/*
 * Copyright (C) 2013 Red Hat
 * Author: Rob Clark <robdclark@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

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

#include "msm_drv.h"
#include "msm_gem.h"
#include "msm_gpu.h"


/* called with dev->struct_mutex held */
static struct page **get_pages(struct drm_gem_object *obj)
{
        struct msm_gem_object *msm_obj = to_msm_bo(obj);

        if (!msm_obj->pages) {
                struct drm_device *dev = obj->dev;
                struct page **p = drm_gem_get_pages(obj, 0);
                int npages = obj->size >> PAGE_SHIFT;

                if (IS_ERR(p)) {
                        dev_err(dev->dev, "could not get pages: %ld\n",
                                        PTR_ERR(p));
                        return p;
                }

                msm_obj->sgt = drm_prime_pages_to_sg(p, npages);
                if (IS_ERR(msm_obj->sgt)) {
                        dev_err(dev->dev, "failed to allocate sgt\n");
                        return ERR_CAST(msm_obj->sgt);
                }

                msm_obj->pages = p;

                /* For non-cached buffers, ensure the new pages are clean
                 * because display controller, GPU, etc. are not coherent:
                 */
                if (msm_obj->flags & (MSM_BO_WC|MSM_BO_UNCACHED))
                        dma_map_sg(dev->dev, msm_obj->sgt->sgl,
                                        msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
        }

        return msm_obj->pages;
}

static void put_pages(struct drm_gem_object *obj)
{
        struct msm_gem_object *msm_obj = to_msm_bo(obj);

        if (msm_obj->pages) {
                /* For non-cached buffers, ensure the new pages are clean
                 * because display controller, GPU, etc. are not coherent:
                 */
                if (msm_obj->flags & (MSM_BO_WC|MSM_BO_UNCACHED))
                        dma_unmap_sg(obj->dev->dev, msm_obj->sgt->sgl,
                                        msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
                sg_free_table(msm_obj->sgt);
                kfree(msm_obj->sgt);

                drm_gem_put_pages(obj, msm_obj->pages, true, false);
                msm_obj->pages = NULL;
        }
}

struct page **msm_gem_get_pages(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct page **p;
        mutex_lock(&dev->struct_mutex);
        p = get_pages(obj);
        mutex_unlock(&dev->struct_mutex);
        return p;
}

void msm_gem_put_pages(struct drm_gem_object *obj)
{
        /* when we start tracking the pin count, then do something here */
}

int msm_gem_mmap_obj(struct drm_gem_object *obj,
                struct vm_area_struct *vma)
{
        struct msm_gem_object *msm_obj = to_msm_bo(obj);

        vma->vm_flags &= ~VM_PFNMAP;
        vma->vm_flags |= VM_MIXEDMAP;

        if (msm_obj->flags & MSM_BO_WC) {
                vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
        } else if (msm_obj->flags & MSM_BO_UNCACHED) {
                vma->vm_page_prot = pgprot_noncached(vm_get_page_prot(vma->vm_flags));
        } else {
                /*
                 * Shunt off cached objs to shmem file so they have their own
                 * address_space (so unmap_mapping_range does what we want,
                 * in particular in the case of mmap'd dmabufs)
                 */
                fput(vma->vm_file);
                get_file(obj->filp);
                vma->vm_pgoff = 0;
                vma->vm_file  = obj->filp;

                vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
        }

        return 0;
}

int msm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
{
        int ret;

        ret = drm_gem_mmap(filp, vma);
        if (ret) {
                DBG("mmap failed: %d", ret);
                return ret;
        }

        return msm_gem_mmap_obj(vma->vm_private_data, vma);
}

int msm_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct drm_gem_object *obj = vma->vm_private_data;
        struct msm_gem_object *msm_obj = to_msm_bo(obj);
        struct drm_device *dev = obj->dev;
        struct page **pages;
        unsigned long pfn;
        pgoff_t pgoff;
        int ret;

