HW2_INT_CLR_STATUS
cx18_write_reg_expect(cx, HW2_I2C1_INT|HW2_I2C2_INT, HW2_INT_CLR_STATUS,
hw2 = cx18_read_reg(cx, HW2_INT_CLR_STATUS) & cx->hw2_irq_mask;
cx18_write_reg_expect(cx, hw2, HW2_INT_CLR_STATUS, ~hw2, hw2);