arch/x86/mm/ioremap_32.c

   1 /*
   2  * arch/i386/mm/ioremap.c
   3  *
   4  * Re-map IO memory to kernel address space so that we can access it.
   5  * This is needed for high PCI addresses that aren't mapped in the
   6  * 640k-1MB IO memory area on PC's
   7  *
   8  * (C) Copyright 1995 1996 Linus Torvalds
   9  */
  10
  11 #include <linux/vmalloc.h>
  12 #include <linux/init.h>
  13 #include <linux/slab.h>
  14 #include <linux/module.h>
  15 #include <linux/io.h>
  16 #include <asm/fixmap.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/tlbflush.h>
  19 #include <asm/pgtable.h>
  20
  21 #define ISA_START_ADDRESS       0xa0000
  22 #define ISA_END_ADDRESS         0x100000
  23
  24 /*
  25  * Generic mapping function (not visible outside):
  26  */
  27
  28 /*
  29  * Remap an arbitrary physical address space into the kernel virtual
  30  * address space. Needed when the kernel wants to access high addresses
  31  * directly.
  32  *
  33  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
  34  * have to convert them into an offset in a page-aligned mapping, but the
  35  * caller shouldn't need to know that small detail.
  36  */
  37 void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
  38 {
  39         void __iomem * addr;
  40         struct vm_struct * area;
  41         unsigned long offset, last_addr;
  42         pgprot_t prot;
  43
  44         /* Don't allow wraparound or zero size */
  45         last_addr = phys_addr + size - 1;
  46         if (!size || last_addr < phys_addr)
  47                 return NULL;
  48
  49         /*
  50          * Don't remap the low PCI/ISA area, it's always mapped..
  51          */
  52         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
  53                 return (void __iomem *) phys_to_virt(phys_addr);
  54
  55         /*
  56          * Don't allow anybody to remap normal RAM that we're using..
  57          */
  58         if (phys_addr <= virt_to_phys(high_memory - 1)) {
  59                 char *t_addr, *t_end;
  60                 struct page *page;
  61
  62                 t_addr = __va(phys_addr);
  63                 t_end = t_addr + (size - 1);
  64
  65                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
  66                         if(!PageReserved(page))
  67                                 return NULL;
  68         }
  69
  70         prot = __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY
  71                         | _PAGE_ACCESSED | flags);
  72
  73         /*
  74          * Mappings have to be page-aligned
  75          */
  76         offset = phys_addr & ~PAGE_MASK;
  77         phys_addr &= PAGE_MASK;
  78         size = PAGE_ALIGN(last_addr+1) - phys_addr;
  79
  80         /*
  81          * Ok, go for it..
  82          */
  83         area = get_vm_area(size, VM_IOREMAP | (flags << 20));
  84         if (!area)
  85                 return NULL;
  86         area->phys_addr = phys_addr;
  87         addr = (void __iomem *) area->addr;
  88         if (ioremap_page_range((unsigned long) addr,
  89                         (unsigned long) addr + size, phys_addr, prot)) {
  90                 vunmap((void __force *) addr);
  91                 return NULL;
  92         }
  93         return (void __iomem *) (offset + (char __iomem *)addr);
  94 }
  95 EXPORT_SYMBOL(__ioremap);
  96
  97 /**
  98  * ioremap_nocache     -   map bus memory into CPU space
  99  * @offset:    bus address of the memory
 100  * @size:      size of the resource to map
 101  *
 102  * ioremap_nocache performs a platform specific sequence of operations to
 103  * make bus memory CPU accessible via the readb/readw/readl/writeb/
 104  * writew/writel functions and the other mmio helpers. The returned
 105  * address is not guaranteed to be usable directly as a virtual
 106  * address.
 107  *
 108  * This version of ioremap ensures that the memory is marked uncachable
 109  * on the CPU as well as honouring existing caching rules from things like
 110  * the PCI bus. Note that there are other caches and buffers on many
 111  * busses. In particular driver authors should read up on PCI writes
 112  *
 113  * It's useful if some control registers are in such an area and
 114  * write combining or read caching is not desirable:
 115  *
 116  * Must be freed with iounmap.
 117  */
 118
 119 void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
 120 {
 121         unsigned long last_addr;
 122         void __iomem *p = __ioremap(phys_addr, size, _PAGE_PCD);
 123         if (!p)
 124                 return p;
 125
 126         /* Guaranteed to be > phys_addr, as per __ioremap() */
 127         last_addr = phys_addr + size - 1;
 128
 129         if (last_addr < virt_to_phys(high_memory) - 1) {
 130                 struct page *ppage = virt_to_page(__va(phys_addr));
 131                 unsigned long npages;
 132
 133                 phys_addr &= PAGE_MASK;
 134
 135                 /* This might overflow and become zero.. */
 136                 last_addr = PAGE_ALIGN(last_addr);
 137
 138                 /* .. but that's ok, because modulo-2**n arithmetic will make
 139                 * the page-aligned "last - first" come out right.