        /* Make sure we don't parallel update on a fault, nor move or remove
         * something from beneath our feet
         */
        ret = mutex_lock_interruptible(&dev->struct_mutex);
        if (ret)
                goto out;

        /* make sure we have pages attached now */
        pages = get_pages(obj);
        if (IS_ERR(pages)) {
                ret = PTR_ERR(pages);
                goto out_unlock;
        }

        /* We don't use vmf->pgoff since that has the fake offset: */
        pgoff = ((unsigned long)vmf->virtual_address -
                        vma->vm_start) >> PAGE_SHIFT;

        pfn = page_to_pfn(msm_obj->pages[pgoff]);

        VERB("Inserting %p pfn %lx, pa %lx", vmf->virtual_address,
                        pfn, pfn << PAGE_SHIFT);

        ret = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);

out_unlock:
        mutex_unlock(&dev->struct_mutex);
out:
        switch (ret) {
        case -EAGAIN:
        case 0:
        case -ERESTARTSYS:
        case -EINTR:
        case -EBUSY:
                /*
                 * EBUSY is ok: this just means that another thread
                 * already did the job.
                 */
                return VM_FAULT_NOPAGE;
        case -ENOMEM:
                return VM_FAULT_OOM;
        default:
                return VM_FAULT_SIGBUS;
        }
}

/** get mmap offset */
static uint64_t mmap_offset(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        int ret;

        WARN_ON(!mutex_is_locked(&dev->struct_mutex));

        /* Make it mmapable */
        ret = drm_gem_create_mmap_offset(obj);

        if (ret) {
                dev_err(dev->dev, "could not allocate mmap offset\n");
                return 0;
        }

        return drm_vma_node_offset_addr(&obj->vma_node);
}

uint64_t msm_gem_mmap_offset(struct drm_gem_object *obj)
{
        uint64_t offset;
        mutex_lock(&obj->dev->struct_mutex);
        offset = mmap_offset(obj);
        mutex_unlock(&obj->dev->struct_mutex);
        return offset;
}

/* helpers for dealing w/ iommu: */
static int map_range(struct iommu_domain *domain, unsigned int iova,
                struct sg_table *sgt, unsigned int len, int prot)
{
        struct scatterlist *sg;
        unsigned int da = iova;
        unsigned int i, j;
        int ret;

        if (!domain || !sgt)
                return -EINVAL;

        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
                u32 pa = sg_phys(sg) - sg->offset;
                size_t bytes = sg->length + sg->offset;

                VERB("map[%d]: %08x %08x(%x)", i, iova, pa, bytes);

                ret = iommu_map(domain, da, pa, bytes, prot);
                if (ret)
                        goto fail;

                da += bytes;
        }

        return 0;

fail:
        da = iova;

        for_each_sg(sgt->sgl, sg, i, j) {
                size_t bytes = sg->length + sg->offset;
                iommu_unmap(domain, da, bytes);
                da += bytes;
        }
        return ret;
}

static void unmap_range(struct iommu_domain *domain, unsigned int iova,
                struct sg_table *sgt, unsigned int len)
{
        struct scatterlist *sg;
        unsigned int da = iova;
        int i;

        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
                size_t bytes = sg->length + sg->offset;
                size_t unmapped;

                unmapped = iommu_unmap(domain, da, bytes);
                if (unmapped < bytes)
                        break;

                VERB("unmap[%d]: %08x(%x)", i, iova, bytes);

