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 <linux/pci.h>
  19 #include <asm/io.h>
  20 #include <asm/page.h>
  21 #include <asm/pgalloc.h>
  22 #include <asm/addrspace.h>
  23 #include <asm/cacheflush.h>
  24 #include <asm/tlbflush.h>
  25
  26 static inline void remap_area_pte(pte_t * pte, unsigned long address,
  27         unsigned long size, unsigned long phys_addr, unsigned long flags)
  28 {
  29         unsigned long end;
  30         unsigned long pfn;
  31         pgprot_t pgprot = __pgprot(_PAGE_PRESENT | _PAGE_RW |
  32                                    _PAGE_DIRTY | _PAGE_ACCESSED |
  33                                    _PAGE_HW_SHARED | _PAGE_FLAGS_HARD | flags);
  34
  35         address &= ~PMD_MASK;
  36         end = address + size;
  37         if (end > PMD_SIZE)
  38                 end = PMD_SIZE;
  39         if (address >= end)
  40                 BUG();
  41         pfn = phys_addr >> PAGE_SHIFT;
  42         do {
  43                 if (!pte_none(*pte)) {
  44                         printk("remap_area_pte: page already exists\n");
  45                         BUG();
  46                 }
  47                 set_pte(pte, pfn_pte(pfn, pgprot));
  48                 address += PAGE_SIZE;
  49                 pfn++;
  50                 pte++;
  51         } while (address && (address < end));
  52 }
  53
  54 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address,
  55         unsigned long size, unsigned long phys_addr, unsigned long flags)
  56 {
  57         unsigned long end;
  58
  59         address &= ~PGDIR_MASK;
  60         end = address + size;
  61         if (end > PGDIR_SIZE)
  62                 end = PGDIR_SIZE;
  63         phys_addr -= address;
  64         if (address >= end)
  65                 BUG();
  66         do {
  67                 pte_t * pte = pte_alloc_kernel(pmd, address);
  68                 if (!pte)
  69                         return -ENOMEM;
  70                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
  71                 address = (address + PMD_SIZE) & PMD_MASK;
  72                 pmd++;
  73         } while (address && (address < end));
  74         return 0;
  75 }
  76
  77 int remap_area_pages(unsigned long address, unsigned long phys_addr,
  78                      unsigned long size, unsigned long flags)
  79 {
  80         int error;
  81         pgd_t * dir;
  82         unsigned long end = address + size;
  83
  84         phys_addr -= address;
  85         dir = pgd_offset_k(address);
  86         flush_cache_all();
  87         if (address >= end)
  88                 BUG();
  89         do {
  90                 pud_t *pud;
  91                 pmd_t *pmd;
  92
  93                 error = -ENOMEM;
  94
  95                 pud = pud_alloc(&init_mm, dir, address);
  96                 if (!pud)
  97                         break;
  98                 pmd = pmd_alloc(&init_mm, pud, address);
  99                 if (!pmd)
 100                         break;
 101                 if (remap_area_pmd(pmd, address, end - address,
 102                                         phys_addr + address, flags))
 103                         break;
 104                 error = 0;
 105                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 106                 dir++;
 107         } while (address && (address < end));
 108         flush_tlb_all();
 109         return error;
 110 }
 111
 112 /*
 113  * Remap an arbitrary physical address space into the kernel virtual
 114  * address space. Needed when the kernel wants to access high addresses
 115  * directly.
 116  *
 117  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 118  * have to convert them into an offset in a page-aligned mapping, but the
 119  * caller shouldn't need to know that small detail.
 120  */
 121 void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
 122                         unsigned long flags)
 123 {
 124         struct vm_struct * area;
 125         unsigned long offset, last_addr, addr, orig_addr;
 126
 127         /* Don't allow wraparound or zero size */
 128         last_addr = phys_addr + size - 1;
 129         if (!size || last_addr < phys_addr)
 130                 return NULL;
 131
 132         /*
 133          * Don't remap the low PCI/ISA area, it's always mapped..
