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 #include <linux/sched.h>
  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         BUG_ON(address >= end);
  31         pfn = phys_addr >> PAGE_SHIFT;
  32         do {
  33                 if (!pte_none(*pte)) {
  34                         printk("remap_area_pte: page already exists\n");
  35                         BUG();
  36                 }
  37                 set_pte(pte, pfn_pte(pfn, pgprot));
  38                 address += PAGE_SIZE;
  39                 pfn++;
  40                 pte++;
  41         } while (address && (address < end));
  42 }
  43
  44 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address,
  45         phys_t size, phys_t phys_addr, unsigned long flags)
  46 {
  47         phys_t end;
  48
  49         address &= ~PGDIR_MASK;
  50         end = address + size;
  51         if (end > PGDIR_SIZE)
  52                 end = PGDIR_SIZE;
  53         phys_addr -= address;
  54         BUG_ON(address >= end);
  55         do {
  56                 pte_t * pte = pte_alloc_kernel(pmd, address);
  57                 if (!pte)
  58                         return -ENOMEM;
  59                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
  60                 address = (address + PMD_SIZE) & PMD_MASK;
  61                 pmd++;
  62         } while (address && (address < end));
  63         return 0;
  64 }
  65
  66 static int remap_area_pages(unsigned long address, phys_t phys_addr,
  67         phys_t size, unsigned long flags)
  68 {
  69         int error;
  70         pgd_t * dir;
  71         unsigned long end = address + size;
  72
  73         phys_addr -= address;
  74         dir = pgd_offset(&init_mm, address);
  75         flush_cache_all();
  76         BUG_ON(address >= end);
  77         do {
  78                 pud_t *pud;
  79                 pmd_t *pmd;
  80
  81                 error = -ENOMEM;
  82                 pud = pud_alloc(&init_mm, dir, address);
  83                 if (!pud)
  84                         break;
  85                 pmd = pmd_alloc(&init_mm, pud, address);
  86                 if (!pmd)
  87                         break;
  88                 if (remap_area_pmd(pmd, address, end - address,
  89                                          phys_addr + address, flags))
  90                         break;
  91                 error = 0;
  92                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
  93                 dir++;
  94         } while (address && (address < end));
  95         flush_tlb_all();
  96         return error;
  97 }
  98
  99 /*
 100  * Generic mapping function (not visible outside):
 101  */
 102
 103 /*
 104  * Remap an arbitrary physical address space into the kernel virtual
 105  * address space. Needed when the kernel wants to access high addresses
 106  * directly.
 107  *
 108  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 109  * have to convert them into an offset in a page-aligned mapping, but the
 110  * caller shouldn't need to know that small detail.
 111  */
 112
 113 #define IS_LOW512(addr) (!((phys_t)(addr) & (phys_t) ~0x1fffffffULL))
 114
 115 void __iomem * __ioremap(phys_t phys_addr, phys_t size, unsigned long flags)
 116 {
 117         struct vm_struct * area;
 118         unsigned long offset;
 119         phys_t last_addr;
 120         void * addr;
 121
 122         phys_addr = fixup_bigphys_addr(phys_addr, size);
 123
 124         /* Don't allow wraparound or zero size */
 125         last_addr = phys_addr + size - 1;
 126         if (!size || last_addr < phys_addr)
 127                 return NULL;
 128
 129         /*
 130          * Map uncached objects in the low 512mb of address space using KSEG1,
 131          * otherwise map using page tables.
 132          */
 133         if (IS_LOW512(phys_addr) && IS_LOW512(last_addr) &&
 134             flags == _CACHE_UNCACHED)
 135                 return (void __iomem *) CKSEG1ADDR(phys_addr);
 136
 137         /*
 138          * Don't allow anybody to remap normal RAM that we're using..
 139          */
 140         if (phys_addr < virt_to_phys(high_memory)) {
 141                 char *t_addr, *t_end;
 142                 struct page *page;
 143
 144                 t_addr = __va(phys_addr);
 145                 t_end = t_addr + (size - 1);
 146
 147                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 148                         if(!PageReserved(page))
 149                                 return NULL;
 150         }
 151
 152         /*
 153          * Mappings have to be page-aligned
 154          */
 155         offset = phys_addr & ~PAGE_MASK;
 156         phys_addr &= PAGE_MASK;
 157         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 158
 159         /*
 160          * Ok, go for it..
 161          */
 162         area = get_vm_area(size, VM_IOREMAP);
 163         if (!area)
 164                 return NULL;
 165         addr = area->addr;
 166         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 167                 vunmap(addr);
 168                 return NULL;
 169         }
 170
 171         return (void __iomem *) (offset + (char *)addr);
 172 }
 173
 174 #define IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == CKSEG1)
 175
 176 void __iounmap(const volatile void __iomem *addr)
 177 {
 178         struct vm_struct *p;
 179
 180         if (IS_KSEG1(addr))
 181                 return;
 182
 183         p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
 184         if (!p)
 185                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
 186
 187         kfree(p);
 188 }
 189
 190 EXPORT_SYMBOL(__ioremap);
 191 EXPORT_SYMBOL(__iounmap);