// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 Russell King
 */

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

#include <drm/armada_drm.h>
#include <drm/drm_prime.h>
#include <drm/drm_print.h>

#include "armada_drm.h"
#include "armada_gem.h"
#include "armada_ioctlP.h"

MODULE_IMPORT_NS("DMA_BUF");

static vm_fault_t armada_gem_vm_fault(struct vm_fault *vmf)
{
        struct drm_gem_object *gobj = vmf->vma->vm_private_data;
        struct armada_gem_object *obj = drm_to_armada_gem(gobj);
        unsigned long pfn = obj->phys_addr >> PAGE_SHIFT;

        pfn += (vmf->address - vmf->vma->vm_start) >> PAGE_SHIFT;
        return vmf_insert_pfn(vmf->vma, vmf->address, pfn);
}

static const struct vm_operations_struct armada_gem_vm_ops = {
        .fault  = armada_gem_vm_fault,
        .open   = drm_gem_vm_open,
        .close  = drm_gem_vm_close,
};

static size_t roundup_gem_size(size_t size)
{
        return roundup(size, PAGE_SIZE);
}

void armada_gem_free_object(struct drm_gem_object *obj)
{
        struct armada_gem_object *dobj = drm_to_armada_gem(obj);
        struct armada_private *priv = drm_to_armada_dev(obj->dev);

        DRM_DEBUG_DRIVER("release obj %p\n", dobj);

        drm_gem_free_mmap_offset(&dobj->obj);

        might_lock(&priv->linear_lock);

        if (dobj->page) {
                /* page backed memory */
                unsigned int order = get_order(dobj->obj.size);
                __free_pages(dobj->page, order);
        } else if (dobj->linear) {
                /* linear backed memory */
                mutex_lock(&priv->linear_lock);
                drm_mm_remove_node(dobj->linear);
                mutex_unlock(&priv->linear_lock);
                kfree(dobj->linear);
                if (dobj->addr)
                        iounmap(dobj->addr);
        }

        if (dobj->obj.import_attach) {
                /* We only ever display imported data */
                if (dobj->sgt)
                        dma_buf_unmap_attachment_unlocked(dobj->obj.import_attach,
                                                          dobj->sgt, DMA_TO_DEVICE);
                drm_prime_gem_destroy(&dobj->obj, NULL);
        }

        drm_gem_object_release(&dobj->obj);

        kfree(dobj);
}

int
armada_gem_linear_back(struct drm_device *dev, struct armada_gem_object *obj)
{
        struct armada_private *priv = drm_to_armada_dev(dev);
        size_t size = obj->obj.size;

        if (obj->page || obj->linear)
                return 0;

        /*
         * If it is a small allocation (typically cursor, which will
         * be 32x64 or 64x32 ARGB pixels) try to get it from the system.
         * Framebuffers will never be this small (our minimum size for
         * framebuffers is larger than this anyway.)  Such objects are
         * only accessed by the CPU so we don't need any special handing
         * here.
         */
        if (size <= 8192) {
                unsigned int order = get_order(size);
                struct page *p = alloc_pages(GFP_KERNEL, order);

                if (p) {
                        obj->addr = page_address(p);
                        obj->phys_addr = page_to_phys(p);
                        obj->page = p;

                        memset(obj->addr, 0, PAGE_ALIGN(size));
                }
        }

        /*
         * We could grab something from DMA if it's enabled, but that
         * involves building in a problem:
         *
         * GEM DMA helper interface uses dma_alloc_coherent(), which provides
         * us with an CPU virtual address and a device address.
         *
         * The CPU virtual address may be either an address in the kernel
         * direct mapped region (for example, as it would be on x86) or
         * it may be remapped into another part of kernel memory space
         * (eg, as it would be on ARM.)  This means virt_to_phys() on the
         * returned virtual address is invalid depending on the architecture
         * implementation.
         *
         * The device address may also not be a physical address; it may
         * be that there is some kind of remapping between the device and
         * system RAM, which makes the use of the device address also
         * unsafe to re-use as a physical address.
         *
         * This makes DRM usage of dma_alloc_coherent() in a generic way
         * at best very questionable and unsafe.
         */

