If you made contributions to your HSA through a payroll deduction scheme, then the amount identified by code "W" in box 12 on your W-2 is the sum of what your employer contributed and what you contributed through the payroll deduction scheme.
These amounts are not broken out from each other on the W-2. You would have to call your HR or payroll department to get the breakdown.
Note that once you enter the code W amount on the W-2 screen, your HSA contributions (which are now part of the "employer contributions") will be carried everywhere as needed in your federal and state returns, and will not need to be re-entered.
If you made any contributions to your HSA outside of your employer, then they would not be on the W-2, of course, but would be on the 5498-SA.