GP_TCLR
bus_space_write_4(gptimer_iot, gptimer_ioh0, GP_TCLR, 0);
bus_space_write_4(gptimer_iot, gptimer_ioh1, GP_TCLR,
bus_space_write_4(gptimer_iot, gptimer_ioh0, GP_TCLR, GP_TCLR_ST);
bus_space_write_4(gptimer_iot, gptimer_ioh0, GP_TCLR, 0);
bus_space_write_4(gptimer_iot, gptimer_ioh0, GP_TCLR, GP_TCLR_ST);