LXR linux/arch/x86/mm/iomap

   1/*
   2 * Copyright Â© 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
  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        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}
  49EXPORT_SYMBOL_GPL(iomap_create_wc);
  50
  51void
  52iomap_free(resource_size_t base, unsigned long size)
  53{
  54        io_free_memtype(base, base + size);
  55}
  56EXPORT_SYMBOL_GPL(iomap_free);
  57
  58void *kmap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot)
  59{
  60        enum fixed_addresses idx;
  61        unsigned long vaddr;
  62
  63        pagefault_disable();
  64
  65        debug_kmap_atomic(type);
  66        idx = type + KM_TYPE_NR * smp_processor_id();
  67        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  68        set_pte(kmap_pte - idx, pfn_pte(pfn, prot));
  69        arch_flush_lazy_mmu_mode();
  70
  71        return (void *)vaddr;
  72}
  73
  74/*
  75 * Map 'pfn' using fixed map 'type' and protections 'prot'
  76 */
  77void *
  78iomap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot)
  79{
  80        /*
  81         * For non-PAT systems, promote PAGE_KERNEL_WC to PAGE_KERNEL_UC_MINUS.
  82         * PAGE_KERNEL_WC maps to PWT, which translates to uncached if the
  83         * MTRR is UC or WC.  UC_MINUS gets the real intention, of the
  84         * user, which is "WC if the MTRR is WC, UC if you can't do that."
  85         */
  86        if (!pat_enabled && pgprot_val(prot) == pgprot_val(PAGE_KERNEL_WC))
  87                prot = PAGE_KERNEL_UC_MINUS;
  88
  89        return kmap_atomic_prot_pfn(pfn, type, prot);
  90}
  91EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
  92
  93void
  94iounmap_atomic(void *kvaddr, enum km_type type)
  95{
  96        unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  97        enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
  98
  99        /*
 100         * Force other mappings to Oops if they'll try to access this pte
 101         * without first remap it.  Keeping stale mappings around is a bad idea
 102         * also, in case the page changes cacheability attributes or becomes
 103         * a protected page in a hypervisor.
 104         */
 105        if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
 106                kpte_clear_flush(kmap_pte-idx, vaddr);
 107
 108        pagefault_enable();
 109}
 110EXPORT_SYMBOL_GPL(iounmap_atomic);
 111