diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl
index 7514dbf..6f53fc0 100644
--- a/Documentation/DocBook/device-drivers.tmpl
+++ b/Documentation/DocBook/device-drivers.tmpl
@@ -126,6 +126,8 @@ X!Edrivers/base/interface.c
      </sect1>
      <sect1><title>Device Drivers DMA Management</title>
 !Edrivers/base/dma-buf.c
+!Edrivers/base/fence.c
+!Iinclude/linux/fence.h
 !Edrivers/base/dma-coherent.c
 !Edrivers/base/dma-mapping.c
      </sect1>
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 5aa2d70..0026563 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -10,7 +10,7 @@ obj-$(CONFIG_CMA) += dma-contiguous.o
 obj-y			+= power/
 obj-$(CONFIG_HAS_DMA)	+= dma-mapping.o
 obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o
-obj-$(CONFIG_DMA_SHARED_BUFFER) += dma-buf.o
+obj-$(CONFIG_DMA_SHARED_BUFFER) += dma-buf.o fence.o
 obj-$(CONFIG_ISA)	+= isa.o
 obj-$(CONFIG_FW_LOADER)	+= firmware_class.o
 obj-$(CONFIG_NUMA)	+= node.o
diff --git a/drivers/base/fence.c b/drivers/base/fence.c
new file mode 100644
index 0000000..28e5ffd
--- /dev/null
+++ b/drivers/base/fence.c
@@ -0,0 +1,286 @@
+/*
+ * Fence mechanism for dma-buf and to allow for asynchronous dma access
+ *
+ * Copyright (C) 2012 Canonical Ltd
+ * Copyright (C) 2012 Texas Instruments
+ *
+ * Authors:
+ * Rob Clark <rob.clark@linaro.org>
+ * Maarten Lankhorst <maarten.lankhorst@canonical.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/fence.h>
+
+atomic_t fence_context_counter = ATOMIC_INIT(0);
+EXPORT_SYMBOL(fence_context_counter);
+
+int __fence_signal(struct fence *fence)
+{
+	struct fence_cb *cur, *tmp;
+	int ret = 0;
+
+	if (WARN_ON(!fence))
+		return -EINVAL;
+
+	if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+		ret = -EINVAL;
+
+		/*
+		 * we might have raced with the unlocked fence_signal,
+		 * still run through all callbacks
+		 */
+	}
+
+	list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
+		list_del_init(&cur->node);
+		cur->func(fence, cur, cur->priv);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(__fence_signal);
+
+/**
+ * fence_signal - signal completion of a fence
+ * @fence: the fence to signal
+ *
+ * Signal completion for software callbacks on a fence, this will unblock
+ * fence_wait() calls and run all the callbacks added with
+ * fence_add_callback(). Can be called multiple times, but since a fence
+ * can only go from unsignaled to signaled state, it will only be effective
+ * the first time.
+ */
+int fence_signal(struct fence *fence)
+{
+	unsigned long flags;
+
+	if (!fence || test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+		return -EINVAL;
+
+	if (test_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) {
+		struct fence_cb *cur, *tmp;
+
+		spin_lock_irqsave(fence->lock, flags);
+		list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
+			list_del_init(&cur->node);
+			cur->func(fence, cur, cur->priv);
+		}
+		spin_unlock_irqrestore(fence->lock, flags);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(fence_signal);
+
+void release_fence(struct kref *kref)
+{
+	struct fence *fence =
+			container_of(kref, struct fence, refcount);
+
+	BUG_ON(!list_empty(&fence->cb_list));
+
+	if (fence->ops->release)
+		fence->ops->release(fence);
+	else
+		kfree(fence);
+}
+EXPORT_SYMBOL(release_fence);
+
+/**
+ * fence_enable_sw_signaling - enable signaling on fence
+ * @fence:	[in]	the fence to enable
+ *
+ * this will request for sw signaling to be enabled, to make the fence
+ * complete as soon as possible
+ */
+void fence_enable_sw_signaling(struct fence *fence)
+{
+	unsigned long flags;
+
+	if (!test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags) &&
+	    !test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+		spin_lock_irqsave(fence->lock, flags);
+
+		if (!fence->ops->enable_signaling(fence))
+			__fence_signal(fence);
+
+		spin_unlock_irqrestore(fence->lock, flags);
+	}
+}
+EXPORT_SYMBOL(fence_enable_sw_signaling);
+
+/**
+ * fence_add_callback - add a callback to be called when the fence
+ * is signaled
+ * @fence:	[in]	the fence to wait on
+ * @cb:		[in]	the callback to register
+ * @func:	[in]	the function to call
+ * @priv:	[in]	the argument to pass to function
+ *
+ * cb will be initialized by fence_add_callback, no initialization
+ * by the caller is required. Any number of callbacks can be registered
+ * to a fence, but a callback can only be registered to one fence at a time.
