arch/cris/mm/ioremap.c

   1 /*
   2  * arch/cris/mm/ioremap.c
   3  *
   4  * Re-map IO memory to kernel address space so that we can access it.
   5  * Needed for memory-mapped I/O devices mapped outside our normal DRAM
   6  * window (that is, all memory-mapped I/O devices).
   7  *
   8  * (C) Copyright 1995 1996 Linus Torvalds
   9  * CRIS-port by Axis Communications AB
  10  */
  11
  12 #include <linux/vmalloc.h>
  13 #include <asm/io.h>
  14 #include <asm/pgalloc.h>
  15 #include <asm/cacheflush.h>
  16 #include <asm/tlbflush.h>
  17
  18 extern inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
  19         unsigned long phys_addr, unsigned long flags)
  20 {
  21         unsigned long end;
  22
  23         address &= ~PMD_MASK;
  24         end = address + size;
  25         if (end > PMD_SIZE)
  26                 end = PMD_SIZE;
  27         if (address >= end)
  28                 BUG();
  29         do {
  30                 if (!pte_none(*pte)) {
  31                         printk("remap_area_pte: page already exists\n");
  32                         BUG();
  33                 }
  34                 set_pte(pte, mk_pte_phys(phys_addr, __pgprot(_PAGE_PRESENT | __READABLE |
  35                                                              __WRITEABLE | _PAGE_GLOBAL |
  36                                                              _PAGE_KERNEL | flags)));
  37                 address += PAGE_SIZE;
  38                 phys_addr += PAGE_SIZE;
  39                 pte++;
  40         } while (address && (address < end));
  41 }
  42
  43 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
  44         unsigned long phys_addr, unsigned long flags)
  45 {
  46         unsigned long end;
  47
  48         address &= ~PGDIR_MASK;
  49         end = address + size;
  50         if (end > PGDIR_SIZE)
  51                 end = PGDIR_SIZE;
  52         phys_addr -= address;
  53         if (address >= end)
  54                 BUG();
  55         do {
  56                 pte_t * pte = pte_alloc_kernel(&init_mm, 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, unsigned long phys_addr,
  67                                  unsigned long 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         if (address >= end)
  77                 BUG();
  78         spin_lock(&init_mm.page_table_lock);
  79         do {
  80                 pmd_t *pmd;
  81                 pmd = pmd_alloc(&init_mm, dir, address);
  82                 error = -ENOMEM;
  83                 if (!pmd)
  84                         break;
  85                 if (remap_area_pmd(pmd, address, end - address,
  86                                    phys_addr + address, flags))
  87                         break;
  88                 error = 0;
  89                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
  90                 dir++;
  91         } while (address && (address < end));
  92         spin_unlock(&init_mm.page_table_lock);
  93         flush_tlb_all();
  94         return error;
  95 }
  96
  97 /*
  98  * Generic mapping function (not visible outside):
  99  */
 100
 101 /*
 102  * Remap an arbitrary physical address space into the kernel virtual
 103  * address space. Needed when the kernel wants to access high addresses
 104  * directly.
 105  *
 106  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 107  * have to convert them into an offset in a page-aligned mapping, but the
 108  * caller shouldn't need to know that small detail.
 109  */
 110 void * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 111 {
 112         void * addr;
 113         struct vm_struct * area;
 114         unsigned long offset, last_addr;
 115
 116         /* Don't allow wraparound or zero size */
 117         last_addr = phys_addr + size - 1;
 118         if (!size || last_addr < phys_addr)
 119                 return NULL;
 120
 121         /*
 122          * Mappings have to be page-aligned
 123          */
 124         offset = phys_addr & ~PAGE_MASK;
 125         phys_addr &= PAGE_MASK;
 126         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 127
 128         /*
 129          * Ok, go for it..
 130          */
 131         area = get_vm_area(size, VM_IOREMAP);
 132         if (!area)
 133                 return NULL;
 134         addr = area->addr;
 135         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 136                 vfree(addr);
 137                 return NULL;
 138         }
 139         return (void *) (offset + (char *)addr);
 140 }
 141
 142 void iounmap(void *addr)
 143 {
 144         if (addr > high_memory)
 145                 return vfree((void *) (PAGE_MASK & (unsigned long) addr));
 146 }