1/*
2 * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
3 * Copyright (C) 2009 Wind River Systems Inc
4 * Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
5 * Copyright (C) 2004 Microtronix Datacom Ltd.
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License. See the file "COPYING" in the main directory of this archive
9 * for more details.
10 */
11
12#include <linux/export.h>
13#include <linux/sched.h>
14#include <linux/mm.h>
15#include <linux/slab.h>
16#include <linux/vmalloc.h>
17#include <linux/io.h>
18
19#include <asm/cacheflush.h>
20#include <asm/tlbflush.h>
21
22static inline void remap_area_pte(pte_t *pte, unsigned long address,
23 unsigned long size, unsigned long phys_addr,
24 unsigned long flags)
25{
26 unsigned long end;
27 unsigned long pfn;
28 pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | _PAGE_READ
29 | _PAGE_WRITE | flags);
30
31 address &= ~PMD_MASK;
32 end = address + size;
33 if (end > PMD_SIZE)
34 end = PMD_SIZE;
35 if (address >= end)
36 BUG();
37 pfn = PFN_DOWN(phys_addr);
38 do {
39 if (!pte_none(pte: *pte)) {
40 pr_err("remap_area_pte: page already exists\n");
41 BUG();
42 }
43 set_pte(ptep: pte, pte: pfn_pte(page_nr: pfn, pgprot));
44 address += PAGE_SIZE;
45 pfn++;
46 pte++;
47 } while (address && (address < end));
48}
49
50static inline int remap_area_pmd(pmd_t *pmd, unsigned long address,
51 unsigned long size, unsigned long phys_addr,
52 unsigned long flags)
53{
54 unsigned long end;
55
56 address &= ~PGDIR_MASK;
57 end = address + size;
58 if (end > PGDIR_SIZE)
59 end = PGDIR_SIZE;
60 phys_addr -= address;
61 if (address >= end)
62 BUG();
63 do {
64 pte_t *pte = pte_alloc_kernel(pmd, address);
65
66 if (!pte)
67 return -ENOMEM;
68 remap_area_pte(pte, address, size: end - address, phys_addr: address + phys_addr,
69 flags);
70 address = (address + PMD_SIZE) & PMD_MASK;
71 pmd++;
72 } while (address && (address < end));
73 return 0;
74}
75
76static int remap_area_pages(unsigned long address, unsigned long phys_addr,
77 unsigned long size, unsigned long flags)
78{
79 int error;
80 pgd_t *dir;
81 unsigned long end = address + size;
82
83 phys_addr -= address;
84 dir = pgd_offset(&init_mm, address);
85 flush_cache_all();
86 if (address >= end)
87 BUG();
88 do {
89 p4d_t *p4d;
90 pud_t *pud;
91 pmd_t *pmd;
92
93 error = -ENOMEM;
94 p4d = p4d_alloc(mm: &init_mm, pgd: dir, address);
95 if (!p4d)
96 break;
97 pud = pud_alloc(mm: &init_mm, p4d, address);
98 if (!pud)
99 break;
100 pmd = pmd_alloc(mm: &init_mm, pud, address);
101 if (!pmd)
102 break;
103 if (remap_area_pmd(pmd, address, size: end - address,
104 phys_addr: phys_addr + address, flags))
105 break;
106 error = 0;
107 address = (address + PGDIR_SIZE) & PGDIR_MASK;
108 dir++;
109 } while (address && (address < end));
110 flush_tlb_all();
111 return error;
112}
113
114#define IS_MAPPABLE_UNCACHEABLE(addr) (addr < 0x20000000UL)
115
116/*
117 * Map some physical address range into the kernel address space.
118 */
119void __iomem *ioremap(unsigned long phys_addr, unsigned long size)
120{
121 struct vm_struct *area;
122 unsigned long offset;
123 unsigned long last_addr;
124 void *addr;
125
126 /* Don't allow wraparound or zero size */
127 last_addr = phys_addr + size - 1;
128
129 if (!size || last_addr < phys_addr)
130 return NULL;
131
132 /* Don't allow anybody to remap normal RAM that we're using */
133 if (phys_addr > PHYS_OFFSET && phys_addr < virt_to_phys(address: high_memory)) {
134 char *t_addr, *t_end;
135 struct page *page;
136
137 t_addr = __va(phys_addr);
138 t_end = t_addr + (size - 1);
139 for (page = virt_to_page(t_addr);
140 page <= virt_to_page(t_end); page++)
141 if (!PageReserved(page))
142 return NULL;
143 }
144
145 /*
146 * Map uncached objects in the low part of address space to
147 * CONFIG_NIOS2_IO_REGION_BASE
148 */
149 if (IS_MAPPABLE_UNCACHEABLE(phys_addr) &&
150 IS_MAPPABLE_UNCACHEABLE(last_addr))
151 return (void __iomem *)(CONFIG_NIOS2_IO_REGION_BASE + phys_addr);
152
153 /* Mappings have to be page-aligned */
154 offset = phys_addr & ~PAGE_MASK;
155 phys_addr &= PAGE_MASK;
156 size = PAGE_ALIGN(last_addr + 1) - phys_addr;
157
158 /* Ok, go for it */
159 area = get_vm_area(size, VM_IOREMAP);
160 if (!area)
161 return NULL;
162 addr = area->addr;
163 if (remap_area_pages(address: (unsigned long) addr, phys_addr, size, flags: 0)) {
164 vunmap(addr);
165 return NULL;
166 }
167 return (void __iomem *) (offset + (char *)addr);
168}
169EXPORT_SYMBOL(ioremap);
170
171/*
172 * iounmap unmaps nearly everything, so be careful
173 * it doesn't free currently pointer/page tables anymore but it
174 * wasn't used anyway and might be added later.
175 */
176void iounmap(void __iomem *addr)
177{
178 struct vm_struct *p;
179
180 if ((unsigned long) addr > CONFIG_NIOS2_IO_REGION_BASE)
181 return;
182
183 p = remove_vm_area(addr: (void *) (PAGE_MASK & (unsigned long __force) addr));
184 if (!p)
185 pr_err("iounmap: bad address %p\n", addr);
186 kfree(objp: p);
187}
188EXPORT_SYMBOL(iounmap);
189

source code of linux/arch/nios2/mm/ioremap.c