/*-
 * Copyright (c) 2012 NetApp, Inc.
 * 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.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``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 NETAPP, INC 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.
 *
 * $FreeBSD$
 */

/*
 * Memory ranges are represented with an RB tree. On insertion, the range
 * is checked for overlaps. On lookup, the key has the same base and limit
 * so it can be searched within the range.
 *
 * It is assumed that all setup of ranges takes place in single-threaded
 * mode before vCPUs have been started. As such, no locks are used on the
 * RB tree. If this is no longer the case, then a r/w lock could be used,
 * with readers on the lookup and a writer if the tree needs to be changed
 * (and per vCPU caches flushed)
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/types.h>
#include <sys/tree.h>
#include <sys/errno.h>
#include <machine/vmm.h>

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#include "mem.h"

struct mmio_rb_range {
	RB_ENTRY(mmio_rb_range)	mr_link;	/* RB tree links */
	struct mem_range	mr_param;
	uint64_t                mr_base;
	uint64_t                mr_end;
};

struct mmio_rb_tree;
RB_PROTOTYPE(mmio_rb_tree, mmio_rb_range, mr_link, mmio_rb_range_compare);

RB_HEAD(mmio_rb_tree, mmio_rb_range) mmio_rbroot;

/*
 * Per-vCPU cache. Since most accesses from a vCPU will be to
 * consecutive addresses in a range, it makes sense to cache the
 * result of a lookup.
 */
static struct mmio_rb_range	*mmio_hint[VM_MAXCPU];

static int
mmio_rb_range_compare(struct mmio_rb_range *a, struct mmio_rb_range *b)
{
	if (a->mr_end < b->mr_base)
		return (-1);
	else if (a->mr_base > b->mr_end)
		return (1);
	return (0);
}

static int
mmio_rb_lookup(uint64_t addr, struct mmio_rb_range **entry)
{
	struct mmio_rb_range find, *res;

	find.mr_base = find.mr_end = addr;

	res = RB_FIND(mmio_rb_tree, &mmio_rbroot, &find);

	if (res != NULL) {
		*entry = res;
		return (0);
	}
	
	return (ENOENT);
}

static int
mmio_rb_add(struct mmio_rb_range *new)
{
	struct mmio_rb_range *overlap;

	overlap = RB_INSERT(mmio_rb_tree, &mmio_rbroot, new);

	if (overlap != NULL) {
#ifdef RB_DEBUG
		printf("overlap detected: new %lx:%lx, tree %lx:%lx\n",
		       new->mr_base, new->mr_end,
		       overlap->mr_base, overlap->mr_end);
#endif

		return (EEXIST);
	}

	return (0);
}

#if 0
static void
mmio_rb_dump(void)
{
	struct mmio_rb_range *np;

	RB_FOREACH(np, mmio_rb_tree, &mmio_rbroot) {
		printf(" %lx:%lx, %s\n", np->mr_base, np->mr_end,
		       np->mr_param.name);
	}
}
#endif

RB_GENERATE(mmio_rb_tree, mmio_rb_range, mr_link, mmio_rb_range_compare);

static int
mem_read(void *ctx, int vcpu, uint64_t gpa, uint64_t *rval, int size, void *arg)
{
	int error;
	struct mem_range *mr = arg;

	error = (*mr->handler)(ctx, vcpu, MEM_F_READ, gpa, size,
			       rval, mr->arg1, mr->arg2);
	return (error);
}

static int
mem_write(void *ctx, int vcpu, uint64_t gpa, uint64_t wval, int size, void *arg)
{
	int error;
	struct mem_range *mr = arg;

	error = (*mr->handler)(ctx, vcpu, MEM_F_WRITE, gpa, size,
			       &wval, mr->arg1, mr->arg2);
	return (error);
}

int
emulate_mem(struct vmctx *ctx, int vcpu, uint64_t paddr, struct vie *vie)
{
	struct mmio_rb_range *entry;
	int err;

	/*
	 * First check the per-vCPU cache
	 */
	if (mmio_hint[vcpu] &&
	    paddr >= mmio_hint[vcpu]->mr_base &&
	    paddr <= mmio_hint[vcpu]->mr_end) {
		entry = mmio_hint[vcpu];
	} else
		entry = NULL;

	if (entry == NULL) {
		if (mmio_rb_lookup(paddr, &entry))
			return (ESRCH);

		/* Update the per-vCPU cache */
		mmio_hint[vcpu] = entry;
	}

	assert(entry != NULL && entry == mmio_hint[vcpu]);

	err = vmm_emulate_instruction(ctx, vcpu, paddr, vie,
				      mem_read, mem_write, &entry->mr_param);
	return (err);
}

int
register_mem(struct mem_range *memp)
{
	struct mmio_rb_range *mrp;
	int		err;

	err = 0;

	mrp = malloc(sizeof(struct mmio_rb_range));

	if (mrp != NULL) {
		mrp->mr_param = *memp;
		mrp->mr_base = memp->base;
		mrp->mr_end = memp->base + memp->size - 1;

		err = mmio_rb_add(mrp);
		if (err)
			free(mrp);
	} else
		err = ENOMEM;

	return (err);
}

void
init_mem(void)
{

	RB_INIT(&mmio_rbroot);
}