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 #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         unsigned long flag = _PAGE_CACHE_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, &flag);
  43         if (ret)
  44                 return ret;
  45
  46         *prot = __pgprot(__PAGE_KERNEL | flag);
  47         return 0;
  48 }
  49 EXPORT_SYMBOL_GPL(iomap_create_wc);
  50
  51 void iomap_free(resource_size_t base, unsigned long size)
  52 {
  53         io_free_memtype(base, base + size);
  54 }
  55 EXPORT_SYMBOL_GPL(iomap_free);
  56
  57 void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
  58 {
  59         unsigned long vaddr;
  60         int idx, type;
  61
  62         pagefault_disable();
  63
  64         type = kmap_atomic_idx_push();
  65         idx = type + KM_TYPE_NR * smp_processor_id();
  66         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  67         set_pte(kmap_pte - idx, pfn_pte(pfn, prot));
  68         arch_flush_lazy_mmu_mode();
  69
  70         return (void *)vaddr;
  71 }
  72
  73 /*
  74  * Map 'pfn' using protections 'prot'
  75  */
  76 void __iomem *
  77 iomap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
  78 {
  79         /*
  80          * For non-PAT systems, promote PAGE_KERNEL_WC to PAGE_KERNEL_UC_MINUS.
  81          * PAGE_KERNEL_WC maps to PWT, which translates to uncached if the
  82          * MTRR is UC or WC.  UC_MINUS gets the real intention, of the
  83          * user, which is "WC if the MTRR is WC, UC if you can't do that."
  84          */
  85         if (!pat_enabled && pgprot_val(prot) == pgprot_val(PAGE_KERNEL_WC))
  86                 prot = PAGE_KERNEL_UC_MINUS;
  87
  88         return (void __force __iomem *) kmap_atomic_prot_pfn(pfn, prot);
  89 }
  90 EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
  91
  92 void
  93 iounmap_atomic(void __iomem *kvaddr)
  94 {
  95         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  96
  97         if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
  98             vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
  99                 int idx, type;
 100
 101                 type = kmap_atomic_idx();
 102                 idx = type + KM_TYPE_NR * smp_processor_id();
 103
 104 #ifdef CONFIG_DEBUG_HIGHMEM
 105                 WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 106 #endif
 107                 /*
 108                  * Force other mappings to Oops if they'll try to access this
 109                  * pte without first remap it.  Keeping stale mappings around
 110                  * is a bad idea also, in case the page changes cacheability
 111                  * attributes or becomes a protected page in a hypervisor.
 112                  */
 113                 kpte_clear_flush(kmap_pte-idx, vaddr);
 114                 kmap_atomic_idx_pop();
 115         }
 116
 117         pagefault_enable();
 118 }
 119 EXPORT_SYMBOL_GPL(iounmap_atomic);