staging: sync: Add synchronization framework

Sync is a framework for synchronization between multiple
drivers. Sync implementations can take advantage of hardware
synchronization built into devices like GPUs.

Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Rob Clark <robclark@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Erik Gilling <konkers@android.com>
[jstultz: Added commit message, moved to staging, squished minor fix in]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/Kconfig

@@ -72,6 +72,15 @@ config ANDROID_INTF_ALARM_DEV
 	  elapsed realtime, and a non-wakeup alarm on the monotonic clock.
 	  Also exports the alarm interface to user-space.
 
+config SYNC
+	bool "Synchronization framework"
+	default n
+	select ANON_INODES
+	help
+	  This option enables the framework for synchronization between multiple
+	  drivers.  Sync implementations can take advantage of hardware
+	  synchronization built into devices like GPUs.
+
 endif # if ANDROID
 
 endmenu

drivers/staging/android/Makefile

@@ -7,3 +7,4 @@ obj-$(CONFIG_ANDROID_TIMED_OUTPUT)	+= timed_output.o
 obj-$(CONFIG_ANDROID_TIMED_GPIO)	+= timed_gpio.o
 obj-$(CONFIG_ANDROID_LOW_MEMORY_KILLER)	+= lowmemorykiller.o
 obj-$(CONFIG_ANDROID_INTF_ALARM_DEV)	+= alarm-dev.o
+obj-$(CONFIG_SYNC)			+= sync.o

drivers/staging/android/sync.h

+/*
+ * 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/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
+ */
+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);
+};
+
+/**
+ * struct sync_timeline - sync object
+ * @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
+ */
+struct sync_timeline {
+	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 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
+ * @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
+ */
+struct sync_pt {
+	struct sync_timeline		*parent;
+	struct list_head	child_list;
+
+	struct list_head	active_list;
+
+	struct sync_fence	*fence;
+	struct list_head	pt_list;
+
+	/* protected by parent->active_list_lock */
+	int			status;
+};
+
+/**
+ * struct sync_fence - sync fence
+ * @file:		file representing this 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
+ */
+struct sync_fence {
+	struct file		*file;
+	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 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;
+
+	void (*callback)(struct sync_fence *fence, void *data);
+	void *callback_data;
+};
+
+/*
+ * 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
+ * @callback:		callback
+ * @callback_data	data to pass to the callback
+ *
+ * Returns 1 if @fence has already signaled.
+ *
+ * Registers a callback to be called when @fence signals or has an error
+ */
+int sync_fence_wait_async(struct sync_fence *fence,
+			  void (*callback)(struct sync_fence *, void *data),
+			  void *callback_data);
+
+/**
+ * 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 indefintly
+ * if @timeout = 0
+ */
+int sync_fence_wait(struct sync_fence *fence, long timeout);
+
+/* useful for sync driver's debug print handlers */
+const char *sync_status_str(int status);
+
+#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 */
+};
+
+#define SYNC_IOC_MAGIC		'>'
+
+/**
+ * DOC: SYNC_IOC_WAIT - wait for a fence to signal
+ *
+ * pass timeout in milliseconds.
+ */
+#define SYNC_IOC_WAIT		_IOW(SYNC_IOC_MAGIC, 0, __u32)
+
+/**
+ * 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)
+
+#endif /* _LINUX_SYNC_H */