// SPDX-License-Identifier: GPL-2.0-or-later
/* exynos_drm_gem.c
 *
 * Copyright (c) 2011 Samsung Electronics Co., Ltd.
 * Author: Inki Dae <inki.dae@samsung.com>
 */


#include <linux/dma-buf.h>
#include <linux/shmem_fs.h>
#include <linux/module.h>

#include <drm/drm_dumb_buffers.h>
#include <drm/drm_prime.h>
#include <drm/drm_print.h>
#include <drm/drm_vma_manager.h>
#include <drm/exynos_drm.h>

#include "exynos_drm_drv.h"
#include "exynos_drm_gem.h"

MODULE_IMPORT_NS("DMA_BUF");

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

static int exynos_drm_alloc_buf(struct exynos_drm_gem *exynos_gem, bool kvmap)
{
        struct drm_device *dev = exynos_gem->base.dev;
        unsigned long attr = 0;

        if (exynos_gem->dma_addr) {
                DRM_DEV_DEBUG_KMS(to_dma_dev(dev), "already allocated.\n");
                return 0;
        }

        /*
         * if EXYNOS_BO_CONTIG, fully physically contiguous memory
         * region will be allocated else physically contiguous
         * as possible.
         */
        if (!(exynos_gem->flags & EXYNOS_BO_NONCONTIG))
                attr |= DMA_ATTR_FORCE_CONTIGUOUS;

        /*
         * if EXYNOS_BO_WC or EXYNOS_BO_NONCACHABLE, writecombine mapping
         * else cachable mapping.
         */
        if (exynos_gem->flags & EXYNOS_BO_WC ||
                        !(exynos_gem->flags & EXYNOS_BO_CACHABLE))
                attr |= DMA_ATTR_WRITE_COMBINE;

        /* FBDev emulation requires kernel mapping */
        if (!kvmap)
                attr |= DMA_ATTR_NO_KERNEL_MAPPING;

        exynos_gem->dma_attrs = attr;
        exynos_gem->cookie = dma_alloc_attrs(to_dma_dev(dev), exynos_gem->size,
                                             &exynos_gem->dma_addr, GFP_KERNEL,
                                             exynos_gem->dma_attrs);
        if (!exynos_gem->cookie) {
                DRM_DEV_ERROR(to_dma_dev(dev), "failed to allocate buffer.\n");
                return -ENOMEM;
        }

        if (kvmap)
                exynos_gem->kvaddr = exynos_gem->cookie;

        DRM_DEV_DEBUG_KMS(to_dma_dev(dev), "dma_addr(0x%lx), size(0x%lx)\n",
                        (unsigned long)exynos_gem->dma_addr, exynos_gem->size);
        return 0;
}

static void exynos_drm_free_buf(struct exynos_drm_gem *exynos_gem)
{
        struct drm_device *dev = exynos_gem->base.dev;

        if (!exynos_gem->dma_addr) {
                DRM_DEV_DEBUG_KMS(dev->dev, "dma_addr is invalid.\n");
                return;
        }

        DRM_DEV_DEBUG_KMS(dev->dev, "dma_addr(0x%lx), size(0x%lx)\n",
                        (unsigned long)exynos_gem->dma_addr, exynos_gem->size);

        dma_free_attrs(to_dma_dev(dev), exynos_gem->size, exynos_gem->cookie,
                        (dma_addr_t)exynos_gem->dma_addr,
                        exynos_gem->dma_attrs);
}

static int exynos_drm_gem_handle_create(struct drm_gem_object *obj,
                                        struct drm_file *file_priv,
                                        unsigned int *handle)
{
        int ret;

        /*
         * 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, obj, handle);
        if (ret)
                return ret;

        DRM_DEV_DEBUG_KMS(to_dma_dev(obj->dev), "gem handle = 0x%x\n", *handle);

        /* drop reference from allocate - handle holds it now. */
        drm_gem_object_put(obj);

        return 0;
}

void exynos_drm_gem_destroy(struct exynos_drm_gem *exynos_gem)
{
        struct drm_gem_object *obj = &exynos_gem->base;

        DRM_DEV_DEBUG_KMS(to_dma_dev(obj->dev), "handle count = %d\n",
                          obj->handle_count);

        /*
         * do not release memory region from exporter.
         *
         * the region will be released by exporter
         * once dmabuf's refcount becomes 0.
         */
        if (obj->import_attach)
                drm_prime_gem_destroy(obj, exynos_gem->sgt);
        else
                exynos_drm_free_buf(exynos_gem);

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

        kfree(exynos_gem);
}

static const struct vm_operations_struct exynos_drm_gem_vm_ops = {
        .open = drm_gem_vm_open,
        .close = drm_gem_vm_close,
};

static const struct drm_gem_object_funcs exynos_drm_gem_object_funcs = {
        .free = exynos_drm_gem_free_object,
        .get_sg_table = exynos_drm_gem_prime_get_sg_table,
        .mmap = exynos_drm_gem_mmap,
        .vm_ops = &exynos_drm_gem_vm_ops,
};

static struct exynos_drm_gem *exynos_drm_gem_init(struct drm_device *dev,
                                                  unsigned long size)
{
        struct exynos_drm_gem *exynos_gem;
        struct drm_gem_object *obj;
        int ret;

