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
  16 extern inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
  17         unsigned long phys_addr, unsigned long flags)
  18 {
  19         unsigned long end;
  20
  21         address &= ~PMD_MASK;
  22         end = address + size;
  23         if (end > PMD_SIZE)
  24                 end = PMD_SIZE;
  25         if (address >= end)
  26                 BUG();
  27         do {
  28                 if (!pte_none(*pte)) {
  29                         printk("remap_area_pte: page already exists\n");
  30                         BUG();
  31                 }
  32                 set_pte(pte, mk_pte_phys(phys_addr, __pgprot(_PAGE_PRESENT | __READABLE |
  33                                                              __WRITEABLE | _PAGE_GLOBAL |
  34                                                              _PAGE_KERNEL | flags)));
  35                 address += PAGE_SIZE;
  36                 phys_addr += PAGE_SIZE;
  37                 pte++;
  38         } while (address && (address < end));
  39 }
  40
  41 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
  42         unsigned long phys_addr, unsigned long flags)
  43 {
  44         unsigned long end;
  45
  46         address &= ~PGDIR_MASK;
  47         end = address + size;
  48         if (end > PGDIR_SIZE)
  49                 end = PGDIR_SIZE;
  50         phys_addr -= address;
  51         if (address >= end)
  52                 BUG();
  53         do {
  54                 pte_t * pte = pte_alloc(&init_mm, pmd, address);
  55                 if (!pte)
  56                         return -ENOMEM;
  57                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
  58                 address = (address + PMD_SIZE) & PMD_MASK;
  59                 pmd++;
  60         } while (address && (address < end));
  61         return 0;
  62 }
  63
  64 static int remap_area_pages(unsigned long address, unsigned long phys_addr,
  65                                  unsigned long size, unsigned long flags)
  66 {
  67         int error;
  68         pgd_t * dir;
  69         unsigned long end = address + size;
  70
  71         phys_addr -= address;
  72         dir = pgd_offset(&init_mm, address);
  73         flush_cache_all();
  74         if (address >= end)
  75                 BUG();
  76         spin_lock(&init_mm.page_table_lock);
  77         do {
  78                 pmd_t *pmd;
  79                 pmd = pmd_alloc(&init_mm, dir, address);
  80                 error = -ENOMEM;
  81                 if (!pmd)
  82                         break;
  83                 if (remap_area_pmd(pmd, address, end - address,
  84                                    phys_addr + address, flags))
  85                         break;
  86                 error = 0;
  87                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
  88                 dir++;
  89         } while (address && (address < end));
  90         spin_unlock(&init_mm.page_table_lock);
  91         flush_tlb_all();
  92         return error;
  93 }
  94
  95 /*
  96  * Generic mapping function (not visible outside):
  97  */
  98
  99 /*
 100  * Remap an arbitrary physical address space into the kernel virtual
 101  * address space. Needed when the kernel wants to access high addresses
 102  * directly.
 103  *
 104  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 105  * have to convert them into an offset in a page-aligned mapping, but the
 106  * caller shouldn't need to know that small detail.
 107  */
 108 void * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 109 {
 110         void * addr;
 111         struct vm_struct * area;
 112         unsigned long offset, last_addr;
 113
 114         /* Don't allow wraparound or zero size */
 115         last_addr = phys_addr + size - 1;
 116         if (!size || last_addr < phys_addr)
 117                 return NULL;
 118
 119 #if 0
 120         /* TODO: Here we can put checks for driver-writer abuse...  */
 121
 122         /*
 123          * Don't remap the low PCI/ISA area, it's always mapped..
 124          */
 125         if (phys_addr >= 0xA0000 && last_addr < 0x100000)
 126                 return phys_to_virt(phys_addr);
 127
 128         /*
 129          * Don't allow anybody to remap normal RAM that we're using..
 130          */
 131         if (phys_addr < virt_to_phys(high_memory)) {
 132                 char *t_addr, *t_end;
 133                 struct page *page;
 134
 135                 t_addr = __va(phys_addr);
 136                 t_end = t_addr + (size - 1);
 137
 138                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 139                         if(!PageReserved(page))
 140                                 return NULL;
 141         }
 142 #endif
 143
 144         /*
 145          * Mappings have to be page-aligned
 146          */
 147         offset = phys_addr & ~PAGE_MASK;
 148         phys_addr &= PAGE_MASK;
 149         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 150
 151         /*
 152          * Ok, go for it..
 153          */
 154         area = get_vm_area(size, VM_IOREMAP);
 155         if (!area)
 156                 return NULL;
 157         addr = area->addr;
 158         if (remap_area_pages(VMALLOC_VMADDR(addr), phys_addr, size, flags)) {
 159                 vfree(addr);
 160                 return NULL;
 161         }
 162         return (void *) (offset + (char *)addr);
 163 }
 164
 165 void iounmap(void *addr)
 166 {
 167         if (addr > high_memory)
 168                 return vfree((void *) (PAGE_MASK & (unsigned long) addr));
 169 }