+};
+
+/**
+ * Transport-neutral representation of queued DAP transactions, supporting
+ * both JTAG and SWD transports. All submitted transactions are logically
+ * queued, until the queue is executed by run(). Some implementations might
+ * execute transactions as soon as they're submitted, but no status is made
+ * availablue until run().
+ */
+struct dap_ops {
+ /** If the DAP transport isn't SWD, it must be JTAG. Upper level
+ * code may need to care about the difference in some cases.
+ */
+ bool is_swd;
+
+ /** Reads the DAP's IDCODe register. */
+ int (*queue_idcode_read)(struct adiv5_dap *dap,
+ uint8_t *ack, uint32_t *data);
+
+ /** DP register read. */
+ int (*queue_dp_read)(struct adiv5_dap *dap, unsigned reg,
+ uint32_t *data);
+ /** DP register write. */
+ int (*queue_dp_write)(struct adiv5_dap *dap, unsigned reg,
+ uint32_t data);
+
+ /** AP register read. */
+ int (*queue_ap_read)(struct adiv5_dap *dap, unsigned reg,
+ uint32_t *data);
+ /** AP register write. */
+ int (*queue_ap_write)(struct adiv5_dap *dap, unsigned reg,
+ uint32_t data);
+ /** AP operation abort. */
+ int (*queue_ap_abort)(struct adiv5_dap *dap, uint8_t *ack);
+
+ /** Executes all queued DAP operations. */
+ int (*run)(struct adiv5_dap *dap);
+};
+
+/**
+ * Queue an IDCODE register read. This is primarily useful for SWD
+ * transports, where it is required as part of link initialization.
+ * (For JTAG, this register is read as part of scan chain setup.)
+ *
+ * @param dap The DAP used for reading.
+ * @param ack Pointer to where transaction status will be stored.
+ * @param data Pointer saying where to store the IDCODE value.
+ *
+ * @return ERROR_OK for success, else a fault code.
+ */
+static inline int dap_queue_idcode_read(struct adiv5_dap *dap,
+ uint8_t *ack, uint32_t *data)
+{
+ assert(dap->ops != NULL);
+ return dap->ops->queue_idcode_read(dap, ack, data);
+}
+
+/**
+ * Queue a DP register read.
+ * Note that not all DP registers are readable; also, that JTAG and SWD
+ * have slight differences in DP register support.
+ *
+ * @param dap The DAP used for reading.
+ * @param reg The two-bit number of the DP register being read.
+ * @param data Pointer saying where to store the register's value
+ * (in host endianness).
+ *
+ * @return ERROR_OK for success, else a fault code.
+ */
+static inline int dap_queue_dp_read(struct adiv5_dap *dap,
+ unsigned reg, uint32_t *data)
+{
+ assert(dap->ops != NULL);
+ return dap->ops->queue_dp_read(dap, reg, data);
+}