include/linux/io-mapping.h

   1 /*
   2  * Copyright © 2008 Keith Packard <keithp@keithp.com>
   3  *
   4  * This file is free software; you can redistribute it and/or modify
   5  * it under the terms of version 2 of the GNU General Public License
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
  16  */
  17
  18 #ifndef _LINUX_IO_MAPPING_H
  19 #define _LINUX_IO_MAPPING_H
  20
  21 #include <linux/types.h>
  22 #include <asm/io.h>
  23 #include <asm/page.h>
  24 #include <asm/iomap.h>
  25
  26 /*
  27  * The io_mapping mechanism provides an abstraction for mapping
  28  * individual pages from an io device to the CPU in an efficient fashion.
  29  *
  30  * See Documentation/io_mapping.txt
  31  */
  32
  33 #ifdef CONFIG_HAVE_ATOMIC_IOMAP
  34
  35 struct io_mapping {
  36         resource_size_t base;
  37         unsigned long size;
  38         pgprot_t prot;
  39 };
  40
  41 /*
  42  * For small address space machines, mapping large objects
  43  * into the kernel virtual space isn't practical. Where
  44  * available, use fixmap support to dynamically map pages
  45  * of the object at run time.
  46  */
  47
  48 static inline struct io_mapping *
  49 io_mapping_create_wc(resource_size_t base, unsigned long size)
  50 {
  51         struct io_mapping *iomap;
  52         pgprot_t prot;
  53
  54         iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
  55         if (!iomap)
  56                 goto out_err;
  57
  58         if (iomap_create_wc(base, size, &prot))
  59                 goto out_free;
  60
  61         iomap->base = base;
  62         iomap->size = size;
  63         iomap->prot = prot;
  64         return iomap;
  65
  66 out_free:
  67         kfree(iomap);
  68 out_err:
  69         return NULL;
  70 }
  71
  72 static inline void
  73 io_mapping_free(struct io_mapping *mapping)
  74 {
  75         iomap_free(mapping->base, mapping->size);
  76         kfree(mapping);
  77 }
  78
  79 /* Atomic map/unmap */
  80 static inline void *
  81 io_mapping_map_atomic_wc(struct io_mapping *mapping, unsigned long offset)
  82 {
  83         resource_size_t phys_addr;
  84         unsigned long pfn;
  85
  86         BUG_ON(offset >= mapping->size);
  87         phys_addr = mapping->base + offset;
  88         pfn = (unsigned long) (phys_addr >> PAGE_SHIFT);
  89         return iomap_atomic_prot_pfn(pfn, KM_USER0, mapping->prot);
  90 }
  91
  92 static inline void
  93 io_mapping_unmap_atomic(void *vaddr)
  94 {
  95         iounmap_atomic(vaddr, KM_USER0);
  96 }
  97
  98 static inline void *
  99 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 100 {
 101         resource_size_t phys_addr;
 102
 103         BUG_ON(offset >= mapping->size);
 104         phys_addr = mapping->base + offset;
 105
 106         return ioremap_wc(phys_addr, PAGE_SIZE);
 107 }
 108
 109 static inline void
 110 io_mapping_unmap(void *vaddr)
 111 {
 112         iounmap(vaddr);
 113 }
 114
 115 #else
 116
 117 /* this struct isn't actually defined anywhere */
 118 struct io_mapping;
 119
 120 /* Create the io_mapping object*/
 121 static inline struct io_mapping *
 122 io_mapping_create_wc(resource_size_t base, unsigned long size)
 123 {
 124         return (struct io_mapping *) ioremap_wc(base, size);
 125 }
 126
 127 static inline void
 128 io_mapping_free(struct io_mapping *mapping)
 129 {
 130         iounmap(mapping);
 131 }
 132
 133 /* Atomic map/unmap */
 134 static inline void *
 135 io_mapping_map_atomic_wc(struct io_mapping *mapping, unsigned long offset)
 136 {
 137         return ((char *) mapping) + offset;
 138 }
 139
 140 static inline void
 141 io_mapping_unmap_atomic(void *vaddr)
 142 {
 143 }
 144
 145 /* Non-atomic map/unmap */
 146 static inline void *
 147 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 148 {
 149         return ((char *) mapping) + offset;
 150 }
 151
 152 static inline void
 153 io_mapping_unmap(void *vaddr)
 154 {
 155 }
 156
 157 #endif /* HAVE_ATOMIC_IOMAP */
 158
 159 #endif /* _LINUX_IO_MAPPING_H */