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     PNP(3)							PNP(3)

     NAME
	  pnp -	Plug 'n' Play ISA and PCI Interfaces

     SYNOPSIS
	  bind -a '#$' /dev
	  /dev/pci/bus.dev.fnctl
	  /dev/pci/bus.dev.fnraw
	  /dev/pnp/ctl
	  /dev/pnp/csnnctl
	  /dev/pnp/csnnraw
	  ...

     DESCRIPTION
	  This device provides a limited interface to the PCI bus and
	  Plug 'n' Play	ISA devices.

	PCI Interface
	  PCI devices are addressed logically by a bus number, a
	  device number	on that	bus, and a function number within the
	  device.  The set of all such device functions	may be
	  enumerated by	traversing the /dev/pci	directory; the driver
	  serves two files for each function.  These are a control
	  file (`/dev/pci/bus.dev.fnctl') which	may be read for	a tex-
	  tual summary of the device function, and a `raw' file
	  (`/dev/pci/bus.dev.fnraw') which may be used to read or
	  write	the raw	contents of PCI	configuration space.

	  The first field of a PCI control file	contains the class,
	  sub-class and	programming interface values for the device
	  function, expressed as 2-digit hexadecimal values, and
	  separated by periods.	 The second field yields the vendor ID
	  and device ID, each as 4-digit hex numbers, separated	by a
	  slash.  The third field is the associated interrupt line in
	  decimal.  The	remainder of the line enumerates any valid
	  base address registers for the function, using two fields
	  for each.  In	the first field, the index of the register is
	  followed by a	colon, and then	the value of the register
	  itself.  The following field gives the associated size of
	  the memory (or I/O space) that is mapped by the register.

	Plug 'n' Play
	  Plug 'n' Play	ISA devices are	discovered by sending a	fixed
	  `unlock' sequence over an I/O	port, and then reading back
	  data from another port.  An arbitration algorithm is used to
	  separate out the individual cards and	enumerate them in
	  turn.	 Each card is assigned a unique	number,	called a CSN,
	  in the range 1-255 as	a result of enumeration.  Cards	also
	  have a fixed 64 bit identification number, set by the
	  manufacturer,	which is used by the arbitration algorithm to
	  resolve conflicts.  The first	32 bits	describe the type of
	  the card, and	the second 32 bits form	a serial number	for
	  the particular instance of that card type.  When formatted
	  textually, it	appears	as 3 upper-case	letters	(typically
	  representing the manufacturer), followed by 4	hex digits,
	  then a period, then 8	hex digits.  The substring before the
	  period is the	card type, and the substring after the period
	  is the serial	number.

	  The enumeration algorithm needs to be	enabled	by specifying
	  the port number to write the unlock sequence out on.	This
	  can be configured to take place at boot time by adding a
	  line like the	following to plan9.ini:

	       pnp0=port=0x203

	  Here port should be chosen to	not conflict with any existing
	  devices.  It must be in the range 0x203-0x3ff.  Alterna-
	  tively, one can use the following command:

	       echo port 0x203 >/dev/pnp/ctl

	  Note that a side-effect of PnP enumeration is	to reset the
	  configuration	state of all such cards; any settings made by
	  a Plug and Play BIOS will be lost.  Reading the file
	  /dev/pnp/ctl returns one of the strings enabled port or
	  disabled.

	  For each enumerated card, two	files are served in /dev/pnp.
	  A control file (`/dev/pnp/csnnctl') may be read to determine
	  the ID of the	card, and a raw	file (`/dev/pnp/csnnraw') may
	  be read to obtain the	configuration data associated with the
	  card.	 It is intended	that the control file should take com-
	  mands	which set the various configurable resources of	the
	  card,	but this has not been implemented yet.

	  A mechanism is provided for configuring cards	via
	  plan9.ini(8).	A line of the form pnpn=idstring ...  will
	  cause	the driver to look for the card	named by idstring and,
	  if found, assign it the CSN n. The intention is that any
	  additional text after	the idstring is	interpreted as if it
	  was written to the card's ctl	file, but this is not yet
	  implemented.

     EXAMPLES
	  To list all PCI functions:

	       cat /dev/pci/*ctl

	  To find just the PCI video card (class 3):

	       grep '^03' /dev/pci/*ctl

     SOURCE
	  /sys/src/9/port/devpnp.c

     SEE ALSO
	  pci(8)

     BUGS
	  Access to the	I/O and	memory regions of a PCI	device is not
	  provided.

	  The ability to set a Plug 'n'	Play card's configurable set-
	  tings	has not	been implemented.

	  There	should be a user program for identifying and configur-
	  ing Plug 'n' Play cards.

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