/*-
 * CAM request queue management definitions.
 *
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 1997 Justin T. Gibbs.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification, immediately at the beginning of the file.
 * 2. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 * $FreeBSD: releng/12.4/sys/cam/cam_queue.h 326265 2017-11-27 15:12:43Z pfg $
 */

#ifndef _CAM_CAM_QUEUE_H
#define _CAM_CAM_QUEUE_H 1

#ifdef _KERNEL

#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/queue.h>
#include <cam/cam.h>

/*
 * This structure implements a heap based priority queue.  The queue
 * assumes that the objects stored in it begin with a cam_qentry
 * structure holding the priority information used to sort the objects.
 * This structure is opaque to clients (outside of the XPT layer) to allow
 * the implementation to change without affecting them.
 */
struct camq {
	cam_pinfo **queue_array;
	int	   array_size;
	int	   entries;
	u_int32_t  generation;
	u_int32_t  qfrozen_cnt;
};

TAILQ_HEAD(ccb_hdr_tailq, ccb_hdr);
LIST_HEAD(ccb_hdr_list, ccb_hdr);
SLIST_HEAD(ccb_hdr_slist, ccb_hdr);

struct cam_ccbq {
	struct	camq queue;
	struct ccb_hdr_tailq	queue_extra_head;
	int	queue_extra_entries;
	int	total_openings;
	int	allocated;
	int	dev_openings;
	int	dev_active;
};

struct cam_ed;

struct cam_devq {
	struct mtx	 send_mtx;
	struct camq	 send_queue;
	int		 send_openings;
	int		 send_active;
};


struct cam_devq *cam_devq_alloc(int devices, int openings);

int		 cam_devq_init(struct cam_devq *devq, int devices,
			       int openings);

void		 cam_devq_free(struct cam_devq *devq);

u_int32_t	 cam_devq_resize(struct cam_devq *camq, int openings);
	
/*
 * Allocate a cam_ccb_queue structure and initialize it.
 */
struct cam_ccbq	*cam_ccbq_alloc(int openings);

u_int32_t	cam_ccbq_resize(struct cam_ccbq *ccbq, int devices);

int		cam_ccbq_init(struct cam_ccbq *ccbq, int openings);

void		cam_ccbq_free(struct cam_ccbq *ccbq);

void		cam_ccbq_fini(struct cam_ccbq *ccbq);

/*
 * Allocate and initialize a cam_queue structure.
 */
struct camq	*camq_alloc(int size);

/*
 * Resize a cam queue
 */
u_int32_t	camq_resize(struct camq *queue, int new_size);

/* 
 * Initialize a camq structure.  Return 0 on success, 1 on failure.
 */
int		camq_init(struct camq *camq, int size);

/*
 * Free a cam_queue structure.  This should only be called if a controller
 * driver failes somehow during its attach routine or is unloaded and has
 * obtained a cam_queue structure.
 */
void		camq_free(struct camq *queue);

/*
 * Finialize any internal storage or state of a cam_queue.
 */
void		camq_fini(struct camq *queue);

/*
 * cam_queue_insert: Given a CAM queue with at least one open spot,
 * insert the new entry maintaining order.
 */
void		camq_insert(struct camq *queue, cam_pinfo *new_entry);

/*
 * camq_remove: Remove and arbitrary entry from the queue maintaining
 * queue order.
 */
cam_pinfo	*camq_remove(struct camq *queue, int index);
#define CAMQ_HEAD 1	/* Head of queue index */

/* Index the first element in the heap */
#define CAMQ_GET_HEAD(camq) ((camq)->queue_array[CAMQ_HEAD])

/* Get the first element priority. */
#define CAMQ_GET_PRIO(camq) (((camq)->entries > 0) ?			\
			    ((camq)->queue_array[CAMQ_HEAD]->priority) : 0)

/*
 * camq_change_priority: Raise or lower the priority of an entry
 * maintaining queue order.
 */
void		camq_change_priority(struct camq *queue, int index,
				     u_int32_t new_priority);

static __inline int
cam_ccbq_pending_ccb_count(struct cam_ccbq *ccbq);

static __inline void
cam_ccbq_take_opening(struct cam_ccbq *ccbq);

static __inline void
cam_ccbq_insert_ccb(struct cam_ccbq *ccbq, union ccb *new_ccb);

static __inline void
cam_ccbq_remove_ccb(struct cam_ccbq *ccbq, union ccb *ccb);

static __inline union ccb *
cam_ccbq_peek_ccb(struct cam_ccbq *ccbq, int index);

static __inline void
cam_ccbq_send_ccb(struct cam_ccbq *queue, union ccb *send_ccb);

