// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2015 MediaTek Inc.
 * Copyright (c) 2025 Collabora Ltd.
 *                    AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
 */

#include <linux/dma-buf.h>
#include <linux/vmalloc.h>

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

#include "mtk_drm_drv.h"
#include "mtk_gem.h"

static int mtk_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);

static void mtk_gem_free_object(struct drm_gem_object *obj)
{
        struct drm_gem_dma_object *dma_obj = to_drm_gem_dma_obj(obj);
        struct mtk_drm_private *priv = obj->dev->dev_private;

        if (dma_obj->sgt)
                drm_prime_gem_destroy(obj, dma_obj->sgt);
        else
                dma_free_wc(priv->dma_dev, dma_obj->base.size,
                            dma_obj->vaddr, dma_obj->dma_addr);

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

        kfree(dma_obj);
}

/*
 * 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.
 */
static struct sg_table *mtk_gem_prime_get_sg_table(struct drm_gem_object *obj)
{
        struct drm_gem_dma_object *dma_obj = to_drm_gem_dma_obj(obj);
        struct mtk_drm_private *priv = obj->dev->dev_private;
        struct sg_table *sgt;
        int ret;

        sgt = kzalloc_obj(*sgt);
        if (!sgt)
                return ERR_PTR(-ENOMEM);

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

        return sgt;
}

static const struct drm_gem_object_funcs mtk_gem_object_funcs = {
        .free = mtk_gem_free_object,
        .print_info = drm_gem_dma_object_print_info,
        .get_sg_table = mtk_gem_prime_get_sg_table,
        .vmap = drm_gem_dma_object_vmap,
        .mmap = mtk_gem_object_mmap,
        .vm_ops = &drm_gem_dma_vm_ops,
};

static struct drm_gem_dma_object *mtk_gem_init(struct drm_device *dev,
                                        unsigned long size, bool private)
{
        struct drm_gem_dma_object *dma_obj;
        int ret;

        size = round_up(size, PAGE_SIZE);

        if (size == 0)
                return ERR_PTR(-EINVAL);

        dma_obj = kzalloc_obj(*dma_obj);
        if (!dma_obj)
                return ERR_PTR(-ENOMEM);

        dma_obj->base.funcs = &mtk_gem_object_funcs;

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

        return dma_obj;
}

static struct drm_gem_dma_object *mtk_gem_create(struct drm_device *dev, size_t size)
{
        struct mtk_drm_private *priv = dev->dev_private;
        struct drm_gem_dma_object *dma_obj;
        struct drm_gem_object *obj;
        int ret;

        dma_obj = mtk_gem_init(dev, size, false);
        if (IS_ERR(dma_obj))
                return ERR_CAST(dma_obj);

        obj = &dma_obj->base;

        dma_obj->vaddr = dma_alloc_wc(priv->dma_dev, obj->size,
                                      &dma_obj->dma_addr,
                                      GFP_KERNEL | __GFP_NOWARN);
        if (!dma_obj->vaddr) {
                DRM_ERROR("failed to allocate %zx byte dma buffer", obj->size);
                ret = -ENOMEM;
                goto err_gem_free;
        }

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

        return dma_obj;

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

int mtk_gem_dumb_create(struct drm_file *file_priv, struct drm_device *dev,
                        struct drm_mode_create_dumb *args)
{
        struct drm_gem_dma_object *dma_obj;
        int ret;

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

        /*
         * Multiply 2 variables of different types,
         * for example: args->size = args->spacing * args->height;
         * may cause coverity issue with unintentional overflow.
         */
        args->size = args->pitch;
        args->size *= args->height;

        dma_obj = mtk_gem_create(dev, args->size);
        if (IS_ERR(dma_obj))
                return PTR_ERR(dma_obj);

        /*
         * 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, &dma_obj->base, &args->handle);
        if (ret)
                goto err_handle_create;

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

        return 0;

err_handle_create:
        mtk_gem_free_object(&dma_obj->base);
        return ret;
}

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

{
        struct drm_gem_dma_object *dma_obj = to_drm_gem_dma_obj(obj);
        struct mtk_drm_private *priv = obj->dev->dev_private;
        int ret;

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

        /*
         * 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().
         */
        vm_flags_mod(vma, VM_IO | VM_DONTEXPAND | VM_DONTDUMP, VM_PFNMAP);

        vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
        vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);

        ret = dma_mmap_wc(priv->dma_dev, vma, dma_obj->vaddr,
                          dma_obj->dma_addr, obj->size);
        if (ret)
                drm_gem_vm_close(vma);

        return ret;
}

struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
                        struct dma_buf_attachment *attach, struct sg_table *sgt)
{
        struct drm_gem_dma_object *dma_obj;

        /* check if the entries in the sg_table are contiguous */
        if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size) {
                DRM_ERROR("sg_table is not contiguous");
                return ERR_PTR(-EINVAL);
        }

        dma_obj = mtk_gem_init(dev, attach->dmabuf->size, true);
        if (IS_ERR(dma_obj))
                return ERR_CAST(dma_obj);

        dma_obj->dma_addr = sg_dma_address(sgt->sgl);
        dma_obj->sgt = sgt;

        return &dma_obj->base;
}