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1802d0be | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
606b23ad ML |
2 | /* |
3 | * seqno-fence, using a dma-buf to synchronize fencing | |
4 | * | |
5 | * Copyright (C) 2012 Texas Instruments | |
6 | * Copyright (C) 2012 Canonical Ltd | |
7 | * Authors: | |
8 | * Rob Clark <robdclark@gmail.com> | |
9 | * Maarten Lankhorst <maarten.lankhorst@canonical.com> | |
606b23ad ML |
10 | */ |
11 | ||
12 | #ifndef __LINUX_SEQNO_FENCE_H | |
13 | #define __LINUX_SEQNO_FENCE_H | |
14 | ||
f54d1867 | 15 | #include <linux/dma-fence.h> |
606b23ad ML |
16 | #include <linux/dma-buf.h> |
17 | ||
18 | enum seqno_fence_condition { | |
19 | SEQNO_FENCE_WAIT_GEQUAL, | |
20 | SEQNO_FENCE_WAIT_NONZERO | |
21 | }; | |
22 | ||
23 | struct seqno_fence { | |
f54d1867 | 24 | struct dma_fence base; |
606b23ad | 25 | |
f54d1867 | 26 | const struct dma_fence_ops *ops; |
606b23ad ML |
27 | struct dma_buf *sync_buf; |
28 | uint32_t seqno_ofs; | |
29 | enum seqno_fence_condition condition; | |
30 | }; | |
31 | ||
f54d1867 | 32 | extern const struct dma_fence_ops seqno_fence_ops; |
606b23ad ML |
33 | |
34 | /** | |
35 | * to_seqno_fence - cast a fence to a seqno_fence | |
36 | * @fence: fence to cast to a seqno_fence | |
37 | * | |
38 | * Returns NULL if the fence is not a seqno_fence, | |
39 | * or the seqno_fence otherwise. | |
40 | */ | |
41 | static inline struct seqno_fence * | |
f54d1867 | 42 | to_seqno_fence(struct dma_fence *fence) |
606b23ad ML |
43 | { |
44 | if (fence->ops != &seqno_fence_ops) | |
45 | return NULL; | |
46 | return container_of(fence, struct seqno_fence, base); | |
47 | } | |
48 | ||
49 | /** | |
50 | * seqno_fence_init - initialize a seqno fence | |
51 | * @fence: seqno_fence to initialize | |
52 | * @lock: pointer to spinlock to use for fence | |
53 | * @sync_buf: buffer containing the memory location to signal on | |
54 | * @context: the execution context this fence is a part of | |
55 | * @seqno_ofs: the offset within @sync_buf | |
56 | * @seqno: the sequence # to signal on | |
1f58d946 | 57 | * @cond: fence wait condition |
606b23ad ML |
58 | * @ops: the fence_ops for operations on this seqno fence |
59 | * | |
60 | * This function initializes a struct seqno_fence with passed parameters, | |
61 | * and takes a reference on sync_buf which is released on fence destruction. | |
62 | * | |
63 | * A seqno_fence is a dma_fence which can complete in software when | |
64 | * enable_signaling is called, but it also completes when | |
65 | * (s32)((sync_buf)[seqno_ofs] - seqno) >= 0 is true | |
66 | * | |
67 | * The seqno_fence will take a refcount on the sync_buf until it's | |
68 | * destroyed, but actual lifetime of sync_buf may be longer if one of the | |
69 | * callers take a reference to it. | |
70 | * | |
71 | * Certain hardware have instructions to insert this type of wait condition | |
72 | * in the command stream, so no intervention from software would be needed. | |
73 | * This type of fence can be destroyed before completed, however a reference | |
74 | * on the sync_buf dma-buf can be taken. It is encouraged to re-use the same | |
75 | * dma-buf for sync_buf, since mapping or unmapping the sync_buf to the | |
76 | * device's vm can be expensive. | |
77 | * | |
f54d1867 | 78 | * It is recommended for creators of seqno_fence to call dma_fence_signal() |
606b23ad | 79 | * before destruction. This will prevent possible issues from wraparound at |
f54d1867 | 80 | * time of issue vs time of check, since users can check dma_fence_is_signaled() |
606b23ad ML |
81 | * before submitting instructions for the hardware to wait on the fence. |
82 | * However, when ops.enable_signaling is not called, it doesn't have to be | |
83 | * done as soon as possible, just before there's any real danger of seqno | |
84 | * wraparound. | |
85 | */ | |
86 | static inline void | |
87 | seqno_fence_init(struct seqno_fence *fence, spinlock_t *lock, | |
88 | struct dma_buf *sync_buf, uint32_t context, | |
89 | uint32_t seqno_ofs, uint32_t seqno, | |
90 | enum seqno_fence_condition cond, | |
f54d1867 | 91 | const struct dma_fence_ops *ops) |
606b23ad ML |
92 | { |
93 | BUG_ON(!fence || !sync_buf || !ops); | |
94 | BUG_ON(!ops->wait || !ops->enable_signaling || | |
95 | !ops->get_driver_name || !ops->get_timeline_name); | |
96 | ||
97 | /* | |
f54d1867 | 98 | * ops is used in dma_fence_init for get_driver_name, so needs to be |
606b23ad ML |
99 | * initialized first |
100 | */ | |
101 | fence->ops = ops; | |
f54d1867 | 102 | dma_fence_init(&fence->base, &seqno_fence_ops, lock, context, seqno); |
606b23ad ML |
103 | get_dma_buf(sync_buf); |
104 | fence->sync_buf = sync_buf; | |
105 | fence->seqno_ofs = seqno_ofs; | |
106 | fence->condition = cond; | |
107 | } | |
108 | ||
109 | #endif /* __LINUX_SEQNO_FENCE_H */ |