A driver for programming the AGP hardware. This is only very lightly

tested on Intel BX chipsets only. The other agp minidrivers are totally
untested.

The programming api is a subset of the Linux api and is only intended to
be enough for the X server to use. There is also an in-kernel api for the
use of other kernel modules such as the 3D DRI.

1 files changed, 790 insertions, 0 deletions

diff --git a/sys/pci/agp.c b/sys/pci/agp.c
new file mode 100644
index 0000000..e1d6583
--- /dev/null
+++ b/sys/pci/agp.c
@@ -0,0 +1,790 @@
+/*-
+ * Copyright (c) 2000 Doug Rabson
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	$FreeBSD$
+ */
+
+#include "opt_bus.h"
+#include "opt_pci.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/kernel.h>
+#include <sys/bus.h>
+#include <sys/conf.h>
+#include <sys/ioccom.h>
+#include <sys/agpio.h>
+#include <sys/lock.h>
+#include <sys/proc.h>
+
+#include <pci/pcivar.h>
+#include <pci/pcireg.h>
+#include <pci/agppriv.h>
+#include <pci/agpvar.h>
+#include <pci/agpreg.h>
+
+#include <vm/vm.h>
+#include <vm/vm_object.h>
+#include <vm/vm_page.h>
+#include <vm/vm_pageout.h>
+#include <vm/pmap.h>
+
+#include <machine/md_var.h>
+#include <machine/bus.h>
+#include <machine/resource.h>
+#include <sys/rman.h>
+
+MODULE_VERSION(agp, 1);
+
+MALLOC_DEFINE(M_AGP, "agp", "AGP data structures");
+
+#define CDEV_MAJOR	148
+				/* agp_drv.c */
+static d_open_t agp_open;
+static d_close_t agp_close;
+static d_ioctl_t agp_ioctl;
+static d_mmap_t agp_mmap;
+
+static struct cdevsw agp_cdevsw = {
+	/* open */	agp_open,
+	/* close */	agp_close,
+	/* read */	noread,
+	/* write */	nowrite,
+	/* ioctl */	agp_ioctl,
+	/* poll */	nopoll,
+	/* mmap */	agp_mmap,
+	/* strategy */	nostrategy,
+	/* name */	"agp",
+	/* maj */	CDEV_MAJOR,
+	/* dump */	nodump,
+	/* psize */	nopsize,
+	/* flags */	D_TTY,
+	/* bmaj */	-1
+};
+
+static devclass_t agp_devclass;
+#define KDEV2DEV(kdev)	devclass_get_device(agp_devclass, minor(kdev))
+
+/* Helper functions for implementing chipset mini drivers. */
+
+#ifdef __i386__
+#define agp_flush_cache()	wbinvd()
+#endif
+
+u_int8_t
+agp_find_caps(device_t dev)
+{
+	u_int32_t status;
+	u_int8_t ptr, next;
+
+	/*
+	 * Check the CAP_LIST bit of the PCI status register first.
+	 */
+	status = pci_read_config(dev, PCIR_STATUS, 2);
+	if (!(status & 0x10))
+		return 0;
+
+	/*
+	 * Traverse the capabilities list.
+	 */
+	for (ptr = pci_read_config(dev, AGP_CAPPTR, 1);
+	     ptr != 0;
+	     ptr = next) {
+		u_int32_t capid = pci_read_config(dev, ptr, 4);
+		next = AGP_CAPID_GET_NEXT_PTR(capid);
+
+		/*
+		 * If this capability entry ID is 2, then we are done.
+		 */
+		if (AGP_CAPID_GET_CAP_ID(capid) == 2)
+			return ptr;
+	}
+
+	return 0;
+}
+
+/*
+ * Find an AGP display device (if any).
