NAME

agp - accelerated graphics port driver

SYNOPSIS

agp* at pchb?

DESCRIPTION

The agp driver provides machine-independent support for the accelerated graphics port (AGP) found on many PC-based and PCI systems. The AGP specification was designed by Intel.

The AGP chipset is positioned between the PCI-Host bridge and the graphics accelerator to provide a high-performance dedicated graphics bus for moving large amounts of data directly from host memory to the graphics accelerator. The specification currently supports a peak bandwidth of 528 MB/s. AGP uses a Graphics Address Remapping Table (GART) to provide a physically-contiguous view of scattered pages in host memory for DMA transfers.

The agp driver supports the following chipsets:

- ALI M1541 host-to-AGP bridge
- AMD 751 and 761 host-to-AGP bridges
- Intel 82810, 82810-DC100, 82810E, and 82815 SVGA controllers
- SiS 5591 host-to-AGP bridge
- VIA

The agp driver also provides an interface to user processes for use by X servers. A user process communicates to the device initially by means of ioctl(2) calls. The calls supported are:

AGPIOC_INFO
Get AGP information, setting the members in the agp_info structure as defined in <sys/agpio.h>:
typedef struct _agp_info {
        agp_version version;    /* version of the driver        */
        uint32_t bridge_id;    /* bridge vendor/device         */
        uint32_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;

AGPIOC_ACQUIRE
Acquire AGP.

AGPIOC_RELEASE
Release AGP.

AGPIOC_SETUP
Set up AGP, using the members in the agp_setup structure as defined in <sys/agpio.h>:
typedef struct _agp_setup {
        uint32_t agp_mode;     /* mode info of bridge          */
} agp_setup;

AGPIOC_ALLOCATE
Allocate AGP space, using and setting the members in the agp_allocate structure as defined in <sys/agpio.h>:
typedef struct _agp_allocate {
        int key;                /* tag of allocation            */
        size_t pg_count;        /* number of pages              */
        uint32_t type;         /* 0 == normal, other devspec   */
        paddr_t physical;       /* device specific (some devices
                                 * need a phys address of the
                                 * actual page behind the gatt
                                 * table)                       */
} agp_allocate;

AGPIOC_DEALLOCATE
Deallocate AGP space.

AGPIOC_BIND
Bind AGP space, using the members in the agp_bind structure as defined in <sys/agpio.h>:
typedef struct _agp_bind {
        int key;                /* tag of allocation            */
        off_t pg_start;         /* starting page to populate    */
} agp_bind;

AGPIOC_UNBIND
Unbind AGP space, using the members in the agp_unbind structure as defined in <sys/agpio.h>:
typedef struct _agp_unbind {
        int key;                /* tag of allocation            */
        uint32_t priority;     /* priority for paging out      */
} agp_unbind;

FILES

/dev/agp?
AGP GART device special files
/dev/agpgart
AGP GART device special file

EXAMPLES

This short code fragment is an example of opening the AGP device and performing some basic operations:
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/agpio.h>
#include <fcntl.h>
#include <err.h>
        

int main(int argc, char **argv) { int fd; agp_info info; agp_allocate alloc; agp_setup setup; agp_bind bind; agp_unbind unbind;

fd = open("/dev/agp0", O_RDWR); if (fd < 0) err(1, "open");

if (ioctl(fd, AGPIOC_INFO, &info) < 0) err(2, "ioctl AGPIOC_INFO");

printf("version: %u.%u\n", info.version.major, info.version.minor);

printf("id: %x\n", info.bridge_id); printf("mode: %x\n", info.agp_mode); printf("base: %x\n", info.aper_base); printf("size: %uM\n", info.aper_size); printf("total mem: %u\n", info.pg_total); printf("system mem: %u\n", info.pg_system); printf("used mem: %u\n\n", info.pg_used);

setup.agp_mode = info.agp_mode;

if (ioctl(fd, AGPIOC_SETUP, &setup) < 0) err(3, "ioctl AGPIOC_SETUP");

if (ioctl(fd, AGPIOC_ACQUIRE, 0) < 0) err(3, "ioctl AGPIOC_ACQUIRE");

alloc.type = 0; alloc.pg_count = 64;

if (ioctl(fd, AGPIOC_ALLOCATE, &alloc) < 0) err(4, "ioctl AGPIOC_ALLOCATE");

printf("alloc key %d, paddr %x\n", alloc.key, alloc.physical); if (ioctl(fd, AGPIOC_INFO, &info) < 0) err(5, "ioctl AGPIOC_INFO");

bind.key = alloc.key; bind.pg_start = 0x1000;

if (ioctl(fd, AGPIOC_BIND, &bind) < 0) err(6, "ioctl AGPIOC_BIND");

printf("used mem now: %u\n\n", info.pg_used);

unbind.key = alloc.key; unbind.priority = 0;

if (ioctl(fd, AGPIOC_UNBIND, &unbind) < 0) err(6, "ioctl AGPIOC_BIND");

if (ioctl(fd, AGPIOC_DEALLOCATE, &alloc.key) < 0) err(6, "ioctl AGPIOC_DEALLOCATE");

if (ioctl(fd, AGPIOC_RELEASE, 0) < 0) err(7, "ioctl AGPIOC_RELEASE");

close(fd);

printf("agp test successful\n");

return 0; }

SEE ALSO

ioctl(2), pci(4)

HISTORY

The agp driver first appeared in FreeBSD4.1. It was adopted in NetBSD1.6.