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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 König <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                 :            :  */
      26                 :            : struct 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                 :            : 
      36                 :            : extern 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                 :            :  */
      45                 :            : static inline struct dma_fence_chain *
      46                 :            : to_dma_fence_chain(struct dma_fence *fence)
      47                 :            : {
      48   [ #  #  #  #  :          0 :         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                 :            : 
      66                 :            : struct dma_fence *dma_fence_chain_walk(struct dma_fence *fence);
      67                 :            : int dma_fence_chain_find_seqno(struct dma_fence **pfence, uint64_t seqno);
      68                 :            : void 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 */