/*
 * Copyright (c) 2015-2016, Linaro Limited
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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.
 *
 */
#include <linux/device.h>
#include <linux/dma-buf.h>
#include <linux/fdtable.h>
#include <linux/idr.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/tee_drv.h>
#include "tee_private.h"

static void tee_shm_release(struct tee_shm *shm)
{
        struct tee_device *teedev = shm->teedev;

        mutex_lock(&teedev->mutex);
        idr_remove(&teedev->idr, shm->id);
        if (shm->ctx)
                list_del(&shm->link);
        mutex_unlock(&teedev->mutex);

        if (shm->flags & TEE_SHM_POOL) {
                struct tee_shm_pool_mgr *poolm;

                if (shm->flags & TEE_SHM_DMA_BUF)
                        poolm = teedev->pool->dma_buf_mgr;
                else
                        poolm = teedev->pool->private_mgr;

                poolm->ops->free(poolm, shm);
        } else if (shm->flags & TEE_SHM_REGISTER) {
                size_t n;
                int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);

                if (rc)
                        dev_err(teedev->dev.parent,
                                "unregister shm %p failed: %d", shm, rc);

                for (n = 0; n < shm->num_pages; n++)
                        put_page(shm->pages[n]);

                kfree(shm->pages);
        }

        if (shm->ctx)
                teedev_ctx_put(shm->ctx);

        kfree(shm);

        tee_device_put(teedev);
}

static struct sg_table *tee_shm_op_map_dma_buf(struct dma_buf_attachment
                        *attach, enum dma_data_direction dir)
{
        return NULL;
}

static void tee_shm_op_unmap_dma_buf(struct dma_buf_attachment *attach,
                                     struct sg_table *table,
                                     enum dma_data_direction dir)
{
}

static void tee_shm_op_release(struct dma_buf *dmabuf)
{
        struct tee_shm *shm = dmabuf->priv;

        tee_shm_release(shm);
}

static void *tee_shm_op_map_atomic(struct dma_buf *dmabuf, unsigned long pgnum)
{
        return NULL;
}

static void *tee_shm_op_map(struct dma_buf *dmabuf, unsigned long pgnum)
{
        return NULL;
}

static int tee_shm_op_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
{
        struct tee_shm *shm = dmabuf->priv;
        size_t size = vma->vm_end - vma->vm_start;

        /* Refuse sharing shared memory provided by application */
        if (shm->flags & TEE_SHM_REGISTER)
                return -EINVAL;

        return remap_pfn_range(vma, vma->vm_start, shm->paddr >> PAGE_SHIFT,
                               size, vma->vm_page_prot);
}

static const struct dma_buf_ops tee_shm_dma_buf_ops = {
        .map_dma_buf = tee_shm_op_map_dma_buf,
        .unmap_dma_buf = tee_shm_op_unmap_dma_buf,
        .release = tee_shm_op_release,
        .map_atomic = tee_shm_op_map_atomic,
        .map = tee_shm_op_map,
        .mmap = tee_shm_op_mmap,
};

static struct tee_shm *__tee_shm_alloc(struct tee_context *ctx,
                                       struct tee_device *teedev,
                                       size_t size, u32 flags)
{
        struct tee_shm_pool_mgr *poolm = NULL;
        struct tee_shm *shm;
        void *ret;
        int rc;

        if (ctx && ctx->teedev != teedev) {
                dev_err(teedev->dev.parent, "ctx and teedev mismatch\n");
                return ERR_PTR(-EINVAL);
        }

        if (!(flags & TEE_SHM_MAPPED)) {
                dev_err(teedev->dev.parent,
                        "only mapped allocations supported\n");
                return ERR_PTR(-EINVAL);
        }

        if ((flags & ~(TEE_SHM_MAPPED | TEE_SHM_DMA_BUF))) {
                dev_err(teedev->dev.parent, "invalid shm flags 0x%x", flags);
                return ERR_PTR(-EINVAL);
        }

        if (!tee_device_get(teedev))
                return ERR_PTR(-EINVAL);

