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         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(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         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 /*
 103  * Generic mapping function (not visible outside):
 104  */
 105
 106 /*
 107  * Remap an arbitrary physical address space into the kernel virtual
 108  * address space. Needed when the kernel wants to access high addresses
 109  * directly.
 110  *
 111  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 112  * have to convert them into an offset in a page-aligned mapping, but the
 113  * caller shouldn't need to know that small detail.
 114  */
 115
 116 #define IS_LOW512(addr) (!((phys_t)(addr) & (phys_t) ~0x1fffffffULL))
 117
 118 void __iomem * __ioremap(phys_t phys_addr, phys_t size, unsigned long flags)
 119 {
 120         struct vm_struct * area;
 121         unsigned long offset;
 122         phys_t last_addr;
 123         void * addr;
 124
 125         phys_addr = fixup_bigphys_addr(phys_addr, size);
 126
 127         /* Don't allow wraparound or zero size */
 128         last_addr = phys_addr + size - 1;
 129         if (!size || last_addr < phys_addr)
 130                 return NULL;
 131
 132         /*
 133          * Map uncached objects in the low 512mb of address space using KSEG1,
 134          * otherwise map using page tables.
 135          */
 136         if (IS_LOW512(phys_addr) && IS_LOW512(last_addr) &&
 137             flags == _CACHE_UNCACHED)
 138                 return (void __iomem *) CKSEG1ADDR(phys_addr);
 139
 140         /*
 141          * Don't allow anybody to remap normal RAM that we're using..
 142          */
 143         if (phys_addr < virt_to_phys(high_memory)) {
 144                 char *t_addr, *t_end;
 145                 struct page *page;
 146
 147                 t_addr = __va(phys_addr);
 148                 t_end = t_addr + (size - 1);
 149
 150                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 151                         if(!PageReserved(page))
 152                                 return NULL;
 153         }
 154
 155         /*
 156          * Mappings have to be page-aligned
 157          */
 158         offset = phys_addr & ~PAGE_MASK;
 159         phys_addr &= PAGE_MASK;
 160         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 161
 162         /*
 163          * Ok, go for it..
 164          */
 165         area = get_vm_area(size, VM_IOREMAP);
 166         if (!area)
 167                 return NULL;
 168         addr = area->addr;
 169         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 170                 vunmap(addr);
 171                 return NULL;
 172         }
 173
 174         return (void __iomem *) (offset + (char *)addr);
 175 }
 176
 177 #define IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == CKSEG1)
 178
 179 void __iounmap(const volatile void __iomem *addr)
 180 {
 181         struct vm_struct *p;
 182
 183         if (IS_KSEG1(addr))
 184                 return;
 185
 186         p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
 187         if (!p)
 188                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
 189
 190         kfree(p);
 191 }
 192
 193 EXPORT_SYMBOL(__ioremap);
 194 EXPORT_SYMBOL(__iounmap);