cq->rdi;

	flush_kthread_work(&cq->comptask);
	spin_lock(&rdi->n_cqs_lock);
	rdi->n_cqs_allocated--;
	spin_unlock(&rdi->n_cqs_lock);
	if (cq->ip)
		kref_put(&cq->ip->ref, rvt_release_mmap_info);
	else
		vfree(cq->queue);
	kfree(cq);

	return 0;
}

/**
 * rvt_req_notify_cq - change the notification type for a completion queue
 * @ibcq: the completion queue
 * @notify_flags: the type of notification to request
 *
 * This may be called from interrupt context.  Also called by
 * ib_req_notify_cq() in the generic verbs code.
 *
 * Return: 0 for success.
 */
int rvt_req_notify_cq(struct ib_cq *ibcq, enum ib_cq_notify_flags notify_flags)
{
	struct rvt_cq *cq = ibcq_to_rvtcq(ibcq);
	unsigned long flags;
	int ret = 0;

	spin_lock_irqsave(&cq->lock, flags);
	/*
	 * Don't change IB_CQ_NEXT_COMP to IB_CQ_SOLICITED but allow
	 * any other transitions (see C11-31 and C11-32 in ch. 11.4.2.2).
	 */
	if (cq->notify != IB_CQ_NEXT_COMP)
		cq->notify = notify_flags & IB_CQ_SOLICITED_MASK;

	if ((notify_flags & IB_CQ_REPORT_MISSED_EVENTS) &&
	    cq->queue->head != cq->queue->tail)
		ret = 1;

	spin_unlock_irqrestore(&cq->lock, flags);

	return ret;
}

/**
 * rvt_resize_cq - change the size of the CQ
 * @ibcq: the completion queue
 *
 * Return: 0 for success.
 */
int rvt_resize_cq(struct ib_cq *ibcq, int cqe, struct ib_udata *udata)
{
	struct rvt_cq *cq = ibcq_to_rvtcq(ibcq);
	struct rvt_cq_wc *old_wc;
	struct rvt_cq_wc *wc;
	u32 head, tail, n;
	int ret;
	u32 sz;
	struct rvt_dev_info *rdi = cq->rdi;

	if (cqe < 1 || cqe > rdi->dparms.props.max_cqe)
		return -EINVAL;

	/*
	 * Need to use vmalloc() if we want to support large #s of entries.
	 */
	sz = sizeof(*wc);
	if (udata && udata->outlen >= sizeof(__u64))
		sz += sizeof(struct ib_uverbs_wc) * (cqe + 1);
	else
		sz += sizeof(struct ib_wc) * (cqe + 1);
	wc = vmalloc_user(sz);
	if (!wc)
		return -ENOMEM;

	/* Check that we can write the offset to mmap. */
	if (udata && udata->outlen >= sizeof(__u64)) {
		__u64 offset = 0;

		ret = ib_copy_to_udata(udata, &offset, sizeof(offset));
		if (ret)
			goto bail_free;
	}

	spin_lock_irq(&cq->lock);
	/*
	 * Make sure head and tail are sane since they
	 * might be user writable.
	 */
	old_wc = cq->queue;
	head = old_wc->head;
	if (head > (u32)cq->ibcq.cqe)
		head = (u32)cq->ibcq.cqe;
	tail = old_wc->tail;
	if (tail > (u32)cq->ibcq.cqe)
		tail = (u32)cq->ibcq.cqe;
	if (head < tail)
		n = cq->ibcq.cqe + 1 + head - tail;
	else
		n = head - tail;
	if (unlikely((u32)cqe < n)) {
		ret = -EINVAL;
		goto bail_unlock;
	}
	for (n = 0; tail != head; n++) {
		if (cq->ip)
			wc->uqueue[n] = old_wc->uqueue[tail];
		else
			wc->kqueue[n] = old_wc->kqueue[tail];
		if (tail == (u32)cq->ibcq.cqe)
			tail = 0;
		else
			tail++;
	}
	cq->ibcq.cqe = cqe;
	wc->head = n;
	wc->tail = 0;
	cq->queue = wc;
	spin_unlock_irq(&cq->lock);

	vfree(old_wc);

	if (cq->ip) {
		struct rvt_mmap_info *ip = cq->ip;

		rvt_update_mmap_info(rdi, ip, sz, wc);

