Is there a utility to peek and poke PCIe devices

Aug 10, 2011 5 Replies

Is there a utility that does peeks and pokes to PCIe devices. I'm developing an FPGA with a PCIe interface and I'd like to do some simple memory accesses before I move on to the more complicated things like DMA. We have a driver in development but I think there is a standard Altera driver already in the kernel which I assume would be good enough for simple accesses.



I'm running on Scientific Linux 6.1.



lspci identifies the device as an Altera device which is correct.


01:00.0 Unassigned class [ff00]: Altera Corporation Device 0004 (rev 01)

you don't even need a driver for simple memory access. if your device is detected by the kernel you can directly access the BARs via sysfs: # ls -l /sys/bus/pci/devices/0000\:01\:00.0/ [...]

-rw------- 1 root root 256M Aug 11 08:51 resource0

-rw------- 1 root root 256 Aug 11 08:51 resource1

-rw------- 1 root root 64K Aug 2 08:14 resource2 [...]

This is an example of a device with 3 BARs. These files can be read/written/mmapped... you could use "dd" or write a little C program to mmap the files.

HTH

(snip)

I remember doing this with VME based Suns and SunOS. Device mapped VME addressing space, and memory mapped files combine to form memory mapped memory space.

-- glen

How do I determine which device is mine?

Here is the lspci output

01:00.0 Unassigned class [ff00]: Altera Corporation Device 0004 (rev 01)

Here are the devices under /sys/bus/pci_express/devices

0000:00:0b.0:pcie01/ 0000:00:0c.0:pcie01/ 0000:00:0d.0:pcie01/ 0000:00:0e.0:pcie01/ 0000:00:0b.0:pcie08/ 0000:00:0c.0:pcie08/ 0000:00:0d.0:pcie08/ 0000:00:0e.0:pcie08

Here are the devices under /sys/bus/pci/devices

0000:00:00.0/ 0000:00:02.0/ 0000:00:06.0/ 0000:00:09.0/ 0000:00:0c.0/ 0000:00:18.0/ 0000:00:18.3/ 0000:05:00.0/ 0000:00:01.0/ 0000:00:02.1/ 0000:00:07.0/ 0000:00:0a.0/ 0000:00:0d.0/ 0000:00:18.1/ 0000:01:0d.0/ 0000:00:01.1/ 0000:00:04.0/ 0000:00:08.0/ 0000:00:0b.0/ 0000:00:0e.0/ 0000:00:18.2/ 0000:03:00.0

you should be able to use the pci-ID from lspci as directory name in /sys/bus/pcie/devices/

I don't really know why your device 0000:01:00.0 doesn't appear here - did you list the directory on the same machine & while the card is detected? Just a guess: maybe you have to set a device class in the FPGA Firmware other than ff00? (my Xilinx ML605 gets detected as "RAM memory" for example by setting the appropriate device/vendor IDs)

0000:00:0c.0/
0000:00:02.1/
0000:01:0d.0/
0000:00:0e.0/

I'm switching the class to 5 from FF, I'll see what happens.

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