arch/unicore32/mm/ioremap.c

   1 /*
   2  * linux/arch/unicore32/mm/ioremap.c
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  * Copyright (C) 2001-2010 GUAN Xue-tao
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  *
  13  * Re-map IO memory to kernel address space so that we can access it.
  14  *
  15  * This allows a driver to remap an arbitrary region of bus memory into
  16  * virtual space.  One should *only* use readl, writel, memcpy_toio and
  17  * so on with such remapped areas.
  18  *
  19  * Because UniCore only has a 32-bit address space we can't address the
  20  * whole of the (physical) PCI space at once.  PCI huge-mode addressing
  21  * allows us to circumvent this restriction by splitting PCI space into
  22  * two 2GB chunks and mapping only one at a time into processor memory.
  23  * We use MMU protection domains to trap any attempt to access the bank
  24  * that is not currently mapped.  (This isn't fully implemented yet.)
  25  */
  26 #include <linux/module.h>
  27 #include <linux/errno.h>
  28 #include <linux/mm.h>
  29 #include <linux/vmalloc.h>
  30 #include <linux/io.h>
  31
  32 #include <asm/cputype.h>
  33 #include <asm/cacheflush.h>
  34 #include <asm/mmu_context.h>
  35 #include <asm/pgalloc.h>
  36 #include <asm/tlbflush.h>
  37 #include <asm/sizes.h>
  38
  39 #include <mach/map.h>
  40 #include "mm.h"
  41
  42 /*
  43  * Used by ioremap() and iounmap() code to mark (super)section-mapped
  44  * I/O regions in vm_struct->flags field.
  45  */
  46 #define VM_UNICORE_SECTION_MAPPING      0x80000000
  47
  48 int ioremap_page(unsigned long virt, unsigned long phys,
  49                  const struct mem_type *mtype)
  50 {
  51         return ioremap_page_range(virt, virt + PAGE_SIZE, phys,
  52                                   __pgprot(mtype->prot_pte));
  53 }
  54 EXPORT_SYMBOL(ioremap_page);
  55
  56 /*
  57  * Section support is unsafe on SMP - If you iounmap and ioremap a region,
  58  * the other CPUs will not see this change until their next context switch.
  59  * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
  60  * which requires the new ioremap'd region to be referenced, the CPU will
  61  * reference the _old_ region.
  62  *
  63  * Note that get_vm_area_caller() allocates a guard 4K page, so we need to
  64  * mask the size back to 4MB aligned or we will overflow in the loop below.
  65  */
  66 static void unmap_area_sections(unsigned long virt, unsigned long size)
  67 {
  68         unsigned long addr = virt, end = virt + (size & ~(SZ_4M - 1));
  69         pgd_t *pgd;
  70
  71         flush_cache_vunmap(addr, end);
  72         pgd = pgd_offset_k(addr);
  73         do {
  74                 pmd_t pmd, *pmdp = pmd_offset((pud_t *)pgd, addr);
  75
  76                 pmd = *pmdp;
  77                 if (!pmd_none(pmd)) {
  78                         /*
  79                          * Clear the PMD from the page table, and
  80                          * increment the kvm sequence so others
  81                          * notice this change.
  82                          *
  83                          * Note: this is still racy on SMP machines.
  84                          */
  85                         pmd_clear(pmdp);
  86
  87                         /*
  88                          * Free the page table, if there was one.
  89                          */
  90                         if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
  91                                 pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
  92                 }
  93
  94                 addr += PGDIR_SIZE;
  95                 pgd++;
  96         } while (addr < end);
  97
  98         flush_tlb_kernel_range(virt, end);
  99 }
 100
 101 static int
 102 remap_area_sections(unsigned long virt, unsigned long pfn,
 103                     size_t size, const struct mem_type *type)
 104 {
 105         unsigned long addr = virt, end = virt + size;
 106         pgd_t *pgd;
 107
 108         /*
 109          * Remove and free any PTE-based mapping, and
 110          * sync the current kernel mapping.
