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ioremap_32.c

/*
 * arch/sh/mm/ioremap.c
 *
 * Re-map IO memory to kernel address space so that we can access it.
 * This is needed for high PCI addresses that aren't mapped in the
 * 640k-1MB IO memory area on PC's
 *
 * (C) Copyright 1995 1996 Linus Torvalds
 * (C) Copyright 2005, 2006 Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License. See the file "COPYING" in the main directory of this
 * archive for more details.
 */
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/pci.h>
#include <linux/io.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/addrspace.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/mmu.h>

/*
 * Remap an arbitrary physical address space into the kernel virtual
 * address space. Needed when the kernel wants to access high addresses
 * directly.
 *
 * 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)
{
      struct vm_struct * area;
      unsigned long offset, last_addr, addr, orig_addr;
      pgprot_t pgprot;

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

      /*
       * If we're on an SH7751 or SH7780 PCI controller, PCI memory is
       * mapped at the end of the address space (typically 0xfd000000)
       * in a non-translatable area, so mapping through page tables for
       * this area is not only pointless, but also fundamentally
       * broken. Just return the physical address instead.
       *
       * For boards that map a small PCI memory aperture somewhere in
       * P1/P2 space, ioremap() will already do the right thing,
       * and we'll never get this far.
       */
      if (is_pci_memaddr(phys_addr) && is_pci_memaddr(last_addr))
            return (void __iomem *)phys_addr;

      /*
       * Don't allow anybody to remap normal RAM that we're using..
       */
      if (phys_addr < virt_to_phys(high_memory))
            return NULL;

      /*
       * Mappings have to be page-aligned
       */
      offset = phys_addr & ~PAGE_MASK;
      phys_addr &= PAGE_MASK;
      size = PAGE_ALIGN(last_addr+1) - phys_addr;

      /*
       * Ok, go for it..
       */
      area = get_vm_area(size, VM_IOREMAP);
      if (!area)
            return NULL;
      area->phys_addr = phys_addr;
      orig_addr = addr = (unsigned long)area->addr;

#ifdef CONFIG_32BIT
      /*
       * First try to remap through the PMB once a valid VMA has been
       * established. Smaller allocations (or the rest of the size
       * remaining after a PMB mapping due to the size not being
       * perfectly aligned on a PMB size boundary) are then mapped
       * through the UTLB using conventional page tables.
       *
       * PMB entries are all pre-faulted.
       */
      if (unlikely(size >= 0x1000000)) {
            unsigned long mapped = pmb_remap(addr, phys_addr, size, flags);

            if (likely(mapped)) {
                  addr        += mapped;
                  phys_addr   += mapped;
                  size        -= mapped;
            }
      }
#endif

      pgprot = __pgprot(pgprot_val(PAGE_KERNEL_NOCACHE) | flags);
      if (likely(size))
            if (ioremap_page_range(addr, addr + size, phys_addr, pgprot)) {
                  vunmap((void *)orig_addr);
                  return NULL;
            }

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

void __iounmap(void __iomem *addr)
{
      unsigned long vaddr = (unsigned long __force)addr;
      struct vm_struct *p;

      if (PXSEG(vaddr) < P3SEG || is_pci_memaddr(vaddr))
            return;

#ifdef CONFIG_32BIT
      /*
       * Purge any PMB entries that may have been established for this
       * mapping, then proceed with conventional VMA teardown.
       *
       * XXX: Note that due to the way that remove_vm_area() does
       * matching of the resultant VMA, we aren't able to fast-forward
       * the address past the PMB space until the end of the VMA where
       * the page tables reside. As such, unmap_vm_area() will be
       * forced to linearly scan over the area until it finds the page
       * tables where PTEs that need to be unmapped actually reside,
       * which is far from optimal. Perhaps we need to use a separate
       * VMA for the PMB mappings?
       *                            -- PFM.
       */
      pmb_unmap(vaddr);
#endif

      p = remove_vm_area((void *)(vaddr & PAGE_MASK));
      if (!p) {
            printk(KERN_ERR "%s: bad address %p\n", __func__, addr);
            return;
      }

      kfree(p);
}
EXPORT_SYMBOL(__iounmap);

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