Linux Kernel  3.7.1
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iomap_32.c
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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 }
50 
51 void iomap_free(resource_size_t base, unsigned long size)
52 {
53  io_free_memtype(base, base + size);
54 }
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));
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 }
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 }