+ */
+static device_t
+agp_find_display(void)
+{
+	devclass_t pci = devclass_find("pci");
+	device_t bus, dev = 0;
+	device_t *kids;
+	int busnum, numkids, i;
+
+	for (busnum = 0; busnum < devclass_get_maxunit(pci); busnum++) {
+		bus = devclass_get_device(pci, busnum);
+		if (!bus)
+			continue;
+		device_get_children(bus, &kids, &numkids);
+		for (i = 0; i < numkids; i++) {
+			dev = kids[i];
+			if (pci_get_class(dev) == PCIC_DISPLAY
+			    && pci_get_subclass(dev) == PCIS_DISPLAY_VGA)
+				if (agp_find_caps(dev)) {
+					free(kids, M_TEMP);
+					return dev;
+				}
+					
+		}
+		free(kids, M_TEMP);
+	}
+
+	return 0;
+}
+
+struct agp_gatt *
+agp_alloc_gatt(device_t dev)
+{
+	u_int32_t apsize = AGP_GET_APERTURE(dev);
+	u_int32_t entries = apsize >> AGP_PAGE_SHIFT;
+	struct agp_gatt *gatt;
+
+	if (bootverbose)
+		device_printf(dev,
+			      "allocating GATT for aperture of size %dM\n",
+			      apsize / (1024*1024));
+
+	gatt = malloc(sizeof(struct agp_gatt), M_AGP, M_NOWAIT);
+	if (!gatt)
+		return 0;
+
+	gatt->ag_entries = entries;
+	gatt->ag_virtual = contigmalloc(entries * sizeof(u_int32_t), M_AGP, 0,
+					0, ~0, PAGE_SIZE, 0);
+	if (!gatt->ag_virtual) {
+		if (bootverbose)
+			device_printf(dev, "contiguous allocation failed\n");
+		free(gatt, M_AGP);
+		return 0;
+	}
+	bzero(gatt->ag_virtual, entries * sizeof(u_int32_t));
+	gatt->ag_physical = vtophys((vm_offset_t) gatt->ag_virtual);
+	agp_flush_cache();
+
+	return gatt;
+}
+
+void
+agp_free_gatt(struct agp_gatt *gatt)
+{
+	contigfree(gatt->ag_virtual,
+		   gatt->ag_entries * sizeof(u_int32_t), M_AGP);
+	free(gatt, M_AGP);
+}
+
+static int agp_max[][2] = {
+	{0,	0},
+	{32,	4},
+	{64,	28},
+	{128,	96},
+	{256,	204},
+	{512,	440},
+	{1024,	942},
+	{2048,	1920},
+	{4096,	3932}
+};
+#define agp_max_size	(sizeof(agp_max) / sizeof(agp_max[0]))
+
+int
+agp_generic_attach(device_t dev)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+	int rid, memsize, i;
+
+	/*
+	 * Find and map the aperture.
+	 */
+	rid = AGP_APBASE;
+	sc->as_aperture = bus_alloc_resource(dev, SYS_RES_MEMORY, &rid,
+					     0, ~0, 1, RF_ACTIVE);
+	if (!sc->as_aperture)
+		return ENOMEM;
+
+	/*
+	 * Work out an upper bound for agp memory allocation. This
+	 * uses a heurisitc table from the Linux driver.
+	 */
+	memsize = ptoa(Maxmem) >> 20;
+	for (i = 0; i < agp_max_size; i++) {
+		if (memsize <= agp_max[i][0])
+			break;
+	}
+	if (i == agp_max_size) i = agp_max_size - 1;
+	sc->as_maxmem = agp_max[i][1] << 20U;
+
+	/*
+	 * The lock is used to prevent re-entry to
+	 * agp_generic_bind_memory() since that function can sleep.
+	 */
+	lockinit(&sc->as_lock, PZERO|PCATCH, "agplk", 0, 0);
+
+	/*
+	 * Initialise stuff for the userland device.
