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SDB - Self-describing Bus
Commit 3fb49318 authored by Alessandro Rubini's avatar Alessandro Rubini
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docs: added a more complete example (thanks Wesley)

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docs/specification/sdb.tex
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......@@ -852,18 +852,19 @@ The value \textbf{must} point to an SDB array that begins with an \textit{interc
An embedded component info structure, where the type is 0x01 See Table \ref{sdb_component}.
\end{description}
\section{A Simple Real-World Example}
\section{Simple Real-World Examples}
This section shows the simplest real-world example of an SDB array.
The FPGA binary used as an example is the \textit{boot} image to be
This section shows the details of the simplest real-world example of an SDB array,
and an overlook of a more structured device.
\subsection{Simple Binary Data}
The FPGA binary used as the simplest example is the \textit{boot} image to be
programmed in the SPEC cards
(\texttt{http://www.ohwr.org/projects/spec}); it only includes the
\textit{syscon} device, which allows generic access to the FMC
mezzanine card.
\subsection{Binary Data}
The following binary dump appears at offset 0x100 of the memory window
that maps to the programmable device:
......@@ -931,6 +932,35 @@ The previous dump shows how the vendor identifiers in this case have
been allocated in the globally-assigned space, while device identifiers
are pseudo-random numbers, in charge of the respective vendor.
\subsection{A More Structured Device}
The following is the output of \texttt{eb-ls}, and \textit{Etherbone}
tool, when run over a complex White Rabbit device. This output
comes from scanning the SDB structures:
\footnotesize
\begin{verbatim}
root@scul007:~# eb-ls dev/pcie_wb0
BusPath VendorID Product Base(Hex) Description
1 000000000000ce42:66cfeb52 0 WB4-BlockRAM
2 0000000000000651:eef0b198 100000 WB4-Bridge-GSI
2.1 0000000000000651:35aa6b95 100000 GSI_GPIO_32
2.2 0000000000000651:8752bf44 140000 GSI_ECA_UNIT
2.3 0000000000000651:10051981 180000 GSI_TM_LATCH
3 0000000000000651:eef0b198 200000 WB4-Bridge-GSI
3.1 000000000000ce42:66cfeb52 200000 WB4-BlockRAM
3.2 0000000000000651:eef0b198 220000 WB4-Bridge-GSI
3.2.1 000000000000ce42:ab28633a 220000 WR-Mini-NIC
3.2.2 000000000000ce42:650c2d4f 220100 WR-Endpoint
3.2.3 000000000000ce42:65158dc0 220200 WR-Soft-PLL
3.2.4 000000000000ce42:de0d8ced 220300 WR-PPS-Generator
3.2.5 000000000000ce42:ff07fc47 220400 WR-Periph-Syscon
3.2.6 000000000000ce42:e2d13d04 220500 WR-Periph-UART
3.2.7 000000000000ce42:779c5443 220600 WR-Periph-1Wire
3.2.8 000000000000ce42:779c5443 220700 WR-Periph-1Wire
\end{verbatim}
\normalsize
\subsection{Endianness Problems}
Please note that the host may have some issue reading the binary
......@@ -958,5 +988,11 @@ byte-swap each 32-bit word before using the structure in a
little-endian host. After such swapping, the usual rules for
multi-byte values apply.
\subsection{Existing Tools}
As part of the \textit{Etherbone} project, you already find a number
of tools that work with SDB structures (including \texttt{eb-ls} that
printed the table of devices shown above). The project is at
\texttt{http://www.ohwr.org/projects/etherbone-core} .
\end{document}
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