LXR linux/arch/x86/mm/iomap

   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
  24static 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
  34int 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}
  52EXPORT_SYMBOL_GPL(iomap_create_wc);
  53
  54void iomap_free(resource_size_t base, unsigned long size)
  55{
  56        io_free_memtype(base, base + size);
  57}
  58EXPORT_SYMBOL_GPL(iomap_free);
  59
  60void *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 */
  80void __iomem *
  81iomap_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}
  99EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
 100
 101void
 102iounmap_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}
 129EXPORT_SYMBOL_GPL(iounmap_atomic);
 130