RKCANFD_REG_RX_FIFO_CTRL
reg = rkcanfd_read(priv, RKCANFD_REG_RX_FIFO_CTRL);
rkcanfd_write(priv, RKCANFD_REG_RX_FIFO_CTRL, reg);
const u32 reg = rkcanfd_read(priv, RKCANFD_REG_RX_FIFO_CTRL);