        /* Otherwise, grab it from our linear allocation */
        if (!obj->page) {
                struct drm_mm_node *node;
                unsigned align = min_t(unsigned, size, SZ_2M);
                void __iomem *ptr;
                int ret;

                node = kzalloc_obj(*node);
                if (!node)
                        return -ENOSPC;

                mutex_lock(&priv->linear_lock);
                ret = drm_mm_insert_node_generic(&priv->linear, node,
                                                 size, align, 0, 0);
                mutex_unlock(&priv->linear_lock);
                if (ret) {
                        kfree(node);
                        return ret;
                }

                obj->linear = node;

                /* Ensure that the memory we're returning is cleared. */
                ptr = ioremap_wc(obj->linear->start, size);
                if (!ptr) {
                        mutex_lock(&priv->linear_lock);
                        drm_mm_remove_node(obj->linear);
                        mutex_unlock(&priv->linear_lock);
                        kfree(obj->linear);
                        obj->linear = NULL;
                        return -ENOMEM;
                }

                memset_io(ptr, 0, size);
                iounmap(ptr);

                obj->phys_addr = obj->linear->start;
                obj->dev_addr = obj->linear->start;
                obj->mapped = true;
        }

        DRM_DEBUG_DRIVER("obj %p phys %#llx dev %#llx\n", obj,
                         (unsigned long long)obj->phys_addr,
                         (unsigned long long)obj->dev_addr);

        return 0;
}

void *
armada_gem_map_object(struct drm_device *dev, struct armada_gem_object *dobj)
{
        /* only linear objects need to be ioremap'd */
        if (!dobj->addr && dobj->linear)
                dobj->addr = ioremap_wc(dobj->phys_addr, dobj->obj.size);
        return dobj->addr;
}

static const struct drm_gem_object_funcs armada_gem_object_funcs = {
        .free = armada_gem_free_object,
        .export = armada_gem_prime_export,
        .vm_ops = &armada_gem_vm_ops,
};

struct armada_gem_object *
armada_gem_alloc_private_object(struct drm_device *dev, size_t size)
{
        struct armada_gem_object *obj;

        size = roundup_gem_size(size);

        obj = kzalloc_obj(*obj);
        if (!obj)
                return NULL;

        obj->obj.funcs = &armada_gem_object_funcs;

        drm_gem_private_object_init(dev, &obj->obj, size);

        DRM_DEBUG_DRIVER("alloc private obj %p size %zu\n", obj, size);

        return obj;
}

static struct armada_gem_object *armada_gem_alloc_object(struct drm_device *dev,
        size_t size)
{
        struct armada_gem_object *obj;
        struct address_space *mapping;

        size = roundup_gem_size(size);

        obj = kzalloc_obj(*obj);
        if (!obj)
                return NULL;

        obj->obj.funcs = &armada_gem_object_funcs;

        if (drm_gem_object_init(dev, &obj->obj, size)) {
                kfree(obj);
                return NULL;
        }

        mapping = obj->obj.filp->f_mapping;
        mapping_set_gfp_mask(mapping, GFP_HIGHUSER | __GFP_RECLAIMABLE);

        DRM_DEBUG_DRIVER("alloc obj %p size %zu\n", obj, size);

        return obj;
}

/* Dumb alloc support */
int armada_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
        struct drm_mode_create_dumb *args)
{
        struct armada_gem_object *dobj;
        u32 handle;
        size_t size;
        int ret;

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

        dobj = armada_gem_alloc_private_object(dev, size);
        if (dobj == NULL)
                return -ENOMEM;

        ret = armada_gem_linear_back(dev, dobj);
        if (ret)
                goto err;

        ret = drm_gem_handle_create(file, &dobj->obj, &handle);
        if (ret)
                goto err;

        args->handle = handle;

        /* drop reference from allocate - handle holds it now */
        DRM_DEBUG_DRIVER("obj %p size %zu handle %#x\n", dobj, size, handle);
 err:
        drm_gem_object_put(&dobj->obj);
        return ret;
}

/* Private driver gem ioctls */
int armada_gem_create_ioctl(struct drm_device *dev, void *data,
        struct drm_file *file)
{
        struct drm_armada_gem_create *args = data;
        struct armada_gem_object *dobj;
        size_t size;
        u32 handle;
        int ret;

        if (args->size == 0)
                return -ENOMEM;

        size = args->size;

        dobj = armada_gem_alloc_object(dev, size);
        if (dobj == NULL)
                return -ENOMEM;

        ret = drm_gem_handle_create(file, &dobj->obj, &handle);
        if (ret)
                goto err;

        args->handle = handle;

