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 int ioremap_page(unsigned long virt, unsigned long phys,
  40                  const struct mem_type *mtype)
  41 {
  42         return ioremap_page_range(virt, virt + PAGE_SIZE, phys,
  43                                   __pgprot(mtype->prot_pte));
  44 }
  45 EXPORT_SYMBOL(ioremap_page);
  46
  47 void __check_kvm_seq(struct mm_struct *mm)
  48 {
  49         unsigned int seq;
  50
  51         do {
  52                 seq = init_mm.context.kvm_seq;
  53                 memcpy(pgd_offset(mm, VMALLOC_START),
  54                        pgd_offset_k(VMALLOC_START),
  55                        sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
  56                                         pgd_index(VMALLOC_START)));
  57                 mm->context.kvm_seq = seq;
  58         } while (seq != init_mm.context.kvm_seq);
  59 }
  60
  61 #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
  62 /*
  63  * Section support is unsafe on SMP - If you iounmap and ioremap a region,
  64  * the other CPUs will not see this change until their next context switch.
  65  * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
  66  * which requires the new ioremap'd region to be referenced, the CPU will
  67  * reference the _old_ region.
  68  *
  69  * Note that get_vm_area_caller() allocates a guard 4K page, so we need to
  70  * mask the size back to 1MB aligned or we will overflow in the loop below.
  71  */
  72 static void unmap_area_sections(unsigned long virt, unsigned long size)
  73 {
  74         unsigned long addr = virt, end = virt + (size & ~(SZ_1M - 1));
  75         pgd_t *pgd;
  76         pud_t *pud;
  77         pmd_t *pmdp;
  78
  79         flush_cache_vunmap(addr, end);
  80         pgd = pgd_offset_k(addr);
  81         pud = pud_offset(pgd, addr);
  82         pmdp = pmd_offset(pud, addr);
  83         do {
  84                 pmd_t pmd = *pmdp;
  85
  86                 if (!pmd_none(pmd)) {
  87                         /*
  88                          * Clear the PMD from the page table, and
  89                          * increment the kvm sequence so others
  90                          * notice this change.
  91                          *
  92                          * Note: this is still racy on SMP machines.
  93                          */
  94                         pmd_clear(pmdp);
  95                         init_mm.context.kvm_seq++;
  96
  97                         /*
  98                          * Free the page table, if there was one.
  99                          */
 100                         if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
 101                                 pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
 102                 }
 103
 104                 addr += PMD_SIZE;
 105                 pmdp += 2;
 106         } while (addr < end);
 107
 108         /*
 109          * Ensure that the active_mm is up to date - we want to
 110          * catch any use-after-iounmap cases.
 111          */
 112         if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
 113                 __check_kvm_seq(current->active_mm);
 114
 115         flush_tlb_kernel_range(virt, end);
 116 }
 117
 118 static int
 119 remap_area_sections(unsigned long virt, unsigned long pfn,
 120                     size_t size, const struct mem_type *type)
 121 {
 122         unsigned long addr = virt, end = virt + size;
 123         pgd_t *pgd;
 124         pud_t *pud;
 125         pmd_t *pmd;
 126
 127         /*
 128          * Remove and free any PTE-based mapping, and
 129          * sync the current kernel mapping.
 130          */
 131         unmap_area_sections(virt, size);
 132
 133         pgd = pgd_offset_k(addr);
 134         pud = pud_offset(pgd, addr);
 135         pmd = pmd_offset(pud, addr);
 136         do {
 137                 pmd[0] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
 138                 pfn += SZ_1M >> PAGE_SHIFT;
 139                 pmd[1] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
 140                 pfn += SZ_1M >> PAGE_SHIFT;
 141                 flush_pmd_entry(pmd);
 142
 143                 addr += PMD_SIZE;
 144                 pmd += 2;
 145         } while (addr < end);
 146
 147         return 0;
 148 }
 149
 150 static int
 151 remap_area_supersections(unsigned long virt, unsigned long pfn,
 152                          size_t size, const struct mem_type *type)
 153 {
 154         unsigned long addr = virt, end = virt + size;
 155         pgd_t *pgd;
 156         pud_t *pud;
 157         pmd_t *pmd;
 158
 159         /*
 160          * Remove and free any PTE-based mapping, and
 161          * sync the current kernel mapping.
