On 02/21/2013 12:14:12 PM, Alessandro Rubini wrote:
This is selected sections of the current manual for fmc-bus, as
developed outside of the kernel before submission.
Signed-off-by: Alessandro Rubini <rubini@xxxxxxxxx>
Acked-by: Juan David Gonzalez Cobas <dcobas@xxxxxxx>
Acked-by: Emilio G. Cota <cota@xxxxxxxxx>
Acked-by: Samuel Iglesias Gonsalvez <siglesias@xxxxxxxxxx>
Acked-by: Rob Landley <rob@xxxxxxxxxxx>
On the basis it's all nicely in its own subdirectory not bothering
anyone else.
That said:
+The data structure that describe a device is detailed in *note FMC
+Device::, the one that describes a driver is detailed in *note FMC
+Driver::.
What is this *note thingy:: syntax? It recurs a lot. Some sort of
reference into the PDF you started out with a link to, maybe?
From your 00-INDEX additions:
+FMC-and-SDB.txt
+ - What are FMC and SDB, basic concepts for this framework
+What is FMC
+***********
+
+FMC, as said, stands for "FPGA Mezzanine Card". It is a standard
+developed by the VME consortium called VITA (VMEbus International
Trade
+Association and ratified by ANSI, the American National Standard
+Institute. The official documentation is called "ANSI-VITA 57.1".
+
+The FMC card is an almost square PCB, around 70x75 millimeters, that
is
+called mezzanine in this document. It usually lives plugged into
+another PCB for power supply and control; such bigger circuit board
is
+called carrier from now on, and a single carrier may host more than
one
+mezzanine.
A basic concept of this framework is that you have a 70x75 PCB? Is this
part of that ANSI-VITA standard?
+In the typical application the mezzanine is mostly analog while the
+carrier is mostly digital, and hosts an FPGA that must be configured
to
+match the specific mezzanine and the desired application. Thus, you
may
+need to load different FPGA images to drive different instances of
the
+same mezzanine.
From the top level 00-INDEX:
+fmc/
+ - information about the FMC bus abstraction
And then...
+FMC, as such, is not a bus in the usual meaning of the term, because
+most carriers have only one connector, and carriers with several
+connectors have completely separate electrical connections to them.
+This package, however, implements a bus as a software abstraction.
USB is point to point connections with switches in between. It's still
got B in the acronym. I'm not sure what you're saying here.
+
+What is SDB
+***********
+
+SDB (Self Describing Bus) is a set of data structures that we use for
+enumerating the internal structure of an FPGA image. We also use it
as
+a filesystem inside the FMC EEPROM.
Are you trying to document infrastructure to implement a standard, or a
bespoke driver for a specific piece of hardware? How much of this is
generic? Are there other vendors who might someday want to use this
code?
Anyway, no serious objection, but I note that reading to this point I
didn't feel I had enough information to wrap my head around what it's
for. It's documentation by people who already know this stuff, for
people who already know this stuff. (There's a long tradition of that.
Oh well.)
Rob
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