/*
 * include/linux/sync.h
 *
 * Copyright (C) 2012 Google, Inc.
 *
 * 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.
 *
 */

#ifndef _LINUX_SYNC_H
#define _LINUX_SYNC_H

#include <linux/types.h>
#ifdef __KERNEL__

#include <linux/kref.h>
#include <linux/ktime.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/wait.h>

struct sync_timeline;
struct sync_pt;
struct sync_fence;

/**
 * struct sync_timeline_ops - sync object implementation ops
 * @driver_name:        name of the implentation
 * @dup:                duplicate a sync_pt
 * @has_signaled:       returns:
 *                        1 if pt has signaled
 *                        0 if pt has not signaled
 *                       <0 on error
 * @compare:            returns:
 *                        1 if b will signal before a
 *                        0 if a and b will signal at the same time
 *                       -1 if a will signabl before b
 * @free_pt:            called before sync_pt is freed
 * @release_obj:        called before sync_timeline is freed
 * @print_obj:          deprecated
 * @print_pt:           deprecated
 * @fill_driver_data:   write implmentation specific driver data to data.
 *                        should return an error if there is not enough room
 *                        as specified by size.  This information is returned
 *                        to userspace by SYNC_IOC_FENCE_INFO.
 * @timeline_value_str: fill str with the value of the sync_timeline's counter
 * @pt_value_str:       fill str with the value of the sync_pt
 */
struct sync_timeline_ops {
        const char *driver_name;

        /* required */
        struct sync_pt *(*dup)(struct sync_pt *pt);

        /* required */
        int (*has_signaled)(struct sync_pt *pt);

        /* required */
        int (*compare)(struct sync_pt *a, struct sync_pt *b);

        /* optional */
        void (*free_pt)(struct sync_pt *sync_pt);

        /* optional */
        void (*release_obj)(struct sync_timeline *sync_timeline);

        /* deprecated */
        void (*print_obj)(struct seq_file *s,
                          struct sync_timeline *sync_timeline);

        /* deprecated */
        void (*print_pt)(struct seq_file *s, struct sync_pt *sync_pt);

        /* optional */
        int (*fill_driver_data)(struct sync_pt *syncpt, void *data, int size);

        /* optional */
        void (*timeline_value_str)(struct sync_timeline *timeline, char *str,
                                   int size);

        /* optional */
        void (*pt_value_str)(struct sync_pt *pt, char *str, int size);
};

/**
 * struct sync_timeline - sync object
 * @kref:               reference count on fence.
 * @ops:                ops that define the implementaiton of the sync_timeline
 * @name:               name of the sync_timeline. Useful for debugging
 * @destoryed:          set when sync_timeline is destroyed
 * @child_list_head:    list of children sync_pts for this sync_timeline
 * @child_list_lock:    lock protecting @child_list_head, destroyed, and
 *                        sync_pt.status
 * @active_list_head:   list of active (unsignaled/errored) sync_pts
 * @sync_timeline_list: membership in global sync_timeline_list
 */
struct sync_timeline {
        struct kref             kref;
        const struct sync_timeline_ops  *ops;
        char                    name[32];

        /* protected by child_list_lock */
        bool                    destroyed;

        struct list_head        child_list_head;
        spinlock_t              child_list_lock;

        struct list_head        active_list_head;
        spinlock_t              active_list_lock;

        struct list_head        sync_timeline_list;
};

/**
 * struct sync_pt - sync point
 * @parent:             sync_timeline to which this sync_pt belongs
 * @child_list:         membership in sync_timeline.child_list_head
 * @active_list:        membership in sync_timeline.active_list_head
 * @signaled_list:      membership in temorary signaled_list on stack
 * @fence:              sync_fence to which the sync_pt belongs
 * @pt_list:            membership in sync_fence.pt_list_head
 * @status:             1: signaled, 0:active, <0: error
 * @timestamp:          time which sync_pt status transitioned from active to
 *                        singaled or error.
 */
struct sync_pt {
        struct sync_timeline            *parent;
        struct list_head        child_list;

        struct list_head        active_list;
        struct list_head        signaled_list;

        struct sync_fence       *fence;
        struct list_head        pt_list;

        /* protected by parent->active_list_lock */
        int                     status;

        ktime_t                 timestamp;
};