 140                 */
 141                 npages = (last_addr - phys_addr) >> PAGE_SHIFT;
 142
 143                 if (change_page_attr(ppage, npages, PAGE_KERNEL_NOCACHE) < 0) {
 144                         iounmap(p);
 145                         p = NULL;
 146                 }
 147                 global_flush_tlb();
 148         }
 149
 150         return p;
 151 }
 152 EXPORT_SYMBOL(ioremap_nocache);
 153
 154 /**
 155  * iounmap - Free a IO remapping
 156  * @addr: virtual address from ioremap_*
 157  *
 158  * Caller must ensure there is only one unmapping for the same pointer.
 159  */
 160 void iounmap(volatile void __iomem *addr)
 161 {
 162         struct vm_struct *p, *o;
 163
 164         if ((void __force *)addr <= high_memory)
 165                 return;
 166
 167         /*
 168          * __ioremap special-cases the PCI/ISA range by not instantiating a
 169          * vm_area and by simply returning an address into the kernel mapping
 170          * of ISA space.   So handle that here.
 171          */
 172         if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
 173                         addr < phys_to_virt(ISA_END_ADDRESS))
 174                 return;
 175
 176         addr = (volatile void __iomem *)(PAGE_MASK & (unsigned long __force)addr);
 177
 178         /* Use the vm area unlocked, assuming the caller
 179            ensures there isn't another iounmap for the same address
 180            in parallel. Reuse of the virtual address is prevented by
 181            leaving it in the global lists until we're done with it.
 182            cpa takes care of the direct mappings. */
 183         read_lock(&vmlist_lock);
 184         for (p = vmlist; p; p = p->next) {
 185                 if (p->addr == addr)
 186                         break;
 187         }
 188         read_unlock(&vmlist_lock);
 189
 190         if (!p) {
 191                 printk("iounmap: bad address %p\n", addr);
 192                 dump_stack();
 193                 return;
 194         }
 195
 196         /* Reset the direct mapping. Can block */
 197         if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) {
 198                 change_page_attr(virt_to_page(__va(p->phys_addr)),
 199                                  get_vm_area_size(p) >> PAGE_SHIFT,
 200                                  PAGE_KERNEL);
 201                 global_flush_tlb();
 202         }
 203
 204         /* Finally remove it */
 205         o = remove_vm_area((void *)addr);
 206         BUG_ON(p != o || o == NULL);
 207         kfree(p);
 208 }
 209 EXPORT_SYMBOL(iounmap);
 210
 211 void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
 212 {
 213         unsigned long offset, last_addr;
 214         unsigned int nrpages;
 215         enum fixed_addresses idx;
 216
 217         /* Don't allow wraparound or zero size */
 218         last_addr = phys_addr + size - 1;
 219         if (!size || last_addr < phys_addr)
 220                 return NULL;
 221
 222         /*
 223          * Don't remap the low PCI/ISA area, it's always mapped..
 224          */
 225         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
 226                 return phys_to_virt(phys_addr);
 227
 228         /*
 229          * Mappings have to be page-aligned
 230          */
 231         offset = phys_addr & ~PAGE_MASK;
 232         phys_addr &= PAGE_MASK;
 233         size = PAGE_ALIGN(last_addr) - phys_addr;
 234
 235         /*
 236          * Mappings have to fit in the FIX_BTMAP area.
 237          */
 238         nrpages = size >> PAGE_SHIFT;
 239         if (nrpages > NR_FIX_BTMAPS)
 240                 return NULL;
 241
 242         /*
 243          * Ok, go for it..
 244          */
 245         idx = FIX_BTMAP_BEGIN;
 246         while (nrpages > 0) {
 247                 set_fixmap(idx, phys_addr);
 248                 phys_addr += PAGE_SIZE;
 249                 --idx;
 250                 --nrpages;
 251         }
 252         return (void*) (offset + fix_to_virt(FIX_BTMAP_BEGIN));
 253 }
 254
 255 void __init bt_iounmap(void *addr, unsigned long size)
 256 {
 257         unsigned long virt_addr;
 258         unsigned long offset;
 259         unsigned int nrpages;
 260         enum fixed_addresses idx;
 261
 262         virt_addr = (unsigned long)addr;
 263         if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN))
 264                 return;
 265         offset = virt_addr & ~PAGE_MASK;
 266         nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
 267
 268         idx = FIX_BTMAP_BEGIN;
 269         while (nrpages > 0) {
 270                 clear_fixmap(idx);
 271                 --idx;
 272                 --nrpages;
 273         }
 274 }