x86: GART: Convert gart_iommu_hole_init() to use iommu_init hook

This changes gart_iommu_hole_init() to set gart_iommu_init() to
iommu_init hook if gart_iommu_hole_init() finds the GART IOMMU.

We can kill the code to check if we found the IOMMU in
gart_iommu_init() since gart_iommu_hole_init() sets
gart_iommu_init() only when it found the IOMMU.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: chrisw@sous-sol.org
Cc: dwmw2@infradead.org
Cc: joerg.roedel@amd.com
Cc: muli@il.ibm.com
LKML-Reference: <1257849980-22640-4-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/gart.h

@@ -35,7 +35,7 @@ extern int gart_iommu_aperture_allowed;
 extern int gart_iommu_aperture_disabled;
 
 extern void early_gart_iommu_check(void);
-extern void gart_iommu_init(void);
+extern int gart_iommu_init(void);
 extern void __init gart_parse_options(char *);
 extern void gart_iommu_hole_init(void);
 
@@ -47,9 +47,6 @@ extern void gart_iommu_hole_init(void);
 static inline void early_gart_iommu_check(void)
 {
 }
-static inline void gart_iommu_init(void)
-{
-}
 static inline void gart_parse_options(char *options)
 {
 }

arch/x86/kernel/aperture_64.c

@@ -28,6 +28,7 @@
 #include <asm/pci-direct.h>
 #include <asm/dma.h>
 #include <asm/k8.h>
+#include <asm/x86_init.h>
 
 int gart_iommu_aperture;
 int gart_iommu_aperture_disabled __initdata;
@@ -400,6 +401,7 @@ void __init gart_iommu_hole_init(void)
 
 			iommu_detected = 1;
 			gart_iommu_aperture = 1;
+			x86_init.iommu.iommu_init = gart_iommu_init;
 
 			aper_order = (read_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL) >> 1) & 7;
 			aper_size = (32 * 1024 * 1024) << aper_order;

arch/x86/kernel/pci-dma.c

@@ -298,8 +298,6 @@ static int __init pci_iommu_init(void)
 
 	amd_iommu_init();
 
-	gart_iommu_init();
-
 	no_iommu_init();
 	return 0;
 }

arch/x86/kernel/pci-gart_64.c

@@ -709,7 +709,7 @@ static void gart_iommu_shutdown(void)
 	}
 }
 
-void __init gart_iommu_init(void)
+int __init gart_iommu_init(void)
 {
 	struct agp_kern_info info;
 	unsigned long iommu_start;
@@ -719,7 +719,7 @@ void __init gart_iommu_init(void)
 	long i;
 
 	if (cache_k8_northbridges() < 0 || num_k8_northbridges == 0)
-		return;
+		return 0;
 
 #ifndef CONFIG_AGP_AMD64
 	no_agp = 1;
@@ -731,13 +731,6 @@ void __init gart_iommu_init(void)
 		(agp_copy_info(agp_bridge, &info) < 0);
 #endif
 
-	if (swiotlb)
-		return;
-
-	/* Did we detect a different HW IOMMU? */
-	if (iommu_detected && !gart_iommu_aperture)
-		return;
-
 	if (no_iommu ||
 	    (!force_iommu && max_pfn <= MAX_DMA32_PFN) ||
 	    !gart_iommu_aperture ||
@@ -747,7 +740,7 @@ void __init gart_iommu_init(void)
 			       "but GART IOMMU not available.\n");
 			printk(KERN_WARNING "falling back to iommu=soft.\n");
 		}
-		return;
+		return 0;
 	}
 
 	/* need to map that range */
@@ -840,6 +833,8 @@ void __init gart_iommu_init(void)
 	flush_gart();
 	dma_ops = &gart_dma_ops;
 	x86_platform.iommu_shutdown = gart_iommu_shutdown;
+
+	return 0;
 }
 
 void __init gart_parse_options(char *p)