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Linux/arch/mips/mm/ioremap.c

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  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/export.h>
 10 #include <asm/addrspace.h>
 11 #include <asm/byteorder.h>
 12 #include <linux/ioport.h>
 13 #include <linux/sched.h>
 14 #include <linux/slab.h>
 15 #include <linux/vmalloc.h>
 16 #include <linux/mm_types.h>
 17 #include <asm/cacheflush.h>
 18 #include <asm/io.h>
 19 #include <asm/tlbflush.h>
 20 
 21 static inline void remap_area_pte(pte_t * pte, unsigned long address,
 22         phys_addr_t size, phys_addr_t phys_addr, unsigned long flags)
 23 {
 24         phys_addr_t end;
 25         unsigned long pfn;
 26         pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | __READABLE
 27                                    | __WRITEABLE | flags);
 28 
 29         address &= ~PMD_MASK;
 30         end = address + size;
 31         if (end > PMD_SIZE)
 32                 end = PMD_SIZE;
 33         BUG_ON(address >= end);
 34         pfn = phys_addr >> PAGE_SHIFT;
 35         do {
 36                 if (!pte_none(*pte)) {
 37                         printk("remap_area_pte: page already exists\n");
 38                         BUG();
 39                 }
 40                 set_pte(pte, pfn_pte(pfn, pgprot));
 41                 address += PAGE_SIZE;
 42                 pfn++;
 43                 pte++;
 44         } while (address && (address < end));
 45 }
 46 
 47 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address,
 48         phys_addr_t size, phys_addr_t phys_addr, unsigned long flags)
 49 {
 50         phys_addr_t end;
 51 
 52         address &= ~PGDIR_MASK;
 53         end = address + size;
 54         if (end > PGDIR_SIZE)
 55                 end = PGDIR_SIZE;
 56         phys_addr -= address;
 57         BUG_ON(address >= end);
 58         do {
 59                 pte_t * pte = pte_alloc_kernel(pmd, address);
 60                 if (!pte)
 61                         return -ENOMEM;
 62                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
 63                 address = (address + PMD_SIZE) & PMD_MASK;
 64                 pmd++;
 65         } while (address && (address < end));
 66         return 0;
 67 }
 68 
 69 static int remap_area_pages(unsigned long address, phys_addr_t phys_addr,
 70         phys_addr_t size, unsigned long flags)
 71 {
 72         int error;
 73         pgd_t * dir;
 74         unsigned long end = address + size;
 75 
 76         phys_addr -= address;
 77         dir = pgd_offset(&init_mm, address);
 78         flush_cache_all();
 79         BUG_ON(address >= end);
 80         do {
 81                 pud_t *pud;
 82                 pmd_t *pmd;
 83 
 84                 error = -ENOMEM;
 85                 pud = pud_alloc(&init_mm, dir, address);
 86                 if (!pud)
 87                         break;
 88                 pmd = pmd_alloc(&init_mm, pud, address);
 89                 if (!pmd)
 90                         break;
 91                 if (remap_area_pmd(pmd, address, end - address,
 92                                          phys_addr + address, flags))
 93                         break;
 94                 error = 0;
 95                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 96                 dir++;
 97         } while (address && (address < end));
 98         flush_tlb_all();
 99         return error;
100 }
101 
102 static int __ioremap_check_ram(unsigned long start_pfn, unsigned long nr_pages,
103                                void *arg)
104 {
105         unsigned long i;
106 
107         for (i = 0; i < nr_pages; i++) {
108                 if (pfn_valid(start_pfn + i) &&
109                     !PageReserved(pfn_to_page(start_pfn + i)))
110                         return 1;
111         }
112 
113         return 0;
114 }
115 
116 /*
117  * Generic mapping function (not visible outside):
118  */
119 
120 /*
121  * Remap an arbitrary physical address space into the kernel virtual
122  * address space. Needed when the kernel wants to access high addresses
123  * directly.
124  *
125  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
126  * have to convert them into an offset in a page-aligned mapping, but the
127  * caller shouldn't need to know that small detail.
128  */
129 
130 #define IS_LOW512(addr) (!((phys_addr_t)(addr) & (phys_addr_t) ~0x1fffffffULL))
131 
132 void __iomem * __ioremap(phys_addr_t phys_addr, phys_addr_t size, unsigned long flags)
133 {
134         unsigned long offset, pfn, last_pfn;
135         struct vm_struct * area;
136         phys_addr_t last_addr;
137         void * addr;
138 
139         phys_addr = fixup_bigphys_addr(phys_addr, size);
140 
141         /* Don't allow wraparound or zero size */
142         last_addr = phys_addr + size - 1;
143         if (!size || last_addr < phys_addr)
144                 return NULL;
145 
146         /*
147          * Map uncached objects in the low 512mb of address space using KSEG1,
148          * otherwise map using page tables.
149          */
150         if (IS_LOW512(phys_addr) && IS_LOW512(last_addr) &&
151             flags == _CACHE_UNCACHED)
152                 return (void __iomem *) CKSEG1ADDR(phys_addr);
153 
154         /*
155          * Don't allow anybody to remap RAM that may be allocated by the page
156          * allocator, since that could lead to races & data clobbering.
157          */
158         pfn = PFN_DOWN(phys_addr);
159         last_pfn = PFN_DOWN(last_addr);
160         if (walk_system_ram_range(pfn, last_pfn - pfn + 1, NULL,
161                                   __ioremap_check_ram) == 1) {
162                 WARN_ONCE(1, "ioremap on RAM at %pa - %pa\n",
163                           &phys_addr, &last_addr);
164                 return NULL;
165         }
166 
167         /*
168          * Mappings have to be page-aligned
169          */
170         offset = phys_addr & ~PAGE_MASK;
171         phys_addr &= PAGE_MASK;
172         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
173 
174         /*
175          * Ok, go for it..
176          */
177         area = get_vm_area(size, VM_IOREMAP);
178         if (!area)
179                 return NULL;
180         addr = area->addr;
181         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
182                 vunmap(addr);
183                 return NULL;
184         }
185 
186         return (void __iomem *) (offset + (char *)addr);
187 }
188 
189 #define IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == CKSEG1)
190 
191 void __iounmap(const volatile void __iomem *addr)
192 {
193         struct vm_struct *p;
194 
195         if (IS_KSEG1(addr))
196                 return;
197 
198         p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
199         if (!p)
200                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
201 
202         kfree(p);
203 }
204 
205 EXPORT_SYMBOL(__ioremap);
206 EXPORT_SYMBOL(__iounmap);
207 

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