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 #include <linux/io.h>
  28
  29 #include <asm/cputype.h>
  30 #include <asm/cacheflush.h>
  31 #include <asm/mmu_context.h>
  32 #include <asm/pgalloc.h>
  33 #include <asm/tlbflush.h>
  34 #include <asm/sizes.h>
  35
  36 #include <asm/mach/map.h>
  37 #include "mm.h"
  38
  39 /*
  40  * Used by ioremap() and iounmap() code to mark (super)section-mapped
  41  * I/O regions in vm_struct->flags field.
  42  */
  43 #define VM_ARM_SECTION_MAPPING  0x80000000
  44
  45 static int remap_area_pte(pmd_t *pmd, unsigned long addr, unsigned long end,
  46                           unsigned long phys_addr, const struct mem_type *type)
  47 {
  48         pgprot_t prot = __pgprot(type->prot_pte);
  49         pte_t *pte;
  50
  51         pte = pte_alloc_kernel(pmd, addr);
  52         if (!pte)
  53                 return -ENOMEM;
  54
  55         do {
  56                 if (!pte_none(*pte))
  57                         goto bad;
  58
  59                 set_pte_ext(pte, pfn_pte(phys_addr >> PAGE_SHIFT, prot), 0);
  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 int ioremap_page(unsigned long virt, unsigned long phys,
 114                  const struct mem_type *mtype)
 115 {
 116         return remap_area_pages(virt, __phys_to_pfn(phys), PAGE_SIZE, mtype);
 117 }
 118 EXPORT_SYMBOL(ioremap_page);
 119
 120 void __check_kvm_seq(struct mm_struct *mm)
 121 {
 122         unsigned int seq;
 123
 124         do {
 125                 seq = init_mm.context.kvm_seq;
 126                 memcpy(pgd_offset(mm, VMALLOC_START),
 127                        pgd_offset_k(VMALLOC_START),
 128                        sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
 129                                         pgd_index(VMALLOC_START)));
 130                 mm->context.kvm_seq = seq;
 131         } while (seq != init_mm.context.kvm_seq);
 132 }
 133
 134 #ifndef CONFIG_SMP
 135 /*
 136  * Section support is unsafe on SMP - If you iounmap and ioremap a region,
 137  * the other CPUs will not see this change until their next context switch.
 138  * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
 139  * which requires the new ioremap'd region to be referenced, the CPU will
 140  * reference the _old_ region.
 141  *
 142  * Note that get_vm_area() allocates a guard 4K page, so we need to mask
 143  * the size back to 1MB aligned or we will overflow in the loop below.
 144  */
 145 static void unmap_area_sections(unsigned long virt, unsigned long size)
 146 {
 147         unsigned long addr = virt, end = virt + (size & ~(SZ_1M - 1));
 148         pgd_t *pgd;
 149
 150         flush_cache_vunmap(addr, end);
 151         pgd = pgd_offset_k(addr);
 152         do {
 153                 pmd_t pmd, *pmdp = pmd_offset(pgd, addr);
 154
 155                 pmd = *pmdp;
 156                 if (!pmd_none(pmd)) {
 157                         /*
 158                          * Clear the PMD from the page table, and
 159                          * increment the kvm sequence so others
 160                          * notice this change.
 161                          *
 162                          * Note: this is still racy on SMP machines.
 163                          */
 164                         pmd_clear(pmdp);
 165                         init_mm.context.kvm_seq++;
 166
 167                         /*
 168                          * Free the page table, if there was one.
 169                          */
 170                         if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
 171                                 pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
 172                 }
 173
 174                 addr += PGDIR_SIZE;
 175                 pgd++;
 176         } while (addr < end);
 177
 178         /*
 179          * Ensure that the active_mm is up to date - we want to
 180          * catch any use-after-iounmap cases.
 181          */
 182         if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
 183                 __check_kvm_seq(current->active_mm);
 184
 185         flush_tlb_kernel_range(virt, end);
 186 }
 187
 188 static int
 189 remap_area_sections(unsigned long virt, unsigned long pfn,
 190                     size_t size, const struct mem_type *type)
 191 {
 192         unsigned long addr = virt, end = virt + size;
 193         pgd_t *pgd;
 194
 195         /*
 196          * Remove and free any PTE-based mapping, and
 197          * sync the current kernel mapping.
 198          */
 199         unmap_area_sections(virt, size);
 200
 201         pgd = pgd_offset_k(addr);
 202         do {
 203                 pmd_t *pmd = pmd_offset(pgd, addr);
 204
 205                 pmd[0] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
 206                 pfn += SZ_1M >> PAGE_SHIFT;
 207                 pmd[1] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
 208                 pfn += SZ_1M >> PAGE_SHIFT;
 209                 flush_pmd_entry(pmd);
 210
 211                 addr += PGDIR_SIZE;
 212                 pgd++;
 213         } while (addr < end);
 214
 215         return 0;
 216 }
 217
 218 static int
 219 remap_area_supersections(unsigned long virt, unsigned long pfn,
 220                          size_t size, const struct mem_type *type)
 221 {
 222         unsigned long addr = virt, end = virt + size;
 223         pgd_t *pgd;
 224
 225         /*
 226          * Remove and free any PTE-based mapping, and
 227          * sync the current kernel mapping.
