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
  28 #include <asm/cacheflush.h>
  29 #include <asm/hardware.h>
  30 #include <asm/io.h>
  31 #include <asm/tlbflush.h>
  32
  33 static inline void
  34 remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
  35                unsigned long phys_addr, pgprot_t pgprot)
  36 {
  37         unsigned long end;
  38
  39         address &= ~PMD_MASK;
  40         end = address + size;
  41         if (end > PMD_SIZE)
  42                 end = PMD_SIZE;
  43         BUG_ON(address >= end);
  44         do {
  45                 if (!pte_none(*pte))
  46                         goto bad;
  47
  48                 set_pte(pte, pfn_pte(phys_addr >> PAGE_SHIFT, pgprot));
  49                 address += PAGE_SIZE;
  50                 phys_addr += PAGE_SIZE;
  51                 pte++;
  52         } while (address && (address < end));
  53         return;
  54
  55  bad:
  56         printk("remap_area_pte: page already exists\n");
  57         BUG();
  58 }
  59
  60 static inline int
  61 remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
  62                unsigned long phys_addr, unsigned long flags)
  63 {
  64         unsigned long end;
  65         pgprot_t pgprot;
  66
  67         address &= ~PGDIR_MASK;
  68         end = address + size;
  69
  70         if (end > PGDIR_SIZE)
  71                 end = PGDIR_SIZE;
  72
  73         phys_addr -= address;
  74         BUG_ON(address >= end);
  75
  76         pgprot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | L_PTE_WRITE | flags);
  77         do {
  78                 pte_t * pte = pte_alloc_kernel(pmd, address);
  79                 if (!pte)
  80                         return -ENOMEM;
  81                 remap_area_pte(pte, address, end - address, address + phys_addr, pgprot);
  82                 address = (address + PMD_SIZE) & PMD_MASK;
  83                 pmd++;
  84         } while (address && (address < end));
  85         return 0;
  86 }
  87
  88 static int
  89 remap_area_pages(unsigned long start, unsigned long phys_addr,
  90                  unsigned long size, unsigned long flags)
  91 {
  92         unsigned long address = start;
  93         unsigned long end = start + size;
  94         int err = 0;
  95         pgd_t * dir;
  96
  97         phys_addr -= address;
  98         dir = pgd_offset(&init_mm, address);
  99         BUG_ON(address >= end);
 100         do {
 101                 pmd_t *pmd = pmd_alloc(&init_mm, dir, address);
 102                 if (!pmd) {
 103                         err = -ENOMEM;
 104                         break;
 105                 }
 106                 if (remap_area_pmd(pmd, address, end - address,
 107                                          phys_addr + address, flags)) {
 108                         err = -ENOMEM;
 109                         break;
 110                 }
 111
 112                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 113                 dir++;
 114         } while (address && (address < end));
 115
 116         flush_cache_vmap(start, end);
 117         return err;
 118 }
 119
 120 /*
 121  * Remap an arbitrary physical address space into the kernel virtual
 122  * address space. Needed when the kernel wants to access high addresses
 123  * directly.
 124  *
 125  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 126  * have to convert them into an offset in a page-aligned mapping, but the
 127  * caller shouldn't need to know that small detail.
 128  *
 129  * 'flags' are the extra L_PTE_ flags that you want to specify for this
 130  * mapping.  See include/asm-arm/proc-armv/pgtable.h for more information.
 131  */
 132 void __iomem *
 133 __ioremap(unsigned long phys_addr, size_t size, unsigned long flags,
 134           unsigned long align)
 135 {
 136         void * addr;
 137         struct vm_struct * area;
 138         unsigned long offset, last_addr;
 139
 140         /* Don't allow wraparound or zero size */
 141         last_addr = phys_addr + size - 1;
 142         if (!size || last_addr < phys_addr)
 143                 return NULL;
 144
 145         /*
 146          * Mappings have to be page-aligned
 147          */
 148         offset = phys_addr & ~PAGE_MASK;
 149         phys_addr &= PAGE_MASK;
 150         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 151
 152         /*
 153          * Ok, go for it..
 154          */
 155         area = get_vm_area(size, VM_IOREMAP);
 156         if (!area)
 157                 return NULL;
 158         addr = area->addr;
 159         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 160                 vfree(addr);
 161                 return NULL;
 162         }
 163         return (void __iomem *) (offset + (char *)addr);
 164 }
 165 EXPORT_SYMBOL(__ioremap);
 166
 167 void __iounmap(void __iomem *addr)
 168 {
 169         vfree((void *) (PAGE_MASK & (unsigned long) addr));
 170 }
 171 EXPORT_SYMBOL(__iounmap);
 172
 173 #ifdef __io
 174 void __iomem *ioport_map(unsigned long port, unsigned int nr)
 175 {
 176         return __io(port);
 177 }
 178 EXPORT_SYMBOL(ioport_map);
 179
 180 void ioport_unmap(void __iomem *addr)
 181 {
 182 }
 183 EXPORT_SYMBOL(ioport_unmap);
 184 #endif
 185
 186 #ifdef CONFIG_PCI
 187 #include <linux/pci.h>
 188 #include <linux/ioport.h>
 189
 190 void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
 191 {
 192         unsigned long start = pci_resource_start(dev, bar);
 193         unsigned long len   = pci_resource_len(dev, bar);
 194         unsigned long flags = pci_resource_flags(dev, bar);
 195
 196         if (!len || !start)
 197                 return NULL;
 198         if (maxlen && len > maxlen)
 199                 len = maxlen;
 200         if (flags & IORESOURCE_IO)
 201                 return ioport_map(start, len);
 202         if (flags & IORESOURCE_MEM) {
 203                 if (flags & IORESOURCE_CACHEABLE)
 204                         return ioremap(start, len);
 205                 return ioremap_nocache(start, len);
 206         }
 207         return NULL;
 208 }
 209 EXPORT_SYMBOL(pci_iomap);
 210
 211 void pci_iounmap(struct pci_dev *dev, void __iomem *addr)
 212 {
 213         if ((unsigned long)addr >= VMALLOC_START &&
 214             (unsigned long)addr < VMALLOC_END)
 215                 iounmap(addr);
 216 }
 217 EXPORT_SYMBOL(pci_iounmap);
 218 #endif