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
  23 extern int mem_init_done;
  24
  25 static 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  */
  36 void __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 }
  78 EXPORT_SYMBOL(ioremap);
  79
  80 void iounmap(void *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 }
 105 EXPORT_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
 116 pte_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 }