Pci debug

Introduction

pci_debug is a useful tool meant to access PCIe BARx memory from userspace.

Buildroot configuration

• Should be done by default on APF6
• Select pci_debug:

Target packages  --->
    Hardware handling  --->
        [*] pcidebug

• then rebuild your BSP:

$ make

Using pci_debug

• First find your PCI device name with lspci :

# lspci
00:00.0 PCI bridge: Device 16c3:abcd (rev 01)
01:00.0 Unclassified device [0013]: Altera Corporation Device e001 (rev 01)

For example here, we want to access Altera PCI device, then name is : 01:00.0

• Launch pci_debug with the BAR number in option (-b) :

# pci_debug -s 01:00.0 -b0
# ./pci_debug -s 01:00.0 -b0

PCI debug
---------

 - accessing BAR0
 - region size is 4194304-bytes
 - offset into region is 0-bytes

  ?                         Help
  d[width] addr len         Display memory starting from addr
                            [width]
                              8   - 8-bit access
                              16  - 16-bit access
                              32  - 32-bit access (default)
  c[width] addr val         Change memory at addr to val
  e                         Print the endian access mode
  e[mode]                   Change the endian access mode
                            [mode]
                              b - big-endian (default)
                              l - little-endian
  f[width] addr val len inc  Fill memory
                              addr - start address
                              val  - start value
                              len  - length (in bytes)
                              inc  - increment (defaults to 1)
  q                          Quit

  Notes:
    1. addr, len, and val are interpreted as hex values
       addresses are always byte based

PCI> 

• You can then access BAR0 memory on PCI> prompt.
• Reading 0x20 values from address 0 :

PCI> d32 0 20

00000000: 12345678 12345678 12345678 12345678 
00000010: 12345678 12345678 12345678 12345678

PCI>

Links

This tool come from an altera forum post, and the archive code can be found here.