        if (!teedev->pool) {
                /* teedev has been detached from driver */
                ret = ERR_PTR(-EINVAL);
                goto err_dev_put;
        }

        shm = kzalloc(sizeof(*shm), GFP_KERNEL);
        if (!shm) {
                ret = ERR_PTR(-ENOMEM);
                goto err_dev_put;
        }

        shm->flags = flags | TEE_SHM_POOL;
        shm->teedev = teedev;
        shm->ctx = ctx;
        if (flags & TEE_SHM_DMA_BUF)
                poolm = teedev->pool->dma_buf_mgr;
        else
                poolm = teedev->pool->private_mgr;

        rc = poolm->ops->alloc(poolm, shm, size);
        if (rc) {
                ret = ERR_PTR(rc);
                goto err_kfree;
        }

        mutex_lock(&teedev->mutex);
        shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
        mutex_unlock(&teedev->mutex);
        if (shm->id < 0) {
                ret = ERR_PTR(shm->id);
                goto err_pool_free;
        }

        if (flags & TEE_SHM_DMA_BUF) {
                DEFINE_DMA_BUF_EXPORT_INFO(exp_info);

                exp_info.ops = &tee_shm_dma_buf_ops;
                exp_info.size = shm->size;
                exp_info.flags = O_RDWR;
                exp_info.priv = shm;

                shm->dmabuf = dma_buf_export(&exp_info);
                if (IS_ERR(shm->dmabuf)) {
                        ret = ERR_CAST(shm->dmabuf);
                        goto err_rem;
                }
        }

        if (ctx) {
                teedev_ctx_get(ctx);
                mutex_lock(&teedev->mutex);
                list_add_tail(&shm->link, &ctx->list_shm);
                mutex_unlock(&teedev->mutex);
        }

        return shm;
err_rem:
        mutex_lock(&teedev->mutex);
        idr_remove(&teedev->idr, shm->id);
        mutex_unlock(&teedev->mutex);
err_pool_free:
        poolm->ops->free(poolm, shm);
err_kfree:
        kfree(shm);
err_dev_put:
        tee_device_put(teedev);
        return ret;
}

/**
 * tee_shm_alloc() - Allocate shared memory
 * @ctx:        Context that allocates the shared memory
 * @size:       Requested size of shared memory
 * @flags:      Flags setting properties for the requested shared memory.
 *
 * Memory allocated as global shared memory is automatically freed when the
 * TEE file pointer is closed. The @flags field uses the bits defined by
 * TEE_SHM_* in <linux/tee_drv.h>. TEE_SHM_MAPPED must currently always be
 * set. If TEE_SHM_DMA_BUF global shared memory will be allocated and
 * associated with a dma-buf handle, else driver private memory.
 */
struct tee_shm *tee_shm_alloc(struct tee_context *ctx, size_t size, u32 flags)
{
        return __tee_shm_alloc(ctx, ctx->teedev, size, flags);
}
EXPORT_SYMBOL_GPL(tee_shm_alloc);

struct tee_shm *tee_shm_priv_alloc(struct tee_device *teedev, size_t size)
{
        return __tee_shm_alloc(NULL, teedev, size, TEE_SHM_MAPPED);
}
EXPORT_SYMBOL_GPL(tee_shm_priv_alloc);

struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
                                 size_t length, u32 flags)
{
        struct tee_device *teedev = ctx->teedev;
        const u32 req_flags = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED;
        struct tee_shm *shm;
        void *ret;
        int rc;
        int num_pages;
        unsigned long start;

        if (flags != req_flags)
                return ERR_PTR(-ENOTSUPP);

        if (!tee_device_get(teedev))
                return ERR_PTR(-EINVAL);

        if (!teedev->desc->ops->shm_register ||
            !teedev->desc->ops->shm_unregister) {
                tee_device_put(teedev);
                return ERR_PTR(-ENOTSUPP);
        }

        teedev_ctx_get(ctx);

        shm = kzalloc(sizeof(*shm), GFP_KERNEL);
        if (!shm) {
                ret = ERR_PTR(-ENOMEM);
                goto err;
        }

