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 #include <asm/mach/map.h>
  36 #include "mm.h"
  37
  38 /*
  39  * Used by ioremap() and iounmap() code to mark (super)section-mapped
  40  * I/O regions in vm_struct->flags field.
  41  */
  42 #define VM_ARM_SECTION_MAPPING  0x80000000
  43
  44 static int remap_area_pte(pmd_t *pmd, unsigned long addr, unsigned long end,
  45                           unsigned long phys_addr, const struct mem_type *type)
  46 {
  47         pgprot_t prot = __pgprot(type->prot_pte);
  48         pte_t *pte;
  49
  50         pte = pte_alloc_kernel(pmd, addr);
  51         if (!pte)
  52                 return -ENOMEM;
  53
  54         do {
  55                 if (!pte_none(*pte))
  56                         goto bad;
  57
  58                 set_pte_ext(pte, pfn_pte(phys_addr >> PAGE_SHIFT, prot),
  59                             type->prot_pte_ext);
  60                 phys_addr += PAGE_SIZE;
  61         } while (pte++, addr += PAGE_SIZE, addr != end);
  62         return 0;
  63
  64  bad:
  65         printk(KERN_CRIT "remap_area_pte: page already exists\n");
  66         BUG();
  67 }
  68
  69 static inline int remap_area_pmd(pgd_t *pgd, unsigned long addr,
  70                                  unsigned long end, unsigned long phys_addr,
  71                                  const struct mem_type *type)
  72 {
  73         unsigned long next;
  74         pmd_t *pmd;
  75         int ret = 0;
  76
  77         pmd = pmd_alloc(&init_mm, pgd, addr);
  78         if (!pmd)
  79                 return -ENOMEM;
  80
  81         do {
  82                 next = pmd_addr_end(addr, end);
  83                 ret = remap_area_pte(pmd, addr, next, phys_addr, type);
  84                 if (ret)
  85                         return ret;
  86                 phys_addr += next - addr;
  87         } while (pmd++, addr = next, addr != end);
  88         return ret;
  89 }
  90
  91 static int remap_area_pages(unsigned long start, unsigned long pfn,
  92                             size_t size, const struct mem_type *type)
  93 {
  94         unsigned long addr = start;
  95         unsigned long next, end = start + size;
  96         unsigned long phys_addr = __pfn_to_phys(pfn);
  97         pgd_t *pgd;
  98         int err = 0;
  99
 100         BUG_ON(addr >= end);
 101         pgd = pgd_offset_k(addr);
 102         do {
 103                 next = pgd_addr_end(addr, end);
 104                 err = remap_area_pmd(pgd, addr, next, phys_addr, type);
 105                 if (err)
 106                         break;
 107                 phys_addr += next - addr;
 108         } while (pgd++, addr = next, addr != end);
 109
 110         return err;
 111 }
 112
 113
 114 void __check_kvm_seq(struct mm_struct *mm)
 115 {
 116         unsigned int seq;
 117
 118         do {
 119                 seq = init_mm.context.kvm_seq;
 120                 memcpy(pgd_offset(mm, VMALLOC_START),
 121                        pgd_offset_k(VMALLOC_START),
 122                        sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
 123                                         pgd_index(VMALLOC_START)));
 124                 mm->context.kvm_seq = seq;
 125         } while (seq != init_mm.context.kvm_seq);
 126 }
 127
 128 #ifndef CONFIG_SMP
 129 /*
 130  * Section support is unsafe on SMP - If you iounmap and ioremap a region,
 131  * the other CPUs will not see this change until their next context switch.
 132  * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
 133  * which requires the new ioremap'd region to be referenced, the CPU will
 134  * reference the _old_ region.
 135  *
 136  * Note that get_vm_area() allocates a guard 4K page, so we need to mask
 137  * the size back to 1MB aligned or we will overflow in the loop below.
