/*
 * 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_fence_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 == NULL)
                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);

        if (obj->ops->release_obj)
                obj->ops->release_obj(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();

        /*
         * signal any children that their parent is going away.
         */
        sync_timeline_signal(obj);
        sync_timeline_put(obj);
}
EXPORT_SYMBOL(sync_timeline_destroy);

void sync_timeline_signal(struct sync_timeline *obj)
{
        unsigned long flags;
        LIST_HEAD(signaled_pts);
        struct sync_pt *pt, *next;

        trace_sync_timeline(obj);

        spin_lock_irqsave(&obj->child_list_lock, flags);

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

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

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

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

        pt = kzalloc(size, GFP_KERNEL);
        if (pt == NULL)
                return NULL;

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

void sync_pt_free(struct sync_pt *pt)
{
        fence_put(&pt->base);
}
EXPORT_SYMBOL(sync_pt_free);

static struct sync_fence *sync_fence_alloc(int size, const char *name)
{
        struct sync_fence *fence;

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

        fence->file = anon_inode_getfile("sync_fence", &sync_fence_fops,
                                         fence, 0);
        if (IS_ERR(fence->file))
                goto err;

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

        init_waitqueue_head(&fence->wq);

        return fence;

err:
        kfree(fence);
        return NULL;
}

static void fence_check_cb_func(struct fence *f, struct fence_cb *cb)
{
        struct sync_fence_cb *check;
        struct sync_fence *fence;

        check = container_of(cb, struct sync_fence_cb, cb);
        fence = check->fence;

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

/* TODO: implement a create which takes more that one sync_pt */
struct sync_fence *sync_fence_create(const char *name, struct sync_pt *pt)
{
        struct sync_fence *fence;

        fence = sync_fence_alloc(offsetof(struct sync_fence, cbs[1]), name);
        if (fence == NULL)
                return NULL;

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

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

        sync_fence_debug_add(fence);

        return fence;
}
EXPORT_SYMBOL(sync_fence_create);

struct sync_fence *sync_fence_fdget(int fd)
{
        struct file *file = fget(fd);

        if (file == NULL)
                return NULL;

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

        return file->private_data;

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

void sync_fence_put(struct sync_fence *fence)
{
        fput(fence->file);
}
EXPORT_SYMBOL(sync_fence_put);

void sync_fence_install(struct sync_fence *fence, int fd)
{
        fd_install(fd, fence->file);
}
EXPORT_SYMBOL(sync_fence_install);

static void sync_fence_add_pt(struct sync_fence *fence,
                              int *i, struct fence *pt)
{
        fence->cbs[*i].sync_pt = pt;
        fence->cbs[*i].fence = fence;

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

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

        fence = sync_fence_alloc(size, name);
        if (fence == NULL)
                return NULL;

        atomic_set(&fence->status, num_fences);

        /*
         * Assume sync_fence a and b are both ordered and have no
         * duplicates with the same context.
         *
         * If a sync_fence can only be created with sync_fence_merge
         * and sync_fence_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].sync_pt;
                struct fence *pt_b = b->cbs[i_b].sync_pt;

                if (pt_a->context < pt_b->context) {
                        sync_fence_add_pt(fence, &i, pt_a);

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

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

                        i_a++;
                        i_b++;
                }
        }

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

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

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

        sync_fence_debug_add(fence);
        return fence;
}
EXPORT_SYMBOL(sync_fence_merge);

int sync_fence_wake_up_wq(wait_queue_t *curr, unsigned mode,
                                 int wake_flags, void *key)
{
        struct sync_fence_waiter *wait;

        wait = container_of(curr, struct sync_fence_waiter, work);
        list_del_init(&wait->work.task_list);

        wait->callback(wait->work.private, wait);
        return 1;
}

int sync_fence_wait_async(struct sync_fence *fence,
                          struct sync_fence_waiter *waiter)
{
        int err = atomic_read(&fence->status);
        unsigned long flags;

        if (err < 0)
                return err;

        if (!err)
                return 1;