		/*
		 * Return the offset to mmap.
		 * See rvt_mmap() for details.
		 */
		if (udata && udata->outlen >= sizeof(__u64)) {
			ret = ib_copy_to_udata(udata, &ip->offset,
					       sizeof(ip->offset));
			if (ret)
				return ret;
		}

		spin_lock_irq(&rdi->pending_lock);
		if (list_empty(&ip->pending_mmaps))
			list_add(&ip->pending_mmaps, &rdi->pending_mmaps);
		spin_unlock_irq(&rdi->pending_lock);
	}

	return 0;

bail_unlock:
	spin_unlock_irq(&cq->lock);
bail_free:
	vfree(wc);
	return ret;
}

/**
 * rvt_poll_cq - poll for work completion entries
 * @ibcq: the completion queue to poll
 * @num_entries: the maximum number of entries to return
 * @entry: pointer to array where work completions are placed
 *
 * This may be called from interrupt context.  Also called by ib_poll_cq()
 * in the generic verbs code.
 *
 * Return: the number of completion entries polled.
 */
int rvt_poll_cq(struct ib_cq *ibcq, int num_entries, struct ib_wc *entry)
{
	struct rvt_cq *cq = ibcq_to_rvtcq(ibcq);
	struct rvt_cq_wc *wc;
	unsigned long flags;
	int npolled;
	u32 tail;

	/* The kernel can only poll a kernel completion queue */
	if (cq->ip)
		return -EINVAL;

	spin_lock_irqsave(&cq->lock, flags);

	wc = cq->queue;
	tail = wc->tail;
	if (tail > (u32)cq->ibcq.cqe)
		tail = (u32)cq->ibcq.cqe;
	for (npolled = 0; npolled < num_entries; ++npolled, ++entry) {
		if (tail == wc->head)
			break;
		/* The kernel doesn't need a RMB since it has the lock. */
		*entry = wc->kqueue[tail];
		if (tail >= cq->ibcq.cqe)
			tail = 0;
		else
			tail++;
	}
	wc->tail = tail;

	spin_unlock_irqrestore(&cq->lock, flags);

	return npolled;
}

/**
 * rvt_driver_cq_init - Init cq resources on behalf of driver
 * @rdi: rvt dev structure
 *
 * Return: 0 on success
 */
int rvt_driver_cq_init(struct rvt_dev_info *rdi)
{
	int ret = 0;
	int cpu;
	struct task_struct *task;

	if (rdi->worker)
		return 0;
	rdi->worker = kzalloc(sizeof(*rdi->worker), GFP_KERNEL);
	if (!rdi->worker)
		return -ENOMEM;
	init_kthread_worker(rdi->worker);
	task = kthread_create_on_node(
		kthread_worker_fn,
		rdi->worker,
		rdi->dparms.node,
		"%s", rdi->dparms.cq_name);
	if (IS_ERR(task)) {
		kfree(rdi->worker);
		rdi->worker = NULL;
		return PTR_ERR(task);
	}

	set_user_nice(task, MIN_NICE);
	cpu = cpumask_first(cpumask_of_node(rdi->dparms.node));
	kthread_bind(task, cpu);
	wake_up_process(task);
	return ret;
}

/**
 * rvt_cq_exit - tear down cq reources
 * @rdi: rvt dev structure
 */
void rvt_cq_exit(struct rvt_dev_info *rdi)
{
	struct kthread_worker *worker;

	worker = rdi->worker;
	if (!worker)
		return;
	/* blocks future queuing from send_complete() */
	rdi->worker = NULL;
	smp_wmb(); /* See rdi_cq_enter */
	flush_kthread_worker(worker);
	kthread_stop(worker->task);
	kfree(worker);
}