+ *
+ * Note that the callback can be called from an atomic context.  If
+ * fence is already signaled, this function will return -ENOENT (and
+ * *not* call the callback)
+ *
+ * Add a software callback to the fence. Same restrictions apply to
+ * refcount as it does to fence_wait, however the caller doesn't need to
+ * keep a refcount to fence afterwards: when software access is enabled,
+ * the creator of the fence is required to keep the fence alive until
+ * after it signals with fence_signal. The callback itself can be called
+ * from irq context.
+ *
+ */
+int fence_add_callback(struct fence *fence, struct fence_cb *cb,
+		       fence_func_t func, void *priv)
+{
+	unsigned long flags;
+	int ret = 0;
+	bool was_set;
+
+	if (WARN_ON(!fence || !func))
+		return -EINVAL;
+
+	if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+		return -ENOENT;
+
+	spin_lock_irqsave(fence->lock, flags);
+
+	was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags);
+
+	if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+		ret = -ENOENT;
+	else if (!was_set && !fence->ops->enable_signaling(fence)) {
+		__fence_signal(fence);
+		ret = -ENOENT;
+	}
+
+	if (!ret) {
+		cb->func = func;
+		cb->priv = priv;
+		list_add_tail(&cb->node, &fence->cb_list);
+	}
+	spin_unlock_irqrestore(fence->lock, flags);
+
+	return ret;
+}
+EXPORT_SYMBOL(fence_add_callback);
+
+/**
+ * fence_remove_callback - remove a callback from the signaling list
+ * @fence:	[in]	the fence to wait on
+ * @cb:		[in]	the callback to remove
+ *
+ * Remove a previously queued callback from the fence. This function returns
+ * true is the callback is succesfully removed, or false if the fence has
+ * already been signaled.
+ *
+ * *WARNING*:
+ * Cancelling a callback should only be done if you really know what you're
+ * doing, since deadlocks and race conditions could occur all too easily. For
+ * this reason, it should only ever be done on hardware lockup recovery,
+ * with a reference held to the fence.
+ */
+bool
+fence_remove_callback(struct fence *fence, struct fence_cb *cb)
+{
+	unsigned long flags;
+	bool ret;
+
+	spin_lock_irqsave(fence->lock, flags);
+
+	ret = !list_empty(&cb->node);
+	if (ret)
+		list_del_init(&cb->node);
+
+	spin_unlock_irqrestore(fence->lock, flags);
+
+	return ret;
+}
+EXPORT_SYMBOL(fence_remove_callback);
+
+static void
+fence_default_wait_cb(struct fence *fence, struct fence_cb *cb, void *priv)
+{
+	try_to_wake_up(priv, TASK_NORMAL, 0);
+}
+
+/**
+ * fence_default_wait - default sleep until the fence gets signaled
+ * or until timeout elapses
+ * @fence:	[in]	the fence to wait on
+ * @intr:	[in]	if true, do an interruptible wait
+ * @timeout:	[in]	timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ *
+ * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
+ * remaining timeout in jiffies on success.
