ioremap.c

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/*
 * 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
 */
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/io.h>
#include <linux/export.h>
#include <asm/cacheflush.h>
#include <asm/pgtable.h>

static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
        unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
{
    pte_t *pte;
    u64 pfn;

    pfn = phys_addr >> PAGE_SHIFT;
    pte = pte_alloc_kernel(pmd, addr);
    if (!pte)
        return -ENOMEM;
    do {
        BUG_ON(!pte_none(*pte));
        set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
        pfn++;
    } while (pte++, addr += PAGE_SIZE, addr != end);
    return 0;
}

static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
        unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
{
    pmd_t *pmd;
    unsigned long next;

    phys_addr -= addr;
    pmd = pmd_alloc(&init_mm, pud, addr);
    if (!pmd)
        return -ENOMEM;
    do {
        next = pmd_addr_end(addr, end);
        if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
            return -ENOMEM;
    } while (pmd++, addr = next, addr != end);
    return 0;
}

static inline int ioremap_pud_range(pgd_t *pgd, unsigned long addr,
        unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
{
    pud_t *pud;
    unsigned long next;

    phys_addr -= addr;
    pud = pud_alloc(&init_mm, pgd, addr);
    if (!pud)
        return -ENOMEM;
    do {
        next = pud_addr_end(addr, end);
        if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
            return -ENOMEM;
    } while (pud++, addr = next, addr != end);
    return 0;
}

int ioremap_page_range(unsigned long addr,
               unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
{
    pgd_t *pgd;
    unsigned long start;
    unsigned long next;
    int err;

    BUG_ON(addr >= end);

    start = addr;
    phys_addr -= addr;
    pgd = pgd_offset_k(addr);
    do {
        next = pgd_addr_end(addr, end);
        err = ioremap_pud_range(pgd, addr, next, phys_addr+addr, prot);
        if (err)
            break;
    } while (pgd++, addr = next, addr != end);

    flush_cache_vmap(start, end);

    return err;
}
EXPORT_SYMBOL_GPL(ioremap_page_range);