summaryrefslogtreecommitdiffstats
path: root/arch/nios2/mm/ioremap.c
blob: 819bdfcc2e714d64ba1657de319dcc1ba6b6a5da (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
/*
 * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
 * Copyright (C) 2009 Wind River Systems Inc
 *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
 * Copyright (C) 2004 Microtronix Datacom Ltd.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file "COPYING" in the main directory of this archive
 * for more details.
 */

#include <linux/export.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/io.h>

#include <asm/cacheflush.h>
#include <asm/tlbflush.h>

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;
	pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | _PAGE_READ
				| _PAGE_WRITE | flags);

	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	if (address >= end)
		BUG();
	pfn = PFN_DOWN(phys_addr);
	do {
		if (!pte_none(*pte)) {
			pr_err("remap_area_pte: page already exists\n");
			BUG();
		}
		set_pte(pte, pfn_pte(pfn, pgprot));
		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 &= ~PGDIR_MASK;
	end = address + size;
	if (end > PGDIR_SIZE)
		end = PGDIR_SIZE;
	phys_addr -= address;
	if (address >= end)
		BUG();
	do {
		pte_t *pte = pte_alloc_kernel(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 int remap_area_pages(unsigned long address, unsigned long phys_addr,
				unsigned long size, unsigned long flags)
{
	int error;
	pgd_t *dir;
	unsigned long end = address + size;

	phys_addr -= address;
	dir = pgd_offset(&init_mm, address);
	flush_cache_all();
	if (address >= end)
		BUG();
	do {
		pud_t *pud;
		pmd_t *pmd;

		error = -ENOMEM;
		pud = pud_alloc(&init_mm, dir, address);
		if (!pud)
			break;
		pmd = pmd_alloc(&init_mm, pud, address);
		if (!pmd)
			break;
		if (remap_area_pmd(pmd, address, end - address,
			phys_addr + address, flags))
			break;
		error = 0;
		address = (address + PGDIR_SIZE) & PGDIR_MASK;
		dir++;
	} while (address && (address < end));
	flush_tlb_all();
	return error;
}

#define IS_MAPPABLE_UNCACHEABLE(addr) (addr < 0x20000000UL)

/*
 * Map some physical address range into the kernel address space.
 */
void __iomem *ioremap(unsigned long phys_addr, unsigned long size)
{
	struct vm_struct *area;
	unsigned long offset;
	unsigned long last_addr;
	void *addr;

	/* Don't allow wraparound or zero size */
	last_addr = phys_addr + size - 1;

	if (!size || last_addr < phys_addr)
		return NULL;

	/* Don't allow anybody to remap normal RAM that we're using */
	if (phys_addr > PHYS_OFFSET && phys_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;
	}

	/*
	 * Map uncached objects in the low part of address space to
	 * CONFIG_NIOS2_IO_REGION_BASE
	 */
	if (IS_MAPPABLE_UNCACHEABLE(phys_addr) &&
	    IS_MAPPABLE_UNCACHEABLE(last_addr))
		return (void __iomem *)(CONFIG_NIOS2_IO_REGION_BASE + phys_addr);

	/* 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);
	if (!area)
		return NULL;
	addr = area->addr;
	if (remap_area_pages((unsigned long) addr, phys_addr, size, 0)) {
		vunmap(addr);
		return NULL;
	}
	return (void __iomem *) (offset + (char *)addr);
}
EXPORT_SYMBOL(ioremap);

/*
 * iounmap unmaps nearly everything, so be careful
 * it doesn't free currently pointer/page tables anymore but it
 * wasn't used anyway and might be added later.
 */
void iounmap(void __iomem *addr)
{
	struct vm_struct *p;

	if ((unsigned long) addr > CONFIG_NIOS2_IO_REGION_BASE)
		return;

	p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
	if (!p)
		pr_err("iounmap: bad address %p\n", addr);
	kfree(p);
}
EXPORT_SYMBOL(iounmap);