Citizens of member states of the European Union, Iceland, Liechtenstein, Norway and Switzerland generally do not require an entry visa. An identity card is sufficient for entry.
If you plan to stay in Germany for longer than three months, you must report to the City Administration Office (Bürgerbüro) and obtain a certificate of freedom of mobility or a residence permit for citizens of the Swiss Confederation.
You should also find out about the recognition of your health insurance in advance: