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      1 /*	$NetBSD: i915_gem_fence.c,v 1.4 2021/12/19 12:36:15 riastradh Exp $	*/
      2 
      3 /*
      4  * SPDX-License-Identifier: MIT
      5  *
      6  * Copyright  2019 Intel Corporation
      7  */
      8 
      9 #include <sys/cdefs.h>
     10 __KERNEL_RCSID(0, "$NetBSD: i915_gem_fence.c,v 1.4 2021/12/19 12:36:15 riastradh Exp $");
     11 
     12 #include "i915_drv.h"
     13 #include "i915_gem_object.h"
     14 
     15 struct stub_fence {
     16 	struct dma_fence dma;
     17 	spinlock_t lock;
     18 	struct i915_sw_fence chain;
     19 };
     20 
     21 static int __i915_sw_fence_call
     22 stub_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
     23 {
     24 	struct stub_fence *stub = container_of(fence, typeof(*stub), chain);
     25 
     26 	switch (state) {
     27 	case FENCE_COMPLETE:
     28 		dma_fence_signal(&stub->dma);
     29 		break;
     30 
     31 	case FENCE_FREE:
     32 		dma_fence_put(&stub->dma);
     33 		break;
     34 	}
     35 
     36 	return NOTIFY_DONE;
     37 }
     38 
     39 static const char *stub_driver_name(struct dma_fence *fence)
     40 {
     41 	return DRIVER_NAME;
     42 }
     43 
     44 static const char *stub_timeline_name(struct dma_fence *fence)
     45 {
     46 	return "object";
     47 }
     48 
     49 static void stub_release(struct dma_fence *fence)
     50 {
     51 	struct stub_fence *stub = container_of(fence, typeof(*stub), dma);
     52 
     53 	i915_sw_fence_fini(&stub->chain);
     54 
     55 	BUILD_BUG_ON(offsetof(typeof(*stub), dma));
     56 	spin_lock_destroy(&stub->lock);
     57 	dma_fence_free(&stub->dma);
     58 }
     59 
     60 static const struct dma_fence_ops stub_fence_ops = {
     61 	.get_driver_name = stub_driver_name,
     62 	.get_timeline_name = stub_timeline_name,
     63 	.release = stub_release,
     64 };
     65 
     66 struct dma_fence *
     67 i915_gem_object_lock_fence(struct drm_i915_gem_object *obj)
     68 {
     69 	struct stub_fence *stub;
     70 
     71 	assert_object_held(obj);
     72 
     73 	stub = kmalloc(sizeof(*stub), GFP_KERNEL);
     74 	if (!stub)
     75 		return NULL;
     76 
     77 	i915_sw_fence_init(&stub->chain, stub_notify);
     78 	spin_lock_init(&stub->lock);
     79 	dma_fence_init(&stub->dma, &stub_fence_ops, &stub->lock,
     80 		       0, 0);
     81 
     82 	if (i915_sw_fence_await_reservation(&stub->chain,
     83 					    obj->base.resv, NULL,
     84 					    true, I915_FENCE_TIMEOUT,
     85 					    I915_FENCE_GFP) < 0)
     86 		goto err;
     87 
     88 	dma_resv_add_excl_fence(obj->base.resv, &stub->dma);
     89 
     90 	return &stub->dma;
     91 
     92 err:
     93 	stub_release(&stub->dma);
     94 	return NULL;
     95 }
     96 
     97 void i915_gem_object_unlock_fence(struct drm_i915_gem_object *obj,
     98 				  struct dma_fence *fence)
     99 {
    100 	struct stub_fence *stub = container_of(fence, typeof(*stub), dma);
    101 
    102 	i915_sw_fence_commit(&stub->chain);
    103 }
    104