rmi.c

static unsigned char dev_ctl_reg;

void rmi_init(/*...*/)
{
  /* ... */
  dev_ctl_reg = rmi_read_single(RMI_DEVICE_CONTROL);
}

void rmi_set_sleep_mode(int mode)
{
  if((dev_ctl_reg & 7) != mode)
  {
    dev_ctl_reg = (dev_ctl_reg & ~7) | mode;
    rmi_write_single(RMI_DEVICE_CONTROL, dev_ctl_reg);
  }
}