1/*
2 * arch/arm/mm/highmem.c -- ARM highmem support
3 *
4 * Author:	Nicolas Pitre
5 * Created:	september 8, 2008
6 * Copyright:	Marvell Semiconductors Inc.
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/module.h>
14#include <linux/highmem.h>
15#include <linux/interrupt.h>
16#include <asm/fixmap.h>
17#include <asm/cacheflush.h>
18#include <asm/tlbflush.h>
19#include "mm.h"
20
21static inline void set_fixmap_pte(int idx, pte_t pte)
22{
23	unsigned long vaddr = __fix_to_virt(idx);
24	pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
25
26	set_pte_ext(ptep, pte, 0);
27	local_flush_tlb_kernel_page(vaddr);
28}
29
30static inline pte_t get_fixmap_pte(unsigned long vaddr)
31{
32	pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
33
34	return *ptep;
35}
36
37void *kmap(struct page *page)
38{
39	might_sleep();
40	if (!PageHighMem(page))
41		return page_address(page);
42	return kmap_high(page);
43}
44EXPORT_SYMBOL(kmap);
45
46void kunmap(struct page *page)
47{
48	BUG_ON(in_interrupt());
49	if (!PageHighMem(page))
50		return;
51	kunmap_high(page);
52}
53EXPORT_SYMBOL(kunmap);
54
55void *kmap_atomic(struct page *page)
56{
57	unsigned int idx;
58	unsigned long vaddr;
59	void *kmap;
60	int type;
61
62	pagefault_disable();
63	if (!PageHighMem(page))
64		return page_address(page);
65
66#ifdef CONFIG_DEBUG_HIGHMEM
67	/*
68	 * There is no cache coherency issue when non VIVT, so force the
69	 * dedicated kmap usage for better debugging purposes in that case.
70	 */
71	if (!cache_is_vivt())
72		kmap = NULL;
73	else
74#endif
75		kmap = kmap_high_get(page);
76	if (kmap)
77		return kmap;
78
79	type = kmap_atomic_idx_push();
80
81	idx = type + KM_TYPE_NR * smp_processor_id();
82	vaddr = __fix_to_virt(idx);
83#ifdef CONFIG_DEBUG_HIGHMEM
84	/*
85	 * With debugging enabled, kunmap_atomic forces that entry to 0.
86	 * Make sure it was indeed properly unmapped.
87	 */
88	BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
89#endif
90	/*
91	 * When debugging is off, kunmap_atomic leaves the previous mapping
92	 * in place, so the contained TLB flush ensures the TLB is updated
93	 * with the new mapping.
94	 */
95	set_fixmap_pte(idx, mk_pte(page, kmap_prot));
96
97	return (void *)vaddr;
98}
99EXPORT_SYMBOL(kmap_atomic);
100
101void __kunmap_atomic(void *kvaddr)
102{
103	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
104	int idx, type;
105
106	if (kvaddr >= (void *)FIXADDR_START) {
107		type = kmap_atomic_idx();
108		idx = type + KM_TYPE_NR * smp_processor_id();
109
110		if (cache_is_vivt())
111			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
112#ifdef CONFIG_DEBUG_HIGHMEM
113		BUG_ON(vaddr != __fix_to_virt(idx));
114		set_fixmap_pte(idx, __pte(0));
115#else
116		(void) idx;  /* to kill a warning */
117#endif
118		kmap_atomic_idx_pop();
119	} else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
120		/* this address was obtained through kmap_high_get() */
121		kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
122	}
123	pagefault_enable();
124}
125EXPORT_SYMBOL(__kunmap_atomic);
126
127void *kmap_atomic_pfn(unsigned long pfn)
128{
129	unsigned long vaddr;
130	int idx, type;
131	struct page *page = pfn_to_page(pfn);
132
133	pagefault_disable();
134	if (!PageHighMem(page))
135		return page_address(page);
136
137	type = kmap_atomic_idx_push();
138	idx = type + KM_TYPE_NR * smp_processor_id();
139	vaddr = __fix_to_virt(idx);
140#ifdef CONFIG_DEBUG_HIGHMEM
141	BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
142#endif
143	set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
144
145	return (void *)vaddr;
146}
147
148struct page *kmap_atomic_to_page(const void *ptr)
149{
150	unsigned long vaddr = (unsigned long)ptr;
151
152	if (vaddr < FIXADDR_START)
153		return virt_to_page(ptr);
154
155	return pte_page(get_fixmap_pte(vaddr));
156}
157