Hello all, I'm attempting to create an IOKit driver/family for DAQ
devices (specifically those from National Instruments), as well as a
user-space framework for data access, but I'm having some trouble
figuring out how to split the code among the various 'strata' of the
IOKit. Here's my basic understanding of how this should work:
Driver:
DaqDevice ( base class for all daq drivers with virtual methods for
reading/writing registers and taking interrupts)
NIDaq : public IODaqDevice ( base class for NI daq devices with code
that can be shared among them for low level access )
xSeries : public NIDaq ( classes specific to different NIDaq cards )
User Client:
DaqDeviceUserClient ( base class for daq driver user clients, with
virtual methods for configuration, starting & stopping io)
NIDaqUserClient : public DaqDeviceUC ( base class for NI daq devices ... )
xSeriesUC : public NIDaqUC ( device specific methods )
User Application/Framework:
DaqDevice ( base class for controlling the drivers, with methods for
starting/stopping acquisition, pushing buffers into the UC and
retrieving data )
This seems to be the way the IOKit documentation describes a proper
pci driver setup, but I have been totally unable to find any example
code that would show how to access this data properly from the
Application layer. I've found many examples on how to write PCI
ethernet drivers, but since they plug into lower levels of the IOKit,
they don't help me much. The SimplePCIDevice drivers are laughably
simple, and have *zero* information on grabbing device or dma
interrupts, and there doesn't seem to be any other sample code that
does either.
Before anyone lectures me on using the mxBase drivers from NI, the
performance is far too low on OSX for them to be usable in our
experiments. I created a mini-driver for e-series boards using the
mxBase methods (directly mapping the register space into userland) but
the sheer number of calls that cross the user-kernal bridge slows the
acquisition down significantly, plus, e-series drivers won't work on
G5s or MacPros, so we need to move forward with a PCIe driver for
m-series cards.
Does anyone have any good pointers or links which could send me in the
right direction for this project? Or at least any notes on how best to
'stratify' this project so I can keep it general enough to be expanded
in the future?
Thanks,
Rob Dotson
Vision Core Grant, NIH
New York University
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