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117 lines
3.9 KiB
117 lines
3.9 KiB
/* |
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* seqno-fence, using a dma-buf to synchronize fencing |
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* |
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* Copyright (C) 2012 Texas Instruments |
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* Copyright (C) 2012 Canonical Ltd |
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* Authors: |
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* Rob Clark <robdclark@gmail.com> |
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* Maarten Lankhorst <maarten.lankhorst@canonical.com> |
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* |
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* This program is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 as published by |
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* the Free Software Foundation. |
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* |
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* This program is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
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* more details. |
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*/ |
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#ifndef __LINUX_SEQNO_FENCE_H |
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#define __LINUX_SEQNO_FENCE_H |
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#include <linux/fence.h> |
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#include <linux/dma-buf.h> |
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enum seqno_fence_condition { |
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SEQNO_FENCE_WAIT_GEQUAL, |
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SEQNO_FENCE_WAIT_NONZERO |
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}; |
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struct seqno_fence { |
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struct fence base; |
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const struct fence_ops *ops; |
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struct dma_buf *sync_buf; |
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uint32_t seqno_ofs; |
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enum seqno_fence_condition condition; |
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}; |
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extern const struct fence_ops seqno_fence_ops; |
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/** |
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* to_seqno_fence - cast a fence to a seqno_fence |
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* @fence: fence to cast to a seqno_fence |
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* |
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* Returns NULL if the fence is not a seqno_fence, |
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* or the seqno_fence otherwise. |
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*/ |
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static inline struct seqno_fence * |
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to_seqno_fence(struct fence *fence) |
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{ |
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if (fence->ops != &seqno_fence_ops) |
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return NULL; |
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return container_of(fence, struct seqno_fence, base); |
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} |
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/** |
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* seqno_fence_init - initialize a seqno fence |
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* @fence: seqno_fence to initialize |
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* @lock: pointer to spinlock to use for fence |
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* @sync_buf: buffer containing the memory location to signal on |
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* @context: the execution context this fence is a part of |
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* @seqno_ofs: the offset within @sync_buf |
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* @seqno: the sequence # to signal on |
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* @cond: fence wait condition |
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* @ops: the fence_ops for operations on this seqno fence |
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* |
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* This function initializes a struct seqno_fence with passed parameters, |
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* and takes a reference on sync_buf which is released on fence destruction. |
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* |
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* A seqno_fence is a dma_fence which can complete in software when |
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* enable_signaling is called, but it also completes when |
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* (s32)((sync_buf)[seqno_ofs] - seqno) >= 0 is true |
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* |
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* The seqno_fence will take a refcount on the sync_buf until it's |
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* destroyed, but actual lifetime of sync_buf may be longer if one of the |
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* callers take a reference to it. |
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* |
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* Certain hardware have instructions to insert this type of wait condition |
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* in the command stream, so no intervention from software would be needed. |
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* This type of fence can be destroyed before completed, however a reference |
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* on the sync_buf dma-buf can be taken. It is encouraged to re-use the same |
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* dma-buf for sync_buf, since mapping or unmapping the sync_buf to the |
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* device's vm can be expensive. |
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* |
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* It is recommended for creators of seqno_fence to call fence_signal |
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* before destruction. This will prevent possible issues from wraparound at |
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* time of issue vs time of check, since users can check fence_is_signaled |
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* before submitting instructions for the hardware to wait on the fence. |
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* However, when ops.enable_signaling is not called, it doesn't have to be |
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* done as soon as possible, just before there's any real danger of seqno |
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* wraparound. |
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*/ |
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static inline void |
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seqno_fence_init(struct seqno_fence *fence, spinlock_t *lock, |
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struct dma_buf *sync_buf, uint32_t context, |
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uint32_t seqno_ofs, uint32_t seqno, |
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enum seqno_fence_condition cond, |
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const struct fence_ops *ops) |
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{ |
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BUG_ON(!fence || !sync_buf || !ops); |
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BUG_ON(!ops->wait || !ops->enable_signaling || |
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!ops->get_driver_name || !ops->get_timeline_name); |
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/* |
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* ops is used in fence_init for get_driver_name, so needs to be |
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* initialized first |
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*/ |
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fence->ops = ops; |
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fence_init(&fence->base, &seqno_fence_ops, lock, context, seqno); |
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get_dma_buf(sync_buf); |
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fence->sync_buf = sync_buf; |
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fence->seqno_ofs = seqno_ofs; |
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fence->condition = cond; |
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} |
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#endif /* __LINUX_SEQNO_FENCE_H */
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