.\" Copyright (c) 2001 Yar Tikhiy
.\" All rights reserved.
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.Dd October 5, 2001
.Dt AGP 4
.Os
.Sh NAME
.Nm agp
.Nd "generic interface to the Accelerated Graphics Port (AGP)"
.Sh SYNOPSIS
.Cd "device agp"
.Sh DESCRIPTION
The
.Nm
driver provides uniform, abstract methods for controlling
the following devices:
.Bl -bullet -offset indent -compact
.It
Ali M1541 host-to-AGP bridge
.It
.\" 761 not in -stable
AMD 751 and 761 host-to-AGP bridges
.It
Intel i820, i840, i845, i850, and i860 host-to-AGP bridge
.It
Intel i810, i810-DC100, i810E, and i815 SVGA controllers
.It
Intel 82443GX host-to-AGP bridge
.It
SiS 5591 host-to-AGP bridge
.El
.Pp
The most common application of
.Nm
is for running
.Xr XFree86 1
on the Intel i81x controllers.
.Sh IOCTLS
The following
.Xr ioctl 2
operations can be performed on
.Pa /dev/agpgart ,
which are defined in
.Aq Pa sys/agpio.h :
.Ss Dv AGPIOC_INFO
Returns state of the
.Nm
system.
The result is a pointer to the following structure:
.Bd -literal
typedef struct _agp_info {
	agp_version version;  /* version of the driver        */
	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
.Ss 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.
.Ss 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.
.Ss 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 .
.Ss 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
Returns a handle to the allocated memory.
.Ss Dv AGPIOC_DEALLOCATE
Free the previously allocated memory associated with the handle passed.
.Ss Dv AGPIOC_BIND
Bind the allocated memory at given offset with the AGP aperture.
Returns
.Er EINVAL
if the memory is already bound or the offset is not at 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
.Sq tag of allocation ,
is the handle returned by
.Dv AGPIOC_ALLOCATE.
.Ss Dv AGPIOC_UNBIND
Unbind memory from the AGP aperture.
Returns
.Er EINVAL
if the memory is not bound.
This
.Xr ioctl
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
.Sh FILES
.Bl -tag -width ".Pa /dev/agpgart" -compact
.It Pa /dev/agpgart
AGP device node.
.El
.Sh SEE ALSO
.Xr XFree86 1
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 4.1 .