include/linux/dma-fence-chain.h

   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 #include <linux/slab.h>
  16
  17 /**
  18  * struct dma_fence_chain - fence to represent an node of a fence chain
  19  * @base: fence base class
  20  * @prev: previous fence of the chain
  21  * @prev_seqno: original previous seqno before garbage collection
  22  * @fence: encapsulated fence
  23  * @lock: spinlock for fence handling
  24  */
  25 struct dma_fence_chain {
  26         struct dma_fence base;
  27         struct dma_fence __rcu *prev;
  28         u64 prev_seqno;
  29         struct dma_fence *fence;
  30         union {
  31                 /**
  32                  * @cb: callback for signaling
  33                  *
  34                  * This is used to add the callback for signaling the
  35                  * complection of the fence chain. Never used at the same time
  36                  * as the irq work.
  37                  */
  38                 struct dma_fence_cb cb;
  39
  40                 /**
  41                  * @work: irq work item for signaling
  42                  *
  43                  * Irq work structure to allow us to add the callback without
  44                  * running into lock inversion. Never used at the same time as
  45                  * the callback.
  46                  */
  47                 struct irq_work work;
  48         };
  49         spinlock_t lock;
  50 };
  51
  52 extern const struct dma_fence_ops dma_fence_chain_ops;
  53
  54 /**
  55  * to_dma_fence_chain - cast a fence to a dma_fence_chain
  56  * @fence: fence to cast to a dma_fence_array
  57  *
  58  * Returns NULL if the fence is not a dma_fence_chain,
  59  * or the dma_fence_chain otherwise.
  60  */
  61 static inline struct dma_fence_chain *
  62 to_dma_fence_chain(struct dma_fence *fence)
  63 {
  64         if (!fence || fence->ops != &dma_fence_chain_ops)
  65                 return NULL;
  66
  67         return container_of(fence, struct dma_fence_chain, base);
  68 }
  69
  70 /**
  71  * dma_fence_chain_alloc
  72  *
  73  * Returns a new struct dma_fence_chain object or NULL on failure.
  74  */
  75 static inline struct dma_fence_chain *dma_fence_chain_alloc(void)
  76 {
  77         return kmalloc(sizeof(struct dma_fence_chain), GFP_KERNEL);
  78 };
  79
  80 /**
  81  * dma_fence_chain_free
  82  * @chain: chain node to free
  83  *
  84  * Frees up an allocated but not used struct dma_fence_chain object. This
  85  * doesn't need an RCU grace period since the fence was never initialized nor
  86  * published. After dma_fence_chain_init() has been called the fence must be
  87  * released by calling dma_fence_put(), and not through this function.
  88  */
  89 static inline void dma_fence_chain_free(struct dma_fence_chain *chain)
  90 {
  91         kfree(chain);
  92 };
  93
  94 /**
  95  * dma_fence_chain_for_each - iterate over all fences in chain
  96  * @iter: current fence
  97  * @head: starting point
  98  *
  99  * Iterate over all fences in the chain. We keep a reference to the current
 100  * fence while inside the loop which must be dropped when breaking out.
 101  */
 102 #define dma_fence_chain_for_each(iter, head)    \
 103         for (iter = dma_fence_get(head); iter; \
 104              iter = dma_fence_chain_walk(iter))
 105
 106 struct dma_fence *dma_fence_chain_walk(struct dma_fence *fence);
 107 int dma_fence_chain_find_seqno(struct dma_fence **pfence, uint64_t seqno);
 108 void dma_fence_chain_init(struct dma_fence_chain *chain,
 109                           struct dma_fence *prev,
 110                           struct dma_fence *fence,
 111                           uint64_t seqno);
 112
 113 #endif /* __LINUX_DMA_FENCE_CHAIN_H */