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/sched.h>
  12 #include <linux/io.h>
  13 #include <linux/export.h>
  14 #include <asm/cacheflush.h>
  15
  16 #include "pgalloc-track.h"
  17
  18 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
  19 static unsigned int __ro_after_init iomap_max_page_shift = BITS_PER_LONG - 1;
  20
  21 static int __init set_nohugeiomap(char *str)
  22 {
  23         iomap_max_page_shift = PAGE_SHIFT;
  24         return 0;
  25 }
  26 early_param("nohugeiomap", set_nohugeiomap);
  27 #else /* CONFIG_HAVE_ARCH_HUGE_VMAP */
  28 static const unsigned int iomap_max_page_shift = PAGE_SHIFT;
  29 #endif  /* CONFIG_HAVE_ARCH_HUGE_VMAP */
  30
  31 int ioremap_page_range(unsigned long addr,
  32                        unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
  33 {
  34         return vmap_range(addr, end, phys_addr, prot, iomap_max_page_shift);
  35 }
  36
  37 #ifdef CONFIG_GENERIC_IOREMAP
  38 void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot)
  39 {
  40         unsigned long offset, vaddr;
  41         phys_addr_t last_addr;
  42         struct vm_struct *area;
  43
  44         /* Disallow wrap-around or zero size */
  45         last_addr = addr + size - 1;
  46         if (!size || last_addr < addr)
  47                 return NULL;
  48
  49         /* Page-align mappings */
  50         offset = addr & (~PAGE_MASK);
  51         addr -= offset;
  52         size = PAGE_ALIGN(size + offset);
  53
  54         area = get_vm_area_caller(size, VM_IOREMAP,
  55                         __builtin_return_address(0));
  56         if (!area)
  57                 return NULL;
  58         vaddr = (unsigned long)area->addr;
  59
  60         if (ioremap_page_range(vaddr, vaddr + size, addr, __pgprot(prot))) {
  61                 free_vm_area(area);
  62                 return NULL;
  63         }
  64
  65         return (void __iomem *)(vaddr + offset);
  66 }
  67 EXPORT_SYMBOL(ioremap_prot);
  68
  69 void iounmap(volatile void __iomem *addr)
  70 {
  71         vunmap((void *)((unsigned long)addr & PAGE_MASK));
  72 }
  73 EXPORT_SYMBOL(iounmap);
  74 #endif /* CONFIG_GENERIC_IOREMAP */