 134          */
 135         if (phys_addr >= 0xA0000 && last_addr < 0x100000)
 136                 return (void __iomem *)phys_to_virt(phys_addr);
 137
 138         /*
 139          * If we're on an SH7751 or SH7780 PCI controller, PCI memory is
 140          * mapped at the end of the address space (typically 0xfd000000)
 141          * in a non-translatable area, so mapping through page tables for
 142          * this area is not only pointless, but also fundamentally
 143          * broken. Just return the physical address instead.
 144          *
 145          * For boards that map a small PCI memory aperture somewhere in
 146          * P1/P2 space, ioremap() will already do the right thing,
 147          * and we'll never get this far.
 148          */
 149         if (is_pci_memaddr(phys_addr) && is_pci_memaddr(last_addr))
 150                 return (void __iomem *)phys_addr;
 151
 152         /*
 153          * Don't allow anybody to remap normal RAM that we're using..
 154          */
 155         if (phys_addr < virt_to_phys(high_memory))
 156                 return NULL;
 157
 158         /*
 159          * Mappings have to be page-aligned
 160          */
 161         offset = phys_addr & ~PAGE_MASK;
 162         phys_addr &= PAGE_MASK;
 163         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 164
 165         /*
 166          * Ok, go for it..
 167          */
 168         area = get_vm_area(size, VM_IOREMAP);
 169         if (!area)
 170                 return NULL;
 171         area->phys_addr = phys_addr;
 172         orig_addr = addr = (unsigned long)area->addr;
 173
 174 #ifdef CONFIG_32BIT
 175         /*
 176          * First try to remap through the PMB once a valid VMA has been
 177          * established. Smaller allocations (or the rest of the size
 178          * remaining after a PMB mapping due to the size not being
 179          * perfectly aligned on a PMB size boundary) are then mapped
 180          * through the UTLB using conventional page tables.
 181          *
 182          * PMB entries are all pre-faulted.
 183          */
 184         if (unlikely(size >= 0x1000000)) {
 185                 unsigned long mapped = pmb_remap(addr, phys_addr, size, flags);
 186
 187                 if (likely(mapped)) {
 188                         addr            += mapped;
 189                         phys_addr       += mapped;
 190                         size            -= mapped;
 191                 }
 192         }
 193 #endif
 194
 195         if (likely(size))
 196                 if (remap_area_pages(addr, phys_addr, size, flags)) {
 197                         vunmap((void *)orig_addr);
 198                         return NULL;
 199                 }
 200
 201         return (void __iomem *)(offset + (char *)orig_addr);
 202 }
 203 EXPORT_SYMBOL(__ioremap);
 204
 205 void __iounmap(void __iomem *addr)
 206 {
 207         unsigned long vaddr = (unsigned long __force)addr;
 208         struct vm_struct *p;
 209
 210         if (PXSEG(vaddr) < P3SEG || is_pci_memaddr(vaddr))
 211                 return;
 212
 213 #ifdef CONFIG_32BIT
 214         /*
 215          * Purge any PMB entries that may have been established for this
 216          * mapping, then proceed with conventional VMA teardown.
 217          *
 218          * XXX: Note that due to the way that remove_vm_area() does
 219          * matching of the resultant VMA, we aren't able to fast-forward
 220          * the address past the PMB space until the end of the VMA where
 221          * the page tables reside. As such, unmap_vm_area() will be
 222          * forced to linearly scan over the area until it finds the page
 223          * tables where PTEs that need to be unmapped actually reside,
 224          * which is far from optimal. Perhaps we need to use a separate
 225          * VMA for the PMB mappings?
 226          *                                      -- PFM.
 227          */
 228         pmb_unmap(vaddr);
 229 #endif
 230
 231         p = remove_vm_area((void *)(vaddr & PAGE_MASK));
 232         if (!p) {
 233                 printk(KERN_ERR "%s: bad address %p\n", __FUNCTION__, addr);
 234                 return;
 235         }
 236
 237         kfree(p);
 238 }
 239 EXPORT_SYMBOL(__iounmap);