+	 */
+	agp_devclass = devclass_find("agp");
+	TAILQ_INIT(&sc->as_memory);
+	sc->as_nextid = 1;
+
+	sc->as_devnode = make_dev(&agp_cdevsw,
+				  device_get_unit(dev),
+				  UID_ROOT,
+				  GID_WHEEL,
+				  0600,
+				  "agpgart");
+
+	return 0;
+}
+
+int
+agp_generic_detach(device_t dev)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+	bus_release_resource(dev, SYS_RES_MEMORY, AGP_APBASE, sc->as_aperture);
+	lockmgr(&sc->as_lock, LK_DRAIN, 0, curproc);
+	destroy_dev(sc->as_devnode);
+	agp_flush_cache();
+	return 0;
+}
+
+int
+agp_generic_enable(device_t dev, u_int32_t mode)
+{
+	device_t mdev = agp_find_display();
+	u_int32_t tstatus, mstatus;
+	u_int32_t command;
+	int rq, sba, fw, rate;;
+
+	if (!mdev) {
+		AGP_DPF("can't find display\n");
+		return ENXIO;
+	}
+
+	tstatus = pci_read_config(dev, agp_find_caps(dev) + AGP_STATUS, 4);
+	mstatus = pci_read_config(mdev, agp_find_caps(mdev) + AGP_STATUS, 4);
+
+	/* Set RQ to the min of mode, tstatus and mstatus */
+	rq = AGP_MODE_GET_RQ(mode);
+	if (AGP_MODE_GET_RQ(tstatus) < rq)
+		rq = AGP_MODE_GET_RQ(tstatus);
+	if (AGP_MODE_GET_RQ(mstatus) < rq)
+		rq = AGP_MODE_GET_RQ(mstatus);
+
+	/* Set SBA if all three can deal with SBA */
+	sba = (AGP_MODE_GET_SBA(tstatus)
+	       & AGP_MODE_GET_SBA(mstatus)
+	       & AGP_MODE_GET_SBA(mode));
+
+	/* Similar for FW */
+	fw = (AGP_MODE_GET_FW(tstatus)
+	       & AGP_MODE_GET_FW(mstatus)
+	       & AGP_MODE_GET_FW(mode));
+
+	/* Figure out the max rate */
+	rate = (AGP_MODE_GET_RATE(tstatus)
+		& AGP_MODE_GET_RATE(mstatus)
+		& AGP_MODE_GET_RATE(mode));
+	if (rate & AGP_MODE_RATE_4x)
+		rate = AGP_MODE_RATE_4x;
+	else if (rate & AGP_MODE_RATE_2x)
+		rate = AGP_MODE_RATE_2x;
+	else
+		rate = AGP_MODE_RATE_1x;
+
+	/* Construct the new mode word and tell the hardware */
+	command = AGP_MODE_SET_RQ(0, rq);
+	command = AGP_MODE_SET_SBA(command, sba);
+	command = AGP_MODE_SET_FW(command, fw);
+	command = AGP_MODE_SET_RATE(command, rate);
+	command = AGP_MODE_SET_AGP(command, 1);
+	pci_write_config(dev, agp_find_caps(dev) + AGP_COMMAND, command, 4);
+	pci_write_config(mdev, agp_find_caps(mdev) + AGP_COMMAND, command, 4);
+
+	return 0;
+}
+
+struct agp_memory *
+agp_generic_alloc_memory(device_t dev, int type, vm_size_t size)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+	struct agp_memory *mem;
+
+	if ((size & (AGP_PAGE_SIZE - 1)) != 0)
+		return 0;
+
+	if (sc->as_allocated + size > sc->as_maxmem)
+		return 0;
+
+	mem = malloc(sizeof *mem, M_AGP, M_WAITOK);
+	mem->am_id = sc->as_nextid++;
+	mem->am_size = size;
+	mem->am_obj = vm_object_allocate(OBJT_DEFAULT, atop(round_page(size)));
+	mem->am_physical = 0;
+	mem->am_offset = 0;
+	mem->am_is_bound = 0;
+	TAILQ_INSERT_TAIL(&sc->as_memory, mem, am_link);
+	sc->as_allocated += size;
+
+	return mem;
+}
+
+int
+agp_generic_free_memory(device_t dev, struct agp_memory *mem)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+
+	if (mem->am_is_bound)
+		return EBUSY;
+
+	sc->as_allocated -= mem->am_size;
+	TAILQ_REMOVE(&sc->as_memory, mem, am_link);
+	vm_object_deallocate(mem->am_obj);
+	free(mem, M_AGP);
+	return 0;
+}
+
+int
+agp_generic_bind_memory(device_t dev, struct agp_memory *mem,
+			vm_offset_t offset)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+	vm_offset_t i, j, k;
+	vm_page_t m;
+	int error;
+
+	lockmgr(&sc->as_lock, LK_EXCLUSIVE, 0, curproc);
+
+	if (mem->am_is_bound) {
+		device_printf(dev, "memory already bound\n");
+		return EINVAL;
+	}
+	
+	if (offset < 0
+	    || (offset & (AGP_PAGE_SIZE - 1)) != 0
+	    || offset + mem->am_size > AGP_GET_APERTURE(dev)) {
+		device_printf(dev, "binding memory at bad offset %#x\n",
+			      (int) offset);
+		return EINVAL;
+	}
+
+	/*
+	 * Bind the individual pages and flush the chipset's
+	 * TLB.
