Update MIPS to use the 4-level pagetable code thereby getting rid of
[linux-2.6.git] / arch / mips / mm / ioremap.c
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * (C) Copyright 1995 1996 Linus Torvalds
7  * (C) Copyright 2001, 2002 Ralf Baechle
8  */
9 #include <linux/module.h>
10 #include <asm/addrspace.h>
11 #include <asm/byteorder.h>
12
13 #include <linux/vmalloc.h>
14 #include <asm/cacheflush.h>
15 #include <asm/io.h>
16 #include <asm/tlbflush.h>
17
18 static inline void remap_area_pte(pte_t * pte, unsigned long address,
19         phys_t size, phys_t phys_addr, unsigned long flags)
20 {
21         phys_t end;
22         unsigned long pfn;
23         pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | __READABLE
24                                    | __WRITEABLE | flags);
25
26         address &= ~PMD_MASK;
27         end = address + size;
28         if (end > PMD_SIZE)
29                 end = PMD_SIZE;
30         if (address >= end)
31                 BUG();
32         pfn = phys_addr >> PAGE_SHIFT;
33         do {
34                 if (!pte_none(*pte)) {
35                         printk("remap_area_pte: page already exists\n");
36                         BUG();
37                 }
38                 set_pte(pte, pfn_pte(pfn, pgprot));
39                 address += PAGE_SIZE;
40                 pfn++;
41                 pte++;
42         } while (address && (address < end));
43 }
44
45 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address,
46         phys_t size, phys_t phys_addr, unsigned long flags)
47 {
48         phys_t end;
49
50         address &= ~PGDIR_MASK;
51         end = address + size;
52         if (end > PGDIR_SIZE)
53                 end = PGDIR_SIZE;
54         phys_addr -= address;
55         if (address >= end)
56                 BUG();
57         do {
58                 pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address);
59                 if (!pte)
60                         return -ENOMEM;
61                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
62                 address = (address + PMD_SIZE) & PMD_MASK;
63                 pmd++;
64         } while (address && (address < end));
65         return 0;
66 }
67
68 static int remap_area_pages(unsigned long address, phys_t phys_addr,
69         phys_t size, unsigned long flags)
70 {
71         int error;
72         pgd_t * dir;
73         unsigned long end = address + size;
74
75         phys_addr -= address;
76         dir = pgd_offset(&init_mm, address);
77         flush_cache_all();
78         if (address >= end)
79                 BUG();
80         spin_lock(&init_mm.page_table_lock);
81         do {
82                 pud_t *pud;
83                 pmd_t *pmd;
84
85                 error = -ENOMEM;
86                 pud = pud_alloc(&init_mm, dir, address);
87                 if (!pud)
88                         break;
89                 pmd = pmd_alloc(&init_mm, pud, address);
90                 if (!pmd)
91                         break;
92                 if (remap_area_pmd(pmd, address, end - address,
93                                          phys_addr + address, flags))
94                         break;
95                 error = 0;
96                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
97                 dir++;
98         } while (address && (address < end));
99         spin_unlock(&init_mm.page_table_lock);
100         flush_tlb_all();
101         return error;
102 }
103
104 /*
105  * Allow physical addresses to be fixed up to help 36 bit peripherals.
106  */
107 phys_t __attribute__ ((weak))
108 fixup_bigphys_addr(phys_t phys_addr, phys_t size)
109 {
110         return phys_addr;
111 }
112
113 /*
114  * Generic mapping function (not visible outside):
115  */
116
117 /*
118  * Remap an arbitrary physical address space into the kernel virtual
119  * address space. Needed when the kernel wants to access high addresses
120  * directly.
121  *
122  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
123  * have to convert them into an offset in a page-aligned mapping, but the
124  * caller shouldn't need to know that small detail.
125  */
126
127 #define IS_LOW512(addr) (!((phys_t)(addr) & (phys_t) ~0x1fffffffULL))
128
129 void * __ioremap(phys_t phys_addr, phys_t size, unsigned long flags)
130 {
131         struct vm_struct * area;
132         unsigned long offset;
133         phys_t last_addr;
134         void * addr;
135
136         phys_addr = fixup_bigphys_addr(phys_addr, size);
137
138         /* Don't allow wraparound or zero size */
139         last_addr = phys_addr + size - 1;
140         if (!size || last_addr < phys_addr)
141                 return NULL;
142
143         /*
144          * Map uncached objects in the low 512mb of address space using KSEG1,
145          * otherwise map using page tables.
146          */
147         if (IS_LOW512(phys_addr) && IS_LOW512(last_addr) &&
148             flags == _CACHE_UNCACHED)
149                 return (void *) CKSEG1ADDR(phys_addr);
150
151         /*
152          * Don't allow anybody to remap normal RAM that we're using..
153          */
154         if (phys_addr < virt_to_phys(high_memory)) {
155                 char *t_addr, *t_end;
156                 struct page *page;
157
158                 t_addr = __va(phys_addr);
159                 t_end = t_addr + (size - 1);
160
161                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
162                         if(!PageReserved(page))
163                                 return NULL;
164         }
165
166         /*
167          * Mappings have to be page-aligned
168          */
169         offset = phys_addr & ~PAGE_MASK;
170         phys_addr &= PAGE_MASK;
171         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
172
173         /*
174          * Ok, go for it..
175          */
176         area = get_vm_area(size, VM_IOREMAP);
177         if (!area)
178                 return NULL;
179         addr = area->addr;
180         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
181                 vunmap(addr);
182                 return NULL;
183         }
184
185         return (void *) (offset + (char *)addr);
186 }
187
188 #define IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == CKSEG1)
189
190 void __iounmap(volatile void __iomem *addr)
191 {
192         struct vm_struct *p;
193
194         if (IS_KSEG1(addr))
195                 return;
196
197         p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
198         if (!p)
199                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
200
201         kfree(p);
202 }
203
204 EXPORT_SYMBOL(__ioremap);
205 EXPORT_SYMBOL(__iounmap);