        shm->flags = flags | TEE_SHM_REGISTER;
        shm->teedev = teedev;
        shm->ctx = ctx;
        shm->id = -1;
        start = rounddown(addr, PAGE_SIZE);
        shm->offset = addr - start;
        shm->size = length;
        num_pages = (roundup(addr + length, PAGE_SIZE) - start) / PAGE_SIZE;
        shm->pages = kcalloc(num_pages, sizeof(*shm->pages), GFP_KERNEL);
        if (!shm->pages) {
                ret = ERR_PTR(-ENOMEM);
                goto err;
        }

        rc = get_user_pages_fast(start, num_pages, 1, shm->pages);
        if (rc > 0)
                shm->num_pages = rc;
        if (rc != num_pages) {
                if (rc >= 0)
                        rc = -ENOMEM;
                ret = ERR_PTR(rc);
                goto err;
        }

        mutex_lock(&teedev->mutex);
        shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
        mutex_unlock(&teedev->mutex);

        if (shm->id < 0) {
                ret = ERR_PTR(shm->id);
                goto err;
        }

        rc = teedev->desc->ops->shm_register(ctx, shm, shm->pages,
                                             shm->num_pages, start);
        if (rc) {
                ret = ERR_PTR(rc);
                goto err;
        }

        if (flags & TEE_SHM_DMA_BUF) {
                DEFINE_DMA_BUF_EXPORT_INFO(exp_info);

                exp_info.ops = &tee_shm_dma_buf_ops;
                exp_info.size = shm->size;
                exp_info.flags = O_RDWR;
                exp_info.priv = shm;

                shm->dmabuf = dma_buf_export(&exp_info);
                if (IS_ERR(shm->dmabuf)) {
                        ret = ERR_CAST(shm->dmabuf);
                        teedev->desc->ops->shm_unregister(ctx, shm);
                        goto err;
                }
        }

        mutex_lock(&teedev->mutex);
        list_add_tail(&shm->link, &ctx->list_shm);
        mutex_unlock(&teedev->mutex);

        return shm;
err:
        if (shm) {
                size_t n;

                if (shm->id >= 0) {
                        mutex_lock(&teedev->mutex);
                        idr_remove(&teedev->idr, shm->id);
                        mutex_unlock(&teedev->mutex);
                }
                if (shm->pages) {
                        for (n = 0; n < shm->num_pages; n++)
                                put_page(shm->pages[n]);
                        kfree(shm->pages);
                }
        }
        kfree(shm);
        teedev_ctx_put(ctx);
        tee_device_put(teedev);
        return ret;
}
EXPORT_SYMBOL_GPL(tee_shm_register);

/**
 * tee_shm_get_fd() - Increase reference count and return file descriptor
 * @shm:        Shared memory handle
 * @returns user space file descriptor to shared memory
 */
int tee_shm_get_fd(struct tee_shm *shm)
{
        int fd;

        if (!(shm->flags & TEE_SHM_DMA_BUF))
                return -EINVAL;

        fd = dma_buf_fd(shm->dmabuf, O_CLOEXEC);
        if (fd >= 0)
                get_dma_buf(shm->dmabuf);
        return fd;
}

/**
 * tee_shm_free() - Free shared memory
 * @shm:        Handle to shared memory to free
 */
void tee_shm_free(struct tee_shm *shm)
{
        /*
         * dma_buf_put() decreases the dmabuf reference counter and will
         * call tee_shm_release() when the last reference is gone.
         *
         * In the case of driver private memory we call tee_shm_release
         * directly instead as it doesn't have a reference counter.
         */
        if (shm->flags & TEE_SHM_DMA_BUF)
                dma_buf_put(shm->dmabuf);
        else
                tee_shm_release(shm);
}
EXPORT_SYMBOL_GPL(tee_shm_free);

