// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2015-2018 Etnaviv Project
 */

#include <linux/dma-mapping.h>
#include <linux/scatterlist.h>

#include <drm/drm_print.h>

#include "common.xml.h"
#include "etnaviv_cmdbuf.h"
#include "etnaviv_drv.h"
#include "etnaviv_gem.h"
#include "etnaviv_gpu.h"
#include "etnaviv_mmu.h"

static void etnaviv_context_unmap(struct etnaviv_iommu_context *context,
                                 unsigned long iova, size_t size)
{
        size_t unmapped_page, unmapped = 0;
        size_t pgsize = SZ_4K;

        while (unmapped < size) {
                unmapped_page = context->global->ops->unmap(context, iova,
                                                            pgsize);
                if (!unmapped_page)
                        break;

                iova += unmapped_page;
                unmapped += unmapped_page;
        }
}

static int etnaviv_context_map(struct etnaviv_iommu_context *context,
                              unsigned long iova, phys_addr_t paddr,
                              size_t size, int prot)
{
        unsigned long orig_iova = iova;
        size_t pgsize = SZ_4K;
        size_t orig_size = size;
        int ret = 0;

        while (size) {
                ret = context->global->ops->map(context, iova, paddr, pgsize,
                                                prot);
                if (ret)
                        break;

                iova += pgsize;
                paddr += pgsize;
                size -= pgsize;
        }

        /* unroll mapping in case something went wrong */
        if (ret)
                etnaviv_context_unmap(context, orig_iova, orig_size - size);

        return ret;
}

static int etnaviv_iommu_map(struct etnaviv_iommu_context *context,
                             u32 iova, unsigned int va_len,
                             struct sg_table *sgt, int prot)
{
        struct scatterlist *sg;
        unsigned int da = iova;
        unsigned int i;
        int ret;

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

        for_each_sgtable_dma_sg(sgt, sg, i) {
                phys_addr_t pa = sg_dma_address(sg);
                unsigned int da_len = sg_dma_len(sg);
                unsigned int bytes = min_t(unsigned int, da_len, va_len);

                VERB("map[%d]: %08x %pap(%x)", i, da, &pa, bytes);

                if (!IS_ALIGNED(iova | pa | bytes, SZ_4K)) {
                        dev_err(context->global->dev,
                                "unaligned: iova 0x%x pa %pa size 0x%x\n",
                                iova, &pa, bytes);
                        ret = -EINVAL;
                        goto fail;
                }

                ret = etnaviv_context_map(context, da, pa, bytes, prot);
                if (ret)
                        goto fail;

                va_len -= bytes;
                da += bytes;
        }

        context->flush_seq++;

        return 0;

fail:
        etnaviv_context_unmap(context, iova, da - iova);
        return ret;
}

static void etnaviv_iommu_unmap(struct etnaviv_iommu_context *context, u32 iova,
                                struct sg_table *sgt, unsigned len)
{
        etnaviv_context_unmap(context, iova, len);

        context->flush_seq++;
}

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

        lockdep_assert_held(&context->lock);

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

void etnaviv_iommu_reap_mapping(struct etnaviv_vram_mapping *mapping)
{
        struct etnaviv_iommu_context *context = mapping->context;

        lockdep_assert_held(&context->lock);
        WARN_ON(mapping->use);

        etnaviv_iommu_remove_mapping(context, mapping);
        etnaviv_iommu_context_put(mapping->context);
        mapping->context = NULL;
        list_del_init(&mapping->mmu_node);
}

static int etnaviv_iommu_find_iova(struct etnaviv_iommu_context *context,
                                   struct drm_mm_node *node, size_t size)
{
        struct etnaviv_vram_mapping *free = NULL;
        enum drm_mm_insert_mode mode = DRM_MM_INSERT_LOW;
        int ret;

        lockdep_assert_held(&context->lock);

        while (1) {
                struct etnaviv_vram_mapping *m, *n;
                struct drm_mm_scan scan;
                struct list_head list;
                bool found;

                ret = drm_mm_insert_node_in_range(&context->mm, node,
                                                  size, 0, 0, 0, U64_MAX, mode);
                if (ret != -ENOSPC)
                        break;

                /* Try to retire some entries */
                drm_mm_scan_init(&scan, &context->mm, size, 0, 0, mode);

                found = 0;
                INIT_LIST_HEAD(&list);
                list_for_each_entry(free, &context->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(&scan, &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(&scan, &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(&scan, &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 mapping_get finding
                 * this mapping.
                 */
                list_for_each_entry_safe(m, n, &list, scan_node) {
                        etnaviv_iommu_reap_mapping(m);
                        list_del_init(&m->scan_node);
                }

                mode = DRM_MM_INSERT_EVICT;

                /*
                 * We removed enough mappings so that the new allocation will
                 * succeed, retry the allocation one more time.
                 */
        }

        return ret;
}

static int etnaviv_iommu_insert_exact(struct etnaviv_iommu_context *context,
                   struct drm_mm_node *node, size_t size, u64 va)
{
        struct etnaviv_vram_mapping *m, *n;
        struct drm_mm_node *scan_node;
        LIST_HEAD(scan_list);
        int ret;

        lockdep_assert_held(&context->lock);

        ret = drm_mm_insert_node_in_range(&context->mm, node, size, 0, 0, va,
                                          va + size, DRM_MM_INSERT_LOWEST);
        if (ret != -ENOSPC)
                return ret;

