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(*(TOP_PTE(vaddr))));
 73#endif
 74	set_pte_ext(TOP_PTE(vaddr), mk_pte(page, kmap_prot), 0);
 75	/*
 76	 * When debugging is off, kunmap_atomic leaves the previous mapping
 77	 * in place, so this TLB flush ensures the TLB is updated with the
 78	 * new mapping.
 79	 */
 80	local_flush_tlb_kernel_page(vaddr);
 81
 82	return (void *)vaddr;
 83}
 84EXPORT_SYMBOL(__kmap_atomic);
 85
 86void __kunmap_atomic(void *kvaddr)
 87{
 88	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 89	int idx, type;
 90
 91	if (kvaddr >= (void *)FIXADDR_START) {
 92		type = kmap_atomic_idx();
 93		idx = type + KM_TYPE_NR * smp_processor_id();
 94
 95		if (cache_is_vivt())
 96			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 97#ifdef CONFIG_DEBUG_HIGHMEM
 98		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 99		set_pte_ext(TOP_PTE(vaddr), __pte(0), 0);
100		local_flush_tlb_kernel_page(vaddr);
101#else
102		(void) idx;  /* to kill a warning */
103#endif
104		kmap_atomic_idx_pop();
105	} else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
106		/* this address was obtained through kmap_high_get() */
107		kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
108	}
109	pagefault_enable();
110}
111EXPORT_SYMBOL(__kunmap_atomic);
112
113void *kmap_atomic_pfn(unsigned long pfn)
114{
115	unsigned long vaddr;
116	int idx, type;
117
118	pagefault_disable();
119
120	type = kmap_atomic_idx_push();
121	idx = type + KM_TYPE_NR * smp_processor_id();
122	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
123#ifdef CONFIG_DEBUG_HIGHMEM
124	BUG_ON(!pte_none(*(TOP_PTE(vaddr))));
125#endif
126	set_pte_ext(TOP_PTE(vaddr), pfn_pte(pfn, kmap_prot), 0);
127	local_flush_tlb_kernel_page(vaddr);
128
129	return (void *)vaddr;
130}
131
132struct page *kmap_atomic_to_page(const void *ptr)
133{
134	unsigned long vaddr = (unsigned long)ptr;
135	pte_t *pte;
136
137	if (vaddr < FIXADDR_START)
138		return virt_to_page(ptr);
139
140	pte = TOP_PTE(vaddr);
141	return pte_page(*pte);
142}