/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2020 Ruslan Bukin <br@bsdpad.com>
 *
 * This software was developed by SRI International and the University of
 * Cambridge Computer Laboratory (Department of Computer Science and
 * Technology) under DARPA contract HR0011-18-C-0016 ("ECATS"), as part of the
 * DARPA SSITH research programme.
 *
 * Portions of this work was supported by Innovate UK project 105694,
 * "Digital Security by Design (DSbD) Technology Platform Prototype".
 *
 * 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 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.
 */

#include "opt_platform.h"

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/memdesc.h>
#include <sys/tree.h>
#include <sys/taskqueue.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <vm/vm.h>

#include <dev/pci/pcireg.h>
#include <dev/pci/pcivar.h>
#include <machine/bus.h>
#include <dev/iommu/busdma_iommu.h>
#include <machine/vmparam.h>

#ifdef FDT
#include <dev/fdt/fdt_common.h>
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#endif

#include "iommu.h"
#include "iommu_if.h"

static MALLOC_DEFINE(M_IOMMU, "IOMMU", "IOMMU framework");

#define IOMMU_LIST_LOCK()               sx_xlock(&iommu_sx)
#define IOMMU_LIST_UNLOCK()             sx_xunlock(&iommu_sx)
#define IOMMU_LIST_ASSERT_LOCKED()      sx_assert(&iommu_sx, SA_XLOCKED)

#define dprintf(fmt, ...)

static struct sx iommu_sx;

struct iommu_entry {
        struct iommu_unit *iommu;
        LIST_ENTRY(iommu_entry) next;
};
static LIST_HEAD(, iommu_entry) iommu_list = LIST_HEAD_INITIALIZER(iommu_list);

static int
iommu_domain_unmap_buf(struct iommu_domain *iodom,
    struct iommu_map_entry *entry, int flags)
{
        struct iommu_unit *iommu;
        int error;

        iommu = iodom->iommu;
        error = IOMMU_UNMAP(iommu->dev, iodom, entry->start, entry->end -
            entry->start);
        return (error);
}

static int
iommu_domain_map_buf(struct iommu_domain *iodom, struct iommu_map_entry *entry,
    vm_page_t *ma, uint64_t eflags, int flags)
{
        struct iommu_unit *iommu;
        vm_prot_t prot;
        vm_offset_t va;
        int error;

        dprintf("%s: base %lx, size %lx\n", __func__, base, size);

        prot = 0;
        if (eflags & IOMMU_MAP_ENTRY_READ)
                prot |= VM_PROT_READ;
        if (eflags & IOMMU_MAP_ENTRY_WRITE)
                prot |= VM_PROT_WRITE;

        va = entry->start;
        iommu = iodom->iommu;
        error = IOMMU_MAP(iommu->dev, iodom, va, ma, entry->end -
            entry->start, prot);
        return (error);
}

static const struct iommu_domain_map_ops domain_map_ops = {
        .map = iommu_domain_map_buf,
        .unmap = iommu_domain_unmap_buf,
};

static struct iommu_domain *
iommu_domain_alloc(struct iommu_unit *iommu)
{
        struct iommu_domain *iodom;

        iodom = IOMMU_DOMAIN_ALLOC(iommu->dev, iommu);
        if (iodom == NULL)
                return (NULL);

        KASSERT(iodom->end != 0, ("domain end is not set"));

        iommu_domain_init(iommu, iodom, &domain_map_ops);
        iodom->iommu = iommu;
        iommu_gas_init_domain(iodom);

        return (iodom);
}

static int
iommu_domain_free(struct iommu_domain *iodom)
{
        struct iommu_unit *iommu;

        iommu = iodom->iommu;

        IOMMU_LOCK(iommu);

        if ((iodom->flags & IOMMU_DOMAIN_GAS_INITED) != 0) {
                IOMMU_DOMAIN_LOCK(iodom);
                iommu_gas_fini_domain(iodom);
                IOMMU_DOMAIN_UNLOCK(iodom);
        }

        iommu_domain_fini(iodom);