 162          */
 163         unmap_area_sections(virt, size);
 164
 165         pgd = pgd_offset_k(virt);
 166         pud = pud_offset(pgd, addr);
 167         pmd = pmd_offset(pud, addr);
 168         do {
 169                 unsigned long super_pmd_val, i;
 170
 171                 super_pmd_val = __pfn_to_phys(pfn) | type->prot_sect |
 172                                 PMD_SECT_SUPER;
 173                 super_pmd_val |= ((pfn >> (32 - PAGE_SHIFT)) & 0xf) << 20;
 174
 175                 for (i = 0; i < 8; i++) {
 176                         pmd[0] = __pmd(super_pmd_val);
 177                         pmd[1] = __pmd(super_pmd_val);
 178                         flush_pmd_entry(pmd);
 179
 180                         addr += PMD_SIZE;
 181                         pmd += 2;
 182                 }
 183
 184                 pfn += SUPERSECTION_SIZE >> PAGE_SHIFT;
 185         } while (addr < end);
 186
 187         return 0;
 188 }
 189 #endif
 190
 191 void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn,
 192         unsigned long offset, size_t size, unsigned int mtype, void *caller)
 193 {
 194         const struct mem_type *type;
 195         int err;
 196         unsigned long addr;
 197         struct vm_struct * area;
 198
 199 #ifndef CONFIG_ARM_LPAE
 200         /*
 201          * High mappings must be supersection aligned
 202          */
 203         if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
 204                 return NULL;
 205 #endif
 206
 207         type = get_mem_type(mtype);
 208         if (!type)
 209                 return NULL;
 210
 211         /*
 212          * Page align the mapping size, taking account of any offset.
 213          */
 214         size = PAGE_ALIGN(offset + size);
 215
 216         /*
 217          * Try to reuse one of the static mapping whenever possible.
 218          */
 219         read_lock(&vmlist_lock);
 220         for (area = vmlist; area; area = area->next) {
 221                 if (!size || (sizeof(phys_addr_t) == 4 && pfn >= 0x100000))
 222                         break;
 223                 if (!(area->flags & VM_ARM_STATIC_MAPPING))
 224                         continue;
 225                 if ((area->flags & VM_ARM_MTYPE_MASK) != VM_ARM_MTYPE(mtype))
 226                         continue;
 227                 if (__phys_to_pfn(area->phys_addr) > pfn ||
 228                     __pfn_to_phys(pfn) + size-1 > area->phys_addr + area->size-1)
 229                         continue;
 230                 /* we can drop the lock here as we know *area is static */
 231                 read_unlock(&vmlist_lock);
 232                 addr = (unsigned long)area->addr;
 233                 addr += __pfn_to_phys(pfn) - area->phys_addr;
 234                 return (void __iomem *) (offset + addr);
 235         }
 236         read_unlock(&vmlist_lock);
 237
 238         /*
 239          * Don't allow RAM to be mapped - this causes problems with ARMv6+
 240          */
 241         if (WARN_ON(pfn_valid(pfn)))
 242                 return NULL;
 243
 244         area = get_vm_area_caller(size, VM_IOREMAP, caller);
 245         if (!area)
 246                 return NULL;
 247         addr = (unsigned long)area->addr;
 248
 249 #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
 250         if (DOMAIN_IO == 0 &&
 251             (((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) ||
 252                cpu_is_xsc3()) && pfn >= 0x100000 &&
 253                !((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
 254                 area->flags |= VM_ARM_SECTION_MAPPING;
 255                 err = remap_area_supersections(addr, pfn, size, type);
 256         } else if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
 257                 area->flags |= VM_ARM_SECTION_MAPPING;
 258                 err = remap_area_sections(addr, pfn, size, type);
 259         } else
 260 #endif
 261                 err = ioremap_page_range(addr, addr + size, __pfn_to_phys(pfn),
 262                                          __pgprot(type->prot_pte));
 263
 264         if (err) {
 265                 vunmap((void *)addr);
 266                 return NULL;
 267         }
 268
 269         flush_cache_vmap(addr, addr + size);
 270         return (void __iomem *) (offset + addr);
 271 }
 272
 273 void __iomem *__arm_ioremap_caller(unsigned long phys_addr, size_t size,
 274         unsigned int mtype, void *caller)
 275 {
 276         unsigned long last_addr;
 277         unsigned long offset = phys_addr & ~PAGE_MASK;
 278         unsigned long pfn = __phys_to_pfn(phys_addr);
 279
 280         /*
 281          * Don't allow wraparound or zero size
 282          */
 283         last_addr = phys_addr + size - 1;
 284         if (!size || last_addr < phys_addr)
 285                 return NULL;
 286
 287         return __arm_ioremap_pfn_caller(pfn, offset, size, mtype,
 288                         caller);
 289 }
 290
 291 /*
 292  * Remap an arbitrary physical address space into the kernel virtual
 293  * address space. Needed when the kernel wants to access high addresses
 294  * directly.
