| /* SPDX-License-Identifier: GPL-2.0-only */ |
| /* |
| * seqno-fence, using a dma-buf to synchronize fencing |
| * |
| * Copyright (C) 2012 Texas Instruments |
| * Copyright (C) 2012 Canonical Ltd |
| * Authors: |
| * Rob Clark <robdclark@gmail.com> |
| * Maarten Lankhorst <maarten.lankhorst@canonical.com> |
| */ |
| |
| #ifndef __LINUX_SEQNO_FENCE_H |
| #define __LINUX_SEQNO_FENCE_H |
| |
| #include <linux/dma-fence.h> |
| #include <linux/dma-buf.h> |
| |
| enum seqno_fence_condition { |
| SEQNO_FENCE_WAIT_GEQUAL, |
| SEQNO_FENCE_WAIT_NONZERO |
| }; |
| |
| struct seqno_fence { |
| struct dma_fence base; |
| |
| const struct dma_fence_ops *ops; |
| struct dma_buf *sync_buf; |
| uint32_t seqno_ofs; |
| enum seqno_fence_condition condition; |
| }; |
| |
| extern const struct dma_fence_ops seqno_fence_ops; |
| |
| /** |
| * to_seqno_fence - cast a fence to a seqno_fence |
| * @fence: fence to cast to a seqno_fence |
| * |
| * Returns NULL if the fence is not a seqno_fence, |
| * or the seqno_fence otherwise. |
| */ |
| static inline struct seqno_fence * |
| to_seqno_fence(struct dma_fence *fence) |
| { |
| if (fence->ops != &seqno_fence_ops) |
| return NULL; |
| return container_of(fence, struct seqno_fence, base); |
| } |
| |
| /** |
| * seqno_fence_init - initialize a seqno fence |
| * @fence: seqno_fence to initialize |
| * @lock: pointer to spinlock to use for fence |
| * @sync_buf: buffer containing the memory location to signal on |
| * @context: the execution context this fence is a part of |
| * @seqno_ofs: the offset within @sync_buf |
| * @seqno: the sequence # to signal on |
| * @cond: fence wait condition |
| * @ops: the fence_ops for operations on this seqno fence |
| * |
| * This function initializes a struct seqno_fence with passed parameters, |
| * and takes a reference on sync_buf which is released on fence destruction. |
| * |
| * A seqno_fence is a dma_fence which can complete in software when |
| * enable_signaling is called, but it also completes when |
| * (s32)((sync_buf)[seqno_ofs] - seqno) >= 0 is true |
| * |
| * The seqno_fence will take a refcount on the sync_buf until it's |
| * destroyed, but actual lifetime of sync_buf may be longer if one of the |
| * callers take a reference to it. |
| * |
| * Certain hardware have instructions to insert this type of wait condition |
| * in the command stream, so no intervention from software would be needed. |
| * This type of fence can be destroyed before completed, however a reference |
| * on the sync_buf dma-buf can be taken. It is encouraged to re-use the same |
| * dma-buf for sync_buf, since mapping or unmapping the sync_buf to the |
| * device's vm can be expensive. |
| * |
| * It is recommended for creators of seqno_fence to call dma_fence_signal() |
| * before destruction. This will prevent possible issues from wraparound at |
| * time of issue vs time of check, since users can check dma_fence_is_signaled() |
| * before submitting instructions for the hardware to wait on the fence. |
| * However, when ops.enable_signaling is not called, it doesn't have to be |
| * done as soon as possible, just before there's any real danger of seqno |
| * wraparound. |
| */ |
| static inline void |
| seqno_fence_init(struct seqno_fence *fence, spinlock_t *lock, |
| struct dma_buf *sync_buf, uint32_t context, |
| uint32_t seqno_ofs, uint32_t seqno, |
| enum seqno_fence_condition cond, |
| const struct dma_fence_ops *ops) |
| { |
| BUG_ON(!fence || !sync_buf || !ops); |
| BUG_ON(!ops->wait || !ops->enable_signaling || |
| !ops->get_driver_name || !ops->get_timeline_name); |
| |
| /* |
| * ops is used in dma_fence_init for get_driver_name, so needs to be |
| * initialized first |
| */ |
| fence->ops = ops; |
| dma_fence_init(&fence->base, &seqno_fence_ops, lock, context, seqno); |
| get_dma_buf(sync_buf); |
| fence->sync_buf = sync_buf; |
| fence->seqno_ofs = seqno_ofs; |
| fence->condition = cond; |
| } |
| |
| #endif /* __LINUX_SEQNO_FENCE_H */ |