Consider the following MWE
\documentclass{article}
\usepackage[style=authoryear-comp,backend=biber]{biblatex}
\addbibresource{biblatex-examples.bib}
\AtBeginDocument{%
\renewcommand*{\mkbibnamelast}[1]{\textsc{#1}}
}
\begin{document}
\textcite{knuth:ct:e}\\
\fullcite{salam}\\
Footcite\footfullcite{baez/article}
\printbibliography
\end{document}
This will print author surnames in small caps for all cite command both in the document and in the bibliography. Just for the \textcite
command I want the surname (i.e Knuth in the example) to be printed in the text in regular font rather than in small caps.
EDIT: As of March 2016 (biblatex 3.3), you need to change \mkbibnamefamily
instead of \mkbibnamelast