/**
 * tee_shm_va2pa() - Get physical address of a virtual address
 * @shm:        Shared memory handle
 * @va:         Virtual address to tranlsate
 * @pa:         Returned physical address
 * @returns 0 on success and < 0 on failure
 */
int tee_shm_va2pa(struct tee_shm *shm, void *va, phys_addr_t *pa)
{
        if (!(shm->flags & TEE_SHM_MAPPED))
                return -EINVAL;
        /* Check that we're in the range of the shm */
        if ((char *)va < (char *)shm->kaddr)
                return -EINVAL;
        if ((char *)va >= ((char *)shm->kaddr + shm->size))
                return -EINVAL;

        return tee_shm_get_pa(
                        shm, (unsigned long)va - (unsigned long)shm->kaddr, pa);
}
EXPORT_SYMBOL_GPL(tee_shm_va2pa);

/**
 * tee_shm_pa2va() - Get virtual address of a physical address
 * @shm:        Shared memory handle
 * @pa:         Physical address to tranlsate
 * @va:         Returned virtual address
 * @returns 0 on success and < 0 on failure
 */
int tee_shm_pa2va(struct tee_shm *shm, phys_addr_t pa, void **va)
{
        if (!(shm->flags & TEE_SHM_MAPPED))
                return -EINVAL;
        /* Check that we're in the range of the shm */
        if (pa < shm->paddr)
                return -EINVAL;
        if (pa >= (shm->paddr + shm->size))
                return -EINVAL;

        if (va) {
                void *v = tee_shm_get_va(shm, pa - shm->paddr);

                if (IS_ERR(v))
                        return PTR_ERR(v);
                *va = v;
        }
        return 0;
}
EXPORT_SYMBOL_GPL(tee_shm_pa2va);

/**
 * tee_shm_get_va() - Get virtual address of a shared memory plus an offset
 * @shm:        Shared memory handle
 * @offs:       Offset from start of this shared memory
 * @returns virtual address of the shared memory + offs if offs is within
 *      the bounds of this shared memory, else an ERR_PTR
 */
void *tee_shm_get_va(struct tee_shm *shm, size_t offs)
{
        if (!(shm->flags & TEE_SHM_MAPPED))
                return ERR_PTR(-EINVAL);
        if (offs >= shm->size)
                return ERR_PTR(-EINVAL);
        return (char *)shm->kaddr + offs;
}
EXPORT_SYMBOL_GPL(tee_shm_get_va);

/**
 * tee_shm_get_pa() - Get physical address of a shared memory plus an offset
 * @shm:        Shared memory handle
 * @offs:       Offset from start of this shared memory
 * @pa:         Physical address to return
 * @returns 0 if offs is within the bounds of this shared memory, else an
 *      error code.
 */
int tee_shm_get_pa(struct tee_shm *shm, size_t offs, phys_addr_t *pa)
{
        if (offs >= shm->size)
                return -EINVAL;
        if (pa)
                *pa = shm->paddr + offs;
        return 0;
}
EXPORT_SYMBOL_GPL(tee_shm_get_pa);

/**
 * tee_shm_get_from_id() - Find shared memory object and increase reference
 * count
 * @ctx:        Context owning the shared memory
 * @id:         Id of shared memory object
 * @returns a pointer to 'struct tee_shm' on success or an ERR_PTR on failure
 */
struct tee_shm *tee_shm_get_from_id(struct tee_context *ctx, int id)
{
        struct tee_device *teedev;
        struct tee_shm *shm;

        if (!ctx)
                return ERR_PTR(-EINVAL);

        teedev = ctx->teedev;
        mutex_lock(&teedev->mutex);
        shm = idr_find(&teedev->idr, id);
        if (!shm || shm->ctx != ctx)
                shm = ERR_PTR(-EINVAL);
        else if (shm->flags & TEE_SHM_DMA_BUF)
                get_dma_buf(shm->dmabuf);
        mutex_unlock(&teedev->mutex);
        return shm;
}
EXPORT_SYMBOL_GPL(tee_shm_get_from_id);

/**
 * tee_shm_put() - Decrease reference count on a shared memory handle
 * @shm:        Shared memory handle
 */
void tee_shm_put(struct tee_shm *shm)
{
        if (shm->flags & TEE_SHM_DMA_BUF)
                dma_buf_put(shm->dmabuf);
}
EXPORT_SYMBOL_GPL(tee_shm_put);