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