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

        exynos_gem->size = size;
        obj = &exynos_gem->base;

        obj->funcs = &exynos_drm_gem_object_funcs;

        ret = drm_gem_object_init(dev, obj, size);
        if (ret < 0) {
                DRM_DEV_ERROR(dev->dev, "failed to initialize gem object\n");
                kfree(exynos_gem);
                return ERR_PTR(ret);
        }

        ret = drm_gem_create_mmap_offset(obj);
        if (ret < 0) {
                drm_gem_object_release(obj);
                kfree(exynos_gem);
                return ERR_PTR(ret);
        }

        DRM_DEV_DEBUG_KMS(dev->dev, "created file object = %p\n", obj->filp);

        return exynos_gem;
}

struct exynos_drm_gem *exynos_drm_gem_create(struct drm_device *dev,
                                             unsigned int flags,
                                             unsigned long size,
                                             bool kvmap)
{
        struct exynos_drm_gem *exynos_gem;
        int ret;

        if (flags & ~(EXYNOS_BO_MASK)) {
                DRM_DEV_ERROR(dev->dev,
                              "invalid GEM buffer flags: %u\n", flags);
                return ERR_PTR(-EINVAL);
        }

        if (!size) {
                DRM_DEV_ERROR(dev->dev, "invalid GEM buffer size: %lu\n", size);
                return ERR_PTR(-EINVAL);
        }

        size = roundup(size, PAGE_SIZE);

        exynos_gem = exynos_drm_gem_init(dev, size);
        if (IS_ERR(exynos_gem))
                return exynos_gem;

        if (!is_drm_iommu_supported(dev) && (flags & EXYNOS_BO_NONCONTIG)) {
                /*
                 * when no IOMMU is available, all allocated buffers are
                 * contiguous anyway, so drop EXYNOS_BO_NONCONTIG flag
                 */
                flags &= ~EXYNOS_BO_NONCONTIG;
                DRM_WARN("Non-contiguous allocation is not supported without IOMMU, falling back to contiguous buffer\n");
        }

        /* set memory type and cache attribute from user side. */
        exynos_gem->flags = flags;

        ret = exynos_drm_alloc_buf(exynos_gem, kvmap);
        if (ret < 0) {
                drm_gem_object_release(&exynos_gem->base);
                kfree(exynos_gem);
                return ERR_PTR(ret);
        }

        return exynos_gem;
}

int exynos_drm_gem_create_ioctl(struct drm_device *dev, void *data,
                                struct drm_file *file_priv)
{
        struct drm_exynos_gem_create *args = data;
        struct exynos_drm_gem *exynos_gem;
        int ret;

        exynos_gem = exynos_drm_gem_create(dev, args->flags, args->size, false);
        if (IS_ERR(exynos_gem))
                return PTR_ERR(exynos_gem);

        ret = exynos_drm_gem_handle_create(&exynos_gem->base, file_priv,
                                           &args->handle);
        if (ret) {
                exynos_drm_gem_destroy(exynos_gem);
                return ret;
        }

        return 0;
}

int exynos_drm_gem_map_ioctl(struct drm_device *dev, void *data,
                             struct drm_file *file_priv)
{
        struct drm_exynos_gem_map *args = data;

        return drm_gem_dumb_map_offset(file_priv, dev, args->handle,
                                       &args->offset);
}

struct exynos_drm_gem *exynos_drm_gem_get(struct drm_file *filp,
                                          unsigned int gem_handle)
{
        struct drm_gem_object *obj;

        obj = drm_gem_object_lookup(filp, gem_handle);
        if (!obj)
                return NULL;
        return to_exynos_gem(obj);
}

static int exynos_drm_gem_mmap_buffer(struct exynos_drm_gem *exynos_gem,
                                      struct vm_area_struct *vma)
{
        struct drm_device *drm_dev = exynos_gem->base.dev;
        unsigned long vm_size;
        int ret;

        vm_flags_clear(vma, VM_PFNMAP);
        vma->vm_pgoff = 0;

        vm_size = vma->vm_end - vma->vm_start;