 138  */
 139 static void unmap_area_sections(unsigned long virt, unsigned long size)
 140 {
 141         unsigned long addr = virt, end = virt + (size & ~SZ_1M);
 142         pgd_t *pgd;
 143
 144         flush_cache_vunmap(addr, end);
 145         pgd = pgd_offset_k(addr);
 146         do {
 147                 pmd_t pmd, *pmdp = pmd_offset(pgd, addr);
 148
 149                 pmd = *pmdp;
 150                 if (!pmd_none(pmd)) {
 151                         /*
 152                          * Clear the PMD from the page table, and
 153                          * increment the kvm sequence so others
 154                          * notice this change.
 155                          *
 156                          * Note: this is still racy on SMP machines.
 157                          */
 158                         pmd_clear(pmdp);
 159                         init_mm.context.kvm_seq++;
 160
 161                         /*
 162                          * Free the page table, if there was one.
 163                          */
 164                         if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
 165                                 pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
 166                 }
 167
 168                 addr += PGDIR_SIZE;
 169                 pgd++;
 170         } while (addr < end);
 171
 172         /*
 173          * Ensure that the active_mm is up to date - we want to
 174          * catch any use-after-iounmap cases.
 175          */
 176         if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
 177                 __check_kvm_seq(current->active_mm);
 178
 179         flush_tlb_kernel_range(virt, end);
 180 }
 181
 182 static int
 183 remap_area_sections(unsigned long virt, unsigned long pfn,
 184                     size_t size, const struct mem_type *type)
 185 {
 186         unsigned long addr = virt, end = virt + size;
 187         pgd_t *pgd;
 188
 189         /*
 190          * Remove and free any PTE-based mapping, and
 191          * sync the current kernel mapping.
 192          */
 193         unmap_area_sections(virt, size);
 194
 195         pgd = pgd_offset_k(addr);
 196         do {
 197                 pmd_t *pmd = pmd_offset(pgd, addr);
 198
 199                 pmd[0] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
 200                 pfn += SZ_1M >> PAGE_SHIFT;
 201                 pmd[1] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
 202                 pfn += SZ_1M >> PAGE_SHIFT;
 203                 flush_pmd_entry(pmd);
 204
 205                 addr += PGDIR_SIZE;
 206                 pgd++;
 207         } while (addr < end);
 208
 209         return 0;
 210 }
 211
 212 static int
 213 remap_area_supersections(unsigned long virt, unsigned long pfn,
 214                          size_t size, const struct mem_type *type)
 215 {
 216         unsigned long addr = virt, end = virt + size;
 217         pgd_t *pgd;
 218
 219         /*
 220          * Remove and free any PTE-based mapping, and
 221          * sync the current kernel mapping.
 222          */
 223         unmap_area_sections(virt, size);
 224
 225         pgd = pgd_offset_k(virt);
 226         do {
 227                 unsigned long super_pmd_val, i;
 228
 229                 super_pmd_val = __pfn_to_phys(pfn) | type->prot_sect |
 230                                 PMD_SECT_SUPER;
 231                 super_pmd_val |= ((pfn >> (32 - PAGE_SHIFT)) & 0xf) << 20;
 232
 233                 for (i = 0; i < 8; i++) {
 234                         pmd_t *pmd = pmd_offset(pgd, addr);
 235
 236                         pmd[0] = __pmd(super_pmd_val);
 237                         pmd[1] = __pmd(super_pmd_val);
 238                         flush_pmd_entry(pmd);
 239
 240                         addr += PGDIR_SIZE;
 241                         pgd++;
 242                 }
 243
 244                 pfn += SUPERSECTION_SIZE >> PAGE_SHIFT;
 245         } while (addr < end);
 246
 247         return 0;
 248 }
 249 #endif
 250
 251
 252 /*
 253  * Remap an arbitrary physical address space into the kernel virtual
 254  * address space. Needed when the kernel wants to access high addresses
 255  * directly.
 256  *
 257  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 258  * have to convert them into an offset in a page-aligned mapping, but the
 259  * caller shouldn't need to know that small detail.
