/*
 * Copyright (C) 2015 Etnaviv Project
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "etnaviv_drv.h"
#include "etnaviv_gem.h"
#include "etnaviv_gpu.h"
#include "etnaviv_mmu.h"

static int etnaviv_fault_handler(struct iommu_domain *iommu, struct device *dev,
                unsigned long iova, int flags, void *arg)
{
        DBG("*** fault: iova=%08lx, flags=%d", iova, flags);
        return 0;
}

int etnaviv_iommu_map(struct etnaviv_iommu *iommu, u32 iova,
                struct sg_table *sgt, unsigned len, int prot)
{
        struct iommu_domain *domain = iommu->domain;
        struct scatterlist *sg;
        unsigned int da = iova;
        unsigned int i, j;
        int ret;

        if (!domain || !sgt)
                return -EINVAL;

        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
                u32 pa = sg_dma_address(sg) - sg->offset;
                size_t bytes = sg_dma_len(sg) + sg->offset;

                VERB("map[%d]: %08x %08x(%zx)", i, iova, pa, bytes);

                ret = iommu_map(domain, da, pa, bytes, prot);
                if (ret)
                        goto fail;

                da += bytes;
        }

        return 0;

fail:
        da = iova;

        for_each_sg(sgt->sgl, sg, i, j) {
                size_t bytes = sg_dma_len(sg) + sg->offset;

                iommu_unmap(domain, da, bytes);
                da += bytes;
        }
        return ret;
}

int etnaviv_iommu_unmap(struct etnaviv_iommu *iommu, u32 iova,
                struct sg_table *sgt, unsigned len)
{
        struct iommu_domain *domain = iommu->domain;
        struct scatterlist *sg;
        unsigned int da = iova;
        int i;

        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
                size_t bytes = sg_dma_len(sg) + sg->offset;
                size_t unmapped;

                unmapped = iommu_unmap(domain, da, bytes);
                if (unmapped < bytes)
                        return unmapped;

                VERB("unmap[%d]: %08x(%zx)", i, iova, bytes);

                BUG_ON(!PAGE_ALIGNED(bytes));

                da += bytes;
        }

        return 0;
}

static void etnaviv_iommu_remove_mapping(struct etnaviv_iommu *mmu,
        struct etnaviv_vram_mapping *mapping)
{
        struct etnaviv_gem_object *etnaviv_obj = mapping->object;

        etnaviv_iommu_unmap(mmu, mapping->vram_node.start,
                            etnaviv_obj->sgt, etnaviv_obj->base.size);
        drm_mm_remove_node(&mapping->vram_node);
}

int etnaviv_iommu_map_gem(struct etnaviv_iommu *mmu,
        struct etnaviv_gem_object *etnaviv_obj, u32 memory_base,
        struct etnaviv_vram_mapping *mapping)
{
        struct etnaviv_vram_mapping *free = NULL;
        struct sg_table *sgt = etnaviv_obj->sgt;
        struct drm_mm_node *node;
        int ret;

        lockdep_assert_held(&etnaviv_obj->lock);

        mutex_lock(&mmu->lock);

        /* v1 MMU can optimize single entry (contiguous) scatterlists */
        if (sgt->nents == 1 && !(etnaviv_obj->flags & ETNA_BO_FORCE_MMU)) {
                u32 iova;

                iova = sg_dma_address(sgt->sgl) - memory_base;
                if (iova < 0x80000000 - sg_dma_len(sgt->sgl)) {
                        mapping->iova = iova;
                        list_add_tail(&mapping->mmu_node, &mmu->mappings);
                        mutex_unlock(&mmu->lock);
                        return 0;
                }
        }

        node = &mapping->vram_node;
        while (1) {
                struct etnaviv_vram_mapping *m, *n;
                struct list_head list;
                bool found;

                ret = drm_mm_insert_node_in_range(&mmu->mm, node,
                        etnaviv_obj->base.size, 0, mmu->last_iova, ~0UL,
                        DRM_MM_SEARCH_DEFAULT);

                if (ret != -ENOSPC)
                        break;

                /*
                 * If we did not search from the start of the MMU region,
                 * try again in case there are free slots.
                 */
                if (mmu->last_iova) {
                        mmu->last_iova = 0;
                        mmu->need_flush = true;
                        continue;
                }

                /* Try to retire some entries */
                drm_mm_init_scan(&mmu->mm, etnaviv_obj->base.size, 0, 0);

                found = 0;
                INIT_LIST_HEAD(&list);
                list_for_each_entry(free, &mmu->mappings, mmu_node) {
                        /* If this vram node has not been used, skip this. */
                        if (!free->vram_node.mm)
                                continue;

