1/*
2 * arch/x86_64/mm/ioremap.c
3 *
4 * Re-map IO memory to kernel address space so that we can access it.
5 * This is needed for high PCI addresses that aren't mapped in the
6 * 640k-1MB IO memory area on PC's
7 *
8 * (C) Copyright 1995 1996 Linus Torvalds
9 */
10
11#include <linux/vmalloc.h>
12#include <asm/io.h>
13#include <asm/pgalloc.h>
14
15static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
16	unsigned long phys_addr, unsigned long flags)
17{
18	unsigned long end;
19
20	address &= ~PMD_MASK;
21	end = address + size;
22	if (end > PMD_SIZE)
23		end = PMD_SIZE;
24	if (address >= end)
25		BUG();
26	do {
27		if (!pte_none(*pte)) {
28			printk("remap_area_pte: page already exists\n");
29			BUG();
30		}
31		set_pte(pte, mk_pte_phys(phys_addr, __pgprot(_PAGE_PRESENT | _PAGE_RW |
32					_PAGE_GLOBAL | _PAGE_DIRTY | _PAGE_ACCESSED | flags)));
33		address += PAGE_SIZE;
34		phys_addr += PAGE_SIZE;
35		pte++;
36	} while (address && (address < end));
37}
38
39static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
40	unsigned long phys_addr, unsigned long flags)
41{
42	unsigned long end;
43
44	address &= ~PGDIR_MASK;
45	end = address + size;
46	if (end > PGDIR_SIZE)
47		end = PGDIR_SIZE;
48	phys_addr -= address;
49	if (address >= end)
50		BUG();
51	do {
52		pte_t * pte = pte_alloc(&init_mm, pmd, address);
53		if (!pte)
54			return -ENOMEM;
55		remap_area_pte(pte, address, end - address, address + phys_addr, flags);
56		address = (address + PMD_SIZE) & PMD_MASK;
57		pmd++;
58	} while (address && (address < end));
59	return 0;
60}
61
62static int remap_area_pages(unsigned long address, unsigned long phys_addr,
63				 unsigned long size, unsigned long flags)
64{
65	int error;
66	pgd_t * dir;
67	unsigned long end = address + size;
68
69	phys_addr -= address;
70	dir = pgd_offset_k(address);
71	flush_cache_all();
72	if (address >= end)
73		BUG();
74	spin_lock(&init_mm.page_table_lock);
75	do {
76		pmd_t *pmd;
77		pmd = pmd_alloc(&init_mm, dir, address);
78		error = -ENOMEM;
79		if (!pmd)
80			break;
81		if (remap_area_pmd(pmd, address, end - address,
82					 phys_addr + address, flags))
83			break;
84		error = 0;
85		address = (address + PGDIR_SIZE) & PGDIR_MASK;
86		dir++;
87	} while (address && (address < end));
88	spin_unlock(&init_mm.page_table_lock);
89	flush_tlb_all();
90	return error;
91}
92
93/*
94 * Generic mapping function (not visible outside):
95 */
96
97/*
98 * Remap an arbitrary physical address space into the kernel virtual
99 * address space. Needed when the kernel wants to access high addresses
100 * directly.
101 *
102 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
103 * have to convert them into an offset in a page-aligned mapping, but the
104 * caller shouldn't need to know that small detail.
105 */
106void * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
107{
108	void * addr;
109	struct vm_struct * area;
110	unsigned long offset, last_addr;
111
112	/* Don't allow wraparound or zero size */
113	last_addr = phys_addr + size - 1;
114	if (!size || last_addr < phys_addr)
115		return NULL;
116
117	/*
118	 * Don't remap the low PCI/ISA area, it's always mapped..
119	 */
120	if (phys_addr >= 0xA0000 && last_addr < 0x100000)
121		return phys_to_virt(phys_addr);
122
123	/*
124	 * Don't allow anybody to remap normal RAM that we're using..
125	 */
126	if (phys_addr < virt_to_phys(high_memory)) {
127		char *t_addr, *t_end;
128		struct page *page;
129
130		t_addr = __va(phys_addr);
131		t_end = t_addr + (size - 1);
132
133#ifndef CONFIG_DISCONTIGMEM
134		for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
135			if(!PageReserved(page))
136				return NULL;
137#endif
138	}
139
140	/*
141	 * Mappings have to be page-aligned
142	 */
143	offset = phys_addr & ~PAGE_MASK;
144	phys_addr &= PAGE_MASK;
145	size = PAGE_ALIGN(last_addr) - phys_addr;
146
147	/*
148	 * Ok, go for it..
149	 */
150	area = get_vm_area(size, VM_IOREMAP);
151	if (!area)
152		return NULL;
153	addr = area->addr;
154	if (remap_area_pages(VMALLOC_VMADDR(addr), phys_addr, size, flags)) {
155		vfree(addr);
156		return NULL;
157	}
158	return (void *) (offset + (char *)addr);
159}
160
161void iounmap(void *addr)
162{
163	if (addr > high_memory)
164		return vfree((void *) (PAGE_MASK & (unsigned long) addr));
165}
166