        /*
         * When we can't insert the node, due to a existing mapping blocking
         * the address space, there are two possible reasons:
         * 1. Userspace genuinely messed up and tried to reuse address space
         * before the last job using this VMA has finished executing.
         * 2. The existing buffer mappings are idle, but the buffers are not
         * destroyed yet (likely due to being referenced by another context) in
         * which case the mappings will not be cleaned up and we must reap them
         * here to make space for the new mapping.
         */

        drm_mm_for_each_node_in_range(scan_node, &context->mm, va, va + size) {
                m = container_of(scan_node, struct etnaviv_vram_mapping,
                                 vram_node);

                if (m->use)
                        return -ENOSPC;

                list_add(&m->scan_node, &scan_list);
        }

        list_for_each_entry_safe(m, n, &scan_list, scan_node) {
                etnaviv_iommu_reap_mapping(m);
                list_del_init(&m->scan_node);
        }

        return drm_mm_insert_node_in_range(&context->mm, node, size, 0, 0, va,
                                           va + size, DRM_MM_INSERT_LOWEST);
}

int etnaviv_iommu_map_gem(struct etnaviv_iommu_context *context,
        struct etnaviv_gem_object *etnaviv_obj, u32 memory_base,
        struct etnaviv_vram_mapping *mapping, u64 va)
{
        struct sg_table *sgt = etnaviv_obj->sgt;
        struct drm_mm_node *node;
        int ret;

        lockdep_assert_held(&etnaviv_obj->lock);

        mutex_lock(&context->lock);

        /* v1 MMU can optimize single entry (contiguous) scatterlists */
        if (context->global->version == ETNAVIV_IOMMU_V1 &&
            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;
                        mapping->context = etnaviv_iommu_context_get(context);
                        list_add_tail(&mapping->mmu_node, &context->mappings);
                        ret = 0;
                        goto unlock;
                }
        }

        node = &mapping->vram_node;

        if (va)
                ret = etnaviv_iommu_insert_exact(context, node, etnaviv_obj->size, va);
        else
                ret = etnaviv_iommu_find_iova(context, node, etnaviv_obj->size);
        if (ret < 0)
                goto unlock;

        mapping->iova = node->start;
        ret = etnaviv_iommu_map(context, node->start, etnaviv_obj->size, sgt,
                                ETNAVIV_PROT_READ | ETNAVIV_PROT_WRITE);

        if (ret < 0) {
                drm_mm_remove_node(node);
                goto unlock;
        }

        mapping->context = etnaviv_iommu_context_get(context);
        list_add_tail(&mapping->mmu_node, &context->mappings);
unlock:
        mutex_unlock(&context->lock);

        return ret;
}

void etnaviv_iommu_unmap_gem(struct etnaviv_iommu_context *context,
        struct etnaviv_vram_mapping *mapping)
{
        WARN_ON(mapping->use);

        mutex_lock(&context->lock);

        /* Bail if the mapping has been reaped by another thread */
        if (!mapping->context) {
                mutex_unlock(&context->lock);
                return;
        }

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

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

static void etnaviv_iommu_context_free(struct kref *kref)
{
        struct etnaviv_iommu_context *context =
                container_of(kref, struct etnaviv_iommu_context, refcount);

        etnaviv_cmdbuf_suballoc_unmap(context, &context->cmdbuf_mapping);
        mutex_destroy(&context->lock);
        context->global->ops->free(context);
}
void etnaviv_iommu_context_put(struct etnaviv_iommu_context *context)
{
        kref_put(&context->refcount, etnaviv_iommu_context_free);
}

struct etnaviv_iommu_context *
etnaviv_iommu_context_init(struct etnaviv_iommu_global *global,
                           struct etnaviv_cmdbuf_suballoc *suballoc)
{
        struct etnaviv_iommu_context *ctx;
        int ret;

        if (global->version == ETNAVIV_IOMMU_V1)
                ctx = etnaviv_iommuv1_context_alloc(global);
        else
                ctx = etnaviv_iommuv2_context_alloc(global);

        if (!ctx)
                return NULL;

        ret = etnaviv_cmdbuf_suballoc_map(suballoc, ctx, &ctx->cmdbuf_mapping,
                                          global->memory_base);
        if (ret)
                goto out_free;

        if (global->version == ETNAVIV_IOMMU_V1 &&
            ctx->cmdbuf_mapping.iova > 0x80000000) {
                dev_err(global->dev,
                        "command buffer outside valid memory window\n");
                goto out_unmap;
        }

        return ctx;

out_unmap:
        etnaviv_cmdbuf_suballoc_unmap(ctx, &ctx->cmdbuf_mapping);
out_free:
        global->ops->free(ctx);
        return NULL;
}

void etnaviv_iommu_restore(struct etnaviv_gpu *gpu,
                           struct etnaviv_iommu_context *context)
{
        context->global->ops->restore(gpu, context);
}

int etnaviv_iommu_get_suballoc_va(struct etnaviv_iommu_context *context,
                                  struct etnaviv_vram_mapping *mapping,
                                  u32 memory_base, dma_addr_t paddr,
                                  size_t size)
{
        mutex_lock(&context->lock);

        if (mapping->use > 0) {
                mapping->use++;
                mutex_unlock(&context->lock);
                return 0;
        }