+	 *
+	 * XXX Presumably, this needs to be the pci address on alpha
+	 * (i.e. use alpha_XXX_dmamap()). I don't have access to any
+	 * alpha AGP hardware to check.
+	 */
+	for (i = 0; i < mem->am_size; i += PAGE_SIZE) {
+		/*
+		 * Find a page from the object and wire it
+		 * down. This page will be mapped using one or more
+		 * entries in the GATT (assuming that PAGE_SIZE >=
+		 * AGP_PAGE_SIZE. If this is the first call to bind,
+		 * the pages will be allocated and zeroed.
+		 */
+		m = vm_page_grab(mem->am_obj, OFF_TO_IDX(i),
+				 VM_ALLOC_ZERO | VM_ALLOC_RETRY);
+		AGP_DPF("found page pa=%#x\n", VM_PAGE_TO_PHYS(m));
+		vm_page_wire(m);
+
+		/*
+		 * Install entries in the GATT, making sure that if
+		 * AGP_PAGE_SIZE < PAGE_SIZE and mem->am_size is not
+		 * aligned to PAGE_SIZE, we don't modify too many GATT 
+		 * entries.
+		 */
+		for (j = 0; j < PAGE_SIZE && i + j < mem->am_size;
+		     j += AGP_PAGE_SIZE) {
+			vm_offset_t pa = VM_PAGE_TO_PHYS(m) + j;
+			AGP_DPF("binding offset %#x to pa %#x\n",
+				offset + i + j, pa);
+			error = AGP_BIND_PAGE(dev, offset + i + j, pa);
+			if (error) {
+				/*
+				 * Bail out. Reverse all the mappings
+				 * and unwire the pages.
+				 */
+				vm_page_wakeup(m);
+				for (k = 0; k < i + j; k += AGP_PAGE_SIZE)
+					AGP_UNBIND_PAGE(dev, offset + k);
+				for (k = 0; k <= i; k += PAGE_SIZE) {
+					m = vm_page_lookup(mem->am_obj,
+							   OFF_TO_IDX(k));
+					vm_page_unwire(m, 0);
+				}
+				lockmgr(&sc->as_lock, LK_RELEASE, 0, curproc);
+				return error;
+			}
+		}
+		vm_page_wakeup(m);
+	}
+
+	/*
+	 * Flush the cpu cache since we are providing a new mapping
+	 * for these pages.
+	 */
+	agp_flush_cache();
+
+	/*
+	 * Make sure the chipset gets the new mappings.
+	 */
+	AGP_FLUSH_TLB(dev);
+
+	mem->am_offset = offset;
+	mem->am_is_bound = 1;
+
+	lockmgr(&sc->as_lock, LK_RELEASE, 0, curproc);
+
+	return 0;
+}
+
+int
+agp_generic_unbind_memory(device_t dev, struct agp_memory *mem)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+	vm_page_t m;
+	int i;
+
+	lockmgr(&sc->as_lock, LK_EXCLUSIVE, 0, curproc);
+
+	if (!mem->am_is_bound) {
+		device_printf(dev, "memory is not bound\n");
+		return EINVAL;
+	}
+
+
+	/*
+	 * Unbind the individual pages and flush the chipset's
+	 * TLB. Unwire the pages so they can be swapped.
+	 */
+	for (i = 0; i < mem->am_size; i += AGP_PAGE_SIZE)
+		AGP_UNBIND_PAGE(dev, mem->am_offset + i);
+	for (i = 0; i < mem->am_size; i += PAGE_SIZE) {
+		m = vm_page_lookup(mem->am_obj, atop(i));
+		vm_page_unwire(m, 0);
+	}
+		
+	agp_flush_cache();
+	AGP_FLUSH_TLB(dev);
+
+	mem->am_offset = 0;
+	mem->am_is_bound = 0;
+
+	lockmgr(&sc->as_lock, LK_RELEASE, 0, curproc);
+
+	return 0;
+}
+
+/* Helper functions for implementing user/kernel api */
+
+static int
+agp_acquire_helper(device_t dev, enum agp_acquire_state state)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+
+	if (sc->as_state != AGP_ACQUIRE_FREE)
+		return EBUSY;
+	sc->as_state = state;
+
+	return 0;
+}
+
+static int
+agp_release_helper(device_t dev, enum agp_acquire_state state)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+	struct agp_memory *mem;
+
+	if (sc->as_state == AGP_ACQUIRE_FREE)
+		return 0;
+
+	if (sc->as_state != state)
+		return EBUSY;
+
+	/*
+	 * Clear out the aperture and free any outstanding memory blocks.
