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ioremap.c

/*
 * arch/parisc/mm/ioremap.c
 *
 * (C) Copyright 1995 1996 Linus Torvalds
 * (C) Copyright 2001-2006 Helge Deller <deller@gmx.de>
 * (C) Copyright 2005 Kyle McMartin <kyle@parisc-linux.org>
 */

#include <linux/vmalloc.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/io.h>
#include <asm/pgalloc.h>

/*
 * Generic mapping function (not visible outside):
 */

/*
 * Remap an arbitrary physical address space into the kernel virtual
 * address space.
 *
 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 * have to convert them into an offset in a page-aligned mapping, but the
 * caller shouldn't need to know that small detail.
 */
void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
{
      void __iomem *addr;
      struct vm_struct *area;
      unsigned long offset, last_addr;
      pgprot_t pgprot;

#ifdef CONFIG_EISA
      unsigned long end = phys_addr + size - 1;
      /* Support EISA addresses */
      if ((phys_addr >= 0x00080000 && end < 0x000fffff) ||
          (phys_addr >= 0x00500000 && end < 0x03bfffff)) {
            phys_addr |= F_EXTEND(0xfc000000);
            flags |= _PAGE_NO_CACHE;
      }
#endif

      /* Don't allow wraparound or zero size */
      last_addr = phys_addr + size - 1;
      if (!size || last_addr < phys_addr)
            return NULL;

      /*
       * Don't allow anybody to remap normal RAM that we're using..
       */
      if (phys_addr < virt_to_phys(high_memory)) {
            char *t_addr, *t_end;
            struct page *page;

            t_addr = __va(phys_addr);
            t_end = t_addr + (size - 1);
         
            for (page = virt_to_page(t_addr); 
                 page <= virt_to_page(t_end); page++) {
                  if(!PageReserved(page))
                        return NULL;
            }
      }

      pgprot = __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY |
                    _PAGE_ACCESSED | flags);

      /*
       * Mappings have to be page-aligned
       */
      offset = phys_addr & ~PAGE_MASK;
      phys_addr &= PAGE_MASK;
      size = PAGE_ALIGN(last_addr) - phys_addr;

      /*
       * Ok, go for it..
       */
      area = get_vm_area(size, VM_IOREMAP);
      if (!area)
            return NULL;

      addr = (void __iomem *) area->addr;
      if (ioremap_page_range((unsigned long)addr, (unsigned long)addr + size,
                         phys_addr, pgprot)) {
            vfree(addr);
            return NULL;
      }

      return (void __iomem *) (offset + (char __iomem *)addr);
}
EXPORT_SYMBOL(__ioremap);

void iounmap(const volatile void __iomem *addr)
{
      if (addr > high_memory)
            return vfree((void *) (PAGE_MASK & (unsigned long __force) addr));
}
EXPORT_SYMBOL(iounmap);

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