// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2015 MediaTek Inc.
 */

#include <linux/dma-buf.h>

#include <drm/drm.h>
#include <drm/drm_device.h>
#include <drm/drm_gem.h>
#include <drm/drm_prime.h>

#include "mtk_drm_drv.h"
#include "mtk_drm_gem.h"

static struct mtk_drm_gem_obj *mtk_drm_gem_init(struct drm_device *dev,
                                                unsigned long size)
{
        struct mtk_drm_gem_obj *mtk_gem_obj;
        int ret;

        size = round_up(size, PAGE_SIZE);

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

        ret = drm_gem_object_init(dev, &mtk_gem_obj->base, size);
        if (ret < 0) {
                DRM_ERROR("failed to initialize gem object\n");
                kfree(mtk_gem_obj);
                return ERR_PTR(ret);
        }

        return mtk_gem_obj;
}

struct mtk_drm_gem_obj *mtk_drm_gem_create(struct drm_device *dev,
                                           size_t size, bool alloc_kmap)
{
        struct mtk_drm_private *priv = dev->dev_private;
        struct mtk_drm_gem_obj *mtk_gem;
        struct drm_gem_object *obj;
        int ret;

        mtk_gem = mtk_drm_gem_init(dev, size);
        if (IS_ERR(mtk_gem))
                return ERR_CAST(mtk_gem);

        obj = &mtk_gem->base;

        mtk_gem->dma_attrs = DMA_ATTR_WRITE_COMBINE;

        if (!alloc_kmap)
                mtk_gem->dma_attrs |= DMA_ATTR_NO_KERNEL_MAPPING;

        mtk_gem->cookie = dma_alloc_attrs(priv->dma_dev, obj->size,
                                          &mtk_gem->dma_addr, GFP_KERNEL,
                                          mtk_gem->dma_attrs);
        if (!mtk_gem->cookie) {
                DRM_ERROR("failed to allocate %zx byte dma buffer", obj->size);
                ret = -ENOMEM;
                goto err_gem_free;
        }

        if (alloc_kmap)
                mtk_gem->kvaddr = mtk_gem->cookie;

        DRM_DEBUG_DRIVER("cookie = %p dma_addr = %pad size = %zu\n",
                         mtk_gem->cookie, &mtk_gem->dma_addr,
                         size);

        return mtk_gem;

err_gem_free:
        drm_gem_object_release(obj);
        kfree(mtk_gem);
        return ERR_PTR(ret);
}

void mtk_drm_gem_free_object(struct drm_gem_object *obj)
{
        struct mtk_drm_gem_obj *mtk_gem = to_mtk_gem_obj(obj);
        struct mtk_drm_private *priv = obj->dev->dev_private;

        if (mtk_gem->sg)
                drm_prime_gem_destroy(obj, mtk_gem->sg);
        else
                dma_free_attrs(priv->dma_dev, obj->size, mtk_gem->cookie,
                               mtk_gem->dma_addr, mtk_gem->dma_attrs);

        /* release file pointer to gem object. */
        drm_gem_object_release(obj);

        kfree(mtk_gem);
}

int mtk_drm_gem_dumb_create(struct drm_file *file_priv, struct drm_device *dev,
                            struct drm_mode_create_dumb *args)
{
        struct mtk_drm_gem_obj *mtk_gem;
        int ret;

        args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
        args->size = args->pitch * args->height;

        mtk_gem = mtk_drm_gem_create(dev, args->size, false);
        if (IS_ERR(mtk_gem))
                return PTR_ERR(mtk_gem);

        /*
         * allocate a id of idr table where the obj is registered
         * and handle has the id what user can see.
         */
        ret = drm_gem_handle_create(file_priv, &mtk_gem->base, &args->handle);
        if (ret)
                goto err_handle_create;

        /* drop reference from allocate - handle holds it now. */
        drm_gem_object_put_unlocked(&mtk_gem->base);

        return 0;

err_handle_create:
        mtk_drm_gem_free_object(&mtk_gem->base);
        return ret;
}

static int mtk_drm_gem_object_mmap(struct drm_gem_object *obj,
                                   struct vm_area_struct *vma)

{
        int ret;
        struct mtk_drm_gem_obj *mtk_gem = to_mtk_gem_obj(obj);
        struct mtk_drm_private *priv = obj->dev->dev_private;