+	 */
+	while ((mem = TAILQ_FIRST(&sc->as_memory)) != 0) {
+		if (mem->am_is_bound)
+			AGP_UNBIND_MEMORY(dev, mem);
+		AGP_FREE_MEMORY(dev, mem);
+	}
+
+	sc->as_state = AGP_ACQUIRE_FREE;
+	return 0;
+}
+
+static struct agp_memory *
+agp_find_memory(device_t dev, int id)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+	struct agp_memory *mem;
+
+	AGP_DPF("searching for memory block %d\n", id);
+	TAILQ_FOREACH(mem, &sc->as_memory, am_link) {
+		AGP_DPF("considering memory block %d\n", mem->am_id);
+		if (mem->am_id == id)
+			return mem;
+	}
+	return 0;
+}
+
+/* Implementation of the userland ioctl api */
+
+static int
+agp_info_user(device_t dev, agp_info *info)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+
+	bzero(info, sizeof *info);
+	info->bridge_id = pci_get_devid(dev);
+	info->agp_mode = 
+	    pci_read_config(dev, agp_find_caps(dev) + AGP_STATUS, 4);
+	info->aper_base = rman_get_start(sc->as_aperture);
+	info->aper_size = AGP_GET_APERTURE(dev) >> 20;
+	info->pg_total = info->pg_system = sc->as_maxmem >> AGP_PAGE_SHIFT;
+	info->pg_used = sc->as_allocated >> AGP_PAGE_SHIFT;
+
+	return 0;
+}
+
+static int
+agp_setup_user(device_t dev, agp_setup *setup)
+{
+	return AGP_ENABLE(dev, setup->agp_mode);
+}
+
+static int
+agp_allocate_user(device_t dev, agp_allocate *alloc)
+{
+	struct agp_memory *mem;
+
+	mem = AGP_ALLOC_MEMORY(dev,
+			       alloc->type,
+			       alloc->pg_count << AGP_PAGE_SHIFT);
+	alloc->key = mem->am_id;
+	alloc->physical = mem->am_physical;
+
+	return 0;
+}
+
+static int
+agp_deallocate_user(device_t dev, int id)
+{
+	struct agp_memory *mem = agp_find_memory(dev, id);;
+
+	if (mem) {
+		AGP_FREE_MEMORY(dev, mem);
+		return 0;
+	} else {
+		return ENOENT;
+	}
+}
+
+static int
+agp_bind_user(device_t dev, agp_bind *bind)
+{
+	struct agp_memory *mem = agp_find_memory(dev, bind->key);
+
+	if (!mem)
+		return ENOENT;
+
+	return AGP_BIND_MEMORY(dev, mem, bind->pg_start << AGP_PAGE_SHIFT);
+}
+
+static int
+agp_unbind_user(device_t dev, agp_unbind *unbind)
+{
+	struct agp_memory *mem = agp_find_memory(dev, unbind->key);
+
+	if (!mem)
+		return ENOENT;
+
+	return AGP_UNBIND_MEMORY(dev, mem);
+}
+
+static int
+agp_open(dev_t kdev, int oflags, int devtype, struct proc *p)
+{
+	device_t dev = KDEV2DEV(kdev);
+	struct agp_softc *sc = device_get_softc(dev);
+
+	if (!sc->as_isopen) {
+		sc->as_isopen = 1;
+		device_busy(dev);
+	}
+
+	return 0;
+}
+
+static int
+agp_close(dev_t kdev, int fflag, int devtype, struct proc *p)
+{
+	device_t dev = KDEV2DEV(kdev);
+	struct agp_softc *sc = device_get_softc(dev);
+
+	/*
+	 * Clear the GATT and force release on last close
+	 */
+	if (sc->as_state == AGP_ACQUIRE_USER)
+		agp_release_helper(dev, AGP_ACQUIRE_USER);
+	sc->as_isopen = 0;
+	device_unbusy(dev);
+
+	return 0;
+}
+
+static int
+agp_ioctl(dev_t kdev, u_long cmd, caddr_t data, int fflag, struct proc *p)
