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 *
to_dma_fence_chain(struct dma_fence * fence)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 */
dma_fence_chain_alloc(void)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 */
dma_fence_chain_free(struct dma_fence_chain * chain)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 */
114