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
 21void *kmap(struct page *page)
 22{
 23	might_sleep();
 24	if (!PageHighMem(page))
 25		return page_address(page);
 26	return kmap_high(page);
 27}
 28EXPORT_SYMBOL(kmap);
 29
 30void kunmap(struct page *page)
 31{
 32	BUG_ON(in_interrupt());
 33	if (!PageHighMem(page))
 34		return;
 35	kunmap_high(page);
 36}
 37EXPORT_SYMBOL(kunmap);
 38
 39void *kmap_atomic(struct page *page)
 40{
 41	unsigned int idx;
 42	unsigned long vaddr;
 43	void *kmap;
 44	int type;
 45
 46	pagefault_disable();
 47	if (!PageHighMem(page))
 48		return page_address(page);
 49
 50#ifdef CONFIG_DEBUG_HIGHMEM
 51	/*
 52	 * There is no cache coherency issue when non VIVT, so force the
 53	 * dedicated kmap usage for better debugging purposes in that case.
 54	 */
 55	if (!cache_is_vivt())
 56		kmap = NULL;
 57	else
 58#endif
 59		kmap = kmap_high_get(page);
 60	if (kmap)
 61		return kmap;
 62
 63	type = kmap_atomic_idx_push();
 64
 65	idx = type + KM_TYPE_NR * smp_processor_id();
 66	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 67#ifdef CONFIG_DEBUG_HIGHMEM
 68	/*
 69	 * With debugging enabled, kunmap_atomic forces that entry to 0.
 70	 * Make sure it was indeed properly unmapped.
 71	 */
 72	BUG_ON(!pte_none(get_top_pte(vaddr)));
 73#endif
 74	/*
 75	 * When debugging is off, kunmap_atomic leaves the previous mapping
 76	 * in place, so the contained TLB flush ensures the TLB is updated
 77	 * with the new mapping.
 78	 */
 79	set_top_pte(vaddr, mk_pte(page, kmap_prot));
 80
 81	return (void *)vaddr;
 82}
 83EXPORT_SYMBOL(kmap_atomic);
 84
 85void __kunmap_atomic(void *kvaddr)
 86{
 87	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 88	int idx, type;
 89
 90	if (kvaddr >= (void *)FIXADDR_START) {
 91		type = kmap_atomic_idx();
 92		idx = type + KM_TYPE_NR * smp_processor_id();
 93
 94		if (cache_is_vivt())
 95			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 96#ifdef CONFIG_DEBUG_HIGHMEM
 97		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 98		set_top_pte(vaddr, __pte(0));
 99#else
100		(void) idx;  /* to kill a warning */
101#endif
102		kmap_atomic_idx_pop();
103	} else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
104		/* this address was obtained through kmap_high_get() */
105		kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
106	}
107	pagefault_enable();
108}
109EXPORT_SYMBOL(__kunmap_atomic);
110
111void *kmap_atomic_pfn(unsigned long pfn)
112{
113	unsigned long vaddr;
114	int idx, type;
115
116	pagefault_disable();
117
118	type = kmap_atomic_idx_push();
119	idx = type + KM_TYPE_NR * smp_processor_id();
120	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
121#ifdef CONFIG_DEBUG_HIGHMEM
122	BUG_ON(!pte_none(get_top_pte(vaddr)));
123#endif
124	set_top_pte(vaddr, pfn_pte(pfn, kmap_prot));
125
126	return (void *)vaddr;
127}
128
129struct page *kmap_atomic_to_page(const void *ptr)
130{
131	unsigned long vaddr = (unsigned long)ptr;
132
133	if (vaddr < FIXADDR_START)
134		return virt_to_page(ptr);
135
136	return pte_page(get_top_pte(vaddr));
137}