Writing a PCIe-Driver

[John-Mark Gurney]

Dr. Rolf Jansen wrote this message on Sun, Sep 23, 2018 at 12:56 -0300:
> A couple of years ago, with the valuable help of people on this list, I managed to write a PCI driver for the National Instruments DAQ card, NI PCI-6251. The driver was kept very simple, only map the BAR???s and some DMA memory into the user space. The DAC/ADC and DIO is then all controlled from user space by writing command codes to certain offsets from the mapped BAR???s, and reading data from the mapped DMA memory and/or from other given offsets.
> 
> See: How to map device addresses into user space
> https://lists.freebsd.org/pipermail/freebsd-drivers/2013-January/thread.html
> 
> 
> Now, I need to do exactly the same for a PCIe card, namely the NI PCIe-6351. However, I even cannot see where to start. For PCI cards, the respective chapter 11 in the FreeBSD Architecture Handbook was quite helpful, for getting started, in no time, I got the PCI card probed and attached.
> 
> https://www.freebsd.org/doc/en_US.ISO8859-1/books/arch-handbook/pci.html
> 
> The dumb approach, probing the device ID and attaching the PCI(e) driver to the PCIe device in a similar fashion didn???t work - I didn???t expect this either, however, where would I start? How do I attach my driver to a PCIe card on FreeBSD 11 or 12?

I'm a bit surprised that this didn't work, as PCIe is effectively
backwards compatible w/ PCI except a few exceptions like MSI...

Many drivers like em (sys/dev/e1000/if_em.c) are used for both PCI and
PCIe cards..  Maybe look at what they are doing differently than your
driver...

> Please can somebody push me into the right direction. Once I got the driver attached to the card, I guess, I would be able to adapt the mem-mapping code of my old driver for the new card.

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."