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 #include <linux/ioremap.h>
  14
  15 void __iomem *generic_ioremap_prot(phys_addr_t phys_addr, size_t size,
  16                                    pgprot_t prot)
  17 {
  18         unsigned long offset, vaddr;
  19         phys_addr_t last_addr;
  20         struct vm_struct *area;
  21
  22         /* An early platform driver might end up here */
  23         if (WARN_ON_ONCE(!slab_is_available()))
  24                 return NULL;
  25
  26         /* Disallow wrap-around or zero size */
  27         last_addr = phys_addr + size - 1;
  28         if (!size || last_addr < phys_addr)
  29                 return NULL;
  30
  31         /* Page-align mappings */
  32         offset = phys_addr & (~PAGE_MASK);
  33         phys_addr -= offset;
  34         size = PAGE_ALIGN(size + offset);
  35
  36         area = __get_vm_area_caller(size, VM_IOREMAP, IOREMAP_START,
  37                                     IOREMAP_END, __builtin_return_address(0));
  38         if (!area)
  39                 return NULL;
  40         vaddr = (unsigned long)area->addr;
  41         area->phys_addr = phys_addr;
  42
  43         if (ioremap_page_range(vaddr, vaddr + size, phys_addr, prot)) {
  44                 free_vm_area(area);
  45                 return NULL;
  46         }
  47
  48         return (void __iomem *)(vaddr + offset);
  49 }
  50
  51 #ifndef ioremap_prot
  52 void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
  53                            unsigned long prot)
  54 {
  55         return generic_ioremap_prot(phys_addr, size, __pgprot(prot));
  56 }
  57 EXPORT_SYMBOL(ioremap_prot);
  58 #endif
  59
  60 void generic_iounmap(volatile void __iomem *addr)
  61 {
  62         void *vaddr = (void *)((unsigned long)addr & PAGE_MASK);
  63
  64         if (is_ioremap_addr(vaddr))
  65                 vunmap(vaddr);
  66 }
  67
  68 #ifndef iounmap
  69 void iounmap(volatile void __iomem *addr)
  70 {
  71         generic_iounmap(addr);
  72 }
  73 EXPORT_SYMBOL(iounmap);
  74 #endif