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 #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
  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         pud_t *pud;
  83         pmd_t *pmdp;
  84
  85         flush_cache_vunmap(addr, end);
  86         pgd = pgd_offset_k(addr);
  87         pud = pud_offset(pgd, addr);
  88         pmdp = pmd_offset(pud, addr);
  89         do {
  90                 pmd_t pmd = *pmdp;
  91
  92                 if (!pmd_none(pmd)) {
  93                         /*
  94                          * Clear the PMD from the page table, and
  95                          * increment the kvm sequence so others
  96                          * notice this change.
  97                          *
  98                          * Note: this is still racy on SMP machines.
  99                          */
 100                         pmd_clear(pmdp);
 101                         init_mm.context.kvm_seq++;
 102
 103                         /*
 104                          * Free the page table, if there was one.
 105                          */
 106                         if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
 107                                 pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
 108                 }
 109
 110                 addr += PMD_SIZE;
 111                 pmdp += 2;
 112         } while (addr < end);
 113
 114         /*
 115          * Ensure that the active_mm is up to date - we want to
 116          * catch any use-after-iounmap cases.
 117          */
 118         if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
 119                 __check_kvm_seq(current->active_mm);
 120
 121         flush_tlb_kernel_range(virt, end);
 122 }
 123
 124 static int
 125 remap_area_sections(unsigned long virt, unsigned long pfn,
 126                     size_t size, const struct mem_type *type)
 127 {
 128         unsigned long addr = virt, end = virt + size;
 129         pgd_t *pgd;
 130         pud_t *pud;
 131         pmd_t *pmd;
 132
 133         /*
 134          * Remove and free any PTE-based mapping, and
 135          * sync the current kernel mapping.
 136          */
 137         unmap_area_sections(virt, size);
 138
 139         pgd = pgd_offset_k(addr);
 140         pud = pud_offset(pgd, addr);
 141         pmd = pmd_offset(pud, addr);
 142         do {
 143                 pmd[0] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
 144                 pfn += SZ_1M >> PAGE_SHIFT;
 145                 pmd[1] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
 146                 pfn += SZ_1M >> PAGE_SHIFT;
 147                 flush_pmd_entry(pmd);
 148
 149                 addr += PMD_SIZE;
 150                 pmd += 2;
 151         } while (addr < end);
 152
 153         return 0;
 154 }
 155
 156 static int
 157 remap_area_supersections(unsigned long virt, unsigned long pfn,
 158                          size_t size, const struct mem_type *type)
 159 {
 160         unsigned long addr = virt, end = virt + size;
 161         pgd_t *pgd;
 162         pud_t *pud;
 163         pmd_t *pmd;
 164
 165         /*
 166          * Remove and free any PTE-based mapping, and
 167          * sync the current kernel mapping.
 168          */
 169         unmap_area_sections(virt, size);
 170
 171         pgd = pgd_offset_k(virt);
 172         pud = pud_offset(pgd, addr);
 173         pmd = pmd_offset(pud, addr);
 174         do {
 175                 unsigned long super_pmd_val, i;
 176
 177                 super_pmd_val = __pfn_to_phys(pfn) | type->prot_sect |
 178                                 PMD_SECT_SUPER;
 179                 super_pmd_val |= ((pfn >> (32 - PAGE_SHIFT)) & 0xf) << 20;
 180
 181                 for (i = 0; i < 8; i++) {
 182                         pmd[0] = __pmd(super_pmd_val);
 183                         pmd[1] = __pmd(super_pmd_val);
 184                         flush_pmd_entry(pmd);
 185
 186                         addr += PMD_SIZE;
 187                         pmd += 2;
 188                 }
 189
 190                 pfn += SUPERSECTION_SIZE >> PAGE_SHIFT;
 191         } while (addr < end);
 192
 193         return 0;
 194 }
 195 #endif
 196
 197 void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn,
 198         unsigned long offset, size_t size, unsigned int mtype, void *caller)
 199 {
 200         const struct mem_type *type;
 201         int err;
 202         unsigned long addr;
 203         struct vm_struct * area;
 204
 205 #ifndef CONFIG_ARM_LPAE
 206         /*
 207          * High mappings must be supersection aligned
 208          */
 209         if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
 210                 return NULL;
 211 #endif
 212
 213         /*
 214          * Don't allow RAM to be mapped - this causes problems with ARMv6+
 215          */
 216         if (WARN_ON(pfn_valid(pfn)))
 217                 return NULL;
 218
 219         type = get_mem_type(mtype);
 220         if (!type)
 221                 return NULL;
 222
 223         /*
 224          * Page align the mapping size, taking account of any offset.