        IOMMU_DOMAIN_FREE(iommu->dev, iodom);
        IOMMU_UNLOCK(iommu);

        return (0);
}

static void
iommu_tag_init(struct iommu_domain *iodom, struct bus_dma_tag_iommu *t)
{
        bus_addr_t maxaddr;

        maxaddr = MIN(iodom->end, BUS_SPACE_MAXADDR);

        t->common.impl = &bus_dma_iommu_impl;
        t->common.alignment = 1;
        t->common.boundary = 0;
        t->common.lowaddr = maxaddr;
        t->common.highaddr = maxaddr;
        t->common.maxsize = maxaddr;
        t->common.nsegments = BUS_SPACE_UNRESTRICTED;
        t->common.maxsegsz = maxaddr;
}

static struct iommu_ctx *
iommu_ctx_alloc(device_t requester, struct iommu_domain *iodom, bool disabled)
{
        struct iommu_unit *iommu;
        struct iommu_ctx *ioctx;

        iommu = iodom->iommu;

        ioctx = IOMMU_CTX_ALLOC(iommu->dev, iodom, requester, disabled);
        if (ioctx == NULL)
                return (NULL);

        ioctx->domain = iodom;

        return (ioctx);
}

static int
iommu_ctx_init(device_t requester, struct iommu_ctx *ioctx)
{
        struct bus_dma_tag_iommu *tag;
        struct iommu_domain *iodom;
        struct iommu_unit *iommu;
        int error;

        iodom = ioctx->domain;
        iommu = iodom->iommu;

        error = IOMMU_CTX_INIT(iommu->dev, ioctx);
        if (error)
                return (error);

        tag = ioctx->tag = malloc(sizeof(struct bus_dma_tag_iommu),
            M_IOMMU, M_WAITOK | M_ZERO);
        tag->owner = requester;
        tag->ctx = ioctx;
        tag->ctx->domain = iodom;

        iommu_tag_init(iodom, tag);

        return (error);
}

static struct iommu_unit *
iommu_lookup(device_t dev)
{
        struct iommu_entry *entry;
        struct iommu_unit *iommu;

        IOMMU_LIST_LOCK();
        LIST_FOREACH(entry, &iommu_list, next) {
                iommu = entry->iommu;
                if (iommu->dev == dev) {
                        IOMMU_LIST_UNLOCK();
                        return (iommu);
                }
        }
        IOMMU_LIST_UNLOCK();

        return (NULL);
}

#ifdef FDT
struct iommu_ctx *
iommu_get_ctx_ofw(device_t dev, int channel)
{
        struct iommu_domain *iodom;
        struct iommu_unit *iommu;
        struct iommu_ctx *ioctx;
        phandle_t node, parent;
        device_t iommu_dev;
        pcell_t *cells;
        int niommus;
        int ncells;
        int error;

        node = ofw_bus_get_node(dev);
        if (node <= 0) {
                device_printf(dev,
                    "%s called on not ofw based device.\n", __func__);
                return (NULL);
        }

        error = ofw_bus_parse_xref_list_get_length(node,
            "iommus", "#iommu-cells", &niommus);
        if (error) {
                device_printf(dev, "%s can't get iommu list.\n", __func__);
                return (NULL);
        }

        if (niommus == 0) {
                device_printf(dev, "%s iommu list is empty.\n", __func__);
                return (NULL);
        }

        error = ofw_bus_parse_xref_list_alloc(node, "iommus", "#iommu-cells",
            channel, &parent, &ncells, &cells);
        if (error != 0) {
                device_printf(dev, "%s can't get iommu device xref.\n",
                    __func__);
                return (NULL);
        }

        iommu_dev = OF_device_from_xref(parent);
        if (iommu_dev == NULL) {
                device_printf(dev, "%s can't get iommu device.\n", __func__);
                return (NULL);
        }

        iommu = iommu_lookup(iommu_dev);
        if (iommu == NULL) {
                device_printf(dev, "%s can't lookup iommu.\n", __func__);
                return (NULL);
        }

        /*
         * In our current configuration we have a domain per each ctx,
         * so allocate a domain first.
         */
        iodom = iommu_domain_alloc(iommu);
        if (iodom == NULL) {
                device_printf(dev, "%s can't allocate domain.\n", __func__);
                return (NULL);
        }

        ioctx = iommu_ctx_alloc(dev, iodom, false);
        if (ioctx == NULL) {
                iommu_domain_free(iodom);
                return (NULL);
        }

        ioctx->domain = iodom;

        error = IOMMU_OFW_MD_DATA(iommu->dev, ioctx, cells, ncells);
        if (error) {
                device_printf(dev, "%s can't set MD data\n", __func__);
                return (NULL);
        }

        error = iommu_ctx_init(dev, ioctx);
        if (error) {
                IOMMU_CTX_FREE(iommu->dev, ioctx);
                iommu_domain_free(iodom);
                return (NULL);
        }

        return (ioctx);
}
#endif

struct iommu_ctx *
iommu_get_ctx(struct iommu_unit *iommu, device_t requester,
    uint16_t rid, bool disabled, bool rmrr)
{
        struct iommu_domain *iodom;
        struct iommu_ctx *ioctx;
        int error;

        IOMMU_LOCK(iommu);
        ioctx = IOMMU_CTX_LOOKUP(iommu->dev, requester);
        if (ioctx) {
                IOMMU_UNLOCK(iommu);
                return (ioctx);
        }
        IOMMU_UNLOCK(iommu);

