ioremap.c

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/*
 *  linux/arch/m32r/mm/ioremap.c
 *
 *  Copyright (c) 2001, 2002  Hiroyuki Kondo
 *
 *  Taken from mips version.
 *    (C) Copyright 1995 1996 Linus Torvalds
 *    (C) Copyright 2001 Ralf Baechle
 */

/*
 * 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/module.h>
#include <asm/addrspace.h>
#include <asm/byteorder.h>

#include <linux/vmalloc.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. 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.
 */

#define IS_LOW512(addr) (!((unsigned long)(addr) & ~0x1fffffffUL))

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;

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

    /*
     * Map objects in the low 512mb of address space using KSEG1, otherwise
     * map using page tables.
     */
    if (IS_LOW512(phys_addr) && IS_LOW512(phys_addr + size - 1))
        return (void *) KSEG1ADDR(phys_addr);

    /*
     * 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_GLOBAL | _PAGE_PRESENT | _PAGE_READ
              | _PAGE_WRITE | 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;
    area->phys_addr = phys_addr;
    addr = (void __iomem *) area->addr;
    if (ioremap_page_range((unsigned long)addr, (unsigned long)addr + size,
                   phys_addr, pgprot)) {
        vunmap((void __force *) addr);
        return NULL;
    }

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

#define IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == KSEG1)

void iounmap(volatile void __iomem *addr)
{
    if (!IS_KSEG1(addr))
        vfree((void *) (PAGE_MASK & (unsigned long) addr));
}