 225          */
 226         size = PAGE_ALIGN(offset + size);
 227
 228         area = get_vm_area_caller(size, VM_IOREMAP, caller);
 229         if (!area)
 230                 return NULL;
 231         addr = (unsigned long)area->addr;
 232
 233 #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
 234         if (DOMAIN_IO == 0 &&
 235             (((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) ||
 236                cpu_is_xsc3()) && pfn >= 0x100000 &&
 237                !((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
 238                 area->flags |= VM_ARM_SECTION_MAPPING;
 239                 err = remap_area_supersections(addr, pfn, size, type);
 240         } else if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
 241                 area->flags |= VM_ARM_SECTION_MAPPING;
 242                 err = remap_area_sections(addr, pfn, size, type);
 243         } else
 244 #endif
 245                 err = ioremap_page_range(addr, addr + size, __pfn_to_phys(pfn),
 246                                          __pgprot(type->prot_pte));
 247
 248         if (err) {
 249                 vunmap((void *)addr);
 250                 return NULL;
 251         }
 252
 253         flush_cache_vmap(addr, addr + size);
 254         return (void __iomem *) (offset + addr);
 255 }
 256
 257 void __iomem *__arm_ioremap_caller(unsigned long phys_addr, size_t size,
 258         unsigned int mtype, void *caller)
 259 {
 260         unsigned long last_addr;
 261         unsigned long offset = phys_addr & ~PAGE_MASK;
 262         unsigned long pfn = __phys_to_pfn(phys_addr);
 263
 264         /*
 265          * Don't allow wraparound or zero size
 266          */
 267         last_addr = phys_addr + size - 1;
 268         if (!size || last_addr < phys_addr)
 269                 return NULL;
 270
 271         return __arm_ioremap_pfn_caller(pfn, offset, size, mtype,
 272                         caller);
 273 }
 274
 275 /*
 276  * Remap an arbitrary physical address space into the kernel virtual
 277  * address space. Needed when the kernel wants to access high addresses
 278  * directly.
 279  *
 280  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 281  * have to convert them into an offset in a page-aligned mapping, but the
 282  * caller shouldn't need to know that small detail.
 283  */
 284 void __iomem *
 285 __arm_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
 286                   unsigned int mtype)
 287 {
 288         return __arm_ioremap_pfn_caller(pfn, offset, size, mtype,
 289                         __builtin_return_address(0));
 290 }
 291 EXPORT_SYMBOL(__arm_ioremap_pfn);
 292
 293 void __iomem *
 294 __arm_ioremap(unsigned long phys_addr, size_t size, unsigned int mtype)
 295 {
 296         return __arm_ioremap_caller(phys_addr, size, mtype,
 297                         __builtin_return_address(0));
 298 }
 299 EXPORT_SYMBOL(__arm_ioremap);
 300
 301 void __iounmap(volatile void __iomem *io_addr)
 302 {
 303         void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
 304 #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
 305         struct vm_struct **p, *tmp;
 306
 307         /*
 308          * If this is a section based mapping we need to handle it
 309          * specially as the VM subsystem does not know how to handle
 310          * such a beast. We need the lock here b/c we need to clear
 311          * all the mappings before the area can be reclaimed
 312          * by someone else.
 313          */
 314         write_lock(&vmlist_lock);
 315         for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
 316                 if ((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
 317                         if (tmp->flags & VM_ARM_SECTION_MAPPING) {
 318                                 unmap_area_sections((unsigned long)tmp->addr,
 319                                                     tmp->size);
 320                         }
 321                         break;
 322                 }
 323         }
 324         write_unlock(&vmlist_lock);
 325 #endif
 326
 327         vunmap(addr);
 328 }
 329 EXPORT_SYMBOL(__iounmap);