        /*
         * In our current configuration we have a domain per each ctx.
         * So allocate a domain first.
         */
        iodom = iommu_domain_alloc(iommu);
        if (iodom == NULL)
                return (NULL);

        ioctx = iommu_ctx_alloc(requester, iodom, disabled);
        if (ioctx == NULL) {
                iommu_domain_free(iodom);
                return (NULL);
        }

        error = iommu_ctx_init(requester, ioctx);
        if (error) {
                IOMMU_CTX_FREE(iommu->dev, ioctx);
                iommu_domain_free(iodom);
                return (NULL);
        }

        return (ioctx);
}

void
iommu_free_ctx_locked(struct iommu_unit *iommu, struct iommu_ctx *ioctx)
{
        struct bus_dma_tag_iommu *tag;
        int error;

        IOMMU_ASSERT_LOCKED(iommu);

        tag = ioctx->tag;

        IOMMU_CTX_FREE(iommu->dev, ioctx);
        IOMMU_UNLOCK(iommu);

        free(tag, M_IOMMU);

        /* Since we have a domain per each ctx, remove the domain too. */
        error = iommu_domain_free(ioctx->domain);
        if (error)
                device_printf(iommu->dev, "Could not free a domain\n");
}

static void
iommu_domain_free_entry(struct iommu_map_entry *entry, bool free)
{
        iommu_gas_free_space(entry);

        if (free)
                iommu_gas_free_entry(entry);
        else
                entry->flags = 0;
}

void
iommu_domain_unload(struct iommu_domain *iodom,
    struct iommu_map_entries_tailq *entries, bool cansleep)
{
        struct iommu_map_entry *entry, *entry1;
        int error __diagused;

        TAILQ_FOREACH_SAFE(entry, entries, dmamap_link, entry1) {
                KASSERT((entry->flags & IOMMU_MAP_ENTRY_MAP) != 0,
                    ("not mapped entry %p %p", iodom, entry));
                error = iodom->ops->unmap(iodom, entry,
                    cansleep ? IOMMU_PGF_WAITOK : 0);
                KASSERT(error == 0, ("unmap %p error %d", iodom, error));
                TAILQ_REMOVE(entries, entry, dmamap_link);
                iommu_domain_free_entry(entry, true);
        }

        if (TAILQ_EMPTY(entries))
                return;

        panic("entries map is not empty");
}

int
iommu_register(struct iommu_unit *iommu)
{
        struct iommu_entry *entry;

        mtx_init(&iommu->lock, "IOMMU", NULL, MTX_DEF);

        entry = malloc(sizeof(struct iommu_entry), M_IOMMU, M_WAITOK | M_ZERO);
        entry->iommu = iommu;

        IOMMU_LIST_LOCK();
        LIST_INSERT_HEAD(&iommu_list, entry, next);
        IOMMU_LIST_UNLOCK();

        sysctl_ctx_init(&iommu->sysctl_ctx);
        iommu_init_busdma(iommu);

        return (0);
}

int
iommu_unregister(struct iommu_unit *iommu)
{
        struct iommu_entry *entry, *tmp;

        IOMMU_LIST_LOCK();
        LIST_FOREACH_SAFE(entry, &iommu_list, next, tmp) {
                if (entry->iommu == iommu) {
                        LIST_REMOVE(entry, next);
                        free(entry, M_IOMMU);
                }
        }
        IOMMU_LIST_UNLOCK();

        iommu_fini_busdma(iommu);
        sysctl_ctx_free(&iommu->sysctl_ctx);

        mtx_destroy(&iommu->lock);

        return (0);
}

struct iommu_unit *
iommu_find(device_t dev, bool verbose)
{
        struct iommu_entry *entry;
        struct iommu_unit *iommu;
        int error;

        IOMMU_LIST_LOCK();
        LIST_FOREACH(entry, &iommu_list, next) {
                iommu = entry->iommu;
                error = IOMMU_FIND(iommu->dev, dev);
                if (error == 0) {
                        IOMMU_LIST_UNLOCK();
                        return (entry->iommu);
                }
        }
        IOMMU_LIST_UNLOCK();

        return (NULL);
}

void
iommu_unit_pre_instantiate_ctx(struct iommu_unit *unit)
{
}

void
iommu_domain_unload_entry(struct iommu_map_entry *entry, bool free,
    bool cansleep __unused)
{

        dprintf("%s\n", __func__);

        iommu_domain_free_entry(entry, free);
}

static void
iommu_init(void)
{

        sx_init(&iommu_sx, "IOMMU list");
}

SYSINIT(iommu, SI_SUB_DRIVERS, SI_ORDER_FIRST, iommu_init, NULL);