        /* drop reference from allocate - handle holds it now */
        DRM_DEBUG_DRIVER("obj %p size %zu handle %#x\n", dobj, size, handle);
 err:
        drm_gem_object_put(&dobj->obj);
        return ret;
}

/* Map a shmem-backed object into process memory space */
int armada_gem_mmap_ioctl(struct drm_device *dev, void *data,
        struct drm_file *file)
{
        struct drm_armada_gem_mmap *args = data;
        struct armada_gem_object *dobj;
        unsigned long addr;

        dobj = armada_gem_object_lookup(file, args->handle);
        if (dobj == NULL)
                return -ENOENT;

        if (!dobj->obj.filp) {
                drm_gem_object_put(&dobj->obj);
                return -EINVAL;
        }

        addr = vm_mmap(dobj->obj.filp, 0, args->size, PROT_READ | PROT_WRITE,
                       MAP_SHARED, args->offset);
        drm_gem_object_put(&dobj->obj);
        if (IS_ERR_VALUE(addr))
                return addr;

        args->addr = addr;

        return 0;
}

int armada_gem_pwrite_ioctl(struct drm_device *dev, void *data,
        struct drm_file *file)
{
        struct drm_armada_gem_pwrite *args = data;
        struct armada_gem_object *dobj;
        char __user *ptr;
        int ret = 0;

        DRM_DEBUG_DRIVER("handle %u off %u size %u ptr 0x%llx\n",
                args->handle, args->offset, args->size, args->ptr);

        if (args->size == 0)
                return 0;

        ptr = (char __user *)(uintptr_t)args->ptr;

        if (!access_ok(ptr, args->size))
                return -EFAULT;

        if (fault_in_readable(ptr, args->size))
                return -EFAULT;

        dobj = armada_gem_object_lookup(file, args->handle);
        if (dobj == NULL)
                return -ENOENT;

        /* Must be a kernel-mapped object */
        if (!dobj->addr)
                return -EINVAL;

        if (args->offset > dobj->obj.size ||
            args->size > dobj->obj.size - args->offset) {
                DRM_ERROR("invalid size: object size %u\n", dobj->obj.size);
                ret = -EINVAL;
                goto unref;
        }

        if (copy_from_user(dobj->addr + args->offset, ptr, args->size)) {
                ret = -EFAULT;
        } else if (dobj->update) {
                dobj->update(dobj->update_data);
                ret = 0;
        }

 unref:
        drm_gem_object_put(&dobj->obj);
        return ret;
}

/* Prime support */
static struct sg_table *
armada_gem_prime_map_dma_buf(struct dma_buf_attachment *attach,
        enum dma_data_direction dir)
{
        struct drm_gem_object *obj = attach->dmabuf->priv;
        struct armada_gem_object *dobj = drm_to_armada_gem(obj);
        struct scatterlist *sg;
        struct sg_table *sgt;
        int i;

        sgt = kmalloc_obj(*sgt);
        if (!sgt)
                return NULL;

        if (dobj->obj.filp) {
                struct address_space *mapping;
                int count;

                count = dobj->obj.size / PAGE_SIZE;
                if (sg_alloc_table(sgt, count, GFP_KERNEL))
                        goto free_sgt;

                mapping = dobj->obj.filp->f_mapping;

                for_each_sgtable_sg(sgt, sg, i) {
                        struct page *page;

                        page = shmem_read_mapping_page(mapping, i);
                        if (IS_ERR(page))
                                goto release;

