arch/arm/mm/ioremap.c

   1 /*
   2  *  linux/arch/arm/mm/ioremap.c
   3  *
   4  * Re-map IO memory to kernel address space so that we can access it.
   5  *
   6  * (C) Copyright 1995 1996 Linus Torvalds
   7  *
   8  * Hacked for ARM by Phil Blundell <philb@gnu.org>
   9  * Hacked to allow all architectures to build, and various cleanups
  10  * by Russell King
  11  *
  12  * This allows a driver to remap an arbitrary region of bus memory into
  13  * virtual space.  One should *only* use readl, writel, memcpy_toio and
  14  * so on with such remapped areas.
  15  *
  16  * Because the ARM only has a 32-bit address space we can't address the
  17  * whole of the (physical) PCI space at once.  PCI huge-mode addressing
  18  * allows us to circumvent this restriction by splitting PCI space into
  19  * two 2GB chunks and mapping only one at a time into processor memory.
  20  * We use MMU protection domains to trap any attempt to access the bank
  21  * that is not currently mapped.  (This isn't fully implemented yet.)
  22  */
  23 #include <linux/module.h>
  24 #include <linux/errno.h>
  25 #include <linux/mm.h>
  26 #include <linux/vmalloc.h>
  27
  28 #include <asm/cacheflush.h>
  29 #include <asm/io.h>
  30 #include <asm/mmu_context.h>
  31 #include <asm/pgalloc.h>
  32 #include <asm/tlbflush.h>
  33 #include <asm/sizes.h>
  34
  35 /*
  36  * Used by ioremap() and iounmap() code to mark (super)section-mapped
  37  * I/O regions in vm_struct->flags field.
  38  */
  39 #define VM_ARM_SECTION_MAPPING  0x80000000
  40
  41 static inline void
  42 remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
  43                unsigned long phys_addr, pgprot_t pgprot)
  44 {
  45         unsigned long end;
  46
  47         address &= ~PMD_MASK;
  48         end = address + size;
  49         if (end > PMD_SIZE)
  50                 end = PMD_SIZE;
  51         BUG_ON(address >= end);
  52         do {
  53                 if (!pte_none(*pte))
  54                         goto bad;
  55
  56                 set_pte(pte, pfn_pte(phys_addr >> PAGE_SHIFT, pgprot));
  57                 address += PAGE_SIZE;
  58                 phys_addr += PAGE_SIZE;
  59                 pte++;
  60         } while (address && (address < end));
  61         return;
  62
  63  bad:
  64         printk("remap_area_pte: page already exists\n");
  65         BUG();
  66 }
  67
  68 static inline int
  69 remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
  70                unsigned long phys_addr, unsigned long flags)
  71 {
  72         unsigned long end;
  73         pgprot_t pgprot;
  74
  75         address &= ~PGDIR_MASK;
  76         end = address + size;
  77
  78         if (end > PGDIR_SIZE)
  79                 end = PGDIR_SIZE;
  80
  81         phys_addr -= address;
  82         BUG_ON(address >= end);
  83
  84         pgprot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | L_PTE_WRITE | flags);
  85         do {
  86                 pte_t * pte = pte_alloc_kernel(pmd, address);
  87                 if (!pte)
  88                         return -ENOMEM;
  89                 remap_area_pte(pte, address, end - address, address + phys_addr, pgprot);
  90                 address = (address + PMD_SIZE) & PMD_MASK;
  91                 pmd++;
  92         } while (address && (address < end));
  93         return 0;
  94 }
  95
  96 static int
  97 remap_area_pages(unsigned long start, unsigned long pfn,
  98                  unsigned long size, unsigned long flags)
  99 {
 100         unsigned long address = start;
 101         unsigned long end = start + size;
 102         unsigned long phys_addr = __pfn_to_phys(pfn);
 103         int err = 0;
 104         pgd_t * dir;
 105
 106         phys_addr -= address;
 107         dir = pgd_offset(&init_mm, address);
 108         BUG_ON(address >= end);
 109         do {
 110                 pmd_t *pmd = pmd_alloc(&init_mm, dir, address);
 111                 if (!pmd) {
 112                         err = -ENOMEM;
 113                         break;
 114                 }
 115                 if (remap_area_pmd(pmd, address, end - address,
 116                                          phys_addr + address, flags)) {
 117                         err = -ENOMEM;
 118                         break;
 119                 }
 120
 121                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 122                 dir++;
 123         } while (address && (address < end));
 124
 125         return err;
 126 }
 127
 128
 129 void __check_kvm_seq(struct mm_struct *mm)
 130 {
 131         unsigned int seq;
 132
 133         do {
 134                 seq = init_mm.context.kvm_seq;
 135                 memcpy(pgd_offset(mm, VMALLOC_START),
 136                        pgd_offset_k(VMALLOC_START),
 137                        sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
 138                                         pgd_index(VMALLOC_START)));
 139                 mm->context.kvm_seq = seq;
 140         } while (seq != init_mm.context.kvm_seq);
 141 }
 142
 143 #ifndef CONFIG_SMP
 144 /*
 145  * Section support is unsafe on SMP - If you iounmap and ioremap a region,
 146  * the other CPUs will not see this change until their next context switch.
