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 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 */