 228          */
 229         unmap_area_sections(virt, size);
 230
 231         pgd = pgd_offset_k(virt);
 232         do {
 233                 unsigned long super_pmd_val, i;
 234
 235                 super_pmd_val = __pfn_to_phys(pfn) | type->prot_sect |
 236                                 PMD_SECT_SUPER;
 237                 super_pmd_val |= ((pfn >> (32 - PAGE_SHIFT)) & 0xf) << 20;
 238
 239                 for (i = 0; i < 8; i++) {
 240                         pmd_t *pmd = pmd_offset(pgd, addr);
 241
 242                         pmd[0] = __pmd(super_pmd_val);
 243                         pmd[1] = __pmd(super_pmd_val);
 244                         flush_pmd_entry(pmd);
 245
 246                         addr += PGDIR_SIZE;
 247                         pgd++;
 248                 }
 249
 250                 pfn += SUPERSECTION_SIZE >> PAGE_SHIFT;
 251         } while (addr < end);
 252
 253         return 0;
 254 }
 255 #endif
 256
 257
 258 /*
 259  * Remap an arbitrary physical address space into the kernel virtual
 260  * address space. Needed when the kernel wants to access high addresses
 261  * directly.
 262  *
 263  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 264  * have to convert them into an offset in a page-aligned mapping, but the
 265  * caller shouldn't need to know that small detail.
 266  *
 267  * 'flags' are the extra L_PTE_ flags that you want to specify for this
 268  * mapping.  See <asm/pgtable.h> for more information.
 269  */
 270 void __iomem *
 271 __arm_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
 272                   unsigned int mtype)
 273 {
 274         const struct mem_type *type;
 275         int err;
 276         unsigned long addr;
 277         struct vm_struct * area;
 278
 279         /*
 280          * High mappings must be supersection aligned
 281          */
 282         if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
 283                 return NULL;
 284
 285         type = get_mem_type(mtype);
 286         if (!type)
 287                 return NULL;
 288
 289         /*
 290          * Page align the mapping size, taking account of any offset.
 291          */
 292         size = PAGE_ALIGN(offset + size);
 293
 294         area = get_vm_area(size, VM_IOREMAP);
 295         if (!area)
 296                 return NULL;
 297         addr = (unsigned long)area->addr;
 298
 299 #ifndef CONFIG_SMP
 300         if (DOMAIN_IO == 0 &&
 301             (((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) ||
 302                cpu_is_xsc3()) && pfn >= 0x100000 &&
 303                !((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
 304                 area->flags |= VM_ARM_SECTION_MAPPING;
 305                 err = remap_area_supersections(addr, pfn, size, type);
 306         } else if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
 307                 area->flags |= VM_ARM_SECTION_MAPPING;
 308                 err = remap_area_sections(addr, pfn, size, type);
 309         } else
 310 #endif
 311                 err = remap_area_pages(addr, pfn, size, type);
 312
 313         if (err) {
 314                 vunmap((void *)addr);
 315                 return NULL;
 316         }
 317
 318         flush_cache_vmap(addr, addr + size);
 319         return (void __iomem *) (offset + addr);
 320 }
 321 EXPORT_SYMBOL(__arm_ioremap_pfn);
 322
 323 void __iomem *
 324 __arm_ioremap(unsigned long phys_addr, size_t size, unsigned int mtype)
 325 {
 326         unsigned long last_addr;
 327         unsigned long offset = phys_addr & ~PAGE_MASK;
 328         unsigned long pfn = __phys_to_pfn(phys_addr);
 329
 330         /*
 331          * Don't allow wraparound or zero size
 332          */
 333         last_addr = phys_addr + size - 1;
 334         if (!size || last_addr < phys_addr)
 335                 return NULL;
 336
 337         return __arm_ioremap_pfn(pfn, offset, size, mtype);
 338 }
 339 EXPORT_SYMBOL(__arm_ioremap);
 340
 341 void __iounmap(volatile void __iomem *io_addr)
 342 {
 343         void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
 344 #ifndef CONFIG_SMP
 345         struct vm_struct **p, *tmp;
 346
 347         /*
 348          * If this is a section based mapping we need to handle it
 349          * specially as the VM subsystem does not know how to handle
 350          * such a beast. We need the lock here b/c we need to clear
 351          * all the mappings before the area can be reclaimed
 352          * by someone else.
 353          */
 354         write_lock(&vmlist_lock);
 355         for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
 356                 if ((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
 357                         if (tmp->flags & VM_ARM_SECTION_MAPPING) {
 358                                 unmap_area_sections((unsigned long)tmp->addr,
 359                                                     tmp->size);
 360                         }
 361                         break;
 362                 }
 363         }
 364         write_unlock(&vmlist_lock);
 365 #endif
 366
 367         vunmap(addr);
 368 }
 369 EXPORT_SYMBOL(__iounmap);