.\" $OpenBSD: agp.4,v 1.4 2008/03/16 22:23:51 jmc Exp $
.\" Copyright (c) Owain Ainsworth <oga@openbsd.org>
.\"
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.Dd $Mdocdate: March 16 2008 $
.Dt AGP 4
.Os
.Sh NAME
.Nm agp
.Nd accelerated graphics port driver
.Sh SYNOPSIS
.Cd "agp* at vga?"
.Sh DESCRIPTION
The
.Nm
driver provides support for programming the AGP GART through
.Xr ioctl 2 .
This support is used by the X server on some architectures.
.Pp
The following
.Xr ioctl 2
operations can be performed on
.Pa /dev/agp* ,
and are defined in
.Aq Pa sys/agpio.h :
.Bl -tag -width indent
.It Dv AGPIOC_INFO
Returns information about the AGP subsystem.
The result is a pointer to the following structure:
.Bd -literal
typedef struct _agp_info {
	agp_version version;  /* version of driver (unused)   */
	u_int32_t bridge_id;  /* bridge vendor/device         */
	u_int32_t agp_mode;   /* mode info of bridge          */
	off_t aper_base;      /* base of aperture             */
	size_t aper_size;     /* size of aperture             */
	size_t pg_total;      /* max pages (swap + system)    */
	size_t pg_system;     /* max pages (system)           */
	size_t pg_used;       /* current pages used           */
} agp_info;
.Ed
.It Dv AGPIOC_ACQUIRE
Acquire control of the AGP chipset for use by this client.
Returns
.Er EBUSY
if the AGP chipset is already acquired by another client.
.It Dv AGPIOC_RELEASE
Release control of the AGP chipset.
This does not unbind or free any allocated memory, which is the
responsibility of the client to handle if necessary.
.It Dv AGPIOC_SETUP
Enable the AGP hardware with the relevant mode.
This
.Xr ioctl 2
takes the following structure:
.Bd -literal
typedef struct _agp_setup {
	u_int32_t agp_mode;   /* mode info of bridge */
} agp_setup;
.Ed
.Pp
The mode bits are defined in
.Aq Pa sys/agpio.h .
.It Dv AGPIOC_ALLOCATE
Allocate physical memory suitable for mapping into the AGP aperture.
This
.Xr ioctl 2
takes the following structure:
.Bd -literal
typedef struct _agp_allocate {
	int key;              /* tag of allocation            */
	size_t pg_count;      /* number of pages              */
	u_int32_t type;       /* 0 == normal, other devspec   */
	u_int32_t physical;   /* device specific (some devices
			       * need a phys address of the
			       * actual page behind the gatt
			       * table)                       */
} agp_allocate;
.Ed
.Pp
It returns a handle to the allocated memory.
.It Dv AGPIOC_DEALLOCATE
Free the previously allocated memory associated with the
handle passed.
.It Dv AGPIOC_BIND
Bind the allocated memory at a given offset with the AGP
aperture.
Returns
.Er EINVAL
if the memory is already bound or the offset is not at an
AGP page boundary.
This
.Xr ioctl 2
takes the following structure:
.Bd -literal
typedef struct _agp_bind {
	int key;         /* tag of allocation            */
	off_t pg_start;  /* starting page to populate    */
} agp_bind;
.Ed
.Pp
The tag of allocation is the handle returned by
.Dv AGPIOC_ALLOCATE .
.It Dv AGPIOC_UNBIND
Unbind memory from the AGP aperture.
Returns
.Er EINVAL
if the memory is not bound.
This
.Xr ioctl 2
takes the following structure:
.Bd -literal
typedef struct _agp_unbind {
	int key;                /* tag of allocation         */
	u_int32_t priority;     /* priority for paging out   */
} agp_unbind;
.Ed
.El
.Sh FILES
.Bl -tag -width "/dev/agpgartXXX" -compact
.It Pa /dev/agp?
AGP GART device special files.
.It Pa /dev/agpgart
AGP GART device special file.
.El
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr vga 4
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 4.1 .
It was adopted in
.Nx 1.6 .
The driver was then ported in parts to
.Ox ,
and fully integrated in
.Ox 4.3 .