arch/sh/mm/ioremap.c

   1 /*
   2  * arch/sh/mm/ioremap.c
   3  *
   4  * Re-map IO memory to kernel address space so that we can access it.
   5  * This is needed for high PCI addresses that aren't mapped in the
   6  * 640k-1MB IO memory area on PC's
   7  *
   8  * (C) Copyright 1995 1996 Linus Torvalds
   9  * (C) Copyright 2005, 2006 Paul Mundt
  10  *
  11  * This file is subject to the terms and conditions of the GNU General
  12  * Public License. See the file "COPYING" in the main directory of this
  13  * archive for more details.
  14  */
  15 #include <linux/vmalloc.h>
  16 #include <linux/module.h>
  17 #include <linux/mm.h>
  18 #include <asm/io.h>
  19 #include <asm/page.h>
  20 #include <asm/pgalloc.h>
  21 #include <asm/addrspace.h>
  22 #include <asm/cacheflush.h>
  23 #include <asm/tlbflush.h>
  24
  25 static inline void remap_area_pte(pte_t * pte, unsigned long address,
  26         unsigned long size, unsigned long phys_addr, unsigned long flags)
  27 {
  28         unsigned long end;
  29         unsigned long pfn;
  30         pgprot_t pgprot = __pgprot(_PAGE_PRESENT | _PAGE_RW |
  31                                    _PAGE_DIRTY | _PAGE_ACCESSED |
  32                                    _PAGE_HW_SHARED | _PAGE_FLAGS_HARD | flags);
  33
  34         address &= ~PMD_MASK;
  35         end = address + size;
  36         if (end > PMD_SIZE)
  37                 end = PMD_SIZE;
  38         if (address >= end)
  39                 BUG();
  40         pfn = phys_addr >> PAGE_SHIFT;
  41         do {
  42                 if (!pte_none(*pte)) {
  43                         printk("remap_area_pte: page already exists\n");
  44                         BUG();
  45                 }
  46                 set_pte(pte, pfn_pte(pfn, pgprot));
  47                 address += PAGE_SIZE;
  48                 pfn++;
  49                 pte++;
  50         } while (address && (address < end));
  51 }
  52
  53 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address,
  54         unsigned long size, unsigned long phys_addr, unsigned long flags)
  55 {
  56         unsigned long end;
  57
  58         address &= ~PGDIR_MASK;
  59         end = address + size;
  60         if (end > PGDIR_SIZE)
  61                 end = PGDIR_SIZE;
  62         phys_addr -= address;
  63         if (address >= end)
  64                 BUG();
  65         do {
  66                 pte_t * pte = pte_alloc_kernel(pmd, address);
  67                 if (!pte)
  68                         return -ENOMEM;
  69                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
  70                 address = (address + PMD_SIZE) & PMD_MASK;
  71                 pmd++;
  72         } while (address && (address < end));
  73         return 0;
  74 }
  75
  76 int remap_area_pages(unsigned long address, unsigned long phys_addr,
  77                      unsigned long size, unsigned long flags)
  78 {
  79         int error;
  80         pgd_t * dir;
  81         unsigned long end = address + size;
  82
  83         phys_addr -= address;
  84         dir = pgd_offset_k(address);
  85         flush_cache_all();
  86         if (address >= end)
  87                 BUG();
  88         do {
  89                 pud_t *pud;
  90                 pmd_t *pmd;
  91
  92                 error = -ENOMEM;
  93
  94                 pud = pud_alloc(&init_mm, dir, address);
  95                 if (!pud)
  96                         break;
  97                 pmd = pmd_alloc(&init_mm, pud, address);
  98                 if (!pmd)
  99                         break;
 100                 if (remap_area_pmd(pmd, address, end - address,
 101                                         phys_addr + address, flags))
 102                         break;
 103                 error = 0;
 104                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 105                 dir++;
 106         } while (address && (address < end));
 107         flush_tlb_all();
 108         return error;
 109 }
 110
 111 /*
 112  * Remap an arbitrary physical address space into the kernel virtual
 113  * address space. Needed when the kernel wants to access high addresses
 114  * directly.
