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 0;
 219 }
 220 early_param("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         /*
 247          * The boot-ioremap range spans multiple pgds, for which
 248          * we are not prepared:
 249          */
 250         if (pgd != early_ioremap_pgd(fix_to_virt(FIX_BTMAP_END))) {
 251                 WARN_ON(1);
 252                 printk("pgd %p != %p\n",
 253                         pgd, early_ioremap_pgd(fix_to_virt(FIX_BTMAP_END)));
 254                 printk("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
 255                         fix_to_virt(FIX_BTMAP_BEGIN));
 256                 printk("fix_to_virt(FIX_BTMAP_END):   %08lx\n",
 257                         fix_to_virt(FIX_BTMAP_END));
 258
 259                 printk("FIX_BTMAP_END:       %d\n", FIX_BTMAP_END);
 260                 printk("FIX_BTMAP_BEGIN:     %d\n", FIX_BTMAP_BEGIN);
 261         }
 262 }
 263
 264 void __init early_ioremap_clear(void)
 265 {
 266         unsigned long *pgd;
 267
 268         if (early_ioremap_debug)
 269                 printk("early_ioremap_clear()\n");
 270
 271         pgd = early_ioremap_pgd(fix_to_virt(FIX_BTMAP_BEGIN));
 272         *pgd = 0;
 273         __flush_tlb_all();
 274 }
 275
 276 void __init early_ioremap_reset(void)
 277 {
 278         enum fixed_addresses idx;
 279         unsigned long *pte, phys, addr;
 280
 281         after_paging_init = 1;
 282         for (idx = FIX_BTMAP_BEGIN; idx >= FIX_BTMAP_END; idx--) {
 283                 addr = fix_to_virt(idx);
 284                 pte = early_ioremap_pte(addr);
 285                 if (!*pte & _PAGE_PRESENT) {
 286                         phys = *pte & PAGE_MASK;
 287                         set_fixmap(idx, phys);
 288                 }
 289         }
 290 }
 291
 292 static void __init __early_set_fixmap(enum fixed_addresses idx,
 293                                    unsigned long phys, pgprot_t flags)
 294 {
 295         unsigned long *pte, addr = __fix_to_virt(idx);
 296
 297         if (idx >= __end_of_fixed_addresses) {
 298                 BUG();
 299                 return;
 300         }
 301         pte = early_ioremap_pte(addr);
 302         if (pgprot_val(flags))
 303                 *pte = (phys & PAGE_MASK) | pgprot_val(flags);
 304         else
 305                 *pte = 0;
 306         __flush_tlb_one(addr);
 307 }
 308
 309 static inline void __init early_set_fixmap(enum fixed_addresses idx,
 310                                         unsigned long phys)
 311 {
 312         if (after_paging_init)
 313                 set_fixmap(idx, phys);
 314         else
 315                 __early_set_fixmap(idx, phys, PAGE_KERNEL);
 316 }
 317
 318 static inline void __init early_clear_fixmap(enum fixed_addresses idx)
 319 {
 320         if (after_paging_init)
 321                 clear_fixmap(idx);
 322         else
 323                 __early_set_fixmap(idx, 0, __pgprot(0));
 324 }
 325
 326
 327 int __initdata early_ioremap_nested;
 328
 329 static int __init check_early_ioremap_leak(void)
 330 {
 331         if (!early_ioremap_nested)
 332                 return 0;
 333
 334         printk(KERN_WARNING
 335                 "Debug warning: early ioremap leak of %d areas detected.\n",
 336                         early_ioremap_nested);
 337         printk(KERN_WARNING
 338                 "please boot with early_ioremap_debug and report the dmesg.\n");
 339         WARN_ON(1);
 340
 341         return 1;
 342 }
 343 late_initcall(check_early_ioremap_leak);
 344
 345 void __init *early_ioremap(unsigned long phys_addr, unsigned long size)
 346 {
 347         unsigned long offset, last_addr;
 348         unsigned int nrpages, nesting;
 349         enum fixed_addresses idx0, idx;
 350
 351         WARN_ON(system_state != SYSTEM_BOOTING);
 352
 353         nesting = early_ioremap_nested;
 354         if (early_ioremap_debug) {
 355                 printk("early_ioremap(%08lx, %08lx) [%d] => ",
 356                                 phys_addr, size, nesting);
 357                 dump_stack();
 358         }
 359
 360         /* Don't allow wraparound or zero size */
 361         last_addr = phys_addr + size - 1;
 362         if (!size || last_addr < phys_addr) {
 363                 WARN_ON(1);
 364                 return NULL;
 365         }
 366
 367         if (nesting >= FIX_BTMAPS_NESTING) {
 368                 WARN_ON(1);
 369                 return NULL;
 370         }
 371         early_ioremap_nested++;
 372         /*
 373          * Mappings have to be page-aligned
 374          */
 375         offset = phys_addr & ~PAGE_MASK;
 376         phys_addr &= PAGE_MASK;
 377         size = PAGE_ALIGN(last_addr) - phys_addr;
 378
 379         /*
 380          * Mappings have to fit in the FIX_BTMAP area.
 381          */
 382         nrpages = size >> PAGE_SHIFT;
 383         if (nrpages > NR_FIX_BTMAPS) {
 384                 WARN_ON(1);
 385                 return NULL;
 386         }
 387
 388         /*
 389          * Ok, go for it..
 390          */
 391         idx0 = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*nesting;
 392         idx = idx0;
 393         while (nrpages > 0) {
 394                 early_set_fixmap(idx, phys_addr);
 395                 phys_addr += PAGE_SIZE;
 396                 --idx;
 397                 --nrpages;
 398         }
 399         if (early_ioremap_debug)
 400                 printk(KERN_CONT "%08lx + %08lx\n", offset, fix_to_virt(idx0));
 401
 402         return (void*) (offset + fix_to_virt(idx0));
 403 }
 404
 405 void __init early_iounmap(void *addr, unsigned long size)
 406 {
 407         unsigned long virt_addr;
 408         unsigned long offset;
 409         unsigned int nrpages;
 410         enum fixed_addresses idx;
 411         unsigned int nesting;
 412
 413         nesting = --early_ioremap_nested;
 414         WARN_ON(nesting < 0);
 415
 416         if (early_ioremap_debug) {
 417                 printk("early_iounmap(%p, %08lx) [%d]\n", addr, size, nesting);
 418                 dump_stack();
 419         }
 420
 421         virt_addr = (unsigned long)addr;
 422         if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)) {
 423                 WARN_ON(1);
 424                 return;
 425         }
 426         offset = virt_addr & ~PAGE_MASK;
 427         nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
 428
 429         idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*nesting;
 430         while (nrpages > 0) {
 431                 early_clear_fixmap(idx);
 432                 --idx;
 433                 --nrpages;
 434         }
 435 }
 436
 437 void __this_fixmap_does_not_exist(void)
 438 {
 439         WARN_ON(1);
 440 }