Detecting PCI devices

1
Detecting PCI devices

• On identifying the peripheral equipment installed
  in our PC

2
Early PCs

• Peripheral devices in the early PCs used fixed
  i/o-ports and fixed memory-addresses, e.g.
• Video memory address-range 0xA0000-0xBFFFF
• Programmable timer i/o-ports 0x40-0x43
• Keyboard and mouse i/o-ports 0x60-0x64
• Real-Time Clocks i/o-ports 0x70-0x71
• Hard Disk controllers i/o-ports 0x01F0-01F7
• Graphics controllers i/o-ports 0x03C0-0x3CF
• Serial-port controllers i/o-ports 0x03F8-0x03FF
• Parallel-port controllers i/o-ports
  0x0378-0x037A

3
The PCs evolution

• It became clear in the 1990s that there would be
  contention among equipment vendors for fixed
  resource-addresses, which of course were in
  limited supply
• Among the goals that motivated the PCI
  Specification was the creation of a more flexible
  scheme for allocating addresses that future
  peripheral devices could use

4
PCI Configuration Space
A non-volatile parameter-storage area for each
PCI device-function
PCI Configuration Space Header (16 doublewords
fixed format)
PCI Configuration Space Body (48 doublewords
variable format)
64 doublewords
5
PCI Configuration Header
16 doublewords
31
0
31
0
Dwords
Status Register
Command Register
Device ID
Vendor ID
1 - 0
BIST
Cache Line Size
Class Code Class/SubClass/ProgIF
Revision ID
Latency Timer
Header Type
3 - 2
Base Address 0
Base Address 1
5 - 4
Base Address 2
Base Address 3
7 - 6
Base Address 4
Base Address 5
9 - 8
Subsystem Device ID
Subsystem Vendor ID
CardBus CIS Pointer
11 - 10
reserved
capabilities pointer
Expansion ROM Base Address
13 - 12
Minimum Grant
Interrupt Pin
reserved
Interrupt Line
Maximum Latency
15 - 14
6
Three IA-32 address-spaces
accessed using a large variety of processor
instructions (mov, add, or, shr, push, etc.) and
virtual-to-physical address-translation
memory space (4GB)
accessed only by using the processors
special in and out instructions (without
any translation of port-addresses)
PCI configuration space (16MB)
i/o space (64KB)
i/o-ports 0x0CF8-0x0CFF dedicated to accessing
PCI Configuration Space
7
Interface to PCI Configuration Space
PCI Configuration Space Address Port (32-bits)
31 23
16 15 11 10 8 7
2 0
reserved
E N
bus (8-bits)
device (5-bits)
doubleword (6-bits)
function (3-bits)
00
CONFADD ( 0x0CF8)
Enable Configuration Space Mapping (1yes, 0no)
PCI Configuration Space Data Port (32-bits)
31

0
CONFDAT ( 0x0CFC)
8
Reading PCI Configuration Data

• Step one Output the desired longwords address
  (bus, device, function, and dword) with bit 31
  set to 1 (to enable access) to the
  Configuration-Space Address-Port
• Step two Read the designated data from the
  Configuration-Space Data-Port

read the PCI Header-Type field (byte 2 of dword
3) for bus0, device0, function0 movl 0x800000
0C, eax setup address in EAX movw 0x0CF8,
dx setup port-number in DX outl eax,
dx output address to port mov 0x0CFC,
dx setup port-number in DX inl dx, eax
input configuration longword shr 16, eax
shift word 2 into AL register movb al,
header_type store Header Type in variable
9
Demo Program

• We created a short Linux utility that searches
  for and reports all of your systems PCI devices
• Its named pciprobe.cpp on our CS635 website
• It uses some C macros that expand to Intel
  input/output instructions -- which normally are
  privileged instructions that a Linux
  application-program is not allowed to execute
  (segfault!)
• Our system administrator (Alex Fedosov) has
  created a utility (named iopl3) that will allow
  your command-shell to acquire I/O privileges

10
Example network interface

• We identify the network interface controller in
  our classroom PCs by class-code 0x02
• The subclass-code 0x00 is for ethernet
• We can identify the NIC from its VENDOR and
  DEVICE identification-numbers
• VENDOR_ID 0x14E4
• DEVICE_ID 0x1677
• You can use the grep command to search for
  these numbers in this header-file
• lt/usr/src/linux/include/linux/pci_ids.hgt

