File: /usr/src/linux/arch/i386/mm/ioremap.c
1 /*
2 * arch/i386/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
15 static 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_DIRTY | _PAGE_ACCESSED | flags)));
33 address += PAGE_SIZE;
34 phys_addr += PAGE_SIZE;
35 pte++;
36 } while (address && (address < end));
37 }
38
39 static 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
62 static 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(&init_mm, 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 */
106 void * __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 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
134 if(!PageReserved(page))
135 return NULL;
136 }
137
138 /*
139 * Mappings have to be page-aligned
140 */
141 offset = phys_addr & ~PAGE_MASK;
142 phys_addr &= PAGE_MASK;
143 size = PAGE_ALIGN(last_addr) - phys_addr;
144
145 /*
146 * Ok, go for it..
147 */
148 area = get_vm_area(size, VM_IOREMAP);
149 if (!area)
150 return NULL;
151 addr = area->addr;
152 if (remap_area_pages(VMALLOC_VMADDR(addr), phys_addr, size, flags)) {
153 vfree(addr);
154 return NULL;
155 }
156 return (void *) (offset + (char *)addr);
157 }
158
159 void iounmap(void *addr)
160 {
161 if (addr > high_memory)
162 return vfree((void *) (PAGE_MASK & (unsigned long) addr));
163 }
164