+typedef void (*dma_async_tx_callback)(void *dma_async_param);
+/**
+ * struct dma_async_tx_descriptor - async transaction descriptor
+ * ---dma generic offload fields---
+ * @cookie: tracking cookie for this transaction, set to -EBUSY if
+ * this tx is sitting on a dependency list
+ * @ack: the descriptor can not be reused until the client acknowledges
+ * receipt, i.e. has has a chance to establish any dependency chains
+ * @phys: physical address of the descriptor
+ * @tx_list: driver common field for operations that require multiple
+ * descriptors
+ * @chan: target channel for this operation
+ * @tx_submit: set the prepared descriptor(s) to be executed by the engine
+ * @tx_set_dest: set a destination address in a hardware descriptor
+ * @tx_set_src: set a source address in a hardware descriptor
+ * @callback: routine to call after this operation is complete
+ * @callback_param: general parameter to pass to the callback routine
+ * ---async_tx api specific fields---
+ * @depend_list: at completion this list of transactions are submitted
+ * @depend_node: allow this transaction to be executed after another
+ * transaction has completed, possibly on another channel
+ * @parent: pointer to the next level up in the dependency chain
+ * @lock: protect the dependency list
+ */
+struct dma_async_tx_descriptor {
+ dma_cookie_t cookie;
+ int ack;
+ dma_addr_t phys;
+ struct list_head tx_list;
+ struct dma_chan *chan;
+ dma_cookie_t (*tx_submit)(struct dma_async_tx_descriptor *tx);
+ void (*tx_set_dest)(dma_addr_t addr,
+ struct dma_async_tx_descriptor *tx, int index);
+ void (*tx_set_src)(dma_addr_t addr,
+ struct dma_async_tx_descriptor *tx, int index);
+ dma_async_tx_callback callback;
+ void *callback_param;
+ struct list_head depend_list;
+ struct list_head depend_node;
+ struct dma_async_tx_descriptor *parent;
+ spinlock_t lock;
+};
+