/*
 * udl_dmabuf.c
 *
 * Copyright (c) 2014 The Chromium OS Authors
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 *
 * 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 <drm/drmP.h>
#include "udl_drv.h"
#include <linux/shmem_fs.h>
#include <linux/dma-buf.h>

struct udl_drm_dmabuf_attachment {
        struct sg_table sgt;
        enum dma_data_direction dir;
        bool is_mapped;
};

static int udl_attach_dma_buf(struct dma_buf *dmabuf,
                              struct device *dev,
                              struct dma_buf_attachment *attach)
{
        struct udl_drm_dmabuf_attachment *udl_attach;

        DRM_DEBUG_PRIME("[DEV:%s] size:%zd\n", dev_name(attach->dev),
                        attach->dmabuf->size);

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

        udl_attach->dir = DMA_NONE;
        attach->priv = udl_attach;

        return 0;
}

static void udl_detach_dma_buf(struct dma_buf *dmabuf,
                               struct dma_buf_attachment *attach)
{
        struct udl_drm_dmabuf_attachment *udl_attach = attach->priv;
        struct sg_table *sgt;

        if (!udl_attach)
                return;

        DRM_DEBUG_PRIME("[DEV:%s] size:%zd\n", dev_name(attach->dev),
                        attach->dmabuf->size);

        sgt = &udl_attach->sgt;

        if (udl_attach->dir != DMA_NONE)
                dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents,
                                udl_attach->dir);

        sg_free_table(sgt);
        kfree(udl_attach);
        attach->priv = NULL;
}

static struct sg_table *udl_map_dma_buf(struct dma_buf_attachment *attach,
                                        enum dma_data_direction dir)
{
        struct udl_drm_dmabuf_attachment *udl_attach = attach->priv;
        struct udl_gem_object *obj = to_udl_bo(attach->dmabuf->priv);
        struct drm_device *dev = obj->base.dev;
        struct scatterlist *rd, *wr;
        struct sg_table *sgt = NULL;
        unsigned int i;
        int page_count;
        int nents, ret;

        DRM_DEBUG_PRIME("[DEV:%s] size:%zd dir=%d\n", dev_name(attach->dev),
                        attach->dmabuf->size, dir);

        /* just return current sgt if already requested. */
        if (udl_attach->dir == dir && udl_attach->is_mapped)
                return &udl_attach->sgt;

        if (!obj->pages) {
                ret = udl_gem_get_pages(obj);
                if (ret) {
                        DRM_ERROR("failed to map pages.\n");
                        return ERR_PTR(ret);
                }
        }

        page_count = obj->base.size / PAGE_SIZE;
        obj->sg = drm_prime_pages_to_sg(obj->pages, page_count);
        if (IS_ERR(obj->sg)) {
                DRM_ERROR("failed to allocate sgt.\n");
                return ERR_CAST(obj->sg);
        }

        sgt = &udl_attach->sgt;

        ret = sg_alloc_table(sgt, obj->sg->orig_nents, GFP_KERNEL);
        if (ret) {
                DRM_ERROR("failed to alloc sgt.\n");
                return ERR_PTR(-ENOMEM);
        }

        mutex_lock(&dev->struct_mutex);

        rd = obj->sg->sgl;
        wr = sgt->sgl;
        for (i = 0; i < sgt->orig_nents; ++i) {
                sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
                rd = sg_next(rd);
                wr = sg_next(wr);
        }

        if (dir != DMA_NONE) {
                nents = dma_map_sg(attach->dev, sgt->sgl, sgt->orig_nents, dir);
                if (!nents) {
                        DRM_ERROR("failed to map sgl with iommu.\n");
                        sg_free_table(sgt);
                        sgt = ERR_PTR(-EIO);
                        goto err_unlock;
                }
        }

        udl_attach->is_mapped = true;
        udl_attach->dir = dir;
        attach->priv = udl_attach;

