arch/x86/mm/iomap_32.c

   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
  11 static 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
  21 int 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 }
  39 EXPORT_SYMBOL_GPL(iomap_create_wc);
  40
  41 void iomap_free(resource_size_t base, unsigned long size)
  42 {
  43         memtype_free_io(base, base + size);
  44 }
  45 EXPORT_SYMBOL_GPL(iomap_free);
  46
  47 void __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 }
  65 EXPORT_SYMBOL_GPL(__iomap_local_pfn_prot);