 115  *
 116  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 117  * have to convert them into an offset in a page-aligned mapping, but the
 118  * caller shouldn't need to know that small detail.
 119  */
 120 void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
 121                         unsigned long flags)
 122 {
 123         struct vm_struct * area;
 124         unsigned long offset, last_addr, addr, orig_addr;
 125
 126         /* Don't allow wraparound or zero size */
 127         last_addr = phys_addr + size - 1;
 128         if (!size || last_addr < phys_addr)
 129                 return NULL;
 130
 131         /*
 132          * Don't remap the low PCI/ISA area, it's always mapped..
 133          */
 134         if (phys_addr >= 0xA0000 && last_addr < 0x100000)
 135                 return (void __iomem *)phys_to_virt(phys_addr);
 136
 137         /*
 138          * Don't allow anybody to remap normal RAM that we're using..
 139          */
 140         if (phys_addr < virt_to_phys(high_memory))
 141                 return NULL;
 142
 143         /*
 144          * Mappings have to be page-aligned
 145          */
 146         offset = phys_addr & ~PAGE_MASK;
 147         phys_addr &= PAGE_MASK;
 148         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 149
 150         /*
 151          * Ok, go for it..
 152          */
 153         area = get_vm_area(size, VM_IOREMAP);
 154         if (!area)
 155                 return NULL;
 156         area->phys_addr = phys_addr;
 157         orig_addr = addr = (unsigned long)area->addr;
 158
 159 #ifdef CONFIG_32BIT
 160         /*
 161          * First try to remap through the PMB once a valid VMA has been
 162          * established. Smaller allocations (or the rest of the size
 163          * remaining after a PMB mapping due to the size not being
 164          * perfectly aligned on a PMB size boundary) are then mapped
 165          * through the UTLB using conventional page tables.
 166          *
 167          * PMB entries are all pre-faulted.
 168          */
 169         if (unlikely(size >= 0x1000000)) {
 170                 unsigned long mapped = pmb_remap(addr, phys_addr, size, flags);
 171
 172                 if (likely(mapped)) {
 173                         addr            += mapped;
 174                         phys_addr       += mapped;
 175                         size            -= mapped;
 176                 }
 177         }
 178 #endif
 179
 180         if (likely(size))
 181                 if (remap_area_pages(addr, phys_addr, size, flags)) {
 182                         vunmap((void *)orig_addr);
 183                         return NULL;
 184                 }
 185
 186         return (void __iomem *)(offset + (char *)orig_addr);
 187 }
 188 EXPORT_SYMBOL(__ioremap);
 189
 190 void __iounmap(void __iomem *addr)
 191 {
 192         unsigned long vaddr = (unsigned long __force)addr;
 193         struct vm_struct *p;
 194
 195         if (PXSEG(vaddr) < P3SEG)
 196                 return;
 197
 198 #ifdef CONFIG_32BIT
 199         /*
 200          * Purge any PMB entries that may have been established for this
 201          * mapping, then proceed with conventional VMA teardown.
 202          *
 203          * XXX: Note that due to the way that remove_vm_area() does
 204          * matching of the resultant VMA, we aren't able to fast-forward
 205          * the address past the PMB space until the end of the VMA where
 206          * the page tables reside. As such, unmap_vm_area() will be
 207          * forced to linearly scan over the area until it finds the page
 208          * tables where PTEs that need to be unmapped actually reside,
 209          * which is far from optimal. Perhaps we need to use a separate
 210          * VMA for the PMB mappings?
 211          *                                      -- PFM.
 212          */
 213         pmb_unmap(vaddr);
 214 #endif
 215
 216         p = remove_vm_area((void *)(vaddr & PAGE_MASK));
 217         if (!p) {
 218                 printk(KERN_ERR "%s: bad address %p\n", __FUNCTION__, addr);
 219                 return;
 220         }
 221
 222         kfree(p);
 223 }
 224 EXPORT_SYMBOL(__iounmap);