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
  53         if (!is_io_mapping_possible(base, size))
  54                 return NULL;
  55
  56         iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
  57         if (!iomap)
  58                 return NULL;
  59
  60         iomap->base = base;
  61         iomap->size = size;
  62         iomap->prot = pgprot_writecombine(__pgprot(__PAGE_KERNEL));
  63         return iomap;
  64 }
  65
  66 static inline void
  67 io_mapping_free(struct io_mapping *mapping)
  68 {
  69         kfree(mapping);
  70 }
  71
  72 /* Atomic map/unmap */
  73 static inline void *
  74 io_mapping_map_atomic_wc(struct io_mapping *mapping, unsigned long offset)
  75 {
  76         resource_size_t phys_addr;
  77         unsigned long pfn;
  78
  79         BUG_ON(offset >= mapping->size);
  80         phys_addr = mapping->base + offset;
  81         pfn = (unsigned long) (phys_addr >> PAGE_SHIFT);
  82         return iomap_atomic_prot_pfn(pfn, KM_USER0, mapping->prot);
  83 }
  84
  85 static inline void
  86 io_mapping_unmap_atomic(void *vaddr)
  87 {
  88         iounmap_atomic(vaddr, KM_USER0);
  89 }
  90
  91 static inline void *
  92 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
  93 {
  94         BUG_ON(offset >= mapping->size);
  95         resource_size_t phys_addr = mapping->base + offset;
  96         return ioremap_wc(phys_addr, PAGE_SIZE);
  97 }
  98
  99 static inline void
 100 io_mapping_unmap(void *vaddr)
 101 {
 102         iounmap(vaddr);
 103 }
 104
 105 #else
 106
 107 /* this struct isn't actually defined anywhere */
 108 struct io_mapping;
 109
 110 /* Create the io_mapping object*/
 111 static inline struct io_mapping *
 112 io_mapping_create_wc(resource_size_t base, unsigned long size)
 113 {
 114         return (struct io_mapping *) ioremap_wc(base, size);
 115 }
 116
 117 static inline void
 118 io_mapping_free(struct io_mapping *mapping)
 119 {
 120         iounmap(mapping);
 121 }
 122
 123 /* Atomic map/unmap */
 124 static inline void *
 125 io_mapping_map_atomic_wc(struct io_mapping *mapping, unsigned long offset)
 126 {
 127         return ((char *) mapping) + offset;
 128 }
 129
 130 static inline void
 131 io_mapping_unmap_atomic(void *vaddr)
 132 {
 133 }
 134
 135 /* Non-atomic map/unmap */
 136 static inline void *
 137 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 138 {
 139         return ((char *) mapping) + offset;
 140 }
 141
 142 static inline void
 143 io_mapping_unmap(void *vaddr)
 144 {
 145 }
 146
 147 #endif /* HAVE_ATOMIC_IOMAP */
 148
 149 #endif /* _LINUX_IO_MAPPING_H */