/*
 * drivers/base/sync.c
 *
 * Copyright (C) 2012 Google, Inc.
 *
 * 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/debugfs.h>
#include <linux/export.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/anon_inodes.h>

#include "sync.h"

#define CREATE_TRACE_POINTS
#include "trace/sync.h"

static const struct fence_ops android_fence_ops;
static const struct file_operations sync_file_fops;

struct sync_timeline *sync_timeline_create(const struct sync_timeline_ops *ops,
                                           int size, const char *name)
{
        struct sync_timeline *obj;

        if (size < sizeof(struct sync_timeline))
                return NULL;

        obj = kzalloc(size, GFP_KERNEL);
        if (!obj)
                return NULL;

        kref_init(&obj->kref);
        obj->ops = ops;
        obj->context = fence_context_alloc(1);
        strlcpy(obj->name, name, sizeof(obj->name));

        INIT_LIST_HEAD(&obj->child_list_head);
        INIT_LIST_HEAD(&obj->active_list_head);
        spin_lock_init(&obj->child_list_lock);

        sync_timeline_debug_add(obj);

        return obj;
}
EXPORT_SYMBOL(sync_timeline_create);

static void sync_timeline_free(struct kref *kref)
{
        struct sync_timeline *obj =
                container_of(kref, struct sync_timeline, kref);

        sync_timeline_debug_remove(obj);

        kfree(obj);
}

static void sync_timeline_get(struct sync_timeline *obj)
{
        kref_get(&obj->kref);
}

static void sync_timeline_put(struct sync_timeline *obj)
{
        kref_put(&obj->kref, sync_timeline_free);
}

void sync_timeline_destroy(struct sync_timeline *obj)
{
        obj->destroyed = true;
        /*
         * Ensure timeline is marked as destroyed before
         * changing timeline's fences status.
         */
        smp_wmb();

        sync_timeline_put(obj);
}
EXPORT_SYMBOL(sync_timeline_destroy);

void sync_timeline_signal(struct sync_timeline *obj)
{
        unsigned long flags;
        struct fence *fence, *next;

        trace_sync_timeline(obj);

        spin_lock_irqsave(&obj->child_list_lock, flags);

        list_for_each_entry_safe(fence, next, &obj->active_list_head,
                                 active_list) {
                if (fence_is_signaled_locked(fence))
                        list_del_init(&fence->active_list);
        }

        spin_unlock_irqrestore(&obj->child_list_lock, flags);
}
EXPORT_SYMBOL(sync_timeline_signal);

struct fence *sync_pt_create(struct sync_timeline *obj, int size)
{
        unsigned long flags;
        struct fence *fence;

        if (size < sizeof(*fence))
                return NULL;

        fence = kzalloc(size, GFP_KERNEL);
        if (!fence)
                return NULL;

        spin_lock_irqsave(&obj->child_list_lock, flags);
        sync_timeline_get(obj);
        fence_init(fence, &android_fence_ops, &obj->child_list_lock,
                   obj->context, ++obj->value);
        list_add_tail(&fence->child_list, &obj->child_list_head);
        INIT_LIST_HEAD(&fence->active_list);
        spin_unlock_irqrestore(&obj->child_list_lock, flags);
        return fence;
}
EXPORT_SYMBOL(sync_pt_create);

static struct sync_file *sync_file_alloc(int size, const char *name)
{
        struct sync_file *sync_file;

        sync_file = kzalloc(size, GFP_KERNEL);
        if (!sync_file)
                return NULL;

        sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
                                             sync_file, 0);
        if (IS_ERR(sync_file->file))
                goto err;

        kref_init(&sync_file->kref);
        strlcpy(sync_file->name, name, sizeof(sync_file->name));

        init_waitqueue_head(&sync_file->wq);

        return sync_file;

err:
        kfree(sync_file);
        return NULL;
}

static void fence_check_cb_func(struct fence *f, struct fence_cb *cb)
{
        struct sync_file_cb *check;
        struct sync_file *sync_file;

        check = container_of(cb, struct sync_file_cb, cb);
        sync_file = check->sync_file;

        if (atomic_dec_and_test(&sync_file->status))
                wake_up_all(&sync_file->wq);
}

/* TODO: implement a create which takes more that one fence */
struct sync_file *sync_file_create(const char *name, struct fence *fence)
{
        struct sync_file *sync_file;

        sync_file = sync_file_alloc(offsetof(struct sync_file, cbs[1]),
                                    name);
        if (!sync_file)
                return NULL;

        sync_file->num_fences = 1;
        atomic_set(&sync_file->status, 1);

        sync_file->cbs[0].fence = fence;
        sync_file->cbs[0].sync_file = sync_file;
        if (fence_add_callback(fence, &sync_file->cbs[0].cb,
                               fence_check_cb_func))
                atomic_dec(&sync_file->status);

        sync_file_debug_add(sync_file);

        return sync_file;
}
EXPORT_SYMBOL(sync_file_create);

