CSR19
reg = rt2x00mmio_register_read(rt2x00dev, CSR19);
rt2x00mmio_register_write(rt2x00dev, CSR19, reg);
reg = rt2x00mmio_register_read(rt2x00dev, CSR19);
rt2x00mmio_register_write(rt2x00dev, CSR19, reg);