arch/x86/mm/iomap_32.c

   1 /*
   2  * Copyright © 2008 Ingo Molnar
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  17  */
  18
  19 #include <asm/iomap.h>
  20 #include <asm/pat.h>
  21 #include <linux/module.h>
  22
  23 #ifdef CONFIG_X86_PAE
  24 int
  25 is_io_mapping_possible(resource_size_t base, unsigned long size)
  26 {
  27         return 1;
  28 }
  29 #else
  30 int
  31 is_io_mapping_possible(resource_size_t base, unsigned long size)
  32 {
  33         /* There is no way to map greater than 1 << 32 address without PAE */
  34         if (base + size > 0x100000000ULL)
  35                 return 0;
  36
  37         return 1;
  38 }
  39 #endif
  40
  41 /* Map 'pfn' using fixed map 'type' and protections 'prot'
  42  */
  43 void *
  44 iomap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot)
  45 {
  46         enum fixed_addresses idx;
  47         unsigned long vaddr;
  48
  49         pagefault_disable();
  50
  51         /*
  52          * For non-PAT systems, promote PAGE_KERNEL_WC to PAGE_KERNEL_UC_MINUS.
  53          * PAGE_KERNEL_WC maps to PWT, which translates to uncached if the
  54          * MTRR is UC or WC.  UC_MINUS gets the real intention, of the
  55          * user, which is "WC if the MTRR is WC, UC if you can't do that."
  56          */
  57         if (!pat_enabled && pgprot_val(prot) == pgprot_val(PAGE_KERNEL_WC))
  58                 prot = PAGE_KERNEL_UC_MINUS;
  59
  60         idx = type + KM_TYPE_NR*smp_processor_id();
  61         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  62         set_pte(kmap_pte-idx, pfn_pte(pfn, prot));
  63         arch_flush_lazy_mmu_mode();
  64
  65         return (void*) vaddr;
  66 }
  67 EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
  68
  69 void
  70 iounmap_atomic(void *kvaddr, enum km_type type)
  71 {
  72         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  73         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
  74
  75         /*
  76          * Force other mappings to Oops if they'll try to access this pte
  77          * without first remap it.  Keeping stale mappings around is a bad idea
  78          * also, in case the page changes cacheability attributes or becomes
  79          * a protected page in a hypervisor.
  80          */
  81         if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
  82                 kpte_clear_flush(kmap_pte-idx, vaddr);
  83
  84         arch_flush_lazy_mmu_mode();
  85         pagefault_enable();
  86 }
  87 EXPORT_SYMBOL_GPL(iounmap_atomic);