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