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/slab.h>
  14 #include <linux/vmalloc.h>
  15 #include <asm/cacheflush.h>
  16 #include <asm/io.h>
  17 #include <asm/tlbflush.h>
  18
  19 static inline void remap_area_pte(pte_t * pte, unsigned long address,
  20         phys_t size, phys_t phys_addr, unsigned long flags)
  21 {
  22         phys_t end;
  23         unsigned long pfn;
  24         pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | __READABLE
  25                                    | __WRITEABLE | flags);
  26
  27         address &= ~PMD_MASK;
  28         end = address + size;
  29         if (end > PMD_SIZE)
  30                 end = PMD_SIZE;
  31         BUG_ON(address >= end);
  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         BUG_ON(address >= end);
  56         do {
  57                 pte_t * pte = pte_alloc_kernel(pmd, address);
  58                 if (!pte)
  59                         return -ENOMEM;
  60                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
  61                 address = (address + PMD_SIZE) & PMD_MASK;
  62                 pmd++;
  63         } while (address && (address < end));
  64         return 0;
  65 }
  66
  67 static int remap_area_pages(unsigned long address, phys_t phys_addr,
  68         phys_t size, unsigned long flags)
  69 {
  70         int error;
  71         pgd_t * dir;
  72         unsigned long end = address + size;
  73
  74         phys_addr -= address;
  75         dir = pgd_offset(&init_mm, address);
  76         flush_cache_all();
  77         BUG_ON(address >= end);
  78         do {
  79                 pud_t *pud;
  80                 pmd_t *pmd;
  81
  82                 error = -ENOMEM;
  83                 pud = pud_alloc(&init_mm, dir, address);
  84                 if (!pud)
  85                         break;
  86                 pmd = pmd_alloc(&init_mm, pud, address);
  87                 if (!pmd)
  88                         break;
  89                 if (remap_area_pmd(pmd, address, end - address,
  90                                          phys_addr + address, flags))
  91                         break;
  92                 error = 0;
  93                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
  94                 dir++;
  95         } while (address && (address < end));
  96         flush_tlb_all();
  97         return error;
  98 }
  99
 100 /*
 101  * Generic mapping function (not visible outside):
 102  */
 103
 104 /*
 105  * Remap an arbitrary physical address space into the kernel virtual
 106  * address space. Needed when the kernel wants to access high addresses
 107  * directly.
 108  *
 109  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 110  * have to convert them into an offset in a page-aligned mapping, but the
 111  * caller shouldn't need to know that small detail.
 112  */
 113
 114 #define IS_LOW512(addr) (!((phys_t)(addr) & (phys_t) ~0x1fffffffULL))
 115
 116 void __iomem * __ioremap(phys_t phys_addr, phys_t size, unsigned long flags)
 117 {
 118         struct vm_struct * area;
 119         unsigned long offset;
 120         phys_t last_addr;
 121         void * addr;
 122
 123         phys_addr = fixup_bigphys_addr(phys_addr, size);
 124
 125         /* Don't allow wraparound or zero size */
 126         last_addr = phys_addr + size - 1;
 127         if (!size || last_addr < phys_addr)
 128                 return NULL;
 129
 130         /*
 131          * Map uncached objects in the low 512mb of address space using KSEG1,
 132          * otherwise map using page tables.
 133          */
 134         if (IS_LOW512(phys_addr) && IS_LOW512(last_addr) &&
 135             flags == _CACHE_UNCACHED)
 136                 return (void __iomem *) CKSEG1ADDR(phys_addr);
 137
 138         /*
 139          * Don't allow anybody to remap normal RAM that we're using..
 140          */
 141         if (phys_addr < virt_to_phys(high_memory)) {
 142                 char *t_addr, *t_end;
 143                 struct page *page;
 144
 145                 t_addr = __va(phys_addr);
 146                 t_end = t_addr + (size - 1);
 147
 148                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 149                         if(!PageReserved(page))
 150                                 return NULL;
 151         }
 152
 153         /*
 154          * Mappings have to be page-aligned
 155          */
 156         offset = phys_addr & ~PAGE_MASK;
 157         phys_addr &= PAGE_MASK;
 158         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 159
 160         /*
 161          * Ok, go for it..
 162          */
 163         area = get_vm_area(size, VM_IOREMAP);
 164         if (!area)
 165                 return NULL;
 166         addr = area->addr;
 167         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 168                 vunmap(addr);
 169                 return NULL;
 170         }
 171
 172         return (void __iomem *) (offset + (char *)addr);
 173 }
 174
 175 #define IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == CKSEG1)
 176
 177 void __iounmap(const volatile void __iomem *addr)
 178 {
 179         struct vm_struct *p;
 180
 181         if (IS_KSEG1(addr))
 182                 return;
 183
 184         p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
 185         if (!p)
 186                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
 187
 188         kfree(p);
 189 }
 190
 191 EXPORT_SYMBOL(__ioremap);
 192 EXPORT_SYMBOL(__iounmap);