.\" Contributed by Niki A. Rahimi, LTC Security Development
.\" narahimi@us.ibm.com
.\"
.\" %%%LICENSE_START(FREELY_REDISTRIBUTABLE)
.\" May be freely distributed and modified.
.\" %%%LICENSE_END
.\"
.TH PCICONFIG_READ 2 2016-07-17 "Linux" "Linux Programmer's Manual"
.SH NAME
pciconfig_read, pciconfig_write, pciconfig_iobase \- pci device information handling
.SH SYNOPSIS
.nf
.B #include <pci.h>
.PP
.BI "int pciconfig_read(unsigned long " bus ", unsigned long " dfn ,
.BI "          unsigned long " off ", unsigned long " len ", void *" buf );
.BI "int pciconfig_write(unsigned long " bus ", unsigned long " dfn ,
.BI "          unsigned long " off ", unsigned long " len ", void *" buf );
.BI "int pciconfig_iobase(long " which ", unsigned long " bus ,
.BI "          unsigned long " devfn );
.fi
.SH DESCRIPTION
.PP
Most of the interaction with PCI devices is already handled by the
kernel PCI layer,
and thus these calls should not normally need to be accessed from user space.
.TP
.BR pciconfig_read ()
Reads to
.I buf
from device
.I dev
at offset
.I off
value.
.TP
.BR pciconfig_write ()
Writes from
.I buf
to device
.I dev
at offset
.I off
value.
.TP
.BR pciconfig_iobase ()
You pass it a bus/devfn pair and get a physical address for either the
memory offset (for things like prep, this is 0xc0000000),
the IO base for PIO cycles, or the ISA holes if any.
.SH RETURN VALUE
.TP
.BR pciconfig_read ()
On success, zero is returned.
On error, \-1 is returned and
.I errno
is set appropriately.
.TP
.BR pciconfig_write ()
On success, zero is returned.
On error, \-1 is returned and
.I errno
is set appropriately.
.TP
.BR pciconfig_iobase ()
Returns information on locations of various I/O
regions in physical memory according to the
.I which
value.
Values for
.I which
are:
.BR IOBASE_BRIDGE_NUMBER ,
.BR IOBASE_MEMORY ,
.BR IOBASE_IO ,
.BR IOBASE_ISA_IO ,
.BR IOBASE_ISA_MEM .
.SH ERRORS
.TP
.B EINVAL
.I len
value is invalid.
This does not apply to
.BR pciconfig_iobase ().
.TP
.B EIO
I/O error.
.TP
.B ENODEV
For
.BR pciconfig_iobase (),
"hose" value is NULL.
For the other calls, could not find a slot.
.TP
.B ENOSYS
The system has not implemented these calls
.RB ( CONFIG_PCI
not defined).
.TP
.B EOPNOTSUPP
This return value is valid only for
.BR pciconfig_iobase ().
It is returned if the value for
.I which
is invalid.
.TP
.B EPERM
User does not have the
.B CAP_SYS_ADMIN
capability.
This does not apply to
.BR pciconfig_iobase ().
.SH CONFORMING TO
These calls are Linux-specific, available since Linux 2.0.26/2.1.11.
.SH SEE ALSO
.BR capabilities (7)