LXR linux/arch/x86/mm/iomap

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Copyright © 2008 Ingo Molnar
   4 */
   5
   6#include <asm/iomap.h>
   7#include <asm/memtype.h>
   8#include <linux/export.h>
   9#include <linux/highmem.h>
  10
  11static int is_io_mapping_possible(resource_size_t base, unsigned long size)
  12{
  13#if !defined(CONFIG_X86_PAE) && defined(CONFIG_PHYS_ADDR_T_64BIT)
  14        /* There is no way to map greater than 1 << 32 address without PAE */
  15        if (base + size > 0x100000000ULL)
  16                return 0;
  17#endif
  18        return 1;
  19}
  20
  21int iomap_create_wc(resource_size_t base, unsigned long size, pgprot_t *prot)
  22{
  23        enum page_cache_mode pcm = _PAGE_CACHE_MODE_WC;
  24        int ret;
  25
  26        if (!is_io_mapping_possible(base, size))
  27                return -EINVAL;
  28
  29        ret = memtype_reserve_io(base, base + size, &pcm);
  30        if (ret)
  31                return ret;
  32
  33        *prot = __pgprot(__PAGE_KERNEL | cachemode2protval(pcm));
  34        /* Filter out unsupported __PAGE_KERNEL* bits: */
  35        pgprot_val(*prot) &= __default_kernel_pte_mask;
  36
  37        return 0;
  38}
  39EXPORT_SYMBOL_GPL(iomap_create_wc);
  40
  41void iomap_free(resource_size_t base, unsigned long size)
  42{
  43        memtype_free_io(base, base + size);
  44}
  45EXPORT_SYMBOL_GPL(iomap_free);
  46
  47void __iomem *__iomap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
  48{
  49        /*
  50         * For non-PAT systems, translate non-WB request to UC- just in
  51         * case the caller set the PWT bit to prot directly without using
  52         * pgprot_writecombine(). UC- translates to uncached if the MTRR
  53         * is UC or WC. UC- gets the real intention, of the user, which is
  54         * "WC if the MTRR is WC, UC if you can't do that."
  55         */
  56        if (!pat_enabled() && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
  57                prot = __pgprot(__PAGE_KERNEL |
  58                                cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
  59
  60        /* Filter out unsupported __PAGE_KERNEL* bits: */
  61        pgprot_val(prot) &= __default_kernel_pte_mask;
  62
  63        return (void __force __iomem *)__kmap_local_pfn_prot(pfn, prot);
  64}
  65EXPORT_SYMBOL_GPL(__iomap_local_pfn_prot);
  66