/**
 * struct sync_fence - sync fence
 * @file:               file representing this fence
 * @kref:               referenace count on fence.
 * @name:               name of sync_fence.  Useful for debugging
 * @pt_list_head:       list of sync_pts in ths fence.  immutable once fence
 *                        is created
 * @waiter_list_head:   list of asynchronous waiters on this fence
 * @waiter_list_lock:   lock protecting @waiter_list_head and @status
 * @status:             1: signaled, 0:active, <0: error
 *
 * @wq:                 wait queue for fence signaling
 * @sync_fence_list:    membership in global fence list
 */
struct sync_fence {
        struct file             *file;
        struct kref             kref;
        char                    name[32];

        /* this list is immutable once the fence is created */
        struct list_head        pt_list_head;

        struct list_head        waiter_list_head;
        spinlock_t              waiter_list_lock; /* also protects status */
        int                     status;

        wait_queue_head_t       wq;

        struct list_head        sync_fence_list;
};

struct sync_fence_waiter;
typedef void (*sync_callback_t)(struct sync_fence *fence,
                                struct sync_fence_waiter *waiter);

/**
 * struct sync_fence_waiter - metadata for asynchronous waiter on a fence
 * @waiter_list:        membership in sync_fence.waiter_list_head
 * @callback:           function pointer to call when fence signals
 * @callback_data:      pointer to pass to @callback
 */
struct sync_fence_waiter {
        struct list_head        waiter_list;

        sync_callback_t         callback;
};

static inline void sync_fence_waiter_init(struct sync_fence_waiter *waiter,
                                          sync_callback_t callback)
{
        waiter->callback = callback;
}

/*
 * API for sync_timeline implementers
 */

/**
 * sync_timeline_create() - creates a sync object
 * @ops:        specifies the implemention ops for the object
 * @size:       size to allocate for this obj
 * @name:       sync_timeline name
 *
 * Creates a new sync_timeline which will use the implemetation specified by
 * @ops.  @size bytes will be allocated allowing for implemntation specific
 * data to be kept after the generic sync_timeline stuct.
 */
struct sync_timeline *sync_timeline_create(const struct sync_timeline_ops *ops,
                                           int size, const char *name);

/**
 * sync_timeline_destory() - destorys a sync object
 * @obj:        sync_timeline to destroy
 *
 * A sync implemntation should call this when the @obj is going away
 * (i.e. module unload.)  @obj won't actually be freed until all its childern
 * sync_pts are freed.
 */
void sync_timeline_destroy(struct sync_timeline *obj);

/**
 * sync_timeline_signal() - signal a status change on a sync_timeline
 * @obj:        sync_timeline to signal
 *
 * A sync implemntation should call this any time one of it's sync_pts
 * has signaled or has an error condition.
 */
void sync_timeline_signal(struct sync_timeline *obj);

/**
 * sync_pt_create() - creates a sync pt
 * @parent:     sync_pt's parent sync_timeline
 * @size:       size to allocate for this pt
 *
 * Creates a new sync_pt as a chiled of @parent.  @size bytes will be
 * allocated allowing for implemntation specific data to be kept after
 * the generic sync_timeline struct.
 */
struct sync_pt *sync_pt_create(struct sync_timeline *parent, int size);

/**
 * sync_pt_free() - frees a sync pt
 * @pt:         sync_pt to free
 *
 * This should only be called on sync_pts which have been created but
 * not added to a fence.
 */
void sync_pt_free(struct sync_pt *pt);

/**
 * sync_fence_create() - creates a sync fence
 * @name:       name of fence to create
 * @pt:         sync_pt to add to the fence
 *
 * Creates a fence containg @pt.  Once this is called, the fence takes
 * ownership of @pt.
 */
struct sync_fence *sync_fence_create(const char *name, struct sync_pt *pt);

/*
 * API for sync_fence consumers
 */

/**
 * sync_fence_merge() - merge two fences
 * @name:       name of new fence
 * @a:          fence a
 * @b:          fence b
 *
 * Creates a new fence which contains copies of all the sync_pts in both
 * @a and @b.  @a and @b remain valid, independent fences.
 */
struct sync_fence *sync_fence_merge(const char *name,
                                    struct sync_fence *a, struct sync_fence *b);

/**
 * sync_fence_fdget() - get a fence from an fd
 * @fd:         fd referencing a fence
 *
 * Ensures @fd references a valid fence, increments the refcount of the backing
 * file, and returns the fence.
 */
struct sync_fence *sync_fence_fdget(int fd);

/**
 * sync_fence_put() - puts a refernnce of a sync fence
 * @fence:      fence to put
 *
 * Puts a reference on @fence.  If this is the last reference, the fence and
 * all it's sync_pts will be freed
 */
void sync_fence_put(struct sync_fence *fence);