        /*
         * For MMUv1 we don't add the suballoc region to the pagetables, as
         * those GPUs can only work with cmdbufs accessed through the linear
         * window. Instead we manufacture a mapping to make it look uniform
         * to the upper layers.
         */
        if (context->global->version == ETNAVIV_IOMMU_V1) {
                mapping->iova = paddr - memory_base;
        } else {
                struct drm_mm_node *node = &mapping->vram_node;
                int ret;

                ret = etnaviv_iommu_find_iova(context, node, size);
                if (ret < 0) {
                        mutex_unlock(&context->lock);
                        return ret;
                }

                mapping->iova = node->start;
                ret = etnaviv_context_map(context, node->start, paddr, size,
                                          ETNAVIV_PROT_READ);
                if (ret < 0) {
                        drm_mm_remove_node(node);
                        mutex_unlock(&context->lock);
                        return ret;
                }

                context->flush_seq++;
        }

        list_add_tail(&mapping->mmu_node, &context->mappings);
        mapping->use = 1;

        mutex_unlock(&context->lock);

        return 0;
}

void etnaviv_iommu_put_suballoc_va(struct etnaviv_iommu_context *context,
                  struct etnaviv_vram_mapping *mapping)
{
        struct drm_mm_node *node = &mapping->vram_node;

        mutex_lock(&context->lock);
        mapping->use--;

        if (mapping->use > 0 || context->global->version == ETNAVIV_IOMMU_V1) {
                mutex_unlock(&context->lock);
                return;
        }

        etnaviv_context_unmap(context, node->start, node->size);
        drm_mm_remove_node(node);
        mutex_unlock(&context->lock);
}

size_t etnaviv_iommu_dump_size(struct etnaviv_iommu_context *context)
{
        return context->global->ops->dump_size(context);
}

void etnaviv_iommu_dump(struct etnaviv_iommu_context *context, void *buf)
{
        context->global->ops->dump(context, buf);
}

int etnaviv_iommu_global_init(struct etnaviv_gpu *gpu)
{
        enum etnaviv_iommu_version version = ETNAVIV_IOMMU_V1;
        struct etnaviv_drm_private *priv = gpu->drm->dev_private;
        struct etnaviv_iommu_global *global;
        struct device *dev = gpu->drm->dev;

        if (gpu->identity.minor_features1 & chipMinorFeatures1_MMU_VERSION)
                version = ETNAVIV_IOMMU_V2;

        if (priv->mmu_global) {
                if (priv->mmu_global->version != version) {
                        dev_err(gpu->dev,
                                "MMU version doesn't match global version\n");
                        return -ENXIO;
                }

                priv->mmu_global->use++;
                return 0;
        }

        global = kzalloc_obj(*global);
        if (!global)
                return -ENOMEM;

        global->bad_page_cpu = dma_alloc_wc(dev, SZ_4K, &global->bad_page_dma,
                                            GFP_KERNEL);
        if (!global->bad_page_cpu)
                goto free_global;

        memset32(global->bad_page_cpu, 0xdead55aa, SZ_4K / sizeof(u32));

        if (version == ETNAVIV_IOMMU_V2) {
                global->v2.pta_cpu = dma_alloc_wc(dev, ETNAVIV_PTA_SIZE,
                                               &global->v2.pta_dma, GFP_KERNEL);
                if (!global->v2.pta_cpu)
                        goto free_bad_page;
        }

        global->dev = dev;
        global->version = version;
        global->use = 1;
        mutex_init(&global->lock);

        if (version == ETNAVIV_IOMMU_V1)
                global->ops = &etnaviv_iommuv1_ops;
        else
                global->ops = &etnaviv_iommuv2_ops;

        priv->mmu_global = global;

        return 0;

free_bad_page:
        dma_free_wc(dev, SZ_4K, global->bad_page_cpu, global->bad_page_dma);
free_global:
        kfree(global);

        return -ENOMEM;
}

void etnaviv_iommu_global_fini(struct etnaviv_gpu *gpu)
{
        struct etnaviv_drm_private *priv = gpu->drm->dev_private;
        struct etnaviv_iommu_global *global = priv->mmu_global;

        if (!global)
                return;

        if (--global->use > 0)
                return;

        if (global->v2.pta_cpu)
                dma_free_wc(global->dev, ETNAVIV_PTA_SIZE,
                            global->v2.pta_cpu, global->v2.pta_dma);

        if (global->bad_page_cpu)
                dma_free_wc(global->dev, SZ_4K,
                            global->bad_page_cpu, global->bad_page_dma);

        mutex_destroy(&global->lock);
        kfree(global);

        priv->mmu_global = NULL;
}