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.TH PNP 3
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.SH NAME
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pnp \- Plug 'n' Play ISA and PCI Interfaces
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.SH SYNOPSIS
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.nf
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.B bind -a '#$' /dev
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.sp 0.3v
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.BI /dev/pci/ bus\fL.\fPdev\fL.\fPfn ctl
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.BI /dev/pci/ bus\fL.\fPdev\fL.\fPfn raw
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.sp 0.3v
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.BI /dev/pnp/ctl
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.BI /dev/pnp/csn n ctl
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.BI /dev/pnp/csn n raw
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\&...
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.sp 0.3v
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.fi
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.SH DESCRIPTION
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.PP
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This device provides a limited interface to the PCI bus and
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Plug 'n' Play ISA devices.
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.SS PCI Interface
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.PP
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PCI devices are addressed logically by a bus number,
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a device number on that bus, and a function number
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within the device.
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The set of all such device functions may be enumerated
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by traversing the
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.B /dev/pci
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directory; the driver serves two files for each function.
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These are a control file
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.RL ( /dev/pci/\fIbus\fP.\fIdev\fP.\fIfn\fPctl )
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which may be read for a textual summary of the device function,
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and a `raw' file
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.RL ( /dev/pci/\fIbus\fP.\fIdev\fP.\fIfn\fPraw )
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which may be used to read or write the raw contents of PCI configuration space.
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.PP
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The first field of a PCI control file contains the class, sub-class and
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programming interface values for the device function, expressed
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as 2-digit hexadecimal values, and separated by periods.
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The second field yields the vendor ID and device ID, each as 4-digit
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hex numbers, separated by a slash.
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The third field is the associated interrupt line in decimal.
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The remainder of the line enumerates any valid base address
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registers for the function, using two fields for each.
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In the first field, the index of the register is followed by
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a colon, and then the value of the register itself.
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The following field gives the associated size of the memory
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(or I/O space) that is mapped by the register.
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.SS Plug 'n' Play
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.PP
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Plug 'n' Play ISA devices are discovered by sending a fixed `unlock' sequence
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over an I/O port, and then reading back data from another port.
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An arbitration algorithm is used to separate out the individual
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cards and enumerate them in turn.
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Each card is assigned a unique number, called a CSN, in the range 1-255 as a
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result of enumeration.
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Cards also have a fixed 64 bit identification number, set by the
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manufacturer, which is used by the arbitration algorithm to
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resolve conflicts.
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The first 32 bits describe the type of the card, and the second
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32 bits form a serial number for the particular instance of that card type.
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When formatted textually, it appears as 3 upper-case letters
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(typically representing the manufacturer),
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followed by 4 hex digits, then a period, then 8 hex digits.
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The substring before the period is the card type, and the substring
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after the period is the serial number.
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.PP
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The enumeration algorithm needs to be enabled by specifying the
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port number to write the unlock sequence out on.
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This can be configured to take place at boot time by adding a line
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like the following to
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.IR plan9.ini :
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.IP
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.EX
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pnp0=port=0x203
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.EE
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.PP
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Here
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.B port
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should be chosen to not conflict with any existing devices.
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It must be in the range
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.BR 0x203-0x3ff .
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Alternatively, one can use the following command:
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.IP
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.EX
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echo port 0x203 >/dev/pnp/ctl
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.EE
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.PP
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Note that a side-effect of PnP enumeration is to reset the configuration
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state of all such cards; any settings made by a Plug and Play BIOS will be lost.
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Reading the file
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.B /dev/pnp/ctl
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returns one of the strings
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.B "enabled\fI port\fP"
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or
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.BR "disabled" .
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.PP
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For each enumerated card, two files are served in
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.BR /dev/pnp .
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A control file
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.RL ( /dev/pnp/csn\fIn\fPctl )
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may be read to determine the ID of the card, and a raw file
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.RL ( /dev/pnp/csn\fIn\fPraw )
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may be read to obtain the configuration data associated with the card.
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It is intended that the control file should take commands which set the
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various configurable resources of the card, but this has not been
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implemented yet.
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.PP
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A mechanism is provided for configuring cards via
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.IR plan9.ini (8).
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A line of the form
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.BI pnp n = "idstring ..."
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will cause the driver to look for the card named by
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.I idstring
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and, if found, assign it the CSN
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.IR n .
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The intention is that
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any additional text after the idstring is interpreted as if it
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was written to the card's
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.B ctl
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file, but this is not yet implemented.
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.SH EXAMPLES
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.PP
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To list all PCI functions:
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.IP
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.EX
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cat /dev/pci/*ctl
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.EE
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.PP
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To find just the PCI video card (class 3):
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.IP
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.EX
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grep '^03' /dev/pci/*ctl
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.EE
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.SH SOURCE
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.B /sys/src/9/port/devpnp.c
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.SH SEE ALSO
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.IR pci (8)
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.SH BUGS
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Access to the I/O and memory regions of a PCI device is not provided.
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.PP
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The ability to set a Plug 'n' Play card's configurable settings has not been
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implemented.
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.PP
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There should be a user program for identifying and configuring
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Plug 'n' Play cards.
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