/*
 * drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
 *
 * Copyright (C) 2011 Texas Instruments
 * Author: Rob Clark <rob.clark@linaro.org>
 *
 * 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 "omap_drv.h"

#include <linux/dma-buf.h>

static struct sg_table *omap_gem_map_dma_buf(
                struct dma_buf_attachment *attachment,
                enum dma_data_direction dir)
{
        struct drm_gem_object *obj = attachment->dmabuf->priv;
        struct sg_table *sg;
        dma_addr_t paddr;
        int ret;

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

        /* camera, etc, need physically contiguous.. but we need a
         * better way to know this..
         */
        ret = omap_gem_get_paddr(obj, &paddr, true);
        if (ret)
                goto out;

        ret = sg_alloc_table(sg, 1, GFP_KERNEL);
        if (ret)
                goto out;

        sg_init_table(sg->sgl, 1);
        sg_dma_len(sg->sgl) = obj->size;
        sg_set_page(sg->sgl, pfn_to_page(PFN_DOWN(paddr)), obj->size, 0);
        sg_dma_address(sg->sgl) = paddr;

        /* this should be after _get_paddr() to ensure we have pages attached */
        omap_gem_dma_sync(obj, dir);

        return sg;
out:
        kfree(sg);
        return ERR_PTR(ret);
}

static void omap_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
                struct sg_table *sg, enum dma_data_direction dir)
{
        struct drm_gem_object *obj = attachment->dmabuf->priv;
        omap_gem_put_paddr(obj);
        sg_free_table(sg);
        kfree(sg);
}

static void omap_gem_dmabuf_release(struct dma_buf *buffer)
{
        struct drm_gem_object *obj = buffer->priv;
        /* release reference that was taken when dmabuf was exported
         * in omap_gem_prime_set()..
         */
        drm_gem_object_unreference_unlocked(obj);
}


static int omap_gem_dmabuf_begin_cpu_access(struct dma_buf *buffer,
                size_t start, size_t len, enum dma_data_direction dir)
{
        struct drm_gem_object *obj = buffer->priv;
        struct page **pages;
        if (omap_gem_flags(obj) & OMAP_BO_TILED) {
                /* TODO we would need to pin at least part of the buffer to
                 * get de-tiled view.  For now just reject it.
                 */
                return -ENOMEM;
        }
        /* make sure we have the pages: */
        return omap_gem_get_pages(obj, &pages, true);
}

static void omap_gem_dmabuf_end_cpu_access(struct dma_buf *buffer,
                size_t start, size_t len, enum dma_data_direction dir)
{
        struct drm_gem_object *obj = buffer->priv;
        omap_gem_put_pages(obj);
}


static void *omap_gem_dmabuf_kmap_atomic(struct dma_buf *buffer,
                unsigned long page_num)
{
        struct drm_gem_object *obj = buffer->priv;
        struct page **pages;
        omap_gem_get_pages(obj, &pages, false);
        omap_gem_cpu_sync(obj, page_num);
        return kmap_atomic(pages[page_num]);
}

static void omap_gem_dmabuf_kunmap_atomic(struct dma_buf *buffer,
                unsigned long page_num, void *addr)
{
        kunmap_atomic(addr);
}

static void *omap_gem_dmabuf_kmap(struct dma_buf *buffer,
                unsigned long page_num)
{
        struct drm_gem_object *obj = buffer->priv;
        struct page **pages;
        omap_gem_get_pages(obj, &pages, false);
        omap_gem_cpu_sync(obj, page_num);
        return kmap(pages[page_num]);
}

static void omap_gem_dmabuf_kunmap(struct dma_buf *buffer,
                unsigned long page_num, void *addr)
{
        struct drm_gem_object *obj = buffer->priv;
        struct page **pages;
        omap_gem_get_pages(obj, &pages, false);
        kunmap(pages[page_num]);
}

/*
 * TODO maybe we can split up drm_gem_mmap to avoid duplicating
 * some here.. or at least have a drm_dmabuf_mmap helper.
 */
static int omap_gem_dmabuf_mmap(struct dma_buf *buffer,
                struct vm_area_struct *vma)
{
        struct drm_gem_object *obj = buffer->priv;
        int ret = 0;

        if (WARN_ON(!obj->filp))
                return -EINVAL;

        /* Check for valid size. */
        if (omap_gem_mmap_size(obj) < vma->vm_end - vma->vm_start) {
                ret = -EINVAL;
                goto out_unlock;
        }

        if (!obj->dev->driver->gem_vm_ops) {
                ret = -EINVAL;
                goto out_unlock;
        }

        vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
        vma->vm_ops = obj->dev->driver->gem_vm_ops;
        vma->vm_private_data = obj;
        vma->vm_page_prot =  pgprot_writecombine(vm_get_page_prot(vma->vm_flags));

        /* Take a ref for this mapping of the object, so that the fault
         * handler can dereference the mmap offset's pointer to the object.
         * This reference is cleaned up by the corresponding vm_close
         * (which should happen whether the vma was created by this call, or
         * by a vm_open due to mremap or partial unmap or whatever).
         */
        vma->vm_ops->open(vma);

out_unlock:

        return omap_gem_mmap_obj(obj, vma);
}

static struct dma_buf_ops omap_dmabuf_ops = {
                .map_dma_buf = omap_gem_map_dma_buf,
                .unmap_dma_buf = omap_gem_unmap_dma_buf,
                .release = omap_gem_dmabuf_release,
                .begin_cpu_access = omap_gem_dmabuf_begin_cpu_access,
                .end_cpu_access = omap_gem_dmabuf_end_cpu_access,
                .kmap_atomic = omap_gem_dmabuf_kmap_atomic,
                .kunmap_atomic = omap_gem_dmabuf_kunmap_atomic,
                .kmap = omap_gem_dmabuf_kmap,
                .kunmap = omap_gem_dmabuf_kunmap,
                .mmap = omap_gem_dmabuf_mmap,
};

struct dma_buf *omap_gem_prime_export(struct drm_device *dev,
                struct drm_gem_object *obj, int flags)
{
        return dma_buf_export(obj, &omap_dmabuf_ops, obj->size, flags);
}

struct drm_gem_object *omap_gem_prime_import(struct drm_device *dev,
                struct dma_buf *buffer)
{
        struct drm_gem_object *obj;

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

        /*
         * TODO add support for importing buffers from other devices..
         * for now we don't need this but would be nice to add eventually
         */
        return ERR_PTR(-EINVAL);
}