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/ioport.h>
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/mm_types.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/io.h>
  19 #include <asm/tlbflush.h>
  20
  21 static inline void remap_area_pte(pte_t * pte, unsigned long address,
  22         phys_addr_t size, phys_addr_t phys_addr, unsigned long flags)
  23 {
  24         phys_addr_t end;
  25         unsigned long pfn;
  26         pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | __READABLE
  27                                    | __WRITEABLE | flags);
  28
  29         address &= ~PMD_MASK;
  30         end = address + size;
  31         if (end > PMD_SIZE)
  32                 end = PMD_SIZE;
  33         BUG_ON(address >= end);
  34         pfn = phys_addr >> PAGE_SHIFT;
  35         do {
  36                 if (!pte_none(*pte)) {
  37                         printk("remap_area_pte: page already exists\n");
  38                         BUG();
  39                 }
  40                 set_pte(pte, pfn_pte(pfn, pgprot));
  41                 address += PAGE_SIZE;
  42                 pfn++;
  43                 pte++;
  44         } while (address && (address < end));
  45 }
  46
  47 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address,
  48         phys_addr_t size, phys_addr_t phys_addr, unsigned long flags)
  49 {
  50         phys_addr_t end;
  51
  52         address &= ~PGDIR_MASK;
  53         end = address + size;
  54         if (end > PGDIR_SIZE)
  55                 end = PGDIR_SIZE;
  56         phys_addr -= address;
  57         BUG_ON(address >= end);
  58         do {
  59                 pte_t * pte = pte_alloc_kernel(pmd, address);
  60                 if (!pte)
  61                         return -ENOMEM;
  62                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
  63                 address = (address + PMD_SIZE) & PMD_MASK;
  64                 pmd++;
  65         } while (address && (address < end));
  66         return 0;
  67 }
  68
  69 static int remap_area_pages(unsigned long address, phys_addr_t phys_addr,
  70         phys_addr_t size, unsigned long flags)
  71 {
  72         int error;
  73         pgd_t * dir;
  74         unsigned long end = address + size;
  75
  76         phys_addr -= address;
  77         dir = pgd_offset(&init_mm, address);
  78         flush_cache_all();
  79         BUG_ON(address >= end);
  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 static int __ioremap_check_ram(unsigned long start_pfn, unsigned long nr_pages,
 103                                void *arg)
 104 {
 105         unsigned long i;
 106
 107         for (i = 0; i < nr_pages; i++) {
 108                 if (pfn_valid(start_pfn + i) &&
 109                     !PageReserved(pfn_to_page(start_pfn + i)))
 110                         return 1;
 111         }
 112
 113         return 0;
 114 }
 115
 116 /*
 117  * Generic mapping function (not visible outside):
 118  */
 119
 120 /*
 121  * Remap an arbitrary physical address space into the kernel virtual
 122  * address space. Needed when the kernel wants to access high addresses
 123  * directly.
 124  *
 125  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 126  * have to convert them into an offset in a page-aligned mapping, but the
 127  * caller shouldn't need to know that small detail.
 128  */
 129
 130 #define IS_LOW512(addr) (!((phys_addr_t)(addr) & (phys_addr_t) ~0x1fffffffULL))
 131
 132 void __iomem * __ioremap(phys_addr_t phys_addr, phys_addr_t size, unsigned long flags)
 133 {
 134         unsigned long offset, pfn, last_pfn;
 135         struct vm_struct * area;
 136         phys_addr_t last_addr;
 137         void * addr;
 138
 139         phys_addr = fixup_bigphys_addr(phys_addr, size);
 140
 141         /* Don't allow wraparound or zero size */
 142         last_addr = phys_addr + size - 1;
 143         if (!size || last_addr < phys_addr)
 144                 return NULL;
 145
 146         /*
 147          * Map uncached objects in the low 512mb of address space using KSEG1,
 148          * otherwise map using page tables.
 149          */
 150         if (IS_LOW512(phys_addr) && IS_LOW512(last_addr) &&
 151             flags == _CACHE_UNCACHED)
 152                 return (void __iomem *) CKSEG1ADDR(phys_addr);
 153
 154         /*
 155          * Don't allow anybody to remap RAM that may be allocated by the page
 156          * allocator, since that could lead to races & data clobbering.
 157          */
 158         pfn = PFN_DOWN(phys_addr);
 159         last_pfn = PFN_DOWN(last_addr);
 160         if (walk_system_ram_range(pfn, last_pfn - pfn + 1, NULL,
 161                                   __ioremap_check_ram) == 1) {
 162                 WARN_ONCE(1, "ioremap on RAM at %pa - %pa\n",
 163                           &phys_addr, &last_addr);
 164                 return NULL;
 165         }
 166
 167         /*
 168          * Mappings have to be page-aligned
 169          */
 170         offset = phys_addr & ~PAGE_MASK;
 171         phys_addr &= PAGE_MASK;
 172         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 173
 174         /*
 175          * Ok, go for it..
 176          */
 177         area = get_vm_area(size, VM_IOREMAP);
 178         if (!area)
 179                 return NULL;
 180         addr = area->addr;
 181         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 182                 vunmap(addr);
 183                 return NULL;
 184         }
 185
 186         return (void __iomem *) (offset + (char *)addr);
 187 }
 188
 189 #define IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == CKSEG1)
 190
 191 void __iounmap(const volatile void __iomem *addr)
 192 {
 193         struct vm_struct *p;
 194
 195         if (IS_KSEG1(addr))
 196                 return;
 197
 198         p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
 199         if (!p)
 200                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
 201
 202         kfree(p);
 203 }
 204
 205 EXPORT_SYMBOL(__ioremap);
 206 EXPORT_SYMBOL(__iounmap);