iommu: export iommu_area_reserve helper function

x86 has set_bit_string() that does the exact same thing that
set_bit_area() in lib/iommu-helper.c does.

This patch exports set_bit_area() in lib/iommu-helper.c as
iommu_area_reserve(), converts GART, Calgary, and AMD IOMMU to use it.
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/amd_iommu.c

@@ -572,7 +572,7 @@ static void dma_ops_reserve_addresses(struct dma_ops_domain *dom,
 	if (start_page + pages > last_page)
 		pages = last_page - start_page;
 
-	set_bit_string(dom->bitmap, start_page, pages);
+	iommu_area_reserve(dom->bitmap, start_page, pages);
 }
 
 static void dma_ops_free_pagetable(struct dma_ops_domain *dma_dom)

arch/x86/kernel/pci-calgary_64.c

@@ -261,7 +261,7 @@ static void iommu_range_reserve(struct iommu_table *tbl,
 			       badbit, tbl, start_addr, npages);
 	}
 
-	set_bit_string(tbl->it_map, index, npages);
+	iommu_area_reserve(tbl->it_map, index, npages);
 
 	spin_unlock_irqrestore(&tbl->it_lock, flags);
 }

arch/x86/kernel/pci-gart_64.c

@@ -827,7 +827,7 @@ void __init gart_iommu_init(void)
 	 * Out of IOMMU space handling.
 	 * Reserve some invalid pages at the beginning of the GART.
 	 */
-	set_bit_string(iommu_gart_bitmap, 0, EMERGENCY_PAGES);
+	iommu_area_reserve(iommu_gart_bitmap, 0, EMERGENCY_PAGES);
 
 	agp_memory_reserved = iommu_size;
 	printk(KERN_INFO

include/linux/iommu-helper.h

@@ -11,6 +11,7 @@ static inline unsigned long iommu_device_max_index(unsigned long size,
 extern int iommu_is_span_boundary(unsigned int index, unsigned int nr,
 				  unsigned long shift,
 				  unsigned long boundary_size);
+extern void iommu_area_reserve(unsigned long *map, unsigned long i, int len);
 extern unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
 				      unsigned long start, unsigned int nr,
 				      unsigned long shift,

lib/iommu-helper.c

@@ -30,8 +30,7 @@ static unsigned long find_next_zero_area(unsigned long *map,
 	return index;
 }
 
-static inline void set_bit_area(unsigned long *map, unsigned long i,
-				int len)
+void iommu_area_reserve(unsigned long *map, unsigned long i, int len)
 {
 	unsigned long end = i + len;
 	while (i < end) {
@@ -64,7 +63,7 @@ unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
 			start = index + 1;
 			goto again;
 		}
-		set_bit_area(map, index, nr);
+		iommu_area_reserve(map, index, nr);
 	}
 	return index;
 }