ioremap.c

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/*
 * arch/parisc/mm/ioremap.c
 *
 * (C) Copyright 1995 1996 Linus Torvalds
 * (C) Copyright 2001-2006 Helge Deller <[email protected]>
 * (C) Copyright 2005 Kyle McMartin <[email protected]>
 */

#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 + 1) - 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);