                BUG_ON(!IS_ALIGNED(bytes, PAGE_SIZE));

                da += bytes;
        }
}

/* should be called under struct_mutex.. although it can be called
 * from atomic context without struct_mutex to acquire an extra
 * iova ref if you know one is already held.
 *
 * That means when I do eventually need to add support for unpinning
 * the refcnt counter needs to be atomic_t.
 */
int msm_gem_get_iova_locked(struct drm_gem_object *obj, int id,
                uint32_t *iova)
{
        struct msm_gem_object *msm_obj = to_msm_bo(obj);
        int ret = 0;

        if (!msm_obj->domain[id].iova) {
                struct msm_drm_private *priv = obj->dev->dev_private;
                uint32_t offset = (uint32_t)mmap_offset(obj);
                struct page **pages;
                pages = get_pages(obj);
                if (IS_ERR(pages))
                        return PTR_ERR(pages);
                // XXX ideally we would not map buffers writable when not needed...
                ret = map_range(priv->iommus[id], offset, msm_obj->sgt,
                                obj->size, IOMMU_READ | IOMMU_WRITE);
                msm_obj->domain[id].iova = offset;
        }

        if (!ret)
                *iova = msm_obj->domain[id].iova;

        return ret;
}

int msm_gem_get_iova(struct drm_gem_object *obj, int id, uint32_t *iova)
{
        struct msm_gem_object *msm_obj = to_msm_bo(obj);
        int ret;

        /* this is safe right now because we don't unmap until the
         * bo is deleted:
         */
        if (msm_obj->domain[id].iova) {
                *iova = msm_obj->domain[id].iova;
                return 0;
        }

        mutex_lock(&obj->dev->struct_mutex);
        ret = msm_gem_get_iova_locked(obj, id, iova);
        mutex_unlock(&obj->dev->struct_mutex);
        return ret;
}

void msm_gem_put_iova(struct drm_gem_object *obj, int id)
{
        // XXX TODO ..
        // NOTE: probably don't need a _locked() version.. we wouldn't
        // normally unmap here, but instead just mark that it could be
        // unmapped (if the iova refcnt drops to zero), but then later
        // if another _get_iova_locked() fails we can start unmapping
        // things that are no longer needed..
}

int msm_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
                struct drm_mode_create_dumb *args)
{
        args->pitch = align_pitch(args->width, args->bpp);
        args->size  = PAGE_ALIGN(args->pitch * args->height);
        return msm_gem_new_handle(dev, file, args->size,
                        MSM_BO_SCANOUT | MSM_BO_WC, &args->handle);
}

int msm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
                uint32_t handle, uint64_t *offset)
{
        struct drm_gem_object *obj;
        int ret = 0;

        /* GEM does all our handle to object mapping */
        obj = drm_gem_object_lookup(dev, file, handle);
        if (obj == NULL) {
                ret = -ENOENT;
                goto fail;
        }

        *offset = msm_gem_mmap_offset(obj);

        drm_gem_object_unreference_unlocked(obj);

fail:
        return ret;
}

void *msm_gem_vaddr_locked(struct drm_gem_object *obj)
{
        struct msm_gem_object *msm_obj = to_msm_bo(obj);
        WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex));
        if (!msm_obj->vaddr) {
                struct page **pages = get_pages(obj);
                if (IS_ERR(pages))
                        return ERR_CAST(pages);
                msm_obj->vaddr = vmap(pages, obj->size >> PAGE_SHIFT,
                                VM_MAP, pgprot_writecombine(PAGE_KERNEL));
        }
        return msm_obj->vaddr;
}

void *msm_gem_vaddr(struct drm_gem_object *obj)
{
        void *ret;
        mutex_lock(&obj->dev->struct_mutex);
        ret = msm_gem_vaddr_locked(obj);
        mutex_unlock(&obj->dev->struct_mutex);
        return ret;
}

/* setup callback for when bo is no longer busy..
 * TODO probably want to differentiate read vs write..
 */
int msm_gem_queue_inactive_cb(struct drm_gem_object *obj,
                struct msm_fence_cb *cb)
{
        struct drm_device *dev = obj->dev;
        struct msm_drm_private *priv = dev->dev_private;
        struct msm_gem_object *msm_obj = to_msm_bo(obj);
        int ret = 0;

        mutex_lock(&dev->struct_mutex);
        if (!list_empty(&cb->work.entry)) {
                ret = -EINVAL;
        } else if (is_active(msm_obj)) {
                cb->fence = max(msm_obj->read_fence, msm_obj->write_fence);
                list_add_tail(&cb->work.entry, &priv->fence_cbs);
        } else {
                queue_work(priv->wq, &cb->work);
        }
        mutex_unlock(&dev->struct_mutex);

