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 /* this struct isn't actually defined anywhere */
  34 struct io_mapping;
  35
  36 #ifdef CONFIG_HAVE_ATOMIC_IOMAP
  37
  38 /*
  39  * For small address space machines, mapping large objects
  40  * into the kernel virtual space isn't practical. Where
  41  * available, use fixmap support to dynamically map pages
  42  * of the object at run time.
  43  */
  44
  45 static inline struct io_mapping *
  46 io_mapping_create_wc(unsigned long base, unsigned long size)
  47 {
  48         return (struct io_mapping *) base;
  49 }
  50
  51 static inline void
  52 io_mapping_free(struct io_mapping *mapping)
  53 {
  54 }
  55
  56 /* Atomic map/unmap */
  57 static inline void *
  58 io_mapping_map_atomic_wc(struct io_mapping *mapping, unsigned long offset)
  59 {
  60         offset += (unsigned long) mapping;
  61         return iomap_atomic_prot_pfn(offset >> PAGE_SHIFT, KM_USER0,
  62                                      __pgprot(__PAGE_KERNEL_WC));
  63 }
  64
  65 static inline void
  66 io_mapping_unmap_atomic(void *vaddr)
  67 {
  68         iounmap_atomic(vaddr, KM_USER0);
  69 }
  70
  71 static inline void *
  72 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
  73 {
  74         offset += (unsigned long) mapping;
  75         return ioremap_wc(offset, PAGE_SIZE);
  76 }
  77
  78 static inline void
  79 io_mapping_unmap(void *vaddr)
  80 {
  81         iounmap(vaddr);
  82 }
  83
  84 #else
  85
  86 /* Create the io_mapping object*/
  87 static inline struct io_mapping *
  88 io_mapping_create_wc(unsigned long base, unsigned long size)
  89 {
  90         return (struct io_mapping *) ioremap_wc(base, size);
  91 }
  92
  93 static inline void
  94 io_mapping_free(struct io_mapping *mapping)
  95 {
  96         iounmap(mapping);
  97 }
  98
  99 /* Atomic map/unmap */
 100 static inline void *
 101 io_mapping_map_atomic_wc(struct io_mapping *mapping, unsigned long offset)
 102 {
 103         return ((char *) mapping) + offset;
 104 }
 105
 106 static inline void
 107 io_mapping_unmap_atomic(void *vaddr)
 108 {
 109 }
 110
 111 /* Non-atomic map/unmap */
 112 static inline void *
 113 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 114 {
 115         return ((char *) mapping) + offset;
 116 }
 117
 118 static inline void
 119 io_mapping_unmap(void *vaddr)
 120 {
 121 }
 122
 123 #endif /* HAVE_ATOMIC_IOMAP */
 124
 125 #endif /* _LINUX_IO_MAPPING_H */