hdldoc: update wrpc interfaces description

doc/HDLdoc/aux_diag.tex

+\subsection{Auxiliary diagnostics interface}
+\label{sec:aux_diag}
+
+Auxiliary diagnostics interface can be used if a user would like to benefit from
+the WR PTP Core diagnostics capabilities to export some registers from his/her
+IP core. The interface consists of two 32-bit \texttt{std\_logic\_vector}
+arrays. User-defined registers that are to be read from the WRPC SNMP agent (SNMP
+GET requests), should be connected to the \texttt{aux\_diag\_i} vector.
+User-defined values that are written from the WRPC SNMP agent (SNMP SET
+requests) will be available in the \texttt{aux\_diag\_o} vector.
+
+Two VHDL generics \texttt{g\_diag\_id} and \texttt{g\_diag\_ver} are used to let
+the user uniquely identify given application (user-defined set of registers)
+to match it with appropriate, custom SNMP MIB file.

doc/HDLdoc/periph.tex

-\subsection{GPIO/UART/I2C/1-Wire interfaces}
+\subsection{GPIO/UART/I2C/1-Wire/SPI interfaces}
 \label{sec:wrpc_periph}
 
 %\begin{figure}[ht]
@@ -8,17 +8,17 @@
 %  \end{center}
 %\end{figure}
 
-Several hardware peripherals can be connected to the White Rabbit PTP Core. It has a UART, 1-Wire
-and two $I^2C$ interfaces implemented inside. The $I^2C$ connection to the SFP module is used to
-read its Part ID, while the external EEPROM stores calibration values for each supported SFP
-together with an initialization script. That script is executed every time the WRPC is powered on
-and can contain instructions to automatically match the SFP's Part ID with the EEPROM content and
-load appropriate calibration values. The SFP presence indicator is mandatory and has to be
-connected.  Otherwise, the WRPC won't be able to operate properly (without knowing whether the SFP
-transceiver is actually inserted).
-
-Furthermore, a 1-Wire digital thermometer provides on-board temperature, but also its unique ID is
-used to calculate default MAC address of the physical Ethernet interface. The UART interface
-provides a user shell that can be used to interact with the White Rabbit PTP Core. More detailed
-description of the WRPC shell can be found in the \emph{White Rabbit PTP Core User's Manual -
-  Building and Running} \cite{wrpc_man}.
+Several hardware peripherals can be connected to the White Rabbit PTP Core. It
+has:
+\begin{itemize}
+  \item UART - provides access to the WR PTP Core user shell
+  \item 1-Wire - access to a digital thermometer for an on-board temperature and
+    unique ID (used to generate a default MAC address of the WR port)
+  \item SFP $I^2C$ - access to the SFP EEPROM, to read its ID and math with the
+    calibration values
+  \item SPI - access to the Flash memory, used to store calibration
+    parameters and init script
+  \item EEPROM $I^2C$ - [optional] access to the EEPROM memory, used to store
+    calibration parameters and init script - currently SPI Flash is the
+    preferred storage, however, EEPROM can still be used if needed.
+\end{itemize}

doc/HDLdoc/wrc_core.tex

@@ -39,3 +39,4 @@ Section~\ref{sec:hdl_board_spec}).
 \input{fabric.tex}
 \input{txts.tex}
 \input{timecode.tex}
+\input{aux_diag.tex}