+ */
+long
+fence_default_wait(struct fence *fence, bool intr, signed long timeout)
+{
+	struct fence_cb cb;
+	unsigned long flags;
+	long ret = timeout;
+	bool was_set;
+
+	if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+		return timeout;
+
+	spin_lock_irqsave(fence->lock, flags);
+
+	if (intr && signal_pending(current)) {
+		ret = -ERESTARTSYS;
+		goto out;
+	}
+
+	was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags);
+
+	if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+		goto out;
+
+	if (!was_set && !fence->ops->enable_signaling(fence)) {
+		__fence_signal(fence);
+		goto out;
+	}
+
+	cb.func = fence_default_wait_cb;
+	cb.priv = current;
+	list_add(&cb.node, &fence->cb_list);
+
+	while (!test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
+		if (intr)
+			__set_current_state(TASK_INTERRUPTIBLE);
+		else
+			__set_current_state(TASK_UNINTERRUPTIBLE);
+		spin_unlock_irqrestore(fence->lock, flags);
+
+		ret = schedule_timeout(ret);
+
+		spin_lock_irqsave(fence->lock, flags);
+		if (ret > 0 && intr && signal_pending(current))
+			ret = -ERESTARTSYS;
+	}
+
+	if (!list_empty(&cb.node))
+		list_del(&cb.node);
+	__set_current_state(TASK_RUNNING);
+
+out:
+	spin_unlock_irqrestore(fence->lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL(fence_default_wait);
diff --git a/include/linux/fence.h b/include/linux/fence.h
new file mode 100644
index 0000000..d9f091d
--- /dev/null
+++ b/include/linux/fence.h
@@ -0,0 +1,347 @@
+/*
+ * Fence mechanism for dma-buf to allow for asynchronous dma access
+ *
+ * Copyright (C) 2012 Canonical Ltd
+ * Copyright (C) 2012 Texas Instruments
+ *
+ * Authors:
+ * Rob Clark <rob.clark@linaro.org>
+ * Maarten Lankhorst <maarten.lankhorst@canonical.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __LINUX_FENCE_H
+#define __LINUX_FENCE_H
+
+#include <linux/err.h>
+#include <linux/wait.h>
+#include <linux/list.h>
+#include <linux/bitops.h>
+#include <linux/kref.h>
+#include <linux/sched.h>
+#include <linux/printk.h>
+
+struct fence;
+struct fence_ops;
+struct fence_cb;
+
+/**
+ * struct fence - software synchronization primitive
+ * @refcount: refcount for this fence
+ * @ops: fence_ops associated with this fence
+ * @cb_list: list of all callbacks to call
+ * @lock: spin_lock_irqsave used for locking
+ * @priv: fence specific private data
+ * @flags: A mask of FENCE_FLAG_* defined below
+ *
+ * the flags member must be manipulated and read using the appropriate
+ * atomic ops (bit_*), so taking the spinlock will not be needed most
+ * of the time.
+ *
+ * FENCE_FLAG_SIGNALED_BIT - fence is already signaled
+ * FENCE_FLAG_ENABLE_SIGNAL_BIT - enable_signaling might have been called*
+ * FENCE_FLAG_USER_BITS - start of the unused bits, can be used by the
+ * implementer of the fence for its own purposes. Can be used in different
+ * ways by different fence implementers, so do not rely on this.
+ *
+ * *) Since atomic bitops are used, this is not guaranteed to be the case.
+ * Particularly, if the bit was set, but fence_signal was called right
+ * before this bit was set, it would have been able to set the
+ * FENCE_FLAG_SIGNALED_BIT, before enable_signaling was called.
+ * Adding a check for FENCE_FLAG_SIGNALED_BIT after setting
+ * FENCE_FLAG_ENABLE_SIGNAL_BIT closes this race, and makes sure that
+ * after fence_signal was called, any enable_signaling call will have either
+ * been completed, or never called at all.
+ */
+struct fence {
+	struct kref refcount;
+	const struct fence_ops *ops;
+	struct list_head cb_list;
+	spinlock_t *lock;
+	unsigned context, seqno;
+	unsigned long flags;
+};
+
+enum fence_flag_bits {
+	FENCE_FLAG_SIGNALED_BIT,
+	FENCE_FLAG_ENABLE_SIGNAL_BIT,
+	FENCE_FLAG_USER_BITS, /* must always be last member */
+};
+
+typedef void (*fence_func_t)(struct fence *fence, struct fence_cb *cb, void *priv);
+
+/**
+ * struct fence_cb - callback for fence_add_callback
+ * @func: fence_func_t to call
+ * @priv: value of priv to pass to function
+ *
+ * This struct will be initialized by fence_add_callback, additional
+ * data can be passed along by embedding fence_cb in another struct.
+ */
+struct fence_cb {
+	struct list_head node;
+	fence_func_t func;
+	void *priv;
+};
+
+/**
+ * struct fence_ops - operations implemented for fence
+ * @enable_signaling: enable software signaling of fence
+ * @signaled: [optional] peek whether the fence is signaled
+ * @release: [optional] called on destruction of fence
+ *
+ * Notes on enable_signaling:
+ * For fence implementations that have the capability for hw->hw
+ * signaling, they can implement this op to enable the necessary
+ * irqs, or insert commands into cmdstream, etc.  This is called
+ * in the first wait() or add_callback() path to let the fence
+ * implementation know that there is another driver waiting on
+ * the signal (ie. hw->sw case).
