.\" $NetBSD: pcibios.4,v 1.11 2001/04/21 14:33:39 wiz Exp $
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Lennart Augustsson.
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.Dd July 22, 2000
.Dt PCIBIOS 4 i386
.Os
.Sh NAME
.Nm pcibios
.Nd introduction to PCI BIOS support
.Sh SYNOPSIS
.Cd "options   PCIBIOS"
.Cd "options   PCIBIOSVERBOSE"
.Cd "options   PCIBIOS_ADDR_FIXUP"
.Cd "options   PCIBIOS_BUS_FIXUP"
.Cd "options   PCIBIOS_INTR_FIXUP"
.Cd "#options  PCIBIOS_IRQS_HINT=0x0a00 #IRQ 9,11"
.Cd "#options  PCIBIOS_INTR_FIXUP_FORCE"
.Cd "options   PCIBIOS_INTR_GUESS"
.Cd "#options  PCIINTR_DEBUG"
.Pp
.Sh INTRODUCTION
.Nx
provides support for setting up PCI controllers, bridges, and devices
using information extracted from the BIOS.
.Pp
Ideally, the boot firmware of a machine (a.k.a. BIOS) should set
up all PCI devices; assigning them I/O and memory addresses and
interrupts.  Alas, this does not always happen, so there is some
PC specific code that can do the initialization when
.Nx
boots.
.Pp
Options:
.Bl -tag -width PCIBIOS_INTR_FIXUP -offset 3n

.It Nm PCIBIOS
turn on the PCI BIOS support.

.It Nm PCIBIOSVERBOSE
make the setup procedure verbose.

.It Nm PCIBIOS_ADDR_FIXUP
fixup PCI I/O and memory addresses.
.Pp
Some BIOS implementations don't allocate I/O space and
memory space for some PCI devices. Especially, a BIOS
which is
.Qq PnP OS mode enabled
shows this behavior.
Since necessary space isn't allocated, those devices
will not work without special handling.

This option allocates I/O space and memory space
instead of relying upon the BIOS to do so.

If necessary space is already correctly assigned to the devices,
this option leaves the space as is.

Although many BIOS implementations leave CardBus bridges'
space unallocated, the CardBus bridge device driver doesn't
require this option, since the driver allocates necessary space
by itself.

.It Nm PCIBIOS_BUS_FIXUP
fixup PCI bus numbering; needed for many
.Xr cardbus 4
bridges.
.Pp
Each PCI bus and CardBus should have a unique bus number.
But some BIOS implementations don't assign a bus number
for subordinate PCI buses. And many BIOS implementations
don't assign a bus number for CardBuses.

A typical symptom of this is the following boot message:
.D1 Sy cardbus0 at cardslot0: bus 0 device 0...
Please note that this cardbus0 has a bus number
.Sq 0 ,
but normally the bus number 0 is used by the machine's
primary PCI bus. Thus, this bus number for cardbus is
incorrect
.Pq not assigned .
In this situation, a device located in cardbus0 doesn't
show correct device ID,
because its bus number 0 incorrectly refers to the primary
PCI bus, and a device ID in the primary PCI bus is shown
in the boot message instead of the device's ID in the cardbus0.

This option assigns bus numbers for all subordinate
PCI buses and CardBuses.

Since this option renumbers all PCI buses and CardBuses,
all bus numbers of subordinate buses become different
when this option is enabled.

.It Nm PCIBIOS_INTR_FIXUP
fixup PCI interrupt routing.
.Pp
Some BIOS implementations don't assign an interrupt for
some devices.

This option assigns an interrupt for such devices instead
of relying upon the BIOS to do so.

If the BIOS has already assigned an interrupt to a device, this
option leaves the interrupt as is.

.It Nm PCIBIOS_IRQS_HINT
hint for IRQ use.
When the
.Em PCIBIOS_INTR_FIXUP
cannot guess an adequate IRQ for a device, the hint is used.
.Pp
The value is a logical or of power-of-2s of allowable interrupts:
.Bl -column "XX-0xffff" "XX-0xffff" "XX-0xffff" "XX-0xffff" -compact -offset 2n
.It Em   "IRQ Value" Em "\tIRQ Value" Em "\tIRQ Value" Em "\tIRQ Value"
.It    "\& 0 0x0001"    "\t 4 0x0010"    "\t 8 0x0100"    "\t12 0x1000"
.It    "\& 1 0x0002"    "\t 5 0x0020"    "\t 9 0x0200"    "\t13 0x2000"
.It    "\& 2 0x0004"    "\t 6 0x0040"    "\t10 0x0400"    "\t14 0x4000"
.It    "\& 3 0x0008"    "\t 7 0x0080"    "\t11 0x0800"    "\t15 0x8000"
.El
For example,
.Qq Sy options PCIBIOS_IRQS_HINT=0x0a00
allows IRQ 9 and IRQ 11.

The kernel global variable
.Va pcibios_irqs_hint
holds this value,
so a user can override this value without kernel recompilation.
For example:
.Bl -bullet -compact
.It
To specify this value on the fly, type the following command
at the boot prompt to drop into DDB (the in-kernel debugger;
you have to specify
.Qq Sy options DDB
to make kernel with DDB):
.Dl Ic boot -d
And type the following command on
.Qq Sy db>
prompt:
.Dl Ic write pcibios_irqs_hint 0x0a00
Then type the following to continue to boot:
.Dl Ic c
.It
To modify kernel image without kernel recompilation,
run the following command on shell:
.Dl Ic gdb --write /netbsd
And type the following commands at the
.Qq Sy (gdb)
prompt:
.Dl Ic set pcibios_irqs_hint=0xa00
.Dl Ic quit
.El

.It Nm PCIBIOS_INTR_FIXUP_FORCE
.Pp
Some buggy BIOS implementations provide inconsistent
information between the PCI Interrupt Configuration Register
and the PCI Interrupt Routing table. In such case,
the PCI Interrupt Configuration Register takes precedence
by default. If this happens, a kernel with
.Em PCIBIOSVERBOSE
shows
.Qq Sy WARNING: preserving irq XX
in the PCI routing table.

If
.Em PCIBIOS_INTR_FIXUP_FORCE
is specified in addition to the
.Em PCIBIOS_INTR_FIXUP ,
the PCI Interrupt Routing table takes precedence.
In this case, a kernel with
.Em PCIBIOSVERBOSE
shows
.Qq Sy WARNING: overriding irq XX
in the PCI routing table.

.It Nm PCIBIOS_INTR_GUESS
make
.Em PCIBIOS_INTR_FIXUP
work with unknown interrupt router.
.Pp
If a PCI interrupt router is not known, normally interrupt
configuration will not be touched.

But if
.Em PCIBIOS_INTR_GUESS
is specified in addition to the
.Em PCIBIOS_INTR_FIXUP ,
and if a PCI interrupt routing table entry indicates that only
one IRQ is available for the entry, the IRQ is assumed to be already
connected to the device, and corresponding PCI Interrupt
Configuration Register will be configured accordingly.

.It Nm PCIINTR_DEBUG
make the
.Em PCIBIOS_INTR_FIXUP
procedure verbose.

.El
.Sh SEE ALSO
.Xr cardbus 4 ,
.Xr pci 4
.Sh HISTORY
The
.Nm
code appeared in
.Nx 1.5 .
.Sh BUGS
The
.Em PCIBIOS_ADDR_FIXUP
option may conflict with the PCI CardBus driver's own
address fixup.