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

#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 "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 const struct vm_operations_struct vm_ops = {
	.open = drm_gem_vm_open,
	.close = drm_gem_vm_close,
};

static const struct drm_gem_object_funcs mtk_gem_object_funcs = {
	.free = mtk_gem_free_object,
	.get_sg_table = mtk_gem_prime_get_sg_table,
	.vmap = mtk_gem_prime_vmap,
	.vunmap = mtk_gem_prime_vunmap,
	.mmap = mtk_gem_object_mmap,
	.vm_ops = &vm_ops,
};

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

	size = round_up(size, PAGE_SIZE);

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

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

	mtk_gem_obj->base.funcs = &mtk_gem_object_funcs;

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

	mtk_gem = mtk_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_gem_free_object(struct drm_gem_object *obj)
{
	struct mtk_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_gem_dumb_create(struct drm_file *file_priv, struct drm_device *dev,
			struct drm_mode_create_dumb *args)
{
	struct mtk_gem_obj *mtk_gem;
	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;

	mtk_gem = mtk_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(&mtk_gem->base);

	return 0;

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

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

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

	/*
	 * 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;

	/*
	 * 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_set(vma, VM_IO | VM_DONTEXPAND | VM_DONTDUMP);
	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_attrs(priv->dma_dev, vma, mtk_gem->cookie,
			     mtk_gem->dma_addr, obj->size, mtk_gem->dma_attrs);

	return ret;
}

/*
 * 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_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_gem_obj *mtk_gem;

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

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

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

	return &mtk_gem->base;
}

int mtk_gem_prime_vmap(struct drm_gem_object *obj, struct iosys_map *map)
{
	struct mtk_gem_obj *mtk_gem = to_mtk_gem_obj(obj);
	struct sg_table *sgt = NULL;
	unsigned int npages;

	if (mtk_gem->kvaddr)
		goto out;

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

	npages = obj->size >> PAGE_SHIFT;
	mtk_gem->pages = kcalloc(npages, sizeof(*mtk_gem->pages), GFP_KERNEL);
	if (!mtk_gem->pages) {
		sg_free_table(sgt);
		kfree(sgt);
		return -ENOMEM;
	}

	drm_prime_sg_to_page_array(sgt, mtk_gem->pages, npages);

	mtk_gem->kvaddr = vmap(mtk_gem->pages, npages, VM_MAP,
			       pgprot_writecombine(PAGE_KERNEL));
	if (!mtk_gem->kvaddr) {
		sg_free_table(sgt);
		kfree(sgt);
		kfree(mtk_gem->pages);
		return -ENOMEM;
	}
	sg_free_table(sgt);
	kfree(sgt);

out:
	iosys_map_set_vaddr(map, mtk_gem->kvaddr);

	return 0;
}

void mtk_gem_prime_vunmap(struct drm_gem_object *obj, struct iosys_map *map)
{
	struct mtk_gem_obj *mtk_gem = to_mtk_gem_obj(obj);
	void *vaddr = map->vaddr;

	if (!mtk_gem->pages)
		return;

	vunmap(vaddr);
	mtk_gem->kvaddr = NULL;
	kfree(mtk_gem->pages);
}