 111          */
 112         unmap_area_sections(virt, size);
 113
 114         pgd = pgd_offset_k(addr);
 115         do {
 116                 pmd_t *pmd = pmd_offset((pud_t *)pgd, addr);
 117
 118                 set_pmd(pmd, __pmd(__pfn_to_phys(pfn) | type->prot_sect));
 119                 pfn += SZ_4M >> PAGE_SHIFT;
 120                 flush_pmd_entry(pmd);
 121
 122                 addr += PGDIR_SIZE;
 123                 pgd++;
 124         } while (addr < end);
 125
 126         return 0;
 127 }
 128
 129 void __iomem *__uc32_ioremap_pfn_caller(unsigned long pfn,
 130         unsigned long offset, size_t size, unsigned int mtype, void *caller)
 131 {
 132         const struct mem_type *type;
 133         int err;
 134         unsigned long addr;
 135         struct vm_struct *area;
 136
 137         /*
 138          * High mappings must be section aligned
 139          */
 140         if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SECTION_MASK))
 141                 return NULL;
 142
 143         /*
 144          * Don't allow RAM to be mapped
 145          */
 146         if (pfn_valid(pfn)) {
 147                 printk(KERN_WARNING "BUG: Your driver calls ioremap() on\n"
 148                         "system memory.  This leads to architecturally\n"
 149                         "unpredictable behaviour, and ioremap() will fail in\n"
 150                         "the next kernel release. Please fix your driver.\n");
 151                 WARN_ON(1);
 152         }
 153
 154         type = get_mem_type(mtype);
 155         if (!type)
 156                 return NULL;
 157
 158         /*
 159          * Page align the mapping size, taking account of any offset.
 160          */
 161         size = PAGE_ALIGN(offset + size);
 162
 163         area = get_vm_area_caller(size, VM_IOREMAP, caller);
 164         if (!area)
 165                 return NULL;
 166         addr = (unsigned long)area->addr;
 167
 168         if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
 169                 area->flags |= VM_UNICORE_SECTION_MAPPING;
 170                 err = remap_area_sections(addr, pfn, size, type);
 171         } else
 172                 err = ioremap_page_range(addr, addr + size, __pfn_to_phys(pfn),
 173                                          __pgprot(type->prot_pte));
 174
 175         if (err) {
 176                 vunmap((void *)addr);
 177                 return NULL;
 178         }
 179
 180         flush_cache_vmap(addr, addr + size);
 181         return (void __iomem *) (offset + addr);
 182 }
 183
 184 void __iomem *__uc32_ioremap_caller(unsigned long phys_addr, size_t size,
 185         unsigned int mtype, void *caller)
 186 {
 187         unsigned long last_addr;
 188         unsigned long offset = phys_addr & ~PAGE_MASK;
 189         unsigned long pfn = __phys_to_pfn(phys_addr);
 190
 191         /*
 192          * Don't allow wraparound or zero size
 193          */
 194         last_addr = phys_addr + size - 1;
 195         if (!size || last_addr < phys_addr)
 196                 return NULL;
 197
 198         return __uc32_ioremap_pfn_caller(pfn, offset, size, mtype, caller);
 199 }
 200
 201 /*
 202  * Remap an arbitrary physical address space into the kernel virtual
 203  * address space. Needed when the kernel wants to access high addresses
 204  * directly.
 205  *
 206  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 207  * have to convert them into an offset in a page-aligned mapping, but the
 208  * caller shouldn't need to know that small detail.
 209  */
 210 void __iomem *
 211 __uc32_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
 212                   unsigned int mtype)
 213 {
 214         return __uc32_ioremap_pfn_caller(pfn, offset, size, mtype,
 215                         __builtin_return_address(0));
 216 }
 217 EXPORT_SYMBOL(__uc32_ioremap_pfn);
 218
 219 void __iomem *
 220 __uc32_ioremap(unsigned long phys_addr, size_t size)
 221 {
 222         return __uc32_ioremap_caller(phys_addr, size, MT_DEVICE,
 223                         __builtin_return_address(0));
 224 }
 225 EXPORT_SYMBOL(__uc32_ioremap);
 226
 227 void __iomem *
 228 __uc32_ioremap_cached(unsigned long phys_addr, size_t size)
 229 {
 230         return __uc32_ioremap_caller(phys_addr, size, MT_DEVICE_CACHED,
 231                         __builtin_return_address(0));
 232 }
 233 EXPORT_SYMBOL(__uc32_ioremap_cached);
 234
 235 void __uc32_iounmap(volatile void __iomem *io_addr)
 236 {
 237         void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
 238         struct vm_struct *vm;
 239
 240         /*
 241          * If this is a section based mapping we need to handle it
 242          * specially as the VM subsystem does not know how to handle
 243          * such a beast. We need the lock here b/c we need to clear
 244          * all the mappings before the area can be reclaimed
 245          * by someone else.
 246          */
 247         vm = find_vm_area(addr);
 248         if (vm && (vm->flags & VM_IOREMAP) &&
 249                 (vm->flags & VM_UNICORE_SECTION_MAPPING))
 250                 unmap_area_sections((unsigned long)vm->addr, vm->size);
 251
 252         vunmap(addr);
 253 }
 254 EXPORT_SYMBOL(__uc32_iounmap);