        return ret;
}

void msm_gem_move_to_active(struct drm_gem_object *obj,
                struct msm_gpu *gpu, bool write, uint32_t fence)
{
        struct msm_gem_object *msm_obj = to_msm_bo(obj);
        msm_obj->gpu = gpu;
        if (write)
                msm_obj->write_fence = fence;
        else
                msm_obj->read_fence = fence;
        list_del_init(&msm_obj->mm_list);
        list_add_tail(&msm_obj->mm_list, &gpu->active_list);
}

void msm_gem_move_to_inactive(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct msm_drm_private *priv = dev->dev_private;
        struct msm_gem_object *msm_obj = to_msm_bo(obj);

        WARN_ON(!mutex_is_locked(&dev->struct_mutex));

        msm_obj->gpu = NULL;
        msm_obj->read_fence = 0;
        msm_obj->write_fence = 0;
        list_del_init(&msm_obj->mm_list);
        list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
}

int msm_gem_cpu_prep(struct drm_gem_object *obj, uint32_t op,
                struct timespec *timeout)
{
        struct drm_device *dev = obj->dev;
        struct msm_gem_object *msm_obj = to_msm_bo(obj);
        int ret = 0;

        if (is_active(msm_obj)) {
                uint32_t fence = 0;

                if (op & MSM_PREP_READ)
                        fence = msm_obj->write_fence;
                if (op & MSM_PREP_WRITE)
                        fence = max(fence, msm_obj->read_fence);
                if (op & MSM_PREP_NOSYNC)
                        timeout = NULL;

                ret = msm_wait_fence_interruptable(dev, fence, timeout);
        }

        /* TODO cache maintenance */

        return ret;
}

int msm_gem_cpu_fini(struct drm_gem_object *obj)
{
        /* TODO cache maintenance */
        return 0;
}

#ifdef CONFIG_DEBUG_FS
void msm_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
{
        struct drm_device *dev = obj->dev;
        struct msm_gem_object *msm_obj = to_msm_bo(obj);
        uint64_t off = drm_vma_node_start(&obj->vma_node);

        WARN_ON(!mutex_is_locked(&dev->struct_mutex));
        seq_printf(m, "%08x: %c(r=%u,w=%u) %2d (%2d) %08llx %p %d\n",
                        msm_obj->flags, is_active(msm_obj) ? 'A' : 'I',
                        msm_obj->read_fence, msm_obj->write_fence,
                        obj->name, obj->refcount.refcount.counter,
                        off, msm_obj->vaddr, obj->size);
}

void msm_gem_describe_objects(struct list_head *list, struct seq_file *m)
{
        struct msm_gem_object *msm_obj;
        int count = 0;
        size_t size = 0;

        list_for_each_entry(msm_obj, list, mm_list) {
                struct drm_gem_object *obj = &msm_obj->base;
                seq_printf(m, "   ");
                msm_gem_describe(obj, m);
                count++;
                size += obj->size;
        }

        seq_printf(m, "Total %d objects, %zu bytes\n", count, size);
}
#endif

void msm_gem_free_object(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct msm_gem_object *msm_obj = to_msm_bo(obj);
        int id;

        WARN_ON(!mutex_is_locked(&dev->struct_mutex));

        /* object should not be on active list: */
        WARN_ON(is_active(msm_obj));

        list_del(&msm_obj->mm_list);

        for (id = 0; id < ARRAY_SIZE(msm_obj->domain); id++) {
                if (msm_obj->domain[id].iova) {
                        struct msm_drm_private *priv = obj->dev->dev_private;
                        uint32_t offset = (uint32_t)mmap_offset(obj);
                        unmap_range(priv->iommus[id], offset,
                                        msm_obj->sgt, obj->size);
                }
        }

        drm_gem_free_mmap_offset(obj);

        if (obj->import_attach) {
                if (msm_obj->vaddr)
                        dma_buf_vunmap(obj->import_attach->dmabuf, msm_obj->vaddr);

