mm/ioremap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Re-map IO memory to kernel address space so that we can access it.
   4  * This is needed for high PCI addresses that aren't mapped in the
   5  * 640k-1MB IO memory area on PC's
   6  *
   7  * (C) Copyright 1995 1996 Linus Torvalds
   8  */
   9 #include <linux/vmalloc.h>
  10 #include <linux/mm.h>
  11 #include <linux/io.h>
  12 #include <linux/export.h>
  13
  14 void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
  15                            unsigned long prot)
  16 {
  17         unsigned long offset, vaddr;
  18         phys_addr_t last_addr;
  19         struct vm_struct *area;
  20
  21         /* Disallow wrap-around or zero size */
  22         last_addr = phys_addr + size - 1;
  23         if (!size || last_addr < phys_addr)
  24                 return NULL;
  25
  26         /* Page-align mappings */
  27         offset = phys_addr & (~PAGE_MASK);
  28         phys_addr -= offset;
  29         size = PAGE_ALIGN(size + offset);
  30
  31         if (!ioremap_allowed(phys_addr, size, prot))
  32                 return NULL;
  33
  34         area = get_vm_area_caller(size, VM_IOREMAP,
  35                         __builtin_return_address(0));
  36         if (!area)
  37                 return NULL;
  38         vaddr = (unsigned long)area->addr;
  39         area->phys_addr = phys_addr;
  40
  41         if (ioremap_page_range(vaddr, vaddr + size, phys_addr,
  42                                __pgprot(prot))) {
  43                 free_vm_area(area);
  44                 return NULL;
  45         }
  46
  47         return (void __iomem *)(vaddr + offset);
  48 }
  49 EXPORT_SYMBOL(ioremap_prot);
  50
  51 void iounmap(volatile void __iomem *addr)
  52 {
  53         void *vaddr = (void *)((unsigned long)addr & PAGE_MASK);
  54
  55         if (!iounmap_allowed(vaddr))
  56                 return;
  57
  58         if (is_vmalloc_addr(vaddr))
  59                 vunmap(vaddr);
  60 }
  61 EXPORT_SYMBOL(iounmap);