TSSEL_SHIFT
reg |= TIEN << TSSEL_SHIFT(tssr_offset);
reg &= ~(TIEN << TSSEL_SHIFT(tssr_offset));
reg |= TIEN << TSSEL_SHIFT(tssr_offset);
reg &= ~(TIEN << TSSEL_SHIFT(tssr_offset));
u32 tien = reg & (TIEN << TSSEL_SHIFT(tssr_offset));
reg &= ~(TSSEL_MASK << TSSEL_SHIFT(tssr_offset));
reg |= tint << TSSEL_SHIFT(tssr_offset);