JTAG FIFO status and control registers.
| USB_SERIAL_JTAG_IN_FIFO_CNT | JTAT in fifo counter. |
| USB_SERIAL_JTAG_IN_FIFO_EMPTY | 1: JTAG in fifo is empty. |
| USB_SERIAL_JTAG_IN_FIFO_FULL | 1: JTAG in fifo is full. |
| USB_SERIAL_JTAG_OUT_FIFO_CNT | JTAT out fifo counter. |
| USB_SERIAL_JTAG_OUT_FIFO_EMPTY | 1: JTAG out fifo is empty. |
| USB_SERIAL_JTAG_OUT_FIFO_FULL | 1: JTAG out fifo is full. |
| USB_SERIAL_JTAG_IN_FIFO_RESET | Write 1 to reset JTAG in fifo. |
| USB_SERIAL_JTAG_OUT_FIFO_RESET | Write 1 to reset JTAG out fifo. |