linux/include/linux/dma-fence-chain.h
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   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * fence-chain: chain fences together in a timeline
   4 *
   5 * Copyright (C) 2018 Advanced Micro Devices, Inc.
   6 * Authors:
   7 *      Christian K├Ânig <christian.koenig@amd.com>
   8 */
   9
  10#ifndef __LINUX_DMA_FENCE_CHAIN_H
  11#define __LINUX_DMA_FENCE_CHAIN_H
  12
  13#include <linux/dma-fence.h>
  14#include <linux/irq_work.h>
  15
  16/**
  17 * struct dma_fence_chain - fence to represent an node of a fence chain
  18 * @base: fence base class
  19 * @lock: spinlock for fence handling
  20 * @prev: previous fence of the chain
  21 * @prev_seqno: original previous seqno before garbage collection
  22 * @fence: encapsulated fence
  23 * @cb: callback structure for signaling
  24 * @work: irq work item for signaling
  25 */
  26struct dma_fence_chain {
  27        struct dma_fence base;
  28        spinlock_t lock;
  29        struct dma_fence __rcu *prev;
  30        u64 prev_seqno;
  31        struct dma_fence *fence;
  32        struct dma_fence_cb cb;
  33        struct irq_work work;
  34};
  35
  36extern const struct dma_fence_ops dma_fence_chain_ops;
  37
  38/**
  39 * to_dma_fence_chain - cast a fence to a dma_fence_chain
  40 * @fence: fence to cast to a dma_fence_array
  41 *
  42 * Returns NULL if the fence is not a dma_fence_chain,
  43 * or the dma_fence_chain otherwise.
  44 */
  45static inline struct dma_fence_chain *
  46to_dma_fence_chain(struct dma_fence *fence)
  47{
  48        if (!fence || fence->ops != &dma_fence_chain_ops)
  49                return NULL;
  50
  51        return container_of(fence, struct dma_fence_chain, base);
  52}
  53
  54/**
  55 * dma_fence_chain_for_each - iterate over all fences in chain
  56 * @iter: current fence
  57 * @head: starting point
  58 *
  59 * Iterate over all fences in the chain. We keep a reference to the current
  60 * fence while inside the loop which must be dropped when breaking out.
  61 */
  62#define dma_fence_chain_for_each(iter, head)    \
  63        for (iter = dma_fence_get(head); iter; \
  64             iter = dma_fence_chain_walk(iter))
  65
  66struct dma_fence *dma_fence_chain_walk(struct dma_fence *fence);
  67int dma_fence_chain_find_seqno(struct dma_fence **pfence, uint64_t seqno);
  68void dma_fence_chain_init(struct dma_fence_chain *chain,
  69                          struct dma_fence *prev,
  70                          struct dma_fence *fence,
  71                          uint64_t seqno);
  72
  73#endif /* __LINUX_DMA_FENCE_CHAIN_H */
  74