LXR linux/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
  19static unsigned int __ro_after_init iomap_max_page_shift = BITS_PER_LONG - 1;
  20
  21static int __init set_nohugeiomap(char *str)
  22{
  23        iomap_max_page_shift = PAGE_SHIFT;
  24        return 0;
  25}
  26early_param("nohugeiomap", set_nohugeiomap);
  27#else /* CONFIG_HAVE_ARCH_HUGE_VMAP */
  28static const unsigned int iomap_max_page_shift = PAGE_SHIFT;
  29#endif  /* CONFIG_HAVE_ARCH_HUGE_VMAP */
  30
  31int 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
  38void __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}
  67EXPORT_SYMBOL(ioremap_prot);
  68
  69void iounmap(volatile void __iomem *addr)
  70{
  71        vunmap((void *)((unsigned long)addr & PAGE_MASK));
  72}
  73EXPORT_SYMBOL(iounmap);
  74#endif /* CONFIG_GENERIC_IOREMAP */
  75