/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright 2012 Red Hat Inc
 */

#include <linux/dma-buf.h>
#include <linux/highmem.h>
#include <linux/reservation.h>

#include "i915_drv.h"
#include "i915_gem_object.h"
#include "i915_scatterlist.h"

static struct drm_i915_gem_object *dma_buf_to_obj(struct dma_buf *buf)
{
        return to_intel_bo(buf->priv);
}

static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachment,
                                             enum dma_data_direction dir)
{
        struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment->dmabuf);
        struct sg_table *st;
        struct scatterlist *src, *dst;
        int ret, i;

        ret = i915_gem_object_pin_pages(obj);
        if (ret)
                goto err;

        /* Copy sg so that we make an independent mapping */
        st = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
        if (st == NULL) {
                ret = -ENOMEM;
                goto err_unpin_pages;
        }

        ret = sg_alloc_table(st, obj->mm.pages->nents, GFP_KERNEL);
        if (ret)
                goto err_free;

        src = obj->mm.pages->sgl;
        dst = st->sgl;
        for (i = 0; i < obj->mm.pages->nents; i++) {
                sg_set_page(dst, sg_page(src), src->length, 0);
                dst = sg_next(dst);
                src = sg_next(src);
        }

        if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) {
                ret = -ENOMEM;
                goto err_free_sg;
        }

        return st;

err_free_sg:
        sg_free_table(st);
err_free:
        kfree(st);
err_unpin_pages:
        i915_gem_object_unpin_pages(obj);
err:
        return ERR_PTR(ret);
}

static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
                                   struct sg_table *sg,
                                   enum dma_data_direction dir)
{
        struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment->dmabuf);

        dma_unmap_sg(attachment->dev, sg->sgl, sg->nents, dir);
        sg_free_table(sg);
        kfree(sg);

        i915_gem_object_unpin_pages(obj);
}

static void *i915_gem_dmabuf_vmap(struct dma_buf *dma_buf)
{
        struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);

        return i915_gem_object_pin_map(obj, I915_MAP_WB);
}

static void i915_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
{
        struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);

        i915_gem_object_flush_map(obj);
        i915_gem_object_unpin_map(obj);
}

static void *i915_gem_dmabuf_kmap(struct dma_buf *dma_buf, unsigned long page_num)
{
        struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
        struct page *page;

        if (page_num >= obj->base.size >> PAGE_SHIFT)
                return NULL;

        if (!i915_gem_object_has_struct_page(obj))
                return NULL;

        if (i915_gem_object_pin_pages(obj))
                return NULL;

        /* Synchronisation is left to the caller (via .begin_cpu_access()) */
        page = i915_gem_object_get_page(obj, page_num);
        if (IS_ERR(page))
                goto err_unpin;

        return kmap(page);

err_unpin:
        i915_gem_object_unpin_pages(obj);
        return NULL;
}

static void i915_gem_dmabuf_kunmap(struct dma_buf *dma_buf, unsigned long page_num, void *addr)
{
        struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);

        kunmap(virt_to_page(addr));
        i915_gem_object_unpin_pages(obj);
}

static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
{
        struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
        int ret;

        if (obj->base.size < vma->vm_end - vma->vm_start)
                return -EINVAL;

        if (!obj->base.filp)
                return -ENODEV;

        ret = call_mmap(obj->base.filp, vma);
        if (ret)
                return ret;

        fput(vma->vm_file);
        vma->vm_file = get_file(obj->base.filp);

        return 0;
}

static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
{
        struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
        bool write = (direction == DMA_BIDIRECTIONAL || direction == DMA_TO_DEVICE);
        int err;

        err = i915_gem_object_pin_pages(obj);
        if (err)
                return err;

        err = i915_gem_object_lock_interruptible(obj);
        if (err)
                goto out;

        err = i915_gem_object_set_to_cpu_domain(obj, write);
        i915_gem_object_unlock(obj);

out:
        i915_gem_object_unpin_pages(obj);
        return err;
}

static int i915_gem_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
{
        struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
        int err;

        err = i915_gem_object_pin_pages(obj);
        if (err)
                return err;

        err = i915_gem_object_lock_interruptible(obj);
        if (err)
                goto out;

        err = i915_gem_object_set_to_gtt_domain(obj, false);
        i915_gem_object_unlock(obj);

