.\"	$NetBSD: pci.3,v 1.2 2001/09/15 11:16:14 wiz Exp $
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.Dd September 12, 2001
.Os
.Dt PCI 3
.Sh NAME
.Nm pci
.Nd library interface for PCI bus access
.Sh LIBRARY
.Lb libpci
.Sh SYNOPSIS
.Fd #include <pci.h>
.Ft int
.Fn pcibus_conf_read "int pcifd" "u_int bus" "u_int dev" "u_int func" \
"u_int reg" "pcireg_t *valp"
.Ft int
.Fn pcibus_conf_write "int pcifd" "u_int bus" "u_int dev" "u_int func" \
"u_int reg" "pcireg_t val"
.Ft int
.Fn pcidev_conf_read "int devfd" "u_int reg" "pcireg_t *valp"
.Ft int
.Fn pcidev_conf_write "int devfd" "u_int reg" "pcireg_t val"
.Ft char *
.Fn pci_findvendor "pcireg_t id_reg"
.Ft void
.Fn pci_devinfo "pcireg_t id_reg" "pcireg_t class_reg" "char *devinfo"
.Ft void
.Fn pci_conf_print "int pcifd" "u_int bus" "u_int dev" "u_int func"
.Sh DESCRIPTION
The
.Nm
library provides support for accessing the PCI bus by user programs.
.Pp
These functions are available in the
.Nm libpci
library.
Programs should be linked with
.Fl lpci .
.Sh CONFIGURATION SPACE FUNCTIONS
The following functions are used to access PCI configuration space:
.Bl -tag -width 4n
.It Fn pcibus_conf_read
Access the PCI configuration register
.Fa reg
on the device located at
.Fa bus ,
.Fa dev ,
.Fa func ,
and place the result in
.Fa *valp .
.Fa pcifd
must be an open file descriptor to a PCI bus within the target PCI domain.
.It Fn pcibus_conf_write
Write the value specified by
.Fa val
into the PCI configuration register
.Fa rag
on the device located at
.Fa bus ,
.Fa dev ,
.Fa func .
.Fa pcifd
must be an open file descriptor to a PCI bus within the target PCI domain.
.It Fn pcidev_conf_read
Access the PCI configuration register
.Fa reg
on the device associated with the open file descriptor
.Fa devfd
and place the result in
.Fa *valp .
.It Fn pcidev_conf_write
Write the value specified by
.Fa val
into the PCI configuration register
.Fa reg
on the device associated with the open file descriptor
.Fa devfd .
.El
.Sh MISCELLANEOUS FUNCTIONS
The following miscellaneous functions are available:
.Bl -tag -width 4n
.It Fn pci_findvendor
Return an ASCII description of the PCI vendor in the
PCI ID register
.Fa id_reg .
.It Fn pci_devinfo
Return an ASCII description of the PCI vendor, PCI product,
and PCI class specified by the PCI ID register
.Fa id_reg
and PCI class ID register
.Fa class_reg .
The description is placed into the buffer pointed to by
.Fa devinfo .
The buffer should be at least 256 bytes long.
.It Fn pci_conf_print
Print the PCI configuration information for the device located
at
.Fa bus ,
.Fa dev ,
.Fa func .
.Fa pcifd
must be an open file descriptor to a PCI bus within the target PCI domain.
.El
.Sh RETURN VALUES
The
.Fn pcibus_conf_read ,
.Fn pcibus_conf_write ,
.Fn pcidev_conf_read ,
and
.Fn pcidev_conf_write
functions return 0 on success and -1 on failure.
.Pp
The
.Fn pci_findvendor
function returns NULL if the PCI vendor description cannot be
found.
.Sh SEE ALSO
.Xr pci 4
.Sh HISTORY
The
.Fn pcibus_conf_read ,
.Fn pcibus_conf_write ,
.Fn pcidev_conf_read ,
.Fn pcidev_conf_write ,
.Fn pci_findvendor ,
.Fn pci_devinfo ,
and
.Fn pci_conf_print
functions first appeared in
.Nx 1.6 .