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linux_dma_fence_chain.c revision 1.2 
      1 /*	$NetBSD: linux_dma_fence_chain.c,v 1.2 2021/12/19 12:39:16 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2020 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Taylor R. Campbell.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: linux_dma_fence_chain.c,v 1.2 2021/12/19 12:39:16 riastradh Exp $");
     34 
     35 #include <sys/types.h>
     36 
     37 #include <linux/dma-fence.h>
     38 #include <linux/dma-fence-chain.h>
     39 #include <linux/spinlock.h>
     40 
     41 static const struct dma_fence_ops dma_fence_chain_ops;
     42 
     43 /*
     44  * dma_fence_chain_init(chain, prev, fence, seqno)
     45  *
     46  *	Initialize a new fence chain, and either start
     47  */
     48 void
     49 dma_fence_chain_init(struct dma_fence_chain *chain, struct dma_fence *prev,
     50     struct dma_fence *fence, uint64_t seqno)
     51 {
     52 	uint64_t context = -1;	/* XXX */
     53 
     54 	chain->prev_seqno = 0;
     55 	spin_lock_init(&chain->dfc_lock);
     56 
     57 	/* XXX we don't use these yet */
     58 	dma_fence_put(prev);
     59 	dma_fence_put(fence);
     60 
     61 	dma_fence_init(&chain->base, &dma_fence_chain_ops, &chain->dfc_lock,
     62 	    context, seqno);
     63 }
     64 
     65 static void
     66 dma_fence_chain_release(struct dma_fence *fence)
     67 {
     68 	struct dma_fence_chain *chain = to_dma_fence_chain(fence);
     69 
     70 	KASSERT(chain);
     71 
     72 	spin_lock_destroy(&chain->dfc_lock);
     73 	dma_fence_free(&chain->base);
     74 }
     75 
     76 static const struct dma_fence_ops dma_fence_chain_ops = {
     77 	.release = dma_fence_chain_release,
     78 };
     79 
     80 /*
     81  * to_dma_fence_chain(fence)
     82  *
     83  *	If fence is nonnull and in a chain, return the chain.
     84  *	Otherwise return NULL.
     85  */
     86 struct dma_fence_chain *
     87 to_dma_fence_chain(struct dma_fence *fence)
     88 {
     89 
     90 	if (fence == NULL || fence->ops != &dma_fence_chain_ops)
     91 		return NULL;
     92 	return container_of(fence, struct dma_fence_chain, base);
     93 }
     94 
     95 /*
     96  * dma_fence_chain_walk(fence)
     97  *
     98  *	Return the next fence in the chain, or NULL if end of chain,
     99  *	after releasing any fences that have already been signalled.
    100  */
    101 struct dma_fence *
    102 dma_fence_chain_walk(struct dma_fence *fence)
    103 {
    104 
    105 	/* XXX */
    106 	dma_fence_put(fence);
    107 	return NULL;
    108 }
    109 
    110 /*
    111  * dma_fence_chain_find_seqno(&fence, seqno)
    112  *
    113  *	If seqno is zero, do nothing and succeed.
    114  *
    115  *	Otherwise, if fence is not on a chain or if its sequence
    116  *	number has not yet reached seqno, fail with EINVAL.
    117  *
    118  *	Otherwise, set fence to the first fence in the chain which
    119  *	will signal this sequence number.
    120  */
    121 int
    122 dma_fence_chain_find_seqno(struct dma_fence **fencep, uint64_t seqno)
    123 {
    124 	struct dma_fence_chain *chain;
    125 
    126 	if (seqno == 0)
    127 		return 0;
    128 
    129 	chain = to_dma_fence_chain(*fencep);
    130 	if (chain == NULL || chain->base.seqno < seqno)
    131 		return -EINVAL;
    132 
    133 	dma_fence_chain_for_each(*fencep, &chain->base) {
    134 		if ((*fencep)->context != chain->base.context ||
    135 		    to_dma_fence_chain(*fencep)->prev_seqno < seqno)
    136 			break;
    137 	}
    138 
    139 	/* Release reference acquired by dma_fence_chain_for_each.  */
    140 	dma_fence_put(&chain->base);
    141 
    142 	return 0;
    143 }
    144