                        sg_set_page(sg, page, PAGE_SIZE, 0);
                }

                if (dma_map_sgtable(attach->dev, sgt, dir, 0))
                        goto release;
        } else if (dobj->page) {
                /* Single contiguous page */
                if (sg_alloc_table(sgt, 1, GFP_KERNEL))
                        goto free_sgt;

                sg_set_page(sgt->sgl, dobj->page, dobj->obj.size, 0);

                if (dma_map_sgtable(attach->dev, sgt, dir, 0))
                        goto free_table;
        } else if (dobj->linear) {
                /* Single contiguous physical region - no struct page */
                if (sg_alloc_table(sgt, 1, GFP_KERNEL))
                        goto free_sgt;
                sg_dma_address(sgt->sgl) = dobj->dev_addr;
                sg_dma_len(sgt->sgl) = dobj->obj.size;
        } else {
                goto free_sgt;
        }
        return sgt;

 release:
        for_each_sgtable_sg(sgt, sg, i)
                if (sg_page(sg))
                        put_page(sg_page(sg));
 free_table:
        sg_free_table(sgt);
 free_sgt:
        kfree(sgt);
        return NULL;
}

static void armada_gem_prime_unmap_dma_buf(struct dma_buf_attachment *attach,
        struct sg_table *sgt, enum dma_data_direction dir)
{
        struct drm_gem_object *obj = attach->dmabuf->priv;
        struct armada_gem_object *dobj = drm_to_armada_gem(obj);
        int i;

        if (!dobj->linear)
                dma_unmap_sgtable(attach->dev, sgt, dir, 0);

        if (dobj->obj.filp) {
                struct scatterlist *sg;

                for_each_sgtable_sg(sgt, sg, i)
                        put_page(sg_page(sg));
        }

        sg_free_table(sgt);
        kfree(sgt);
}

static int
armada_gem_dmabuf_mmap(struct dma_buf *buf, struct vm_area_struct *vma)
{
        return -EINVAL;
}

static const struct dma_buf_ops armada_gem_prime_dmabuf_ops = {
        .map_dma_buf    = armada_gem_prime_map_dma_buf,
        .unmap_dma_buf  = armada_gem_prime_unmap_dma_buf,
        .release        = drm_gem_dmabuf_release,
        .mmap           = armada_gem_dmabuf_mmap,
};

struct dma_buf *
armada_gem_prime_export(struct drm_gem_object *obj, int flags)
{
        DEFINE_DMA_BUF_EXPORT_INFO(exp_info);

        exp_info.ops = &armada_gem_prime_dmabuf_ops;
        exp_info.size = obj->size;
        exp_info.flags = O_RDWR;
        exp_info.priv = obj;

        return drm_gem_dmabuf_export(obj->dev, &exp_info);
}

struct drm_gem_object *
armada_gem_prime_import(struct drm_device *dev, struct dma_buf *buf)
{
        struct dma_buf_attachment *attach;
        struct armada_gem_object *dobj;

        if (buf->ops == &armada_gem_prime_dmabuf_ops) {
                struct drm_gem_object *obj = buf->priv;
                if (obj->dev == dev) {
                        /*
                         * Importing our own dmabuf(s) increases the
                         * refcount on the gem object itself.
                         */
                        drm_gem_object_get(obj);
                        return obj;
                }
        }

        attach = dma_buf_attach(buf, dev->dev);
        if (IS_ERR(attach))
                return ERR_CAST(attach);

        dobj = armada_gem_alloc_private_object(dev, buf->size);
        if (!dobj) {
                dma_buf_detach(buf, attach);
                return ERR_PTR(-ENOMEM);
        }

        dobj->obj.import_attach = attach;
        get_dma_buf(buf);

        /*
         * Don't call dma_buf_map_attachment() here - it maps the
         * scatterlist immediately for DMA, and this is not always
         * an appropriate thing to do.
         */
        return &dobj->obj;
}

int armada_gem_map_import(struct armada_gem_object *dobj)
{
        int ret;

        dobj->sgt = dma_buf_map_attachment_unlocked(dobj->obj.import_attach,
                                                    DMA_TO_DEVICE);
        if (IS_ERR(dobj->sgt)) {
                ret = PTR_ERR(dobj->sgt);
                dobj->sgt = NULL;
                DRM_ERROR("dma_buf_map_attachment() error: %d\n", ret);
                return ret;
        }
        if (dobj->sgt->nents > 1) {
                DRM_ERROR("dma_buf_map_attachment() returned an (unsupported) scattered list\n");
                return -EINVAL;
        }
        if (sg_dma_len(dobj->sgt->sgl) < dobj->obj.size) {
                DRM_ERROR("dma_buf_map_attachment() returned a small buffer\n");
                return -EINVAL;
        }
        dobj->dev_addr = sg_dma_address(dobj->sgt->sgl);
        dobj->mapped = true;
        return 0;
}