summaryrefslogtreecommitdiff
path: root/arch/x86_64/mm/ioremap.c
blob: 58aac23760efeb3e37aa76ab888e3e900b7ac667 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
/*
 * arch/x86_64/mm/ioremap.c
 *
 * Re-map IO memory to kernel address space so that we can access it.
 * This is needed for high PCI addresses that aren't mapped in the
 * 640k-1MB IO memory area on PC's
 *
 * (C) Copyright 1995 1996 Linus Torvalds
 */

#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <asm/io.h>
#include <asm/pgalloc.h>
#include <asm/fixmap.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/proto.h>

#define ISA_START_ADDRESS      0xa0000
#define ISA_END_ADDRESS                0x100000

static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
	unsigned long phys_addr, unsigned long flags)
{
	unsigned long end;
	unsigned long pfn;

	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	if (address >= end)
		BUG();
	pfn = phys_addr >> PAGE_SHIFT;
	do {
		if (!pte_none(*pte)) {
			printk("remap_area_pte: page already exists\n");
			BUG();
		}
		set_pte(pte, pfn_pte(pfn, __pgprot(_PAGE_PRESENT | _PAGE_RW | 
					_PAGE_GLOBAL | _PAGE_DIRTY | _PAGE_ACCESSED | flags)));
		address += PAGE_SIZE;
		pfn++;
		pte++;
	} while (address && (address < end));
}

static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
	unsigned long phys_addr, unsigned long flags)
{
	unsigned long end;

	address &= ~PUD_MASK;
	end = address + size;
	if (end > PUD_SIZE)
		end = PUD_SIZE;
	phys_addr -= address;
	if (address >= end)
		BUG();
	do {
		pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address);
		if (!pte)
			return -ENOMEM;
		remap_area_pte(pte, address, end - address, address + phys_addr, flags);
		address = (address + PMD_SIZE) & PMD_MASK;
		pmd++;
	} while (address && (address < end));
	return 0;
}

static inline int remap_area_pud(pud_t * pud, unsigned long address, unsigned long size,
	unsigned long phys_addr, unsigned long flags)
{
	unsigned long end;

	address &= ~PGDIR_MASK;
	end = address + size;
	if (end > PGDIR_SIZE)
		end = PGDIR_SIZE;
	phys_addr -= address;
	if (address >= end)
		BUG();
	do {
		pmd_t * pmd = pmd_alloc(&init_mm, pud, address);
		if (!pmd)
			return -ENOMEM;
		remap_area_pmd(pmd, address, end - address, address + phys_addr, flags);
		address = (address + PUD_SIZE) & PUD_MASK;
		pud++;
	} while (address && (address < end));
	return 0;
}

static int remap_area_pages(unsigned long address, unsigned long phys_addr,
				 unsigned long size, unsigned long flags)
{
	int error;
	pgd_t *pgd;
	unsigned long end = address + size;

	phys_addr -= address;
	pgd = pgd_offset_k(address);
	flush_cache_all();
	if (address >= end)
		BUG();
	spin_lock(&init_mm.page_table_lock);
	do {
		pud_t *pud;
		pud = pud_alloc(&init_mm, pgd, address);
		error = -ENOMEM;
		if (!pud)
			break;
		if (remap_area_pud(pud, address, end - address,
					 phys_addr + address, flags))
			break;
		error = 0;
		address = (address + PGDIR_SIZE) & PGDIR_MASK;
		pgd++;
	} while (address && (address < end));
	spin_unlock(&init_mm.page_table_lock);
	flush_tlb_all();
	return error;
}

/*
 * Fix up the linear direct mapping of the kernel to avoid cache attribute
 * conflicts.
 */
static int
ioremap_change_attr(unsigned long phys_addr, unsigned long size,
					unsigned long flags)
{
	int err = 0;
	if (phys_addr + size - 1 < (end_pfn_map << PAGE_SHIFT)) {
		unsigned long npages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
		unsigned long vaddr = (unsigned long) __va(phys_addr);