 147  * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
 148  * which requires the new ioremap'd region to be referenced, the CPU will
 149  * reference the _old_ region.
 150  *
 151  * Note that get_vm_area() allocates a guard 4K page, so we need to mask
 152  * the size back to 1MB aligned or we will overflow in the loop below.
 153  */
 154 static void unmap_area_sections(unsigned long virt, unsigned long size)
 155 {
 156         unsigned long addr = virt, end = virt + (size & ~SZ_1M);
 157         pgd_t *pgd;
 158
 159         flush_cache_vunmap(addr, end);
 160         pgd = pgd_offset_k(addr);
 161         do {
 162                 pmd_t pmd, *pmdp = pmd_offset(pgd, addr);
 163
 164                 pmd = *pmdp;
 165                 if (!pmd_none(pmd)) {
 166                         /*
 167                          * Clear the PMD from the page table, and
 168                          * increment the kvm sequence so others
 169                          * notice this change.
 170                          *
 171                          * Note: this is still racy on SMP machines.
 172                          */
 173                         pmd_clear(pmdp);
 174                         init_mm.context.kvm_seq++;
 175
 176                         /*
 177                          * Free the page table, if there was one.
 178                          */
 179                         if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
 180                                 pte_free_kernel(pmd_page_kernel(pmd));
 181                 }
 182
 183                 addr += PGDIR_SIZE;
 184                 pgd++;
 185         } while (addr < end);
 186
 187         /*
 188          * Ensure that the active_mm is up to date - we want to
 189          * catch any use-after-iounmap cases.
 190          */
 191         if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
 192                 __check_kvm_seq(current->active_mm);
 193
 194         flush_tlb_kernel_range(virt, end);
 195 }
 196
 197 static int
 198 remap_area_sections(unsigned long virt, unsigned long pfn,
 199                     unsigned long size, unsigned long flags)
 200 {
 201         unsigned long prot, addr = virt, end = virt + size;
 202         pgd_t *pgd;
 203
 204         /*
 205          * Remove and free any PTE-based mapping, and
 206          * sync the current kernel mapping.
 207          */
 208         unmap_area_sections(virt, size);
 209
 210         prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_DOMAIN(DOMAIN_IO) |
 211                (flags & (L_PTE_CACHEABLE | L_PTE_BUFFERABLE));
 212
 213         /*
 214          * ARMv6 and above need XN set to prevent speculative prefetches
 215          * hitting IO.
 216          */
 217         if (cpu_architecture() >= CPU_ARCH_ARMv6)
 218                 prot |= PMD_SECT_XN;
 219
 220         pgd = pgd_offset_k(addr);
 221         do {
 222                 pmd_t *pmd = pmd_offset(pgd, addr);
 223
 224                 pmd[0] = __pmd(__pfn_to_phys(pfn) | prot);
 225                 pfn += SZ_1M >> PAGE_SHIFT;
 226                 pmd[1] = __pmd(__pfn_to_phys(pfn) | prot);
 227                 pfn += SZ_1M >> PAGE_SHIFT;
 228                 flush_pmd_entry(pmd);
 229
 230                 addr += PGDIR_SIZE;
 231                 pgd++;
 232         } while (addr < end);
 233
 234         return 0;
 235 }
 236
 237 static int
 238 remap_area_supersections(unsigned long virt, unsigned long pfn,
 239                          unsigned long size, unsigned long flags)
 240 {
 241         unsigned long prot, addr = virt, end = virt + size;
 242         pgd_t *pgd;
 243
 244         /*
 245          * Remove and free any PTE-based mapping, and
 246          * sync the current kernel mapping.
 247          */
 248         unmap_area_sections(virt, size);
 249
 250         prot = PMD_TYPE_SECT | PMD_SECT_SUPER | PMD_SECT_AP_WRITE |
 251                         PMD_DOMAIN(DOMAIN_IO) |
 252                         (flags & (L_PTE_CACHEABLE | L_PTE_BUFFERABLE));
 253
 254         /*
 255          * ARMv6 and above need XN set to prevent speculative prefetches
 256          * hitting IO.
