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 addr, size_t size, unsigned long prot)
  15 {
  16         unsigned long offset, vaddr;
  17         phys_addr_t last_addr;
  18         struct vm_struct *area;
  19
  20         /* Disallow wrap-around or zero size */
  21         last_addr = addr + size - 1;
  22         if (!size || last_addr < addr)
  23                 return NULL;
  24
  25         /* Page-align mappings */
  26         offset = addr & (~PAGE_MASK);
  27         addr -= offset;
  28         size = PAGE_ALIGN(size + offset);
  29
  30         area = get_vm_area_caller(size, VM_IOREMAP,
  31                         __builtin_return_address(0));
  32         if (!area)
  33                 return NULL;
  34         vaddr = (unsigned long)area->addr;
  35
  36         if (ioremap_page_range(vaddr, vaddr + size, addr, __pgprot(prot))) {
  37                 free_vm_area(area);
  38                 return NULL;
  39         }
  40
  41         return (void __iomem *)(vaddr + offset);
  42 }
  43 EXPORT_SYMBOL(ioremap_prot);
  44
  45 void iounmap(volatile void __iomem *addr)
  46 {
  47         vunmap((void *)((unsigned long)addr & PAGE_MASK));
  48 }
  49 EXPORT_SYMBOL(iounmap);