		/*
 		 * Must use a address here and not struct page because the phys addr
		 * can be a in hole between nodes and not have an memmap entry.
		 */
		err = change_page_attr_addr(vaddr,npages,__pgprot(__PAGE_KERNEL|flags));
		if (!err)
			global_flush_tlb();
	}
	return err;
}

/*
 * Generic mapping function
 */

/*
 * Remap an arbitrary physical address space into the kernel virtual
 * address space. Needed when the kernel wants to access high addresses
 * directly.
 *
 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 * have to convert them into an offset in a page-aligned mapping, but the
 * caller shouldn't need to know that small detail.
 */
void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
{
	void * addr;
	struct vm_struct * area;
	unsigned long offset, last_addr;

	/* Don't allow wraparound or zero size */
	last_addr = phys_addr + size - 1;
	if (!size || last_addr < phys_addr)
		return NULL;

	/*
	 * Don't remap the low PCI/ISA area, it's always mapped..
	 */
	if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
		return (__force void __iomem *)phys_to_virt(phys_addr);

#ifndef CONFIG_DISCONTIGMEM
	/*
	 * Don't allow anybody to remap normal RAM that we're using..
	 */
	if (last_addr < virt_to_phys(high_memory)) {
		char *t_addr, *t_end;
 		struct page *page;

		t_addr = __va(phys_addr);
		t_end = t_addr + (size - 1);
	   
		for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
			if(!PageReserved(page))
				return NULL;
	}
#endif

	/*
	 * Mappings have to be page-aligned
	 */
	offset = phys_addr & ~PAGE_MASK;
	phys_addr &= PAGE_MASK;
	size = PAGE_ALIGN(last_addr+1) - phys_addr;

	/*
	 * Ok, go for it..
	 */
	area = get_vm_area(size, VM_IOREMAP | (flags << 20));
	if (!area)
		return NULL;
	area->phys_addr = phys_addr;
	addr = area->addr;
	if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
		remove_vm_area((void *)(PAGE_MASK & (unsigned long) addr));
		return NULL;
	}
	if (flags && ioremap_change_attr(phys_addr, size, flags) < 0) {
		area->flags &= 0xffffff;
		vunmap(addr);
		return NULL;
	}
	return (__force void __iomem *) (offset + (char *)addr);
}

/**
 * ioremap_nocache     -   map bus memory into CPU space
 * @offset:    bus address of the memory
 * @size:      size of the resource to map
 *
 * ioremap_nocache performs a platform specific sequence of operations to
 * make bus memory CPU accessible via the readb/readw/readl/writeb/
 * writew/writel functions and the other mmio helpers. The returned
 * address is not guaranteed to be usable directly as a virtual
 * address. 
 *
 * This version of ioremap ensures that the memory is marked uncachable
 * on the CPU as well as honouring existing caching rules from things like
 * the PCI bus. Note that there are other caches and buffers on many 
 * busses. In particular driver authors should read up on PCI writes
 *
 * It's useful if some control registers are in such an area and
 * write combining or read caching is not desirable:
 * 
 * Must be freed with iounmap.
 */

void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
{
	return __ioremap(phys_addr, size, _PAGE_PCD);
}

void iounmap(volatile void __iomem *addr)
{
	struct vm_struct *p;

	if (addr <= high_memory) 
		return; 
	if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
		addr < phys_to_virt(ISA_END_ADDRESS))
		return;

	write_lock(&vmlist_lock);
	p = __remove_vm_area((void *)((unsigned long)addr & PAGE_MASK));
	if (!p)
		printk("iounmap: bad address %p\n", addr);
	else if (p->flags >> 20)
		ioremap_change_attr(p->phys_addr, p->size, 0);
	write_unlock(&vmlist_lock);
	kfree(p); 
}