 295  *
 296  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 297  * have to convert them into an offset in a page-aligned mapping, but the
 298  * caller shouldn't need to know that small detail.
 299  */
 300 void __iomem *
 301 __arm_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
 302                   unsigned int mtype)
 303 {
 304         return __arm_ioremap_pfn_caller(pfn, offset, size, mtype,
 305                         __builtin_return_address(0));
 306 }
 307 EXPORT_SYMBOL(__arm_ioremap_pfn);
 308
 309 void __iomem *
 310 __arm_ioremap(unsigned long phys_addr, size_t size, unsigned int mtype)
 311 {
 312         return __arm_ioremap_caller(phys_addr, size, mtype,
 313                         __builtin_return_address(0));
 314 }
 315 EXPORT_SYMBOL(__arm_ioremap);
 316
 317 /*
 318  * Remap an arbitrary physical address space into the kernel virtual
 319  * address space as memory. Needed when the kernel wants to execute
 320  * code in external memory. This is needed for reprogramming source
 321  * clocks that would affect normal memory for example. Please see
 322  * CONFIG_GENERIC_ALLOCATOR for allocating external memory.
 323  */
 324 void __iomem *
 325 __arm_ioremap_exec(unsigned long phys_addr, size_t size, bool cached)
 326 {
 327         unsigned int mtype;
 328
 329         if (cached)
 330                 mtype = MT_MEMORY;
 331         else
 332                 mtype = MT_MEMORY_NONCACHED;
 333
 334         return __arm_ioremap_caller(phys_addr, size, mtype,
 335                         __builtin_return_address(0));
 336 }
 337
 338 void __iounmap(volatile void __iomem *io_addr)
 339 {
 340         void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
 341         struct vm_struct *vm;
 342
 343         read_lock(&vmlist_lock);
 344         for (vm = vmlist; vm; vm = vm->next) {
 345                 if (vm->addr > addr)
 346                         break;
 347                 if (!(vm->flags & VM_IOREMAP))
 348                         continue;
 349                 /* If this is a static mapping we must leave it alone */
 350                 if ((vm->flags & VM_ARM_STATIC_MAPPING) &&
 351                     (vm->addr <= addr) && (vm->addr + vm->size > addr)) {
 352                         read_unlock(&vmlist_lock);
 353                         return;
 354                 }
 355 #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
 356                 /*
 357                  * If this is a section based mapping we need to handle it
 358                  * specially as the VM subsystem does not know how to handle
 359                  * such a beast.
 360                  */
 361                 if ((vm->addr == addr) &&
 362                     (vm->flags & VM_ARM_SECTION_MAPPING)) {
 363                         unmap_area_sections((unsigned long)vm->addr, vm->size);
 364                         break;
 365                 }
 366 #endif
 367         }
 368         read_unlock(&vmlist_lock);
 369
 370         vunmap(addr);
 371 }
 372 EXPORT_SYMBOL(__iounmap);