 260  *
 261  * 'flags' are the extra L_PTE_ flags that you want to specify for this
 262  * mapping.  See include/asm-arm/proc-armv/pgtable.h for more information.
 263  */
 264 void __iomem *
 265 __arm_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
 266                   unsigned int mtype)
 267 {
 268         const struct mem_type *type;
 269         int err;
 270         unsigned long addr;
 271         struct vm_struct * area;
 272
 273         /*
 274          * High mappings must be supersection aligned
 275          */
 276         if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
 277                 return NULL;
 278
 279         type = get_mem_type(mtype);
 280         if (!type)
 281                 return NULL;
 282
 283         /*
 284          * Page align the mapping size, taking account of any offset.
 285          */
 286         size = PAGE_ALIGN(offset + size);
 287
 288         area = get_vm_area(size, VM_IOREMAP);
 289         if (!area)
 290                 return NULL;
 291         addr = (unsigned long)area->addr;
 292
 293 #ifndef CONFIG_SMP
 294         if (DOMAIN_IO == 0 &&
 295             (((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) ||
 296                cpu_is_xsc3()) && pfn >= 0x100000 &&
 297                !((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
 298                 area->flags |= VM_ARM_SECTION_MAPPING;
 299                 err = remap_area_supersections(addr, pfn, size, type);
 300         } else if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
 301                 area->flags |= VM_ARM_SECTION_MAPPING;
 302                 err = remap_area_sections(addr, pfn, size, type);
 303         } else
 304 #endif
 305                 err = remap_area_pages(addr, pfn, size, type);
 306
 307         if (err) {
 308                 vunmap((void *)addr);
 309                 return NULL;
 310         }
 311
 312         flush_cache_vmap(addr, addr + size);
 313         return (void __iomem *) (offset + addr);
 314 }
 315 EXPORT_SYMBOL(__arm_ioremap_pfn);
 316
 317 void __iomem *
 318 __arm_ioremap(unsigned long phys_addr, size_t size, unsigned int mtype)
 319 {
 320         unsigned long last_addr;
 321         unsigned long offset = phys_addr & ~PAGE_MASK;
 322         unsigned long pfn = __phys_to_pfn(phys_addr);
 323
 324         /*
 325          * Don't allow wraparound or zero size
 326          */
 327         last_addr = phys_addr + size - 1;
 328         if (!size || last_addr < phys_addr)
 329                 return NULL;
 330
 331         return __arm_ioremap_pfn(pfn, offset, size, mtype);
 332 }
 333 EXPORT_SYMBOL(__arm_ioremap);
 334
 335 void __iounmap(volatile void __iomem *addr)
 336 {
 337 #ifndef CONFIG_SMP
 338         struct vm_struct **p, *tmp;
 339 #endif
 340         unsigned int section_mapping = 0;
 341
 342         addr = (volatile void __iomem *)(PAGE_MASK & (unsigned long)addr);
 343
 344 #ifndef CONFIG_SMP
 345         /*
 346          * If this is a section based mapping we need to handle it
 347          * specially as the VM subsystem does not know how to handle
 348          * such a beast. We need the lock here b/c we need to clear
 349          * all the mappings before the area can be reclaimed
 350          * by someone else.
 351          */
 352         write_lock(&vmlist_lock);
 353         for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
 354                 if((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
 355                         if (tmp->flags & VM_ARM_SECTION_MAPPING) {
 356                                 *p = tmp->next;
 357                                 unmap_area_sections((unsigned long)tmp->addr,
 358                                                     tmp->size);
 359                                 kfree(tmp);
 360                                 section_mapping = 1;
 361                         }
 362                         break;
 363                 }
 364         }
 365         write_unlock(&vmlist_lock);
 366 #endif
 367
 368         if (!section_mapping)
 369                 vunmap((void __force *)addr);
 370 }
 371 EXPORT_SYMBOL(__iounmap);