x86/agp: Fix agp_amd64_init and agp_amd64_cleanup

This fixes the regression introduced by the commit
f405d2c02395a74d3883bd03ded36457aa3697ad.

The above commit fixes the following issue:

  http://marc.info/?l=linux-kernel&m=126192729110083&w=2

However, it doesn't work properly when you remove and insert the
agp_amd64 module again.

agp_amd64_init() and agp_amd64_cleanup should be called only
when gart_iommu is not called earlier (that is, the GART IOMMU
is not enabled). We need to use 'gart_iommu_aperture' to see if
GART IOMMU is enabled or not.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: mitov@issp.bas.bg
Cc: davej@redhat.com
LKML-Reference: <20100104161603L.fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/aperture_64.c

@@ -31,6 +31,7 @@
 #include <asm/x86_init.h>
 
 int gart_iommu_aperture;
+EXPORT_SYMBOL_GPL(gart_iommu_aperture);
 int gart_iommu_aperture_disabled __initdata;
 int gart_iommu_aperture_allowed __initdata;
 

drivers/char/agp/amd64-agp.c

@@ -725,12 +725,11 @@ static struct pci_driver agp_amd64_pci_driver = {
 int __init agp_amd64_init(void)
 {
 	int err = 0;
-	static int done = 0;
 
 	if (agp_off)
 		return -EINVAL;
 
-	if (done++)
+	if (gart_iommu_aperture)
 		return agp_bridges_found ? 0 : -ENODEV;
 
 	err = pci_register_driver(&agp_amd64_pci_driver);
@@ -771,6 +770,8 @@ int __init agp_amd64_init(void)
 
 static void __exit agp_amd64_cleanup(void)
 {
+	if (gart_iommu_aperture)
+		return;
 	if (aperture_resource)
 		release_resource(aperture_resource);
 	pci_unregister_driver(&agp_amd64_pci_driver);