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