pio_reg_write
pio_reg_write(INTR_STATUS, status & STAT_LATENCY_WARNINGS);
pio_reg_write(INTR_STATUS, status & STAT_ALL_ERRORS);
pio_reg_write(INTR_SIGNAL_ENABLE, pio->enabled_irqs);
pio_reg_write(DATA_BUFFER_THLD_CTRL, val);
pio_reg_write(QUEUE_THLD_CTRL, val);
pio_reg_write(INTR_SIGNAL_ENABLE, 0x0);
pio_reg_write(INTR_STATUS_ENABLE, 0xffffffff);
pio_reg_write(INTR_SIGNAL_ENABLE, 0);
pio_reg_write(INTR_SIGNAL_ENABLE, 0x0);
pio_reg_write(COMMAND_QUEUE_PORT, xfer->cmd_desc[0]);
pio_reg_write(COMMAND_QUEUE_PORT, xfer->cmd_desc[1]);
pio_reg_write(COMMAND_QUEUE_PORT, xfer->cmd_desc[2]);
pio_reg_write(COMMAND_QUEUE_PORT, xfer->cmd_desc[3]);
pio_reg_write(XFER_DATA_PORT, *p++);
pio_reg_write(XFER_DATA_PORT, *p);
pio_reg_write(INTR_SIGNAL_ENABLE, pio->enabled_irqs);
pio_reg_write(QUEUE_THLD_CTRL, regval);