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 */
 25struct 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
 53/**
 54 * to_dma_fence_chain - cast a fence to a dma_fence_chain
 55 * @fence: fence to cast to a dma_fence_array
 56 *
 57 * Returns NULL if the fence is not a dma_fence_chain,
 58 * or the dma_fence_chain otherwise.
 59 */
 60static inline struct dma_fence_chain *
 61to_dma_fence_chain(struct dma_fence *fence)
 62{
 63	if (!fence || !dma_fence_is_chain(fence))
 64		return NULL;
 65
 66	return container_of(fence, struct dma_fence_chain, base);
 67}
 68
 69/**
 70 * dma_fence_chain_contained - return the contained fence
 71 * @fence: the fence to test
 72 *
 73 * If the fence is a dma_fence_chain the function returns the fence contained
 74 * inside the chain object, otherwise it returns the fence itself.
 75 */
 76static inline struct dma_fence *
 77dma_fence_chain_contained(struct dma_fence *fence)
 78{
 79	struct dma_fence_chain *chain = to_dma_fence_chain(fence);
 80
 81	return chain ? chain->fence : fence;
 82}
 83
 84/**
 85 * dma_fence_chain_alloc
 86 *
 87 * Returns a new struct dma_fence_chain object or NULL on failure.
 88 *
 89 * This specialized allocator has to be a macro for its allocations to be
 90 * accounted separately (to have a separate alloc_tag). The typecast is
 91 * intentional to enforce typesafety.
 92 */
 93#define dma_fence_chain_alloc()	\
 94		((struct dma_fence_chain *)kmalloc(sizeof(struct dma_fence_chain), GFP_KERNEL))
 95
 96/**
 97 * dma_fence_chain_free
 98 * @chain: chain node to free
 99 *
100 * Frees up an allocated but not used struct dma_fence_chain object. This
101 * doesn't need an RCU grace period since the fence was never initialized nor
102 * published. After dma_fence_chain_init() has been called the fence must be
103 * released by calling dma_fence_put(), and not through this function.
104 */
105static inline void dma_fence_chain_free(struct dma_fence_chain *chain)
106{
107	kfree(chain);
108};
109
110/**
111 * dma_fence_chain_for_each - iterate over all fences in chain
112 * @iter: current fence
113 * @head: starting point
114 *
115 * Iterate over all fences in the chain. We keep a reference to the current
116 * fence while inside the loop which must be dropped when breaking out.
117 *
118 * For a deep dive iterator see dma_fence_unwrap_for_each().
119 */
120#define dma_fence_chain_for_each(iter, head)	\
121	for (iter = dma_fence_get(head); iter; \
122	     iter = dma_fence_chain_walk(iter))
123
124struct dma_fence *dma_fence_chain_walk(struct dma_fence *fence);
125int dma_fence_chain_find_seqno(struct dma_fence **pfence, uint64_t seqno);
126void dma_fence_chain_init(struct dma_fence_chain *chain,
127			  struct dma_fence *prev,
128			  struct dma_fence *fence,
129			  uint64_t seqno);
130
131#endif /* __LINUX_DMA_FENCE_CHAIN_H */