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
  28 extern int mem_init_done;
  29
  30 static 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  */
  41 void __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 EXPORT_SYMBOL(__ioremap);
  84
  85 void iounmap(void *addr)
  86 {
  87         /* If the page is from the fixmap pool then we just clear out
  88          * the fixmap mapping.
  89          */
  90         if (unlikely((unsigned long)addr > FIXADDR_START)) {
  91                 /* This is a bit broken... we don't really know
  92                  * how big the area is so it's difficult to know
  93                  * how many fixed pages to invalidate...
  94                  * just flush tlb and hope for the best...
  95                  * consider this a FIXME
  96                  *
  97                  * Really we should be clearing out one or more page
  98                  * table entries for these virtual addresses so that
  99                  * future references cause a page fault... for now, we
 100                  * rely on two things:
 101                  *   i)  this code never gets called on known boards
 102                  *   ii) invalid accesses to the freed areas aren't made
 103                  */
 104                 flush_tlb_all();
 105                 return;
 106         }
 107
 108         return vfree((void *)(PAGE_MASK & (unsigned long)addr));
 109 }
 110 EXPORT_SYMBOL(iounmap);
 111
 112 /**
 113  * OK, this one's a bit tricky... ioremap can get called before memory is
 114  * initialized (early serial console does this) and will want to alloc a page
 115  * for its mapping.  No userspace pages will ever get allocated before memory
 116  * is initialized so this applies only to kernel pages.  In the event that
 117  * this is called before memory is initialized we allocate the page using
 118  * the memblock infrastructure.
 119  */
 120
 121 pte_t __ref *pte_alloc_one_kernel(struct mm_struct *mm,
 122                                          unsigned long address)
 123 {
 124         pte_t *pte;
 125
 126         if (likely(mem_init_done)) {
 127                 pte = (pte_t *) __get_free_page(GFP_KERNEL);
 128         } else {
 129                 pte = (pte_t *) __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
 130         }
 131
 132         if (pte)
 133                 clear_page(pte);
 134         return pte;
 135 }