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