ioremap.c

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/*
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/slab.h>

#include <asm/pgtable.h>
#include <asm/addrspace.h>

/*
 * Re-map an arbitrary physical address space into the kernel virtual
 * address space. Needed when the kernel wants to access physical
 * memory directly.
 */
void __iomem *__ioremap(unsigned long phys_addr, size_t size,
            unsigned long flags)
{
    unsigned long addr;
    struct vm_struct *area;
    unsigned long offset, last_addr;
    pgprot_t prot;

    /*
     * Check if we can simply use the P4 segment. This area is
     * uncacheable, so if caching/buffering is requested, we can't
     * use it.
     */
    if ((phys_addr >= P4SEG) && (flags == 0))
        return (void __iomem *)phys_addr;

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

    /*
     * XXX: When mapping regular RAM, we'd better make damn sure
     * it's never used for anything else.  But this is really the
     * caller's responsibility...
     */
    if (PHYSADDR(P2SEGADDR(phys_addr)) == phys_addr)
        return (void __iomem *)P2SEGADDR(phys_addr);

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

    prot = __pgprot(_PAGE_PRESENT | _PAGE_GLOBAL | _PAGE_RW | _PAGE_DIRTY
            | _PAGE_ACCESSED | _PAGE_TYPE_SMALL | flags);

    /*
     * Ok, go for it..
     */
    area = get_vm_area(size, VM_IOREMAP);
    if (!area)
        return NULL;
    area->phys_addr = phys_addr;
    addr = (unsigned long )area->addr;
    if (ioremap_page_range(addr, addr + size, phys_addr, prot)) {
        vunmap((void *)addr);
        return NULL;
    }

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

void __iounmap(void __iomem *addr)
{
    struct vm_struct *p;

    if ((unsigned long)addr >= P4SEG)
        return;
    if (PXSEG(addr) == P2SEG)
        return;

    p = remove_vm_area((void *)(PAGE_MASK & (unsigned long __force)addr));
    if (unlikely(!p)) {
        printk (KERN_ERR "iounmap: bad address %p\n", addr);
        return;
    }

    kfree (p);
}
EXPORT_SYMBOL(__iounmap);