err_unlock:
        mutex_unlock(&dev->struct_mutex);
        return sgt;
}

static void udl_unmap_dma_buf(struct dma_buf_attachment *attach,
                              struct sg_table *sgt,
                              enum dma_data_direction dir)
{
        /* Nothing to do. */
        DRM_DEBUG_PRIME("[DEV:%s] size:%zd dir:%d\n", dev_name(attach->dev),
                        attach->dmabuf->size, dir);
}

static void *udl_dmabuf_kmap(struct dma_buf *dma_buf, unsigned long page_num)
{
        /* TODO */

        return NULL;
}

static void *udl_dmabuf_kmap_atomic(struct dma_buf *dma_buf,
                                    unsigned long page_num)
{
        /* TODO */

        return NULL;
}

static void udl_dmabuf_kunmap(struct dma_buf *dma_buf,
                              unsigned long page_num, void *addr)
{
        /* TODO */
}

static void udl_dmabuf_kunmap_atomic(struct dma_buf *dma_buf,
                                     unsigned long page_num,
                                     void *addr)
{
        /* TODO */
}

static int udl_dmabuf_mmap(struct dma_buf *dma_buf,
                           struct vm_area_struct *vma)
{
        /* TODO */

        return -EINVAL;
}

static struct dma_buf_ops udl_dmabuf_ops = {
        .attach                 = udl_attach_dma_buf,
        .detach                 = udl_detach_dma_buf,
        .map_dma_buf            = udl_map_dma_buf,
        .unmap_dma_buf          = udl_unmap_dma_buf,
        .kmap                   = udl_dmabuf_kmap,
        .kmap_atomic            = udl_dmabuf_kmap_atomic,
        .kunmap                 = udl_dmabuf_kunmap,
        .kunmap_atomic          = udl_dmabuf_kunmap_atomic,
        .mmap                   = udl_dmabuf_mmap,
        .release                = drm_gem_dmabuf_release,
};

struct dma_buf *udl_gem_prime_export(struct drm_device *dev,
                                     struct drm_gem_object *obj, int flags)
{
        DEFINE_DMA_BUF_EXPORT_INFO(exp_info);

        exp_info.ops = &udl_dmabuf_ops;
        exp_info.size = obj->size;
        exp_info.flags = flags;
        exp_info.priv = obj;

        return dma_buf_export(&exp_info);
}

static int udl_prime_create(struct drm_device *dev,
                            size_t size,
                            struct sg_table *sg,
                            struct udl_gem_object **obj_p)
{
        struct udl_gem_object *obj;
        int npages;

        npages = size / PAGE_SIZE;

        *obj_p = NULL;
        obj = udl_gem_alloc_object(dev, npages * PAGE_SIZE);
        if (!obj)
                return -ENOMEM;

        obj->sg = sg;
        obj->pages = drm_malloc_ab(npages, sizeof(struct page *));
        if (obj->pages == NULL) {
                DRM_ERROR("obj pages is NULL %d\n", npages);
                return -ENOMEM;
        }

        drm_prime_sg_to_page_addr_arrays(sg, obj->pages, NULL, npages);

        *obj_p = obj;
        return 0;
}

struct drm_gem_object *udl_gem_prime_import(struct drm_device *dev,
                                struct dma_buf *dma_buf)
{
        struct dma_buf_attachment *attach;
        struct sg_table *sg;
        struct udl_gem_object *uobj;
        int ret;

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

        get_dma_buf(dma_buf);

        sg = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
        if (IS_ERR(sg)) {
                ret = PTR_ERR(sg);
                goto fail_detach;
        }

        ret = udl_prime_create(dev, dma_buf->size, sg, &uobj);
        if (ret)
                goto fail_unmap;

        uobj->base.import_attach = attach;
        uobj->flags = UDL_BO_WC;

        return &uobj->base;

fail_unmap:
        dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
fail_detach:
        dma_buf_detach(dma_buf, attach);
        dma_buf_put(dma_buf);
        put_device(dev->dev);
        return ERR_PTR(ret);
}