out:
        i915_gem_object_unpin_pages(obj);
        return err;
}

static const struct dma_buf_ops i915_dmabuf_ops =  {
        .map_dma_buf = i915_gem_map_dma_buf,
        .unmap_dma_buf = i915_gem_unmap_dma_buf,
        .release = drm_gem_dmabuf_release,
        .map = i915_gem_dmabuf_kmap,
        .unmap = i915_gem_dmabuf_kunmap,
        .mmap = i915_gem_dmabuf_mmap,
        .vmap = i915_gem_dmabuf_vmap,
        .vunmap = i915_gem_dmabuf_vunmap,
        .begin_cpu_access = i915_gem_begin_cpu_access,
        .end_cpu_access = i915_gem_end_cpu_access,
};

struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
                                      struct drm_gem_object *gem_obj, int flags)
{
        struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
        DEFINE_DMA_BUF_EXPORT_INFO(exp_info);

        exp_info.ops = &i915_dmabuf_ops;
        exp_info.size = gem_obj->size;
        exp_info.flags = flags;
        exp_info.priv = gem_obj;
        exp_info.resv = obj->base.resv;

        if (obj->ops->dmabuf_export) {
                int ret = obj->ops->dmabuf_export(obj);
                if (ret)
                        return ERR_PTR(ret);
        }

        return drm_gem_dmabuf_export(dev, &exp_info);
}

static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj)
{
        struct sg_table *pages;
        unsigned int sg_page_sizes;

        pages = dma_buf_map_attachment(obj->base.import_attach,
                                       DMA_BIDIRECTIONAL);
        if (IS_ERR(pages))
                return PTR_ERR(pages);

        sg_page_sizes = i915_sg_page_sizes(pages->sgl);

        __i915_gem_object_set_pages(obj, pages, sg_page_sizes);

        return 0;
}

static void i915_gem_object_put_pages_dmabuf(struct drm_i915_gem_object *obj,
                                             struct sg_table *pages)
{
        dma_buf_unmap_attachment(obj->base.import_attach, pages,
                                 DMA_BIDIRECTIONAL);
}

static const struct drm_i915_gem_object_ops i915_gem_object_dmabuf_ops = {
        .get_pages = i915_gem_object_get_pages_dmabuf,
        .put_pages = i915_gem_object_put_pages_dmabuf,
};

struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
                                             struct dma_buf *dma_buf)
{
        struct dma_buf_attachment *attach;
        struct drm_i915_gem_object *obj;
        int ret;

        /* is this one of own objects? */
        if (dma_buf->ops == &i915_dmabuf_ops) {
                obj = dma_buf_to_obj(dma_buf);
                /* is it from our device? */
                if (obj->base.dev == dev) {
                        /*
                         * Importing dmabuf exported from out own gem increases
                         * refcount on gem itself instead of f_count of dmabuf.
                         */
                        return &i915_gem_object_get(obj)->base;
                }
        }

        /* need to attach */
        attach = dma_buf_attach(dma_buf, dev->dev);
        if (IS_ERR(attach))
                return ERR_CAST(attach);

        get_dma_buf(dma_buf);

        obj = i915_gem_object_alloc();
        if (obj == NULL) {
                ret = -ENOMEM;
                goto fail_detach;
        }

        drm_gem_private_object_init(dev, &obj->base, dma_buf->size);
        i915_gem_object_init(obj, &i915_gem_object_dmabuf_ops);
        obj->base.import_attach = attach;
        obj->base.resv = dma_buf->resv;

        /* We use GTT as shorthand for a coherent domain, one that is
         * neither in the GPU cache nor in the CPU cache, where all
         * writes are immediately visible in memory. (That's not strictly
         * true, but it's close! There are internal buffers such as the
         * write-combined buffer or a delay through the chipset for GTT
         * writes that do require us to treat GTT as a separate cache domain.)
         */
        obj->read_domains = I915_GEM_DOMAIN_GTT;
        obj->write_domain = 0;

        return &obj->base;

fail_detach:
        dma_buf_detach(dma_buf, attach);
        dma_buf_put(dma_buf);

        return ERR_PTR(ret);
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftests/mock_dmabuf.c"
#include "selftests/i915_gem_dmabuf.c"
#endif