                /* Don't drop the pages for imported dmabuf, as they are not
                 * ours, just free the array we allocated:
                 */
                if (msm_obj->pages)
                        drm_free_large(msm_obj->pages);

        } else {
                if (msm_obj->vaddr)
                        vunmap(msm_obj->vaddr);
                put_pages(obj);
        }

        if (msm_obj->resv == &msm_obj->_resv)
                reservation_object_fini(msm_obj->resv);

        drm_gem_object_release(obj);

        kfree(msm_obj);
}

/* convenience method to construct a GEM buffer object, and userspace handle */
int msm_gem_new_handle(struct drm_device *dev, struct drm_file *file,
                uint32_t size, uint32_t flags, uint32_t *handle)
{
        struct drm_gem_object *obj;
        int ret;

        ret = mutex_lock_interruptible(&dev->struct_mutex);
        if (ret)
                return ret;

        obj = msm_gem_new(dev, size, flags);

        mutex_unlock(&dev->struct_mutex);

        if (IS_ERR(obj))
                return PTR_ERR(obj);

        ret = drm_gem_handle_create(file, obj, handle);

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

        return ret;
}

static int msm_gem_new_impl(struct drm_device *dev,
                uint32_t size, uint32_t flags,
                struct drm_gem_object **obj)
{
        struct msm_drm_private *priv = dev->dev_private;
        struct msm_gem_object *msm_obj;

        switch (flags & MSM_BO_CACHE_MASK) {
        case MSM_BO_UNCACHED:
        case MSM_BO_CACHED:
        case MSM_BO_WC:
                break;
        default:
                dev_err(dev->dev, "invalid cache flag: %x\n",
                                (flags & MSM_BO_CACHE_MASK));
                return -EINVAL;
        }

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

        msm_obj->flags = flags;

        msm_obj->resv = &msm_obj->_resv;
        reservation_object_init(msm_obj->resv);

        INIT_LIST_HEAD(&msm_obj->submit_entry);
        list_add_tail(&msm_obj->mm_list, &priv->inactive_list);

        *obj = &msm_obj->base;

        return 0;
}

struct drm_gem_object *msm_gem_new(struct drm_device *dev,
                uint32_t size, uint32_t flags)
{
        struct drm_gem_object *obj;
        int ret;

        WARN_ON(!mutex_is_locked(&dev->struct_mutex));

        size = PAGE_ALIGN(size);

        ret = msm_gem_new_impl(dev, size, flags, &obj);
        if (ret)
                goto fail;

        ret = drm_gem_object_init(dev, obj, size);
        if (ret)
                goto fail;

        return obj;

fail:
        if (obj)
                drm_gem_object_unreference_unlocked(obj);

        return ERR_PTR(ret);
}

struct drm_gem_object *msm_gem_import(struct drm_device *dev,
                uint32_t size, struct sg_table *sgt)
{
        struct msm_gem_object *msm_obj;
        struct drm_gem_object *obj;
        int ret, npages;

        size = PAGE_ALIGN(size);

        ret = msm_gem_new_impl(dev, size, MSM_BO_WC, &obj);
        if (ret)
                goto fail;

        drm_gem_private_object_init(dev, obj, size);

        npages = size / PAGE_SIZE;

        msm_obj = to_msm_bo(obj);
        msm_obj->sgt = sgt;
        msm_obj->pages = drm_malloc_ab(npages, sizeof(struct page *));
        if (!msm_obj->pages) {
                ret = -ENOMEM;
                goto fail;
        }

        ret = drm_prime_sg_to_page_addr_arrays(sgt, msm_obj->pages, NULL, npages);
        if (ret)
                goto fail;

        return obj;

fail:
        if (obj)
                drm_gem_object_unreference_unlocked(obj);

        return ERR_PTR(ret);
}