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                 pmd_t *pmd;
  83                 pmd = pmd_alloc(&init_mm, dir, address);
  84                 error = -ENOMEM;
  85                 if (!pmd)
  86                         break;
  87                 if (remap_area_pmd(pmd, address, end - address,
  88                                          phys_addr + address, flags))
  89                         break;
  90                 error = 0;
  91                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
  92                 dir++;
  93         } while (address && (address < end));
  94         spin_unlock(&init_mm.page_table_lock);
  95         flush_tlb_all();
  96         return error;
  97 }
  98
  99 /*
 100  * Allow physical addresses to be fixed up to help 36 bit peripherals.
 101  */
 102 phys_t __attribute__ ((weak))
 103 fixup_bigphys_addr(phys_t phys_addr, phys_t size)
 104 {
 105         return phys_addr;
 106 }
 107
 108 /*
 109  * Generic mapping function (not visible outside):
 110  */
 111
 112 /*
 113  * Remap an arbitrary physical address space into the kernel virtual
 114  * address space. Needed when the kernel wants to access high addresses
 115  * directly.
 116  *
 117  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 118  * have to convert them into an offset in a page-aligned mapping, but the
 119  * caller shouldn't need to know that small detail.
 120  */
 121
 122 #define IS_LOW512(addr) (!((phys_t)(addr) & (phys_t) ~0x1fffffffULL))
 123
 124 void * __ioremap(phys_t phys_addr, phys_t size, unsigned long flags)
 125 {
 126         struct vm_struct * area;
 127         unsigned long offset;
 128         phys_t last_addr;
 129         void * addr;
 130
 131         phys_addr = fixup_bigphys_addr(phys_addr, size);
 132
 133         /* Don't allow wraparound or zero size */
 134         last_addr = phys_addr + size - 1;
 135         if (!size || last_addr < phys_addr)
 136                 return NULL;
 137
 138         /*
 139          * Map uncached objects in the low 512mb of address space using KSEG1,
 140          * otherwise map using page tables.
 141          */
 142         if (IS_LOW512(phys_addr) && IS_LOW512(last_addr) &&
 143             flags == _CACHE_UNCACHED)
 144                 return (void *) KSEG1ADDR(phys_addr);
 145
 146         /*
 147          * Don't allow anybody to remap normal RAM that we're using..
 148          */
 149         if (phys_addr < virt_to_phys(high_memory)) {
 150                 char *t_addr, *t_end;
 151                 struct page *page;
 152
 153                 t_addr = __va(phys_addr);
 154                 t_end = t_addr + (size - 1);
 155
 156                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 157                         if(!PageReserved(page))
 158                                 return NULL;
 159         }
 160
 161         /*
 162          * Mappings have to be page-aligned
 163          */
 164         offset = phys_addr & ~PAGE_MASK;
 165         phys_addr &= PAGE_MASK;
 166         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 167
 168         /*
 169          * Ok, go for it..
 170          */
 171         area = get_vm_area(size, VM_IOREMAP);
 172         if (!area)
 173                 return NULL;
 174         addr = area->addr;
 175         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 176                 vunmap(addr);
 177                 return NULL;
 178         }
 179
 180         return (void *) (offset + (char *)addr);
 181 }
 182
 183 #define IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == KSEG1)
 184
 185 void __iounmap(volatile void __iomem *addr)
 186 {
 187         struct vm_struct *p;
 188
 189         if (IS_KSEG1(addr))
 190                 return;
 191
 192         p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
 193         if (!p) {
 194                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
 195                 return;
 196         }
 197
 198         kfree(p);
 199 }
 200
 201 EXPORT_SYMBOL(__ioremap);
 202 EXPORT_SYMBOL(__iounmap);