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/export.h>
  22 #include <linux/highmem.h>
  23
  24 static int is_io_mapping_possible(resource_size_t base, unsigned long size)
  25 {
  26 #if !defined(CONFIG_X86_PAE) && defined(CONFIG_PHYS_ADDR_T_64BIT)
  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
  34 int iomap_create_wc(resource_size_t base, unsigned long size, pgprot_t *prot)
  35 {
  36         enum page_cache_mode pcm = _PAGE_CACHE_MODE_WC;
  37         int ret;
  38
  39         if (!is_io_mapping_possible(base, size))
  40                 return -EINVAL;
  41
  42         ret = io_reserve_memtype(base, base + size, &pcm);
  43         if (ret)
  44                 return ret;
  45
  46         *prot = __pgprot(__PAGE_KERNEL | cachemode2protval(pcm));
  47         /* Filter out unsupported __PAGE_KERNEL* bits: */
  48         pgprot_val(*prot) &= __default_kernel_pte_mask;
  49
  50         return 0;
  51 }
  52 EXPORT_SYMBOL_GPL(iomap_create_wc);
  53
  54 void iomap_free(resource_size_t base, unsigned long size)
  55 {
  56         io_free_memtype(base, base + size);
  57 }
  58 EXPORT_SYMBOL_GPL(iomap_free);
  59
  60 void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
  61 {
  62         unsigned long vaddr;
  63         int idx, type;
  64
  65         preempt_disable();
  66         pagefault_disable();
  67
  68         type = kmap_atomic_idx_push();
  69         idx = type + KM_TYPE_NR * smp_processor_id();
  70         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  71         set_pte(kmap_pte - idx, pfn_pte(pfn, prot));
  72         arch_flush_lazy_mmu_mode();
  73
  74         return (void *)vaddr;
  75 }
  76
  77 /*
  78  * Map 'pfn' using protections 'prot'
  79  */
  80 void __iomem *
  81 iomap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
  82 {
  83         /*
  84          * For non-PAT systems, translate non-WB request to UC- just in
  85          * case the caller set the PWT bit to prot directly without using
  86          * pgprot_writecombine(). UC- translates to uncached if the MTRR
  87          * is UC or WC. UC- gets the real intention, of the user, which is
  88          * "WC if the MTRR is WC, UC if you can't do that."
  89          */
  90         if (!pat_enabled() && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
  91                 prot = __pgprot(__PAGE_KERNEL |
  92                                 cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
  93
  94         /* Filter out unsupported __PAGE_KERNEL* bits: */
  95         pgprot_val(prot) &= __default_kernel_pte_mask;
  96
  97         return (void __force __iomem *) kmap_atomic_prot_pfn(pfn, prot);
  98 }
  99 EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
 100
 101 void
 102 iounmap_atomic(void __iomem *kvaddr)
 103 {
 104         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 105
 106         if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
 107             vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
 108                 int idx, type;
 109
 110                 type = kmap_atomic_idx();
 111                 idx = type + KM_TYPE_NR * smp_processor_id();
 112
 113 #ifdef CONFIG_DEBUG_HIGHMEM
 114                 WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 115 #endif
 116                 /*
 117                  * Force other mappings to Oops if they'll try to access this
 118                  * pte without first remap it.  Keeping stale mappings around
 119                  * is a bad idea also, in case the page changes cacheability
 120                  * attributes or becomes a protected page in a hypervisor.
 121                  */
 122                 kpte_clear_flush(kmap_pte-idx, vaddr);
 123                 kmap_atomic_idx_pop();
 124         }
 125
 126         pagefault_enable();
 127         preempt_enable();
 128 }
 129 EXPORT_SYMBOL_GPL(iounmap_atomic);