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 <asm/pgalloc.h>
  17 #include <asm/kmap_types.h>
  18 #include <asm/fixmap.h>
  19 #include <asm/bug.h>
  20 #include <asm/pgtable.h>
  21 #include <linux/sched.h>
  22 #include <asm/tlbflush.h>
  23
  24 extern int mem_init_done;
  25
  26 static 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  */
  37 void __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 }
  79 EXPORT_SYMBOL(ioremap);
  80
  81 void 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 }
 106 EXPORT_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
 117 pte_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 }