                        /*
                         * If the iova is pinned, then it's in-use,
                         * so we must keep its mapping.
                         */
                        if (free->use)
                                continue;

                        list_add(&free->scan_node, &list);
                        if (drm_mm_scan_add_block(&free->vram_node)) {
                                found = true;
                                break;
                        }
                }

                if (!found) {
                        /* Nothing found, clean up and fail */
                        list_for_each_entry_safe(m, n, &list, scan_node)
                                BUG_ON(drm_mm_scan_remove_block(&m->vram_node));
                        break;
                }

                /*
                 * drm_mm does not allow any other operations while
                 * scanning, so we have to remove all blocks first.
                 * If drm_mm_scan_remove_block() returns false, we
                 * can leave the block pinned.
                 */
                list_for_each_entry_safe(m, n, &list, scan_node)
                        if (!drm_mm_scan_remove_block(&m->vram_node))
                                list_del_init(&m->scan_node);

                /*
                 * Unmap the blocks which need to be reaped from the MMU.
                 * Clear the mmu pointer to prevent the get_iova finding
                 * this mapping.
                 */
                list_for_each_entry_safe(m, n, &list, scan_node) {
                        etnaviv_iommu_remove_mapping(mmu, m);
                        m->mmu = NULL;
                        list_del_init(&m->mmu_node);
                        list_del_init(&m->scan_node);
                }

                /*
                 * We removed enough mappings so that the new allocation will
                 * succeed.  Ensure that the MMU will be flushed before the
                 * associated commit requesting this mapping, and retry the
                 * allocation one more time.
                 */
                mmu->need_flush = true;
        }

        if (ret < 0) {
                mutex_unlock(&mmu->lock);
                return ret;
        }

        mmu->last_iova = node->start + etnaviv_obj->base.size;
        mapping->iova = node->start;
        ret = etnaviv_iommu_map(mmu, node->start, sgt, etnaviv_obj->base.size,
                                IOMMU_READ | IOMMU_WRITE);

        if (ret < 0) {
                drm_mm_remove_node(node);
                mutex_unlock(&mmu->lock);
                return ret;
        }

        list_add_tail(&mapping->mmu_node, &mmu->mappings);
        mutex_unlock(&mmu->lock);

        return ret;
}

void etnaviv_iommu_unmap_gem(struct etnaviv_iommu *mmu,
        struct etnaviv_vram_mapping *mapping)
{
        WARN_ON(mapping->use);

        mutex_lock(&mmu->lock);

        /* If the vram node is on the mm, unmap and remove the node */
        if (mapping->vram_node.mm == &mmu->mm)
                etnaviv_iommu_remove_mapping(mmu, mapping);

        list_del(&mapping->mmu_node);
        mutex_unlock(&mmu->lock);
}

void etnaviv_iommu_destroy(struct etnaviv_iommu *mmu)
{
        drm_mm_takedown(&mmu->mm);
        iommu_domain_free(mmu->domain);
        kfree(mmu);
}

struct etnaviv_iommu *etnaviv_iommu_new(struct etnaviv_gpu *gpu,
        struct iommu_domain *domain, enum etnaviv_iommu_version version)
{
        struct etnaviv_iommu *mmu;

        mmu = kzalloc(sizeof(*mmu), GFP_KERNEL);
        if (!mmu)
                return ERR_PTR(-ENOMEM);

        mmu->domain = domain;
        mmu->gpu = gpu;
        mmu->version = version;
        mutex_init(&mmu->lock);
        INIT_LIST_HEAD(&mmu->mappings);

        drm_mm_init(&mmu->mm, domain->geometry.aperture_start,
                    domain->geometry.aperture_end -
                      domain->geometry.aperture_start + 1);

        iommu_set_fault_handler(domain, etnaviv_fault_handler, gpu->dev);

        return mmu;
}

size_t etnaviv_iommu_dump_size(struct etnaviv_iommu *iommu)
{
        struct etnaviv_iommu_ops *ops;

        ops = container_of(iommu->domain->ops, struct etnaviv_iommu_ops, ops);

        return ops->dump_size(iommu->domain);
}

void etnaviv_iommu_dump(struct etnaviv_iommu *iommu, void *buf)
{
        struct etnaviv_iommu_ops *ops;

        ops = container_of(iommu->domain->ops, struct etnaviv_iommu_ops, ops);

        ops->dump(iommu->domain, buf);
}