struct sync_file *sync_file_fdget(int fd)
{
        struct file *file = fget(fd);

        if (!file)
                return NULL;

        if (file->f_op != &sync_file_fops)
                goto err;

        return file->private_data;

err:
        fput(file);
        return NULL;
}
EXPORT_SYMBOL(sync_file_fdget);

void sync_file_put(struct sync_file *sync_file)
{
        fput(sync_file->file);
}
EXPORT_SYMBOL(sync_file_put);

void sync_file_install(struct sync_file *sync_file, int fd)
{
        fd_install(fd, sync_file->file);
}
EXPORT_SYMBOL(sync_file_install);

static void sync_file_add_pt(struct sync_file *sync_file, int *i,
                             struct fence *fence)
{
        sync_file->cbs[*i].fence = fence;
        sync_file->cbs[*i].sync_file = sync_file;

        if (!fence_add_callback(fence, &sync_file->cbs[*i].cb,
                                fence_check_cb_func)) {
                fence_get(fence);
                (*i)++;
        }
}

struct sync_file *sync_file_merge(const char *name,
                                  struct sync_file *a, struct sync_file *b)
{
        int num_fences = a->num_fences + b->num_fences;
        struct sync_file *sync_file;
        int i, i_a, i_b;
        unsigned long size = offsetof(struct sync_file, cbs[num_fences]);

        sync_file = sync_file_alloc(size, name);
        if (!sync_file)
                return NULL;

        atomic_set(&sync_file->status, num_fences);

        /*
         * Assume sync_file a and b are both ordered and have no
         * duplicates with the same context.
         *
         * If a sync_file can only be created with sync_file_merge
         * and sync_file_create, this is a reasonable assumption.
         */
        for (i = i_a = i_b = 0; i_a < a->num_fences && i_b < b->num_fences; ) {
                struct fence *pt_a = a->cbs[i_a].fence;
                struct fence *pt_b = b->cbs[i_b].fence;

                if (pt_a->context < pt_b->context) {
                        sync_file_add_pt(sync_file, &i, pt_a);

                        i_a++;
                } else if (pt_a->context > pt_b->context) {
                        sync_file_add_pt(sync_file, &i, pt_b);

                        i_b++;
                } else {
                        if (pt_a->seqno - pt_b->seqno <= INT_MAX)
                                sync_file_add_pt(sync_file, &i, pt_a);
                        else
                                sync_file_add_pt(sync_file, &i, pt_b);

                        i_a++;
                        i_b++;
                }
        }

        for (; i_a < a->num_fences; i_a++)
                sync_file_add_pt(sync_file, &i, a->cbs[i_a].fence);

        for (; i_b < b->num_fences; i_b++)
                sync_file_add_pt(sync_file, &i, b->cbs[i_b].fence);

        if (num_fences > i)
                atomic_sub(num_fences - i, &sync_file->status);
        sync_file->num_fences = i;

        sync_file_debug_add(sync_file);
        return sync_file;
}
EXPORT_SYMBOL(sync_file_merge);

static const char *android_fence_get_driver_name(struct fence *fence)
{
        struct sync_timeline *parent = fence_parent(fence);

        return parent->ops->driver_name;
}

static const char *android_fence_get_timeline_name(struct fence *fence)
{
        struct sync_timeline *parent = fence_parent(fence);

        return parent->name;
}

static void android_fence_release(struct fence *fence)
{
        struct sync_timeline *parent = fence_parent(fence);
        unsigned long flags;

        spin_lock_irqsave(fence->lock, flags);
        list_del(&fence->child_list);
        if (WARN_ON_ONCE(!list_empty(&fence->active_list)))
                list_del(&fence->active_list);
        spin_unlock_irqrestore(fence->lock, flags);

        sync_timeline_put(parent);
        fence_free(fence);
}

static bool android_fence_signaled(struct fence *fence)
{
        struct sync_timeline *parent = fence_parent(fence);
        int ret;

        ret = parent->ops->has_signaled(fence);
        if (ret < 0)
                fence->status = ret;
        return ret;
}

static bool android_fence_enable_signaling(struct fence *fence)
{
        struct sync_timeline *parent = fence_parent(fence);

        if (android_fence_signaled(fence))
                return false;

        list_add_tail(&fence->active_list, &parent->active_list_head);
        return true;
}

static void android_fence_value_str(struct fence *fence,
                                    char *str, int size)
{
        struct sync_timeline *parent = fence_parent(fence);

        if (!parent->ops->fence_value_str) {
                if (size)
                        *str = 0;
                return;
        }
        parent->ops->fence_value_str(fence, str, size);
}

static void android_fence_timeline_value_str(struct fence *fence,
                                             char *str, int size)
{
        struct sync_timeline *parent = fence_parent(fence);

        if (!parent->ops->timeline_value_str) {
                if (size)
                        *str = 0;
                return;
        }
        parent->ops->timeline_value_str(parent, str, size);
}