+{
+	device_t dev = KDEV2DEV(kdev);
+
+	switch (cmd) {
+	case AGPIOC_INFO:
+		return agp_info_user(dev, (agp_info *) data);
+
+	case AGPIOC_ACQUIRE:
+		return agp_acquire_helper(dev, AGP_ACQUIRE_USER);
+
+	case AGPIOC_RELEASE:
+		return agp_release_helper(dev, AGP_ACQUIRE_USER);
+
+	case AGPIOC_SETUP:
+		return agp_setup_user(dev, (agp_setup *)data);
+
+	case AGPIOC_ALLOCATE:
+		return agp_allocate_user(dev, (agp_allocate *)data);
+
+	case AGPIOC_DEALLOCATE:
+		return agp_deallocate_user(dev, *(int *) data);
+
+	case AGPIOC_BIND:
+		return agp_bind_user(dev, (agp_bind *)data);
+
+	case AGPIOC_UNBIND:
+		return agp_unbind_user(dev, (agp_unbind *)data);
+
+	}
+
+	return EINVAL;
+}
+
+static int
+agp_mmap(dev_t kdev, vm_offset_t offset, int prot)
+{
+	device_t dev = KDEV2DEV(kdev);
+	struct agp_softc *sc = device_get_softc(dev);
+
+	if (offset > AGP_GET_APERTURE(dev))
+		return -1;
+	return atop(rman_get_start(sc->as_aperture) + offset);
+}
+
+/* Implementation of the kernel api */
+
+device_t
+agp_find_device()
+{
+	if (!agp_devclass)
+		return 0;
+	return devclass_get_device(agp_devclass, 0);
+}
+
+enum agp_acquire_state
+agp_state(device_t dev)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+	return sc->as_state;
+}
+
+void
+agp_get_info(device_t dev, struct agp_info *info)
+{
+	struct agp_softc *sc = device_get_softc(dev);
+
+	info->ai_mode =
+		pci_read_config(dev, agp_find_caps(dev) + AGP_STATUS, 4);
+	info->ai_aperture_base = rman_get_start(sc->as_aperture);
+	info->ai_aperture_size = (rman_get_end(sc->as_aperture)
+				  - rman_get_start(sc->as_aperture)) + 1;
+	info->ai_memory_allowed = sc->as_maxmem;
+	info->ai_memory_used = sc->as_allocated;
+}
+
+int
+agp_acquire(device_t dev)
+{
+	return agp_acquire_helper(dev, AGP_ACQUIRE_KERNEL);
+}
+
+int
+agp_release(device_t dev)
+{
+	return agp_release_helper(dev, AGP_ACQUIRE_KERNEL);
+}
+
+int
+agp_enable(device_t dev, u_int32_t mode)
+{
+	return AGP_ENABLE(dev, mode);
+}
+
+void *agp_alloc_memory(device_t dev, int type, vm_size_t bytes)
+{
+	return  (void *) AGP_ALLOC_MEMORY(dev, type, bytes);
+}
+
+void agp_free_memory(device_t dev, void *handle)
+{
+	struct agp_memory *mem = (struct agp_memory *) handle;
+	AGP_FREE_MEMORY(dev, mem);
+}
+
+int agp_bind_memory(device_t dev, void *handle, vm_offset_t offset)
+{
+	struct agp_memory *mem = (struct agp_memory *) handle;
+	return AGP_BIND_MEMORY(dev, mem, offset);
+}
+
+int agp_unbind_memory(device_t dev, void *handle)
+{
+	struct agp_memory *mem = (struct agp_memory *) handle;
+	return AGP_UNBIND_MEMORY(dev, mem);
+}
+
+void agp_memory_info(device_t dev, void *handle, struct
+		     agp_memory_info *mi)
+{
+	struct agp_memory *mem = (struct agp_memory *) handle;
+
+	mi->ami_size = mem->am_size;
+	mi->ami_physical = mem->am_physical;
+	mi->ami_offset = mem->am_offset;
+	mi->ami_is_bound = mem->am_is_bound;
+}