LXR linux/arch/openrisc/mm/ioremap.c

   1/*
   2 * OpenRISC ioremap.c
   3 *
   4 * Linux architectural port borrowing liberally from similar works of
   5 * others.  All original copyrights apply as per the original source
   6 * declaration.
   7 *
   8 * Modifications for the OpenRISC architecture:
   9 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  11 *
  12 *      This program is free software; you can redistribute it and/or
  13 *      modify it under the terms of the GNU General Public License
  14 *      as published by the Free Software Foundation; either version
  15 *      2 of the License, or (at your option) any later version.
  16 */
  17
  18#include <linux/vmalloc.h>
  19#include <linux/io.h>
  20#include <asm/pgalloc.h>
  21#include <asm/kmap_types.h>
  22#include <asm/fixmap.h>
  23#include <asm/bug.h>
  24#include <asm/pgtable.h>
  25#include <linux/sched.h>
  26#include <asm/tlbflush.h>
  27
  28extern int mem_init_done;
  29
  30static unsigned int fixmaps_used __initdata;
  31
  32/*
  33 * Remap an arbitrary physical address space into the kernel virtual
  34 * address space. Needed when the kernel wants to access high addresses
  35 * directly.
  36 *
  37 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
  38 * have to convert them into an offset in a page-aligned mapping, but the
  39 * caller shouldn't need to know that small detail.
  40 */
  41void __iomem *__ref
  42__ioremap(phys_addr_t addr, unsigned long size, pgprot_t prot)
  43{
  44        phys_addr_t p;
  45        unsigned long v;
  46        unsigned long offset, last_addr;
  47        struct vm_struct *area = NULL;
  48
  49        /* Don't allow wraparound or zero size */
  50        last_addr = addr + size - 1;
  51        if (!size || last_addr < addr)
  52                return NULL;
  53
  54        /*
  55         * Mappings have to be page-aligned
  56         */
  57        offset = addr & ~PAGE_MASK;
  58        p = addr & PAGE_MASK;
  59        size = PAGE_ALIGN(last_addr + 1) - p;
  60
  61        if (likely(mem_init_done)) {
  62                area = get_vm_area(size, VM_IOREMAP);
  63                if (!area)
  64                        return NULL;
  65                v = (unsigned long)area->addr;
  66        } else {
  67                if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
  68                        return NULL;
  69                v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
  70                fixmaps_used += (size >> PAGE_SHIFT);
  71        }
  72
  73        if (ioremap_page_range(v, v + size, p, prot)) {
  74                if (likely(mem_init_done))
  75                        vfree(area->addr);
  76                else
  77                        fixmaps_used -= (size >> PAGE_SHIFT);
  78                return NULL;
  79        }
  80
  81        return (void __iomem *)(offset + (char *)v);
  82}
  83
  84void iounmap(void *addr)
  85{
  86        /* If the page is from the fixmap pool then we just clear out
  87         * the fixmap mapping.
  88         */
  89        if (unlikely((unsigned long)addr > FIXADDR_START)) {
  90                /* This is a bit broken... we don't really know
  91                 * how big the area is so it's difficult to know
  92                 * how many fixed pages to invalidate...
  93                 * just flush tlb and hope for the best...
  94                 * consider this a FIXME
  95                 *
  96                 * Really we should be clearing out one or more page
  97                 * table entries for these virtual addresses so that
  98                 * future references cause a page fault... for now, we
  99                 * rely on two things:
 100                 *   i)  this code never gets called on known boards
 101                 *   ii) invalid accesses to the freed areas aren't made
 102                 */
 103                flush_tlb_all();
 104                return;
 105        }
 106
 107        return vfree((void *)(PAGE_MASK & (unsigned long)addr));
 108}
 109
 110/**
 111 * OK, this one's a bit tricky... ioremap can get called before memory is
 112 * initialized (early serial console does this) and will want to alloc a page
 113 * for its mapping.  No userspace pages will ever get allocated before memory
 114 * is initialized so this applies only to kernel pages.  In the event that
 115 * this is called before memory is initialized we allocate the page using
 116 * the memblock infrastructure.
 117 */
 118
 119pte_t __ref *pte_alloc_one_kernel(struct mm_struct *mm,
 120                                         unsigned long address)
 121{
 122        pte_t *pte;
 123
 124        if (likely(mem_init_done)) {
 125                pte = (pte_t *) __get_free_page(GFP_KERNEL);
 126        } else {
 127                pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
 128#if 0
 129                /* FIXME: use memblock... */
 130                pte = (pte_t *) __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
 131#endif
 132        }
 133
 134        if (pte)
 135                clear_page(pte);
 136        return pte;
 137}
 138