        init_waitqueue_func_entry(&waiter->work, sync_fence_wake_up_wq);
        waiter->work.private = fence;

        spin_lock_irqsave(&fence->wq.lock, flags);
        err = atomic_read(&fence->status);
        if (err > 0)
                __add_wait_queue_tail(&fence->wq, &waiter->work);
        spin_unlock_irqrestore(&fence->wq.lock, flags);

        if (err < 0)
                return err;

        return !err;
}
EXPORT_SYMBOL(sync_fence_wait_async);

int sync_fence_cancel_async(struct sync_fence *fence,
                             struct sync_fence_waiter *waiter)
{
        unsigned long flags;
        int ret = 0;

        spin_lock_irqsave(&fence->wq.lock, flags);
        if (!list_empty(&waiter->work.task_list))
                list_del_init(&waiter->work.task_list);
        else
                ret = -ENOENT;
        spin_unlock_irqrestore(&fence->wq.lock, flags);
        return ret;
}
EXPORT_SYMBOL(sync_fence_cancel_async);

int sync_fence_wait(struct sync_fence *fence, long timeout)
{
        long ret;
        int i;

        if (timeout < 0)
                timeout = MAX_SCHEDULE_TIMEOUT;
        else
                timeout = msecs_to_jiffies(timeout);

        trace_sync_wait(fence, 1);
        for (i = 0; i < fence->num_fences; ++i)
                trace_sync_pt(fence->cbs[i].sync_pt);
        ret = wait_event_interruptible_timeout(fence->wq,
                                               atomic_read(&fence->status) <= 0,
                                               timeout);
        trace_sync_wait(fence, 0);

        if (ret < 0) {
                return ret;
        } else if (ret == 0) {
                if (timeout) {
                        pr_info("fence timeout on [%p] after %dms\n", fence,
                                jiffies_to_msecs(timeout));
                        sync_dump();
                }
                return -ETIME;
        }

        ret = atomic_read(&fence->status);
        if (ret) {
                pr_info("fence error %ld on [%p]\n", ret, fence);
                sync_dump();
        }
        return ret;
}
EXPORT_SYMBOL(sync_fence_wait);

static const char *android_fence_get_driver_name(struct fence *fence)
{
        struct sync_pt *pt = container_of(fence, struct sync_pt, base);
        struct sync_timeline *parent = sync_pt_parent(pt);

        return parent->ops->driver_name;
}

static const char *android_fence_get_timeline_name(struct fence *fence)
{
        struct sync_pt *pt = container_of(fence, struct sync_pt, base);
        struct sync_timeline *parent = sync_pt_parent(pt);

        return parent->name;
}

static void android_fence_release(struct fence *fence)
{
        struct sync_pt *pt = container_of(fence, struct sync_pt, base);
        struct sync_timeline *parent = sync_pt_parent(pt);
        unsigned long flags;

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

        if (parent->ops->free_pt)
                parent->ops->free_pt(pt);

        sync_timeline_put(parent);
        fence_free(&pt->base);
}

static bool android_fence_signaled(struct fence *fence)
{
        struct sync_pt *pt = container_of(fence, struct sync_pt, base);
        struct sync_timeline *parent = sync_pt_parent(pt);
        int ret;

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

static bool android_fence_enable_signaling(struct fence *fence)
{
        struct sync_pt *pt = container_of(fence, struct sync_pt, base);
        struct sync_timeline *parent = sync_pt_parent(pt);

        if (android_fence_signaled(fence))
                return false;

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

static int android_fence_fill_driver_data(struct fence *fence,
                                          void *data, int size)
{
        struct sync_pt *pt = container_of(fence, struct sync_pt, base);
        struct sync_timeline *parent = sync_pt_parent(pt);

        if (!parent->ops->fill_driver_data)
                return 0;
        return parent->ops->fill_driver_data(pt, data, size);
}

static void android_fence_value_str(struct fence *fence,
                                    char *str, int size)
{
        struct sync_pt *pt = container_of(fence, struct sync_pt, base);
        struct sync_timeline *parent = sync_pt_parent(pt);

