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 <asm/highmem.h>
  22 #include <linux/module.h>
  23
  24 int is_io_mapping_possible(resource_size_t base, unsigned long size)
  25 {
  26 #ifndef CONFIG_X86_PAE
  27         /* There is no way to map greater than 1 << 32 address without PAE */
  28         if (base + size > 0x100000000ULL)
  29                 return 0;
  30 #endif
  31         return 1;
  32 }
  33 EXPORT_SYMBOL_GPL(is_io_mapping_possible);
  34
  35 /* Map 'pfn' using fixed map 'type' and protections 'prot'
  36  */
  37 void *
  38 iomap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot)
  39 {
  40         /*
  41          * For non-PAT systems, promote PAGE_KERNEL_WC to PAGE_KERNEL_UC_MINUS.
  42          * PAGE_KERNEL_WC maps to PWT, which translates to uncached if the
  43          * MTRR is UC or WC.  UC_MINUS gets the real intention, of the
  44          * user, which is "WC if the MTRR is WC, UC if you can't do that."
  45          */
  46         if (!pat_enabled && pgprot_val(prot) == pgprot_val(PAGE_KERNEL_WC))
  47                 prot = PAGE_KERNEL_UC_MINUS;
  48
  49         return kmap_atomic_prot_pfn(pfn, type, prot);
  50 }
  51 EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
  52
  53 void
  54 iounmap_atomic(void *kvaddr, enum km_type type)
  55 {
  56         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  57         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
  58
  59         /*
  60          * Force other mappings to Oops if they'll try to access this pte
  61          * without first remap it.  Keeping stale mappings around is a bad idea
  62          * also, in case the page changes cacheability attributes or becomes
  63          * a protected page in a hypervisor.
  64          */
  65         if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
  66                 kpte_clear_flush(kmap_pte-idx, vaddr);
  67
  68         arch_flush_lazy_mmu_mode();
  69         pagefault_enable();
  70 }
  71 EXPORT_SYMBOL_GPL(iounmap_atomic);