+ *
+ * This function can be called called from atomic context, but not
+ * from irq context, so normal spinlocks can be used.
+ *
+ * A return value of false indicates the fence already passed,
+ * or some failure occured that made it impossible to enable
+ * signaling. True indicates succesful enabling.
+ *
+ * Calling fence_signal before enable_signaling is called allows
+ * for a tiny race window in which enable_signaling is called during,
+ * before, or after fence_signal. To fight this, it is recommended
+ * that before enable_signaling returns true an extra reference is
+ * taken on the fence, to be released when the fence is signaled.
+ * This will mean fence_signal will still be called twice, but
+ * the second time will be a noop since it was already signaled.
+ *
+ * Notes on release:
+ * Can be NULL, this function allows additional commands to run on
+ * destruction of the fence. Can be called from irq context.
+ * If pointer is set to NULL, kfree will get called instead.
+ */
+
+struct fence_ops {
+	bool (*enable_signaling)(struct fence *fence);
+	bool (*signaled)(struct fence *fence);
+	long (*wait)(struct fence *fence, bool intr, signed long);
+	void (*release)(struct fence *fence);
+};
+
+/**
+ * __fence_init - Initialize a custom fence.
+ * @fence:	[in]	the fence to initialize
+ * @ops:	[in]	the fence_ops for operations on this fence
+ * @lock:	[in]	the irqsafe spinlock to use for locking this fence
+ * @context:	[in]	the execution context this fence is run on
+ * @seqno:	[in]	a linear increasing sequence number for this context
+ *
+ * Initializes an allocated fence, the caller doesn't have to keep its
+ * refcount after committing with this fence, but it will need to hold a
+ * refcount again if fence_ops.enable_signaling gets called. This can
+ * be used for other implementing other types of fence.
+ *
+ * context and seqno are used for easy comparison between fences, allowing
+ * to check which fence is later by simply using fence_later.
+ */
+static inline void
+__fence_init(struct fence *fence, const struct fence_ops *ops,
+	     spinlock_t *lock, unsigned context, unsigned seqno)
+{
+	BUG_ON(!ops || !lock || !ops->enable_signaling || !ops->wait);
+
+	kref_init(&fence->refcount);
+	fence->ops = ops;
+	INIT_LIST_HEAD(&fence->cb_list);
+	fence->lock = lock;
+	fence->context = context;
+	fence->seqno = seqno;
+	fence->flags = 0UL;
+}
+
+/**
+ * fence_get - increases refcount of the fence
+ * @fence:	[in]	fence to increase refcount of
+ */
+static inline void fence_get(struct fence *fence)
+{
+	if (WARN_ON(!fence))
+		return;
+	kref_get(&fence->refcount);
+}
+
+extern void release_fence(struct kref *kref);
+
+/**
+ * fence_put - decreases refcount of the fence
+ * @fence:	[in]	fence to reduce refcount of
+ */
+static inline void fence_put(struct fence *fence)
+{
+	if (WARN_ON(!fence))
+		return;
+	kref_put(&fence->refcount, release_fence);
+}
+
+int fence_signal(struct fence *fence);
+int __fence_signal(struct fence *fence);
+long fence_default_wait(struct fence *fence, bool intr, signed long);
+int fence_add_callback(struct fence *fence, struct fence_cb *cb,
+		       fence_func_t func, void *priv);
+bool fence_remove_callback(struct fence *fence, struct fence_cb *cb);
+void fence_enable_sw_signaling(struct fence *fence);
+
+/**
+ * fence_is_signaled - Return an indication if the fence is signaled yet.
+ * @fence:	[in]	the fence to check
+ *
+ * Returns true if the fence was already signaled, false if not. Since this
+ * function doesn't enable signaling, it is not guaranteed to ever return true
+ * If fence_add_callback, fence_wait or fence_enable_sw_signaling
+ * haven't been called before.
+ *
+ * It's recommended for seqno fences to call fence_signal when the
+ * operation is complete, it makes it possible to prevent issues from
+ * wraparound between time of issue and time of use by checking the return
+ * value of this function before calling hardware-specific wait instructions.