/**
 * sync_fence_install() - installs a fence into a file descriptor
 * @fence:      fence to instal
 * @fd:         file descriptor in which to install the fence
 *
 * Installs @fence into @fd.  @fd's should be acquired through get_unused_fd().
 */
void sync_fence_install(struct sync_fence *fence, int fd);

/**
 * sync_fence_wait_async() - registers and async wait on the fence
 * @fence:              fence to wait on
 * @waiter:             waiter callback struck
 *
 * Returns 1 if @fence has already signaled.
 *
 * Registers a callback to be called when @fence signals or has an error.
 * @waiter should be initialized with sync_fence_waiter_init().
 */
int sync_fence_wait_async(struct sync_fence *fence,
                          struct sync_fence_waiter *waiter);

/**
 * sync_fence_cancel_async() - cancels an async wait
 * @fence:              fence to wait on
 * @waiter:             waiter callback struck
 *
 * returns 0 if waiter was removed from fence's async waiter list.
 * returns -ENOENT if waiter was not found on fence's async waiter list.
 *
 * Cancels a previously registered async wait.  Will fail gracefully if
 * @waiter was never registered or if @fence has already signaled @waiter.
 */
int sync_fence_cancel_async(struct sync_fence *fence,
                            struct sync_fence_waiter *waiter);

/**
 * sync_fence_wait() - wait on fence
 * @fence:      fence to wait on
 * @tiemout:    timeout in ms
 *
 * Wait for @fence to be signaled or have an error.  Waits indefinitely
 * if @timeout < 0
 */
int sync_fence_wait(struct sync_fence *fence, long timeout);

#endif /* __KERNEL__ */

/**
 * struct sync_merge_data - data passed to merge ioctl
 * @fd2:        file descriptor of second fence
 * @name:       name of new fence
 * @fence:      returns the fd of the new fence to userspace
 */
struct sync_merge_data {
        __s32   fd2; /* fd of second fence */
        char    name[32]; /* name of new fence */
        __s32   fence; /* fd on newly created fence */
};

/**
 * struct sync_pt_info - detailed sync_pt information
 * @len:                length of sync_pt_info including any driver_data
 * @obj_name:           name of parent sync_timeline
 * @driver_name:        name of driver implmenting the parent
 * @status:             status of the sync_pt 0:active 1:signaled <0:error
 * @timestamp_ns:       timestamp of status change in nanoseconds
 * @driver_data:        any driver dependant data
 */
struct sync_pt_info {
        __u32   len;
        char    obj_name[32];
        char    driver_name[32];
        __s32   status;
        __u64   timestamp_ns;

        __u8    driver_data[0];
};

/**
 * struct sync_fence_info_data - data returned from fence info ioctl
 * @len:        ioctl caller writes the size of the buffer its passing in.
 *              ioctl returns length of sync_fence_data reutnred to userspace
 *              including pt_info.
 * @name:       name of fence
 * @status:     status of fence. 1: signaled 0:active <0:error
 * @pt_info:    a sync_pt_info struct for every sync_pt in the fence
 */
struct sync_fence_info_data {
        __u32   len;
        char    name[32];
        __s32   status;

        __u8    pt_info[0];
};

#define SYNC_IOC_MAGIC          '>'

/**
 * DOC: SYNC_IOC_WAIT - wait for a fence to signal
 *
 * pass timeout in milliseconds.  Waits indefinitely timeout < 0.
 */
#define SYNC_IOC_WAIT           _IOW(SYNC_IOC_MAGIC, 0, __s32)

/**
 * DOC: SYNC_IOC_MERGE - merge two fences
 *
 * Takes a struct sync_merge_data.  Creates a new fence containing copies of
 * the sync_pts in both the calling fd and sync_merge_data.fd2.  Returns the
 * new fence's fd in sync_merge_data.fence
 */
#define SYNC_IOC_MERGE          _IOWR(SYNC_IOC_MAGIC, 1, struct sync_merge_data)

/**
 * DOC: SYNC_IOC_FENCE_INFO - get detailed information on a fence
 *
 * Takes a struct sync_fence_info_data with extra space allocated for pt_info.
 * Caller should write the size of the buffer into len.  On return, len is
 * updated to reflect the total size of the sync_fence_info_data including
 * pt_info.
 *
 * pt_info is a buffer containing sync_pt_infos for every sync_pt in the fence.
 * To itterate over the sync_pt_infos, use the sync_pt_info.len field.
 */
#define SYNC_IOC_FENCE_INFO     _IOWR(SYNC_IOC_MAGIC, 2,\
        struct sync_fence_info_data)

#endif /* _LINUX_SYNC_H */