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

static void android_fence_timeline_value_str(struct fence *fence,
                                             char *str, int size)
{
        struct sync_pt *pt = container_of(fence, struct sync_pt, base);
        struct sync_timeline *parent = sync_pt_parent(pt);

        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,
        .fill_driver_data = android_fence_fill_driver_data,
        .fence_value_str = android_fence_value_str,
        .timeline_value_str = android_fence_timeline_value_str,
};

static void sync_fence_free(struct kref *kref)
{
        struct sync_fence *fence = container_of(kref, struct sync_fence, kref);
        int i, status = atomic_read(&fence->status);

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

        kfree(fence);
}

static int sync_fence_release(struct inode *inode, struct file *file)
{
        struct sync_fence *fence = file->private_data;

        sync_fence_debug_remove(fence);

        kref_put(&fence->kref, sync_fence_free);
        return 0;
}

static unsigned int sync_fence_poll(struct file *file, poll_table *wait)
{
        struct sync_fence *fence = file->private_data;
        int status;

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

        status = atomic_read(&fence->status);

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

static long sync_fence_ioctl_wait(struct sync_fence *fence, unsigned long arg)
{
        __s32 value;

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

        return sync_fence_wait(fence, value);
}

static long sync_fence_ioctl_merge(struct sync_fence *fence, unsigned long arg)
{
        int fd = get_unused_fd_flags(O_CLOEXEC);
        int err;
        struct sync_fence *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_fence_fdget(data.fd2);
        if (fence2 == NULL) {
                err = -ENOENT;
                goto err_put_fd;
        }

        data.name[sizeof(data.name) - 1] = '\0';
        fence3 = sync_fence_merge(data.name, fence, fence2);
        if (fence3 == NULL) {
                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_fence_install(fence3, fd);
        sync_fence_put(fence2);
        return 0;

err_put_fence3:
        sync_fence_put(fence3);

err_put_fence2:
        sync_fence_put(fence2);

err_put_fd:
        put_unused_fd(fd);
        return err;
}

static int sync_fill_pt_info(struct fence *fence, void *data, int size)
{
        struct sync_pt_info *info = data;
        int ret;

        if (size < sizeof(struct sync_pt_info))
                return -ENOMEM;

        info->len = sizeof(struct sync_pt_info);

        if (fence->ops->fill_driver_data) {
                ret = fence->ops->fill_driver_data(fence, info->driver_data,
                                                   size - sizeof(*info));
                if (ret < 0)
                        return ret;

                info->len += ret;
        }

        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 info->len;
}

static long sync_fence_ioctl_fence_info(struct sync_fence *fence,
                                        unsigned long arg)
{
        struct sync_fence_info_data *data;
        __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_fence_info_data))
                return -EINVAL;

        if (size > 4096)
                size = 4096;

        data = kzalloc(size, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

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

        len = sizeof(struct sync_fence_info_data);

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

                ret = sync_fill_pt_info(pt, (u8 *)data + len, size - len);

                if (ret < 0)
                        goto out;

                len += ret;
        }

        data->len = len;

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

out:
        kfree(data);

        return ret;
}

static long sync_fence_ioctl(struct file *file, unsigned int cmd,
                             unsigned long arg)
{
        struct sync_fence *fence = file->private_data;

        switch (cmd) {
        case SYNC_IOC_WAIT:
                return sync_fence_ioctl_wait(fence, arg);

        case SYNC_IOC_MERGE:
                return sync_fence_ioctl_merge(fence, arg);

        case SYNC_IOC_FENCE_INFO:
                return sync_fence_ioctl_fence_info(fence, arg);

        default:
                return -ENOTTY;
        }
}

static const struct file_operations sync_fence_fops = {
        .release = sync_fence_release,
        .poll = sync_fence_poll,
        .unlocked_ioctl = sync_fence_ioctl,
        .compat_ioctl = sync_fence_ioctl,
};