static __inline void
cam_ccbq_ccb_done(struct cam_ccbq *ccbq, union ccb *done_ccb);

static __inline void
cam_ccbq_release_opening(struct cam_ccbq *ccbq);


static __inline int
cam_ccbq_pending_ccb_count(struct cam_ccbq *ccbq)
{
	return (ccbq->queue.entries + ccbq->queue_extra_entries);
}

static __inline void
cam_ccbq_take_opening(struct cam_ccbq *ccbq)
{

	ccbq->allocated++;
}

static __inline void
cam_ccbq_insert_ccb(struct cam_ccbq *ccbq, union ccb *new_ccb)
{
	struct ccb_hdr *old_ccb;
	struct camq *queue = &ccbq->queue;

	KASSERT((new_ccb->ccb_h.func_code & XPT_FC_QUEUED) != 0 &&
	    (new_ccb->ccb_h.func_code & XPT_FC_USER_CCB) == 0,
	    ("%s: Cannot queue ccb %p func_code %#x", __func__, new_ccb,
	     new_ccb->ccb_h.func_code));

	/*
	 * If queue is already full, try to resize.
	 * If resize fail, push CCB with lowest priority out to the TAILQ.
	 */
	if (queue->entries == queue->array_size &&
	    camq_resize(&ccbq->queue, queue->array_size * 2) != CAM_REQ_CMP) {
		old_ccb = (struct ccb_hdr *)camq_remove(queue, queue->entries);
		TAILQ_INSERT_HEAD(&ccbq->queue_extra_head, old_ccb,
		    xpt_links.tqe);
		old_ccb->pinfo.index = CAM_EXTRAQ_INDEX;
		ccbq->queue_extra_entries++;
	}

	camq_insert(queue, &new_ccb->ccb_h.pinfo);
}

static __inline void
cam_ccbq_remove_ccb(struct cam_ccbq *ccbq, union ccb *ccb)
{
	struct ccb_hdr *cccb, *bccb;
	struct camq *queue = &ccbq->queue;
	cam_pinfo *removed_entry __unused;

	/* If the CCB is on the TAILQ, remove it from there. */
	if (ccb->ccb_h.pinfo.index == CAM_EXTRAQ_INDEX) {
		TAILQ_REMOVE(&ccbq->queue_extra_head, &ccb->ccb_h,
		    xpt_links.tqe);
		ccb->ccb_h.pinfo.index = CAM_UNQUEUED_INDEX;
		ccbq->queue_extra_entries--;
		return;
	}

	removed_entry = camq_remove(queue, ccb->ccb_h.pinfo.index);
	KASSERT(removed_entry == &ccb->ccb_h.pinfo,
	    ("%s: Removed wrong entry from queue (%p != %p)", __func__,
	     removed_entry, &ccb->ccb_h.pinfo));

	/*
	 * If there are some CCBs on TAILQ, find the best one and move it
	 * to the emptied space in the queue.
	 */
	bccb = TAILQ_FIRST(&ccbq->queue_extra_head);
	if (bccb == NULL)
		return;
	TAILQ_FOREACH(cccb, &ccbq->queue_extra_head, xpt_links.tqe) {
		if (bccb->pinfo.priority > cccb->pinfo.priority ||
		    (bccb->pinfo.priority == cccb->pinfo.priority &&
		     GENERATIONCMP(bccb->pinfo.generation, >,
		      cccb->pinfo.generation)))
		        bccb = cccb;
	}
	TAILQ_REMOVE(&ccbq->queue_extra_head, bccb, xpt_links.tqe);
	ccbq->queue_extra_entries--;
	camq_insert(queue, &bccb->pinfo);
}

static __inline union ccb *
cam_ccbq_peek_ccb(struct cam_ccbq *ccbq, int index)
{
	return((union ccb *)ccbq->queue.queue_array[index]);
}

static __inline void
cam_ccbq_send_ccb(struct cam_ccbq *ccbq, union ccb *send_ccb)
{

	send_ccb->ccb_h.pinfo.index = CAM_ACTIVE_INDEX;
	ccbq->dev_active++;
	ccbq->dev_openings--;
}

static __inline void
cam_ccbq_ccb_done(struct cam_ccbq *ccbq, union ccb *done_ccb)
{

	ccbq->dev_active--;
	ccbq->dev_openings++;
}

static __inline void
cam_ccbq_release_opening(struct cam_ccbq *ccbq)
{

	ccbq->allocated--;
}

#endif /* _KERNEL */
#endif  /* _CAM_CAM_QUEUE_H */
