1 /*
2  * highmem.h: virtual kernel memory mappings for high memory
3  *
4  * PowerPC version, stolen from the i386 version.
5  *
6  * Used in CONFIG_HIGHMEM systems for memory pages which
7  * are not addressable by direct kernel virtual addresses.
8  *
9  * Copyright (C) 1999 Gerhard Wichert, Siemens AG
10  *		      Gerhard.Wichert@pdb.siemens.de
11  *
12  *
13  * Redesigned the x86 32-bit VM architecture to deal with
14  * up to 16 Terrabyte physical memory. With current x86 CPUs
15  * we now support up to 64 Gigabytes physical RAM.
16  *
17  * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
18  */
19 
20 #ifndef _ASM_HIGHMEM_H
21 #define _ASM_HIGHMEM_H
22 
23 #ifdef __KERNEL__
24 
25 #include <linux/interrupt.h>
26 #include <asm/kmap_types.h>
27 #include <asm/tlbflush.h>
28 #include <asm/page.h>
29 #include <asm/fixmap.h>
30 
31 extern pte_t *kmap_pte;
32 extern pgprot_t kmap_prot;
33 extern pte_t *pkmap_page_table;
34 
35 /*
36  * Right now we initialize only a single pte table. It can be extended
37  * easily, subsequent pte tables have to be allocated in one physical
38  * chunk of RAM.
39  */
40 /*
41  * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
42  * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
43  * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
44  * in case of 16K/64K/256K page sizes.
45  */
46 #ifdef CONFIG_PPC_4K_PAGES
47 #define PKMAP_ORDER	PTE_SHIFT
48 #else
49 #define PKMAP_ORDER	9
50 #endif
51 #define LAST_PKMAP	(1 << PKMAP_ORDER)
52 #ifndef CONFIG_PPC_4K_PAGES
53 #define PKMAP_BASE	(FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1))
54 #else
55 #define PKMAP_BASE	((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
56 #endif
57 #define LAST_PKMAP_MASK	(LAST_PKMAP-1)
58 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
59 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
60 
61 extern void *kmap_high(struct page *page);
62 extern void kunmap_high(struct page *page);
63 extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
64 extern void __kunmap_atomic(void *kvaddr);
65 
kmap(struct page * page)66 static inline void *kmap(struct page *page)
67 {
68 	might_sleep();
69 	if (!PageHighMem(page))
70 		return page_address(page);
71 	return kmap_high(page);
72 }
73 
kunmap(struct page * page)74 static inline void kunmap(struct page *page)
75 {
76 	BUG_ON(in_interrupt());
77 	if (!PageHighMem(page))
78 		return;
79 	kunmap_high(page);
80 }
81 
kmap_atomic(struct page * page)82 static inline void *kmap_atomic(struct page *page)
83 {
84 	return kmap_atomic_prot(page, kmap_prot);
85 }
86 
kmap_atomic_to_page(void * ptr)87 static inline struct page *kmap_atomic_to_page(void *ptr)
88 {
89 	unsigned long idx, vaddr = (unsigned long) ptr;
90 	pte_t *pte;
91 
92 	if (vaddr < FIXADDR_START)
93 		return virt_to_page(ptr);
94 
95 	idx = virt_to_fix(vaddr);
96 	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
97 	return pte_page(*pte);
98 }
99 
100 
101 #define flush_cache_kmaps()	flush_cache_all()
102 
103 #endif /* __KERNEL__ */
104 
105 #endif /* _ASM_HIGHMEM_H */
106