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

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * OpenRISC ioremap.c
   4 *
   5 * Linux architectural port borrowing liberally from similar works of
   6 * others.  All original copyrights apply as per the original source
   7 * declaration.
   8 *
   9 * Modifications for the OpenRISC architecture:
  10 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  11 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  12 */
  13
  14#include <linux/vmalloc.h>
  15#include <linux/io.h>
  16#include <linux/pgtable.h>
  17#include <asm/pgalloc.h>
  18#include <asm/kmap_types.h>
  19#include <asm/fixmap.h>
  20#include <asm/bug.h>
  21#include <linux/sched.h>
  22#include <asm/tlbflush.h>
  23
  24extern int mem_init_done;
  25
  26static unsigned int fixmaps_used __initdata;
  27
  28/*
  29 * Remap an arbitrary physical address space into the kernel virtual
  30 * address space. Needed when the kernel wants to access high addresses
  31 * directly.
  32 *
  33 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
  34 * have to convert them into an offset in a page-aligned mapping, but the
  35 * caller shouldn't need to know that small detail.
  36 */
  37void __iomem *__ref ioremap(phys_addr_t addr, unsigned long size)
  38{
  39        phys_addr_t p;
  40        unsigned long v;
  41        unsigned long offset, last_addr;
  42        struct vm_struct *area = NULL;
  43
  44        /* Don't allow wraparound or zero size */
  45        last_addr = addr + size - 1;
  46        if (!size || last_addr < addr)
  47                return NULL;
  48
  49        /*
  50         * Mappings have to be page-aligned
  51         */
  52        offset = addr & ~PAGE_MASK;
  53        p = addr & PAGE_MASK;
  54        size = PAGE_ALIGN(last_addr + 1) - p;
  55
  56        if (likely(mem_init_done)) {
  57                area = get_vm_area(size, VM_IOREMAP);
  58                if (!area)
  59                        return NULL;
  60                v = (unsigned long)area->addr;
  61        } else {
  62                if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
  63                        return NULL;
  64                v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
  65                fixmaps_used += (size >> PAGE_SHIFT);
  66        }
  67
  68        if (ioremap_page_range(v, v + size, p,
  69                        __pgprot(pgprot_val(PAGE_KERNEL) | _PAGE_CI))) {
  70                if (likely(mem_init_done))
  71                        vfree(area->addr);
  72                else
  73                        fixmaps_used -= (size >> PAGE_SHIFT);
  74                return NULL;
  75        }
  76
  77        return (void __iomem *)(offset + (char *)v);
  78}
  79EXPORT_SYMBOL(ioremap);
  80
  81void iounmap(void *addr)
  82{
  83        /* If the page is from the fixmap pool then we just clear out
  84         * the fixmap mapping.
  85         */
  86        if (unlikely((unsigned long)addr > FIXADDR_START)) {
  87                /* This is a bit broken... we don't really know
  88                 * how big the area is so it's difficult to know
  89                 * how many fixed pages to invalidate...
  90                 * just flush tlb and hope for the best...
  91                 * consider this a FIXME
  92                 *
  93                 * Really we should be clearing out one or more page
  94                 * table entries for these virtual addresses so that
  95                 * future references cause a page fault... for now, we
  96                 * rely on two things:
  97                 *   i)  this code never gets called on known boards
  98                 *   ii) invalid accesses to the freed areas aren't made
  99                 */
 100                flush_tlb_all();
 101                return;
 102        }
 103
 104        return vfree((void *)(PAGE_MASK & (unsigned long)addr));
 105}
 106EXPORT_SYMBOL(iounmap);
 107
 108/**
 109 * OK, this one's a bit tricky... ioremap can get called before memory is
 110 * initialized (early serial console does this) and will want to alloc a page
 111 * for its mapping.  No userspace pages will ever get allocated before memory
 112 * is initialized so this applies only to kernel pages.  In the event that
 113 * this is called before memory is initialized we allocate the page using
 114 * the memblock infrastructure.
 115 */
 116
 117pte_t __ref *pte_alloc_one_kernel(struct mm_struct *mm)
 118{
 119        pte_t *pte;
 120
 121        if (likely(mem_init_done)) {
 122                pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
 123        } else {
 124                pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
 125                if (!pte)
 126                        panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
 127                              __func__, PAGE_SIZE, PAGE_SIZE);
 128        }
 129
 130        return pte;
 131}
 132