FUSB_REG_FIFOS
ret = fusb302_i2c_block_write(chip, FUSB_REG_FIFOS, pos, buf);
ret = fusb302_i2c_read(chip, FUSB_REG_FIFOS, &token);
ret = fusb302_i2c_block_read(chip, FUSB_REG_FIFOS, 2,
ret = fusb302_i2c_block_read(chip, FUSB_REG_FIFOS, len,
ret = fusb302_i2c_block_read(chip, FUSB_REG_FIFOS, 4, crc);