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 | _PAGE_PWT);
 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
 212 int __initdata early_ioremap_debug;
 213
 214 static int __init early_ioremap_debug_setup(char *str)
 215 {
 216         early_ioremap_debug = 1;
 217
 218         return 1;
 219 }
 220 __setup("early_ioremap_debug", early_ioremap_debug_setup);
 221
 222 static __initdata int after_paging_init;
 223 static __initdata unsigned long bm_pte[1024]
 224                                 __attribute__((aligned(PAGE_SIZE)));
 225
 226 static inline unsigned long * __init early_ioremap_pgd(unsigned long addr)
 227 {
 228         return (unsigned long *)swapper_pg_dir + ((addr >> 22) & 1023);
 229 }
 230
 231 static inline unsigned long * __init early_ioremap_pte(unsigned long addr)
 232 {
 233         return bm_pte + ((addr >> PAGE_SHIFT) & 1023);
 234 }
 235
 236 void __init early_ioremap_init(void)
 237 {
 238         unsigned long *pgd;
 239
 240         if (early_ioremap_debug)
 241                 printk("early_ioremap_init()\n");
 242
 243         pgd = early_ioremap_pgd(fix_to_virt(FIX_BTMAP_BEGIN));
 244         *pgd = __pa(bm_pte) | _PAGE_TABLE;
 245         memset(bm_pte, 0, sizeof(bm_pte));
 246         BUG_ON(pgd != early_ioremap_pgd(fix_to_virt(FIX_BTMAP_END)));
 247 }
 248
 249 void __init early_ioremap_clear(void)
 250 {
 251         unsigned long *pgd;
 252
 253         if (early_ioremap_debug)
 254                 printk("early_ioremap_clear()\n");
 255
 256         pgd = early_ioremap_pgd(fix_to_virt(FIX_BTMAP_BEGIN));
 257         *pgd = 0;
 258         __flush_tlb_all();
 259 }
 260
 261 void __init early_ioremap_reset(void)
 262 {
 263         enum fixed_addresses idx;
 264         unsigned long *pte, phys, addr;
 265
 266         after_paging_init = 1;
 267         for (idx = FIX_BTMAP_BEGIN; idx >= FIX_BTMAP_END; idx--) {
 268                 addr = fix_to_virt(idx);
 269                 pte = early_ioremap_pte(addr);
 270                 if (!*pte & _PAGE_PRESENT) {
 271                         phys = *pte & PAGE_MASK;
 272                         set_fixmap(idx, phys);
 273                 }
 274         }
 275 }
 276
 277 static void __init __early_set_fixmap(enum fixed_addresses idx,
 278                                    unsigned long phys, pgprot_t flags)
 279 {
 280         unsigned long *pte, addr = __fix_to_virt(idx);
 281
 282         if (idx >= __end_of_fixed_addresses) {
 283                 BUG();
 284                 return;
 285         }
 286         pte = early_ioremap_pte(addr);
 287         if (pgprot_val(flags))
 288                 *pte = (phys & PAGE_MASK) | pgprot_val(flags);
 289         else
 290                 *pte = 0;
 291         __flush_tlb_one(addr);
 292 }
 293
 294 static inline void __init early_set_fixmap(enum fixed_addresses idx,
 295                                         unsigned long phys)
 296 {
 297         if (after_paging_init)
 298                 set_fixmap(idx, phys);
 299         else
 300                 __early_set_fixmap(idx, phys, PAGE_KERNEL);
 301 }
 302
 303 static inline void __init early_clear_fixmap(enum fixed_addresses idx)
 304 {
 305         if (after_paging_init)
 306                 clear_fixmap(idx);
 307         else
 308                 __early_set_fixmap(idx, 0, __pgprot(0));
 309 }
 310
 311
 312 int __initdata early_ioremap_nested;
 313
 314 void __init *early_ioremap(unsigned long phys_addr, unsigned long size)
 315 {
 316         unsigned long offset, last_addr;
 317         unsigned int nrpages, nesting;
 318         enum fixed_addresses idx0, idx;
 319
 320         WARN_ON(system_state != SYSTEM_BOOTING);
 321
 322         nesting = early_ioremap_nested;
 323         if (early_ioremap_debug) {
 324                 printk("early_ioremap(%08lx, %08lx) [%d] => ",
 325                                 phys_addr, size, nesting);
 326                 dump_stack();
 327         }
 328
 329         /* Don't allow wraparound or zero size */
 330         last_addr = phys_addr + size - 1;
 331         if (!size || last_addr < phys_addr) {
 332                 WARN_ON(1);
 333                 return NULL;
 334         }
 335
 336         if (nesting >= FIX_BTMAPS_NESTING) {
 337                 WARN_ON(1);
 338                 return NULL;
 339         }
 340         early_ioremap_nested++;
 341         /*
 342          * Mappings have to be page-aligned
 343          */
 344         offset = phys_addr & ~PAGE_MASK;
 345         phys_addr &= PAGE_MASK;
 346         size = PAGE_ALIGN(last_addr) - phys_addr;
 347
 348         /*
 349          * Mappings have to fit in the FIX_BTMAP area.
 350          */
 351         nrpages = size >> PAGE_SHIFT;
 352         if (nrpages > NR_FIX_BTMAPS) {
 353                 WARN_ON(1);
 354                 return NULL;
 355         }
 356
 357         /*
 358          * Ok, go for it..
 359          */
 360         idx0 = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*nesting;
 361         idx = idx0;
 362         while (nrpages > 0) {
 363                 early_set_fixmap(idx, phys_addr);
 364                 phys_addr += PAGE_SIZE;
 365                 --idx;
 366                 --nrpages;
 367         }
 368         if (early_ioremap_debug)
 369                 printk(KERN_CONT "%08lx + %08lx\n", offset, fix_to_virt(idx0));
 370
 371         return (void*) (offset + fix_to_virt(idx0));
 372 }
 373
 374 void __init early_iounmap(void *addr, unsigned long size)
 375 {
 376         unsigned long virt_addr;
 377         unsigned long offset;
 378         unsigned int nrpages;
 379         enum fixed_addresses idx;
 380         unsigned int nesting;
 381
 382         nesting = --early_ioremap_nested;
 383         WARN_ON(nesting < 0);
 384
 385         if (early_ioremap_debug) {
 386                 printk("early_iounmap(%p, %08lx) [%d]\n", addr, size, nesting);
 387                 dump_stack();
 388         }
 389
 390         virt_addr = (unsigned long)addr;
 391         if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)) {
 392                 WARN_ON(1);
 393                 return;
 394         }
 395         offset = virt_addr & ~PAGE_MASK;
 396         nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
 397
 398         idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*nesting;
 399         while (nrpages > 0) {
 400                 early_clear_fixmap(idx);
 401                 --idx;
 402                 --nrpages;
 403         }
 404 }
 405
 406 void __this_fixmap_does_not_exist(void)
 407 {
 408         WARN_ON(1);
 409 }