        /* check if user-requested size is valid. */
        if (vm_size > exynos_gem->size)
                return -EINVAL;

        ret = dma_mmap_attrs(to_dma_dev(drm_dev), vma, exynos_gem->cookie,
                             exynos_gem->dma_addr, exynos_gem->size,
                             exynos_gem->dma_attrs);
        if (ret < 0) {
                DRM_ERROR("failed to mmap.\n");
                return ret;
        }

        return 0;
}

int exynos_drm_gem_get_ioctl(struct drm_device *dev, void *data,
                                      struct drm_file *file_priv)
{
        struct exynos_drm_gem *exynos_gem;
        struct drm_exynos_gem_info *args = data;
        struct drm_gem_object *obj;

        obj = drm_gem_object_lookup(file_priv, args->handle);
        if (!obj) {
                DRM_DEV_ERROR(dev->dev, "failed to lookup gem object.\n");
                return -EINVAL;
        }

        exynos_gem = to_exynos_gem(obj);

        args->flags = exynos_gem->flags;
        args->size = exynos_gem->size;

        drm_gem_object_put(obj);

        return 0;
}

void exynos_drm_gem_free_object(struct drm_gem_object *obj)
{
        exynos_drm_gem_destroy(to_exynos_gem(obj));
}

int exynos_drm_gem_dumb_create(struct drm_file *file_priv,
                               struct drm_device *dev,
                               struct drm_mode_create_dumb *args)
{
        struct exynos_drm_gem *exynos_gem;
        unsigned int flags;
        int ret;

        ret = drm_mode_size_dumb(dev, args, 0, 0);
        if (ret)
                return ret;

        /*
         * allocate memory to be used for framebuffer.
         * - this callback would be called by user application
         *      with DRM_IOCTL_MODE_CREATE_DUMB command.
         */

        if (is_drm_iommu_supported(dev))
                flags = EXYNOS_BO_NONCONTIG | EXYNOS_BO_WC;
        else
                flags = EXYNOS_BO_CONTIG | EXYNOS_BO_WC;

        exynos_gem = exynos_drm_gem_create(dev, flags, args->size, false);
        if (IS_ERR(exynos_gem)) {
                dev_warn(dev->dev, "FB allocation failed.\n");
                return PTR_ERR(exynos_gem);
        }

        ret = exynos_drm_gem_handle_create(&exynos_gem->base, file_priv,
                                           &args->handle);
        if (ret) {
                exynos_drm_gem_destroy(exynos_gem);
                return ret;
        }

        return 0;
}

static int exynos_drm_gem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
{
        struct exynos_drm_gem *exynos_gem = to_exynos_gem(obj);
        int ret;

        if (obj->import_attach)
                return dma_buf_mmap(obj->dma_buf, vma, 0);

        vm_flags_set(vma, VM_IO | VM_DONTEXPAND | VM_DONTDUMP);

        DRM_DEV_DEBUG_KMS(to_dma_dev(obj->dev), "flags = 0x%x\n",
                          exynos_gem->flags);

        /* non-cachable as default. */
        if (exynos_gem->flags & EXYNOS_BO_CACHABLE)
                vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
        else if (exynos_gem->flags & EXYNOS_BO_WC)
                vma->vm_page_prot =
                        pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
        else
                vma->vm_page_prot =
                        pgprot_noncached(vm_get_page_prot(vma->vm_flags));

        ret = exynos_drm_gem_mmap_buffer(exynos_gem, vma);
        if (ret)
                goto err_close_vm;

        return ret;

err_close_vm:
        drm_gem_vm_close(vma);

        return ret;
}

/* low-level interface prime helpers */
struct drm_gem_object *exynos_drm_gem_prime_import(struct drm_device *dev,
                                            struct dma_buf *dma_buf)
{
        return drm_gem_prime_import_dev(dev, dma_buf, to_dma_dev(dev));
}

struct sg_table *exynos_drm_gem_prime_get_sg_table(struct drm_gem_object *obj)
{
        struct exynos_drm_gem *exynos_gem = to_exynos_gem(obj);
        struct drm_device *drm_dev = obj->dev;
        struct sg_table *sgt;
        int ret;

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

        ret = dma_get_sgtable_attrs(to_dma_dev(drm_dev), sgt, exynos_gem->cookie,
                                    exynos_gem->dma_addr, exynos_gem->size,
                                    exynos_gem->dma_attrs);
        if (ret) {
                DRM_ERROR("failed to get sgtable, %d\n", ret);
                kfree(sgt);
                return ERR_PTR(ret);
        }

        return sgt;
}

struct drm_gem_object *
exynos_drm_gem_prime_import_sg_table(struct drm_device *dev,
                                     struct dma_buf_attachment *attach,
                                     struct sg_table *sgt)
{
        struct exynos_drm_gem *exynos_gem;

        /* check if the entries in the sg_table are contiguous */
        if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size) {
                DRM_ERROR("buffer chunks must be mapped contiguously");
                return ERR_PTR(-EINVAL);
        }

        exynos_gem = exynos_drm_gem_init(dev, attach->dmabuf->size);
        if (IS_ERR(exynos_gem))
                return ERR_CAST(exynos_gem);

        /*
         * Buffer has been mapped as contiguous into DMA address space,
         * but if there is IOMMU, it can be either CONTIG or NONCONTIG.
         * We assume a simplified logic below:
         */
        if (is_drm_iommu_supported(dev))
                exynos_gem->flags |= EXYNOS_BO_NONCONTIG;
        else
                exynos_gem->flags |= EXYNOS_BO_CONTIG;

        exynos_gem->dma_addr = sg_dma_address(sgt->sgl);
        exynos_gem->sgt = sgt;
        return &exynos_gem->base;
}