1 files changed, 129 insertions, 0 deletions
diff --git a/include/linux/dma-fence-chain.h b/include/linux/dma-fence-chain.h
new file mode 100644
index 000000000..4bdf0b96d
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+++ b/include/linux/dma-fence-chain.h
@@ -0,0 +1,129 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * fence-chain: chain fences together in a timeline
+ *
+ * Copyright (C) 2018 Advanced Micro Devices, Inc.
+ * Authors:
+ *	Christian König <christian.koenig@amd.com>
+ */
+
+#ifndef __LINUX_DMA_FENCE_CHAIN_H
+#define __LINUX_DMA_FENCE_CHAIN_H
+
+#include <linux/dma-fence.h>
+#include <linux/irq_work.h>
+#include <linux/slab.h>
+
+/**
+ * struct dma_fence_chain - fence to represent an node of a fence chain
+ * @base: fence base class
+ * @prev: previous fence of the chain
+ * @prev_seqno: original previous seqno before garbage collection
+ * @fence: encapsulated fence
+ * @lock: spinlock for fence handling
+ */
+struct dma_fence_chain {
+	struct dma_fence base;
+	struct dma_fence __rcu *prev;
+	u64 prev_seqno;
+	struct dma_fence *fence;
+	union {
+		/**
+		 * @cb: callback for signaling
+		 *
+		 * This is used to add the callback for signaling the
+		 * complection of the fence chain. Never used at the same time
+		 * as the irq work.
+		 */
+		struct dma_fence_cb cb;
+
+		/**
+		 * @work: irq work item for signaling
+		 *
+		 * Irq work structure to allow us to add the callback without
+		 * running into lock inversion. Never used at the same time as
+		 * the callback.
+		 */
+		struct irq_work work;
+	};
+	spinlock_t lock;
+};
+
+
+/**
+ * to_dma_fence_chain - cast a fence to a dma_fence_chain
+ * @fence: fence to cast to a dma_fence_array
+ *
+ * Returns NULL if the fence is not a dma_fence_chain,
+ * or the dma_fence_chain otherwise.
+ */
+static inline struct dma_fence_chain *
+to_dma_fence_chain(struct dma_fence *fence)
+{
+	if (!fence || !dma_fence_is_chain(fence))
+		return NULL;
+
+	return container_of(fence, struct dma_fence_chain, base);
+}
+
+/**
+ * dma_fence_chain_contained - return the contained fence
+ * @fence: the fence to test
+ *
+ * If the fence is a dma_fence_chain the function returns the fence contained
+ * inside the chain object, otherwise it returns the fence itself.
+ */
+static inline struct dma_fence *
+dma_fence_chain_contained(struct dma_fence *fence)
+{
+	struct dma_fence_chain *chain = to_dma_fence_chain(fence);
+
+	return chain ? chain->fence : fence;
+}
+
+/**
+ * dma_fence_chain_alloc
+ *
+ * Returns a new struct dma_fence_chain object or NULL on failure.
+ */
+static inline struct dma_fence_chain *dma_fence_chain_alloc(void)
+{
+	return kmalloc(sizeof(struct dma_fence_chain), GFP_KERNEL);
+};
+
+/**
+ * dma_fence_chain_free
+ * @chain: chain node to free
+ *
+ * Frees up an allocated but not used struct dma_fence_chain object. This
+ * doesn't need an RCU grace period since the fence was never initialized nor
+ * published. After dma_fence_chain_init() has been called the fence must be
+ * released by calling dma_fence_put(), and not through this function.
+ */
+static inline void dma_fence_chain_free(struct dma_fence_chain *chain)
+{
+	kfree(chain);
+};
+
+/**
+ * dma_fence_chain_for_each - iterate over all fences in chain
+ * @iter: current fence
+ * @head: starting point
+ *
+ * Iterate over all fences in the chain. We keep a reference to the current
+ * fence while inside the loop which must be dropped when breaking out.
+ *
+ * For a deep dive iterator see dma_fence_unwrap_for_each().
+ */
+#define dma_fence_chain_for_each(iter, head)	\
+	for (iter = dma_fence_get(head); iter; \
+	     iter = dma_fence_chain_walk(iter))
+
+struct dma_fence *dma_fence_chain_walk(struct dma_fence *fence);
+int dma_fence_chain_find_seqno(struct dma_fence **pfence, uint64_t seqno);
+void dma_fence_chain_init(struct dma_fence_chain *chain,
+			  struct dma_fence *prev,
+			  struct dma_fence *fence,
+			  uint64_t seqno);
+
+#endif /* __LINUX_DMA_FENCE_CHAIN_H */