11
Vendors identity

• The VENDOR-ID 0x14E4 belongs to the Broadcom
  Corporation (headquarters in Irvine, California)
• Information about this firm may be learned from
  the corporations website
• lthttp//www.broadcom.comgt
• The DEVICE-ID 0x1677 is used to signify
  Broadcoms BCM5751 ethernet product

12
Typical NIC

main memory
packet
nic
TX FIFO
transceiver
buffer
LAN cable
B U S
RX FIFO
CPU
13
Packet filtering capability

• Network Interfaces hardware needs to implement
  filtering of network packets
• Otherwise the PCs memory-usage and
  processor-time will be wasted handling packets
  not meant for this PC to receive

network packets layout
Destination-address (6-bytes)
Source-address (6-bytes)
Each data-packet begins with the 6-byte
device-address of the network interface which is
intended to receive it
14
Your NICs unique address

• You can see the Hardware Address of the ethernet
  controller on your PC by typing
• /sbin/ifconfig
• Look for it in the first line of screen-output
  that is labeled eth0, for example
• (The NICs filter-register stores this value)

eth0 Link encap Ethernet HWaddr
001143C9503A
15
Our tigon3.c demo

• We wrote a kernel module that lets users see
  certain register-values which pertain to the
  BCM5751 network interface in your classroom
  workstation
• (1) the PCI Configuration Space registers
• (2) the Media Access Controllers address
• It also shows your machines node-name (in case
  you want to save the information)

16
How we got the MAC-address

• We do not have Broadcoms programming datasheet
  -- but we do have Linux source code for the
  tigon3 device-driver, which includes a
  header-file tg3.h found here
• lt/usr/src/linux/drivers/net/gt
• If you scroll through the define directives you
  will see the offset where the hardware address is
  stored in the memory-mapped register-space of the
  tigon3 interface

17
Drivers authors

• The Linux kernels open-source driver for the
  Broadcom tigon3 network controller was jointly
  written by David S. Miller (see photo below) and
  Jeff Garzik

David Millers announcement in Feb 2002 of their
drivers BETA version is online. It includes his
candid comments about the challenge of writing
such a driver when the vendor does not make
available its devices programming documentation.

18
How we got tigon3 registers
16 doublewords
31
0
31
0
Dwords
Status Register
Command Register
DeviceID 0x1677
VendorID 0x14E4
1 - 0
BIST
Cache Line Size
Class Code Class/SubClass/ProgIF
Revision ID
Latency Timer
Header Type
3 - 2
Base Address 0
Base Address 1
5 - 4
Base Address 2
Base Address 3
7 - 6
Base Address 4
Base Address 5
9 - 8
Subsystem Device ID
Subsystem Vendor ID
CardBus CIS Pointer
11 - 10
reserved
capabilities pointer
Expansion ROM Base Address
13 - 12
Minimum Grant
Interrupt Pin
reserved
Interrupt Line
Maximum Latency
15 - 14
19
Linux helper-functions
include ltlinux/pci.hgt struct pci_dev devp unsi
gned int iomem_base, iomem_size void io dev
p pci_get_device( 0x14E4, 0x1677, NULL ) if (
!devp ) return ENODEV iomem_base
pci_resource_start( devp, 0 ) iomem_size
pci_resource_len( devp, 0 ) io ioremap(
iomem_base, iomem_size ) if ( !io ) return
-EBUSY
20
Big-Endian to Little-Endian
Broadcom network interface storage-addresses
0x0410 0x0411 0x0412 0x0413 0x0414
0x0415 0x0416 0x0417
mac 1
mac 0
mac 5
mac 4
mac 3
mac 2
mac 0
mac 1
mac 2
mac 3
mac 4
mac 5
Intel IA-32 character-array storage
21
In-class exercise

• Copy the tigon3.c source-module to your own
  directory, then rename it anchor.c
• Your assignment is to modify it so that it will
  show information about the Intel NICs in our
  anchor clusters machines
• define VENDOR_ID 0x8086 // Intel Corp
• define DEVICE_ID 0x109A // 82573L NIC
• Intels filter-register at offset 0x5400 uses the
  little endian storage-convention

22
Little-Endian to Little-Endian
Intel network interface storage-addresses
0x5400 0x5401 0x5402 0x5403 0x5404
0x5405 0x5406 0x5407
mac 0
mac 1
mac 2
mac 3
mac 4
mac 5
mac 0
mac 1
mac 2
mac 3
mac 4
mac 5
Intel IA-32 character-array storage