        /*
         * dma_alloc_attrs() allocated a struct page table for mtk_gem, so clear
         * VM_PFNMAP flag that was set by drm_gem_mmap_obj()/drm_gem_mmap().
         */
        vma->vm_flags &= ~VM_PFNMAP;

        ret = dma_mmap_attrs(priv->dma_dev, vma, mtk_gem->cookie,
                             mtk_gem->dma_addr, obj->size, mtk_gem->dma_attrs);
        if (ret)
                drm_gem_vm_close(vma);

        return ret;
}

int mtk_drm_gem_mmap_buf(struct drm_gem_object *obj, struct vm_area_struct *vma)
{
        int ret;

        ret = drm_gem_mmap_obj(obj, obj->size, vma);
        if (ret)
                return ret;

        return mtk_drm_gem_object_mmap(obj, vma);
}

int mtk_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
{
        struct drm_gem_object *obj;
        int ret;

        ret = drm_gem_mmap(filp, vma);
        if (ret)
                return ret;

        obj = vma->vm_private_data;

        /*
         * Set vm_pgoff (used as a fake buffer offset by DRM) to 0 and map the
         * whole buffer from the start.
         */
        vma->vm_pgoff = 0;

        return mtk_drm_gem_object_mmap(obj, vma);
}

/*
 * Allocate a sg_table for this GEM object.
 * Note: Both the table's contents, and the sg_table itself must be freed by
 *       the caller.
 * Returns a pointer to the newly allocated sg_table, or an ERR_PTR() error.
 */
struct sg_table *mtk_gem_prime_get_sg_table(struct drm_gem_object *obj)
{
        struct mtk_drm_gem_obj *mtk_gem = to_mtk_gem_obj(obj);
        struct mtk_drm_private *priv = obj->dev->dev_private;
        struct sg_table *sgt;
        int ret;

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

        ret = dma_get_sgtable_attrs(priv->dma_dev, sgt, mtk_gem->cookie,
                                    mtk_gem->dma_addr, obj->size,
                                    mtk_gem->dma_attrs);
        if (ret) {
                DRM_ERROR("failed to allocate sgt, %d\n", ret);
                kfree(sgt);
                return ERR_PTR(ret);
        }

        return sgt;
}

struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
                        struct dma_buf_attachment *attach, struct sg_table *sg)
{
        struct mtk_drm_gem_obj *mtk_gem;
        int ret;
        struct scatterlist *s;
        unsigned int i;
        dma_addr_t expected;

        mtk_gem = mtk_drm_gem_init(dev, attach->dmabuf->size);

        if (IS_ERR(mtk_gem))
                return ERR_CAST(mtk_gem);

        expected = sg_dma_address(sg->sgl);
        for_each_sg(sg->sgl, s, sg->nents, i) {
                if (sg_dma_address(s) != expected) {
                        DRM_ERROR("sg_table is not contiguous");
                        ret = -EINVAL;
                        goto err_gem_free;
                }
                expected = sg_dma_address(s) + sg_dma_len(s);
        }

        mtk_gem->dma_addr = sg_dma_address(sg->sgl);
        mtk_gem->sg = sg;

        return &mtk_gem->base;

err_gem_free:
        kfree(mtk_gem);
        return ERR_PTR(ret);
}

void *mtk_drm_gem_prime_vmap(struct drm_gem_object *obj)
{
        struct mtk_drm_gem_obj *mtk_gem = to_mtk_gem_obj(obj);
        struct sg_table *sgt;
        struct sg_page_iter iter;
        unsigned int npages;
        unsigned int i = 0;

        if (mtk_gem->kvaddr)
                return mtk_gem->kvaddr;

        sgt = mtk_gem_prime_get_sg_table(obj);
        if (IS_ERR(sgt))
                return NULL;

        npages = obj->size >> PAGE_SHIFT;
        mtk_gem->pages = kcalloc(npages, sizeof(*mtk_gem->pages), GFP_KERNEL);
        if (!mtk_gem->pages)
                goto out;

        for_each_sg_page(sgt->sgl, &iter, sgt->orig_nents, 0) {
                mtk_gem->pages[i++] = sg_page_iter_page(&iter);
                if (i > npages)
                        break;
        }
        mtk_gem->kvaddr = vmap(mtk_gem->pages, npages, VM_MAP,
                               pgprot_writecombine(PAGE_KERNEL));

out:
        kfree((void *)sgt);

        return mtk_gem->kvaddr;
}

void mtk_drm_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
{
        struct mtk_drm_gem_obj *mtk_gem = to_mtk_gem_obj(obj);

        if (!mtk_gem->pages)
                return;

        vunmap(vaddr);
        mtk_gem->kvaddr = 0;
        kfree((void *)mtk_gem->pages);
}