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Diffstat (limited to 'drivers/dma-buf/fence.c')
-rw-r--r--drivers/dma-buf/fence.c431
1 files changed, 431 insertions, 0 deletions
diff --git a/drivers/dma-buf/fence.c b/drivers/dma-buf/fence.c
new file mode 100644
index 000000000000..948bf00d955e
--- /dev/null
+++ b/drivers/dma-buf/fence.c
@@ -0,0 +1,431 @@
+/*
+ * 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 <robdclark@gmail.com>
+ * 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.
+ */
+
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/atomic.h>
+#include <linux/fence.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/fence.h>
+
+EXPORT_TRACEPOINT_SYMBOL(fence_annotate_wait_on);
+EXPORT_TRACEPOINT_SYMBOL(fence_emit);
+
+/**
+ * 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.
+ */
+static atomic_t fence_context_counter = ATOMIC_INIT(0);
+
+/**
+ * fence_context_alloc - allocate an array of fence contexts
+ * @num: [in] amount of contexts to allocate
+ *
+ * This function will return the first index of the number of fences allocated.
+ * The fence context is used for setting fence->context to a unique number.
+ */
+unsigned fence_context_alloc(unsigned num)
+{
+ BUG_ON(!num);
+ return atomic_add_return(num, &fence_context_counter) - num;
+}
+EXPORT_SYMBOL(fence_context_alloc);
+
+/**
+ * fence_signal_locked - 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.
+ *
+ * Unlike fence_signal, this function must be called with fence->lock held.
+ */
+int fence_signal_locked(struct fence *fence)
+{
+ struct fence_cb *cur, *tmp;
+ int ret = 0;
+
+ if (WARN_ON(!fence))
+ return -EINVAL;
+
+ if (!ktime_to_ns(fence->timestamp)) {
+ fence->timestamp = ktime_get();
+ smp_mb__before_atomic();
+ }
+
+ 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
+ */
+ } else
+ trace_fence_signaled(fence);
+
+ list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
+ list_del_init(&cur->node);
+ cur->func(fence, cur);
+ }
+ return ret;
+}
+EXPORT_SYMBOL(fence_signal_locked);
+
+/**
+ * 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)
+ return -EINVAL;
+
+ if (!ktime_to_ns(fence->timestamp)) {
+ fence->timestamp = ktime_get();
+ smp_mb__before_atomic();
+ }
+
+ if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+ return -EINVAL;
+
+ trace_fence_signaled(fence);
+
+ 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);
+ }
+ spin_unlock_irqrestore(fence->lock, flags);
+ }
+ return 0;
+}
+EXPORT_SYMBOL(fence_signal);
+
+/**
+ * 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.
+ */
+signed long
+fence_wait_timeout(struct fence *fence, bool intr, signed long timeout)
+{
+ signed long ret;
+
+ if (WARN_ON(timeout < 0))
+ return -EINVAL;
+
+ trace_fence_wait_start(fence);
+ ret = fence->ops->wait(fence, intr, timeout);
+ trace_fence_wait_end(fence);
+ return ret;
+}
+EXPORT_SYMBOL(fence_wait_timeout);
+
+void fence_release(struct kref *kref)
+{
+ struct fence *fence =
+ container_of(kref, struct fence, refcount);
+
+ trace_fence_destroy(fence);
+
+ BUG_ON(!list_empty(&fence->cb_list));
+
+ if (fence->ops->release)
+ fence->ops->release(fence);
+ else
+ fence_free(fence);
+}
+EXPORT_SYMBOL(fence_release);
+
+void fence_free(struct fence *fence)
+{
+ kfree(fence);
+}
+EXPORT_SYMBOL(fence_free);
+
+/**
+ * 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)) {
+ trace_fence_enable_signal(fence);
+
+ spin_lock_irqsave(fence->lock, flags);
+
+ if (!fence->ops->enable_signaling(fence))
+ fence_signal_locked(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
+ *
+ * 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)
+{
+ 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)) {
+ INIT_LIST_HEAD(&cb->node);
+ 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) {
+ trace_fence_enable_signal(fence);
+
+ if (!fence->ops->enable_signaling(fence)) {
+ fence_signal_locked(fence);
+ ret = -ENOENT;
+ }
+ }
+
+ if (!ret) {
+ cb->func = func;
+ list_add_tail(&cb->node, &fence->cb_list);
+ } else
+ INIT_LIST_HEAD(&cb->node);
+ 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 if 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);
+
+struct default_wait_cb {
+ struct fence_cb base;
+ struct task_struct *task;
+};
+
+static void
+fence_default_wait_cb(struct fence *fence, struct fence_cb *cb)
+{
+ struct default_wait_cb *wait =
+ container_of(cb, struct default_wait_cb, base);
+
+ wake_up_state(wait->task, TASK_NORMAL);
+}
+
+/**
+ * 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.
+ */
+signed long
+fence_default_wait(struct fence *fence, bool intr, signed long timeout)
+{
+ struct default_wait_cb cb;
+ unsigned long flags;
+ signed 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) {
+ trace_fence_enable_signal(fence);
+
+ if (!fence->ops->enable_signaling(fence)) {
+ fence_signal_locked(fence);
+ goto out;
+ }
+ }
+
+ cb.base.func = fence_default_wait_cb;
+ cb.task = current;
+ list_add(&cb.base.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.base.node))
+ list_del(&cb.base.node);
+ __set_current_state(TASK_RUNNING);
+
+out:
+ spin_unlock_irqrestore(fence->lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL(fence_default_wait);
+
+/**
+ * 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.
+ */
+void
+fence_init(struct fence *fence, const struct fence_ops *ops,
+ spinlock_t *lock, unsigned context, unsigned seqno)
+{
+ BUG_ON(!lock);
+ BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
+ !ops->get_driver_name || !ops->get_timeline_name);
+
+ 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;
+
+ trace_fence_init(fence);
+}
+EXPORT_SYMBOL(fence_init);