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 <linux/slab.h>
  23 #include <asm/io.h>
  24 #include <asm/page.h>
  25 #include <asm/iomap.h>
  26
  27 /*
  28  * The io_mapping mechanism provides an abstraction for mapping
  29  * individual pages from an io device to the CPU in an efficient fashion.
  30  *
  31  * See Documentation/io_mapping.txt
  32  */
  33
  34 #ifdef CONFIG_HAVE_ATOMIC_IOMAP
  35
  36 struct io_mapping {
  37         resource_size_t base;
  38         unsigned long size;
  39         pgprot_t prot;
  40 };
  41
  42 /*
  43  * For small address space machines, mapping large objects
  44  * into the kernel virtual space isn't practical. Where
  45  * available, use fixmap support to dynamically map pages
  46  * of the object at run time.
  47  */
  48
  49 static inline struct io_mapping *
  50 io_mapping_create_wc(resource_size_t base, unsigned long size)
  51 {
  52         struct io_mapping *iomap;
  53         pgprot_t prot;
  54
  55         iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
  56         if (!iomap)
  57                 goto out_err;
  58
  59         if (iomap_create_wc(base, size, &prot))
  60                 goto out_free;
  61
  62         iomap->base = base;
  63         iomap->size = size;
  64         iomap->prot = prot;
  65         return iomap;
  66
  67 out_free:
  68         kfree(iomap);
  69 out_err:
  70         return NULL;
  71 }
  72
  73 static inline void
  74 io_mapping_free(struct io_mapping *mapping)
  75 {
  76         iomap_free(mapping->base, mapping->size);
  77         kfree(mapping);
  78 }
  79
  80 /* Atomic map/unmap */
  81 static inline void *
  82 io_mapping_map_atomic_wc(struct io_mapping *mapping,
  83                          unsigned long offset,
  84                          int slot)
  85 {
  86         resource_size_t phys_addr;
  87         unsigned long pfn;
  88
  89         BUG_ON(offset >= mapping->size);
  90         phys_addr = mapping->base + offset;
  91         pfn = (unsigned long) (phys_addr >> PAGE_SHIFT);
  92         return iomap_atomic_prot_pfn(pfn, slot, mapping->prot);
  93 }
  94
  95 static inline void
  96 io_mapping_unmap_atomic(void *vaddr, int slot)
  97 {
  98         iounmap_atomic(vaddr, slot);
  99 }
 100
 101 static inline void *
 102 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 103 {
 104         resource_size_t phys_addr;
 105
 106         BUG_ON(offset >= mapping->size);
 107         phys_addr = mapping->base + offset;
 108
 109         return ioremap_wc(phys_addr, PAGE_SIZE);
 110 }
 111
 112 static inline void
 113 io_mapping_unmap(void *vaddr)
 114 {
 115         iounmap(vaddr);
 116 }
 117
 118 #else
 119
 120 /* this struct isn't actually defined anywhere */
 121 struct io_mapping;
 122
 123 /* Create the io_mapping object*/
 124 static inline struct io_mapping *
 125 io_mapping_create_wc(resource_size_t base, unsigned long size)
 126 {
 127         return (struct io_mapping *) ioremap_wc(base, size);
 128 }
 129
 130 static inline void
 131 io_mapping_free(struct io_mapping *mapping)
 132 {
 133         iounmap(mapping);
 134 }
 135
 136 /* Atomic map/unmap */
 137 static inline void *
 138 io_mapping_map_atomic_wc(struct io_mapping *mapping,
 139                          unsigned long offset,
 140                          int slot)
 141 {
 142         return ((char *) mapping) + offset;
 143 }
 144
 145 static inline void
 146 io_mapping_unmap_atomic(void *vaddr, int slot)
 147 {
 148 }
 149
 150 /* Non-atomic map/unmap */
 151 static inline void *
 152 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 153 {
 154         return ((char *) mapping) + offset;
 155 }
 156
 157 static inline void
 158 io_mapping_unmap(void *vaddr)
 159 {
 160 }
 161
 162 #endif /* HAVE_ATOMIC_IOMAP */
 163
 164 #endif /* _LINUX_IO_MAPPING_H */