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1 : : /* SPDX-License-Identifier: GPL-2.0-only */ 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> 10 : : */ 11 : : 12 : : #ifndef __LINUX_SEQNO_FENCE_H 13 : : #define __LINUX_SEQNO_FENCE_H 14 : : 15 : : #include <linux/dma-fence.h> 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 { 24 : : struct dma_fence base; 25 : : 26 : : const struct dma_fence_ops *ops; 27 : : struct dma_buf *sync_buf; 28 : : uint32_t seqno_ofs; 29 : : enum seqno_fence_condition condition; 30 : : }; 31 : : 32 : : extern const struct dma_fence_ops seqno_fence_ops; 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 * 42 : 0 : to_seqno_fence(struct dma_fence *fence) 43 : : { 44 [ # # # # : 0 : if (fence->ops != &seqno_fence_ops) # # # # # # # # ] 45 : 0 : 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 57 : : * @cond: fence wait condition 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 : : * 78 : : * It is recommended for creators of seqno_fence to call dma_fence_signal() 79 : : * before destruction. This will prevent possible issues from wraparound at 80 : : * time of issue vs time of check, since users can check dma_fence_is_signaled() 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, 91 : : const struct dma_fence_ops *ops) 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 : : /* 98 : : * ops is used in dma_fence_init for get_driver_name, so needs to be 99 : : * initialized first 100 : : */ 101 : : fence->ops = ops; 102 : : dma_fence_init(&fence->base, &seqno_fence_ops, lock, context, seqno); 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 */