 257          */
 258         if (cpu_architecture() >= CPU_ARCH_ARMv6)
 259                 prot |= PMD_SECT_XN;
 260
 261         pgd = pgd_offset_k(virt);
 262         do {
 263                 unsigned long super_pmd_val, i;
 264
 265                 super_pmd_val = __pfn_to_phys(pfn) | prot;
 266                 super_pmd_val |= ((pfn >> (32 - PAGE_SHIFT)) & 0xf) << 20;
 267
 268                 for (i = 0; i < 8; i++) {
 269                         pmd_t *pmd = pmd_offset(pgd, addr);
 270
 271                         pmd[0] = __pmd(super_pmd_val);
 272                         pmd[1] = __pmd(super_pmd_val);
 273                         flush_pmd_entry(pmd);
 274
 275                         addr += PGDIR_SIZE;
 276                         pgd++;
 277                 }
 278
 279                 pfn += SUPERSECTION_SIZE >> PAGE_SHIFT;
 280         } while (addr < end);
 281
 282         return 0;
 283 }
 284 #endif
 285
 286
 287 /*
 288  * Remap an arbitrary physical address space into the kernel virtual
 289  * address space. Needed when the kernel wants to access high addresses
 290  * directly.
 291  *
 292  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 293  * have to convert them into an offset in a page-aligned mapping, but the
 294  * caller shouldn't need to know that small detail.
 295  *
 296  * 'flags' are the extra L_PTE_ flags that you want to specify for this
 297  * mapping.  See include/asm-arm/proc-armv/pgtable.h for more information.
 298  */
 299 void __iomem *
 300 __ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
 301               unsigned long flags)
 302 {
 303         int err;
 304         unsigned long addr;
 305         struct vm_struct * area;
 306
 307         /*
 308          * High mappings must be supersection aligned
 309          */
 310         if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
 311                 return NULL;
 312
 313         area = get_vm_area(size, VM_IOREMAP);
 314         if (!area)
 315                 return NULL;
 316         addr = (unsigned long)area->addr;
 317
 318 #ifndef CONFIG_SMP
 319         if ((((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) ||
 320                cpu_is_xsc3()) &&
 321                !((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
 322                 area->flags |= VM_ARM_SECTION_MAPPING;
 323                 err = remap_area_supersections(addr, pfn, size, flags);
 324         } else if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
 325                 area->flags |= VM_ARM_SECTION_MAPPING;
 326                 err = remap_area_sections(addr, pfn, size, flags);
 327         } else
 328 #endif
 329                 err = remap_area_pages(addr, pfn, size, flags);
 330
 331         if (err) {
 332                 vunmap((void *)addr);
 333                 return NULL;
 334         }
 335
 336         flush_cache_vmap(addr, addr + size);
 337         return (void __iomem *) (offset + addr);
 338 }
 339 EXPORT_SYMBOL(__ioremap_pfn);
 340
 341 void __iomem *
 342 __ioremap(unsigned long phys_addr, size_t size, unsigned long flags)
 343 {
 344         unsigned long last_addr;
 345         unsigned long offset = phys_addr & ~PAGE_MASK;
 346         unsigned long pfn = __phys_to_pfn(phys_addr);
 347
 348         /*
 349          * Don't allow wraparound or zero size
 350          */
 351         last_addr = phys_addr + size - 1;
 352         if (!size || last_addr < phys_addr)
 353                 return NULL;
 354
 355         /*
 356          * Page align the mapping size
 357          */
 358         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 359
 360         return __ioremap_pfn(pfn, offset, size, flags);
 361 }
 362 EXPORT_SYMBOL(__ioremap);
 363
 364 void __iounmap(void __iomem *addr)
 365 {
 366 #ifndef CONFIG_SMP
 367         struct vm_struct **p, *tmp;
 368 #endif
 369         unsigned int section_mapping = 0;
 370
 371         addr = (void __iomem *)(PAGE_MASK & (unsigned long)addr);
 372
 373 #ifndef CONFIG_SMP
 374         /*
 375          * If this is a section based mapping we need to handle it
 376          * specially as the VM subysystem does not know how to handle
 377          * such a beast. We need the lock here b/c we need to clear
 378          * all the mappings before the area can be reclaimed
 379          * by someone else.
 380          */
 381         write_lock(&vmlist_lock);
 382         for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
 383                 if((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
 384                         if (tmp->flags & VM_ARM_SECTION_MAPPING) {
 385                                 *p = tmp->next;
 386                                 unmap_area_sections((unsigned long)tmp->addr,
 387                                                     tmp->size);
 388                                 kfree(tmp);
 389                                 section_mapping = 1;
 390                         }
 391                         break;
 392                 }
 393         }
 394         write_unlock(&vmlist_lock);
 395 #endif
 396
 397         if (!section_mapping)
 398                 vunmap(addr);
 399 }
 400 EXPORT_SYMBOL(__iounmap);