ioremap.c

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/*
 * OpenRISC ioremap.c
 *
 * Linux architectural port borrowing liberally from similar works of
 * others.  All original copyrights apply as per the original source
 * declaration.
 *
 * Modifications for the OpenRISC architecture:
 * Copyright (C) 2003 Matjaz Breskvar <[email protected]>
 * Copyright (C) 2010-2011 Jonas Bonn <[email protected]>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <linux/vmalloc.h>
#include <linux/io.h>
#include <asm/pgalloc.h>
#include <asm/kmap_types.h>
#include <asm/fixmap.h>
#include <asm/bug.h>
#include <asm/pgtable.h>
#include <linux/sched.h>
#include <asm/tlbflush.h>

extern int mem_init_done;

static unsigned int fixmaps_used __initdata;

/*
 * 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 *__init_refok
__ioremap(phys_addr_t addr, unsigned long size, pgprot_t prot)
{
    phys_addr_t p;
    unsigned long v;
    unsigned long offset, last_addr;
    struct vm_struct *area = NULL;

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

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

    if (likely(mem_init_done)) {
        area = get_vm_area(size, VM_IOREMAP);
        if (!area)
            return NULL;
        v = (unsigned long)area->addr;
    } else {
        if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
            return NULL;
        v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
        fixmaps_used += (size >> PAGE_SHIFT);
    }

    if (ioremap_page_range(v, v + size, p, prot)) {
        if (likely(mem_init_done))
            vfree(area->addr);
        else
            fixmaps_used -= (size >> PAGE_SHIFT);
        return NULL;
    }

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

void iounmap(void *addr)
{
    /* If the page is from the fixmap pool then we just clear out
     * the fixmap mapping.
     */
    if (unlikely((unsigned long)addr > FIXADDR_START)) {
        /* This is a bit broken... we don't really know
         * how big the area is so it's difficult to know
         * how many fixed pages to invalidate...
         * just flush tlb and hope for the best...
         * consider this a FIXME
         *
         * Really we should be clearing out one or more page
         * table entries for these virtual addresses so that
         * future references cause a page fault... for now, we
         * rely on two things:
         *   i)  this code never gets called on known boards
         *   ii) invalid accesses to the freed areas aren't made
         */
        flush_tlb_all();
        return;
    }

    return vfree((void *)(PAGE_MASK & (unsigned long)addr));
}

pte_t __init_refok *pte_alloc_one_kernel(struct mm_struct *mm,
                     unsigned long address)
{
    pte_t *pte;

    if (likely(mem_init_done)) {
        pte = (pte_t *) __get_free_page(GFP_KERNEL | __GFP_REPEAT);
    } else {
        pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
#if 0
        /* FIXME: use memblock... */
        pte = (pte_t *) __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
#endif
    }

    if (pte)
        clear_page(pte);
    return pte;
}