static const struct fence_ops android_fence_ops = {
        .get_driver_name = android_fence_get_driver_name,
        .get_timeline_name = android_fence_get_timeline_name,
        .enable_signaling = android_fence_enable_signaling,
        .signaled = android_fence_signaled,
        .wait = fence_default_wait,
        .release = android_fence_release,
        .fence_value_str = android_fence_value_str,
        .timeline_value_str = android_fence_timeline_value_str,
};

static void sync_file_free(struct kref *kref)
{
        struct sync_file *sync_file = container_of(kref, struct sync_file,
                                                     kref);
        int i;

        for (i = 0; i < sync_file->num_fences; ++i) {
                fence_remove_callback(sync_file->cbs[i].fence,
                                      &sync_file->cbs[i].cb);
                fence_put(sync_file->cbs[i].fence);
        }

        kfree(sync_file);
}

static int sync_file_release(struct inode *inode, struct file *file)
{
        struct sync_file *sync_file = file->private_data;

        sync_file_debug_remove(sync_file);

        kref_put(&sync_file->kref, sync_file_free);
        return 0;
}

static unsigned int sync_file_poll(struct file *file, poll_table *wait)
{
        struct sync_file *sync_file = file->private_data;
        int status;

        poll_wait(file, &sync_file->wq, wait);

        status = atomic_read(&sync_file->status);

        if (!status)
                return POLLIN;
        if (status < 0)
                return POLLERR;
        return 0;
}

static long sync_file_ioctl_merge(struct sync_file *sync_file,
                                   unsigned long arg)
{
        int fd = get_unused_fd_flags(O_CLOEXEC);
        int err;
        struct sync_file *fence2, *fence3;
        struct sync_merge_data data;

        if (fd < 0)
                return fd;

        if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
                err = -EFAULT;
                goto err_put_fd;
        }

        fence2 = sync_file_fdget(data.fd2);
        if (!fence2) {
                err = -ENOENT;
                goto err_put_fd;
        }

        data.name[sizeof(data.name) - 1] = '\0';
        fence3 = sync_file_merge(data.name, sync_file, fence2);
        if (!fence3) {
                err = -ENOMEM;
                goto err_put_fence2;
        }

        data.fence = fd;
        if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
                err = -EFAULT;
                goto err_put_fence3;
        }

        sync_file_install(fence3, fd);
        sync_file_put(fence2);
        return 0;

err_put_fence3:
        sync_file_put(fence3);

err_put_fence2:
        sync_file_put(fence2);

err_put_fd:
        put_unused_fd(fd);
        return err;
}

static int sync_fill_fence_info(struct fence *fence, void *data, int size)
{
        struct sync_fence_info *info = data;

        if (size < sizeof(*info))
                return -ENOMEM;

        strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
                sizeof(info->obj_name));
        strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
                sizeof(info->driver_name));
        if (fence_is_signaled(fence))
                info->status = fence->status >= 0 ? 1 : fence->status;
        else
                info->status = 0;
        info->timestamp_ns = ktime_to_ns(fence->timestamp);

        return sizeof(*info);
}

static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
                                        unsigned long arg)
{
        struct sync_file_info *info;
        __u32 size;
        __u32 len = 0;
        int ret, i;

        if (copy_from_user(&size, (void __user *)arg, sizeof(size)))
                return -EFAULT;

        if (size < sizeof(struct sync_file_info))
                return -EINVAL;

        if (size > 4096)
                size = 4096;

        info = kzalloc(size, GFP_KERNEL);
        if (!info)
                return -ENOMEM;

        strlcpy(info->name, sync_file->name, sizeof(info->name));
        info->status = atomic_read(&sync_file->status);
        if (info->status >= 0)
                info->status = !info->status;

        len = sizeof(struct sync_file_info);

        for (i = 0; i < sync_file->num_fences; ++i) {
                struct fence *fence = sync_file->cbs[i].fence;

                ret = sync_fill_fence_info(fence, (u8 *)info + len, size - len);

                if (ret < 0)
                        goto out;

                len += ret;
        }

        info->len = len;

        if (copy_to_user((void __user *)arg, info, len))
                ret = -EFAULT;
        else
                ret = 0;

out:
        kfree(info);

        return ret;
}

static long sync_file_ioctl(struct file *file, unsigned int cmd,
                             unsigned long arg)
{
        struct sync_file *sync_file = file->private_data;

        switch (cmd) {
        case SYNC_IOC_MERGE:
                return sync_file_ioctl_merge(sync_file, arg);

        case SYNC_IOC_FENCE_INFO:
                return sync_file_ioctl_fence_info(sync_file, arg);

        default:
                return -ENOTTY;
        }
}

static const struct file_operations sync_file_fops = {
        .release = sync_file_release,
        .poll = sync_file_poll,
        .unlocked_ioctl = sync_file_ioctl,
        .compat_ioctl = sync_file_ioctl,
};