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 static int
  25 is_io_mapping_possible(resource_size_t base, unsigned long size)
  26 {
  27         return 1;
  28 }
  29 #else
  30 static 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 int
  42 reserve_io_memtype_wc(u64 base, unsigned long size, pgprot_t *prot)
  43 {
  44         unsigned long ret_flag;
  45
  46         if (!is_io_mapping_possible(base, size))
  47                 goto out_err;
  48
  49         if (!pat_enabled) {
  50                 *prot = pgprot_noncached(PAGE_KERNEL);
  51                 return 0;
  52         }
  53
  54         if (reserve_memtype(base, base + size, _PAGE_CACHE_WC, &ret_flag))
  55                 goto out_err;
  56
  57         if (ret_flag == _PAGE_CACHE_WB)
  58                 goto out_free;
  59
  60         if (kernel_map_sync_memtype(base, size, ret_flag))
  61                 goto out_free;
  62
  63         *prot = __pgprot(__PAGE_KERNEL | ret_flag);
  64         return 0;
  65
  66 out_free:
  67         free_memtype(base, base + size);
  68 out_err:
  69         return -EINVAL;
  70 }
  71 EXPORT_SYMBOL_GPL(reserve_io_memtype_wc);
  72
  73 void
  74 free_io_memtype(u64 base, unsigned long size)
  75 {
  76         if (pat_enabled)
  77                 free_memtype(base, base + size);
  78 }
  79 EXPORT_SYMBOL_GPL(free_io_memtype);
  80
  81 /* Map 'pfn' using fixed map 'type' and protections 'prot'
  82  */
  83 void *
  84 iomap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot)
  85 {
  86         enum fixed_addresses idx;
  87         unsigned long vaddr;
  88
  89         pagefault_disable();
  90
  91         /*
  92          * For non-PAT systems, promote PAGE_KERNEL_WC to PAGE_KERNEL_UC_MINUS.
  93          * PAGE_KERNEL_WC maps to PWT, which translates to uncached if the
  94          * MTRR is UC or WC.  UC_MINUS gets the real intention, of the
  95          * user, which is "WC if the MTRR is WC, UC if you can't do that."
  96          */
  97         if (!pat_enabled && pgprot_val(prot) == pgprot_val(PAGE_KERNEL_WC))
  98                 prot = PAGE_KERNEL_UC_MINUS;
  99
 100         idx = type + KM_TYPE_NR*smp_processor_id();
 101         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 102         set_pte(kmap_pte-idx, pfn_pte(pfn, prot));
 103         arch_flush_lazy_mmu_mode();
 104
 105         return (void*) vaddr;
 106 }
 107 EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
 108
 109 void
 110 iounmap_atomic(void *kvaddr, enum km_type type)
 111 {
 112         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 113         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
 114
 115         /*
 116          * Force other mappings to Oops if they'll try to access this pte
 117          * without first remap it.  Keeping stale mappings around is a bad idea
 118          * also, in case the page changes cacheability attributes or becomes
 119          * a protected page in a hypervisor.
 120          */
 121         if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
 122                 kpte_clear_flush(kmap_pte-idx, vaddr);
 123
 124         arch_flush_lazy_mmu_mode();
 125         pagefault_enable();
 126 }
 127 EXPORT_SYMBOL_GPL(iounmap_atomic);