+ */
+static inline bool
+fence_is_signaled(struct fence *fence)
+{
+	if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+		return true;
+
+	if (fence->ops->signaled && fence->ops->signaled(fence)) {
+		fence_signal(fence);
+		return true;
+	}
+
+	return false;
+}
+
+/**
+ * fence_later - return the chronologically later fence
+ * @f1:	[in]	the first fence from the same context
+ * @f2:	[in]	the second fence from the same context
+ *
+ * Returns NULL if both fences are signaled, otherwise the fence that would be
+ * signaled last. Both fences must be from the same context, since a seqno is
+ * not re-used across contexts.
+ */
+static inline struct fence *fence_later(struct fence *f1, struct fence *f2)
+{
+	bool sig1, sig2;
+
+	/*
+	 * can't check just FENCE_FLAG_SIGNALED_BIT here, it may never have been
+	 * set called if enable_signaling wasn't, and enabling that here is
+	 * overkill.
+	 */
+	sig1 = fence_is_signaled(f1);
+	sig2 = fence_is_signaled(f2);
+
+	if (sig1 && sig2)
+		return NULL;
+
+	BUG_ON(f1->context != f2->context);
+
+	if (sig1 || f2->seqno - f2->seqno <= INT_MAX)
+		return f2;
+	else
+		return f1;
+}
+
+/**
+ * fence_wait_timeout - sleep until the fence gets signaled
+ * or until timeout elapses
+ * @fence:	[in]	the fence to wait on
+ * @intr:	[in]	if true, do an interruptible wait
+ * @timeout:	[in]	timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ *
+ * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
+ * remaining timeout in jiffies on success. Other error values may be
+ * returned on custom implementations.
+ *
+ * Performs a synchronous wait on this fence. It is assumed the caller
+ * directly or indirectly (buf-mgr between reservation and committing)
+ * holds a reference to the fence, otherwise the fence might be
+ * freed before return, resulting in undefined behavior.
+ */
+static inline long
+fence_wait_timeout(struct fence *fence, bool intr, signed long timeout)
+{
+	if (WARN_ON(timeout < 0))
+		return -EINVAL;
+
+	return fence->ops->wait(fence, intr, timeout);
+}
+
+/**
+ * fence_wait - sleep until the fence gets signaled
+ * @fence:	[in]	the fence to wait on
+ * @intr:	[in]	if true, do an interruptible wait
+ *
+ * This function will return -ERESTARTSYS if interrupted by a signal,
+ * or 0 if the fence was signaled. Other error values may be
+ * returned on custom implementations.
+ *
+ * Performs a synchronous wait on this fence. It is assumed the caller
+ * directly or indirectly (buf-mgr between reservation and committing)
+ * holds a reference to the fence, otherwise the fence might be
+ * freed before return, resulting in undefined behavior.
+ */
+static inline long fence_wait(struct fence *fence, bool intr)
+{
+	long ret;
+
+	/* Since fence_wait_timeout cannot timeout with
+	 * MAX_SCHEDULE_TIMEOUT, only valid return values are
+	 * -ERESTARTSYS and MAX_SCHEDULE_TIMEOUT.
+	 */
+	ret = fence_wait_timeout(fence, intr, MAX_SCHEDULE_TIMEOUT);
+
+	return ret < 0 ? ret : 0;
+}
+
+/**
+ * fence context counter: each execution context should have its own
+ * fence context, this allows checking if fences belong to the same
+ * context or not. One device can have multiple separate contexts,
+ * and they're used if some engine can run independently of another.
+ */
+extern atomic_t fence_context_counter;
+
+static inline unsigned fence_context_alloc(unsigned num)
+{
+	BUG_ON(!num);
+	return atomic_add_return(num, &fence_context_counter) - num;
+}
+
+#define FENCE_TRACE(f, fmt, args...) \
+	do {									\
+		struct fence *__ff = (f);					\
+		pr_info("f %u#%u: " fmt, __ff->context, __ff->seqno, ##args);	\
+	} while (0)
+
+#define FENCE_WARN(f, fmt, args...) \
+	do {									\
+		struct fence *__ff = (f);					\
+		pr_warn("f %u#%u: " fmt, __ff->context, __ff->seqno, ##args);	\
+	} while (0)
+
+#define FENCE_ERR(f, fmt, args...) \
+	do {									\
+		struct fence *__ff = (f);					\
+		pr_err("f %u#%u: " fmt, __ff->context, __ff->seqno, ##args);	\
+	} while (0)
+
+#endif /* __LINUX_FENCE_H */
