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, unsigned long offset)
  83 {
  84         resource_size_t phys_addr;
  85         unsigned long pfn;
  86
  87         BUG_ON(offset >= mapping->size);
  88         phys_addr = mapping->base + offset;
  89         pfn = (unsigned long) (phys_addr >> PAGE_SHIFT);
  90         return iomap_atomic_prot_pfn(pfn, KM_USER0, mapping->prot);
  91 }
  92
  93 static inline void
  94 io_mapping_unmap_atomic(void *vaddr)
  95 {
  96         iounmap_atomic(vaddr, KM_USER0);
  97 }
  98
  99 static inline void *
 100 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 101 {
 102         resource_size_t phys_addr;
 103
 104         BUG_ON(offset >= mapping->size);
 105         phys_addr = mapping->base + offset;
 106
 107         return ioremap_wc(phys_addr, PAGE_SIZE);
 108 }
 109
 110 static inline void
 111 io_mapping_unmap(void *vaddr)
 112 {
 113         iounmap(vaddr);
 114 }
 115
 116 #else
 117
 118 /* this struct isn't actually defined anywhere */
 119 struct io_mapping;
 120
 121 /* Create the io_mapping object*/
 122 static inline struct io_mapping *
 123 io_mapping_create_wc(resource_size_t base, unsigned long size)
 124 {
 125         return (struct io_mapping *) ioremap_wc(base, size);
 126 }
 127
 128 static inline void
 129 io_mapping_free(struct io_mapping *mapping)
 130 {
 131         iounmap(mapping);
 132 }
 133
 134 /* Atomic map/unmap */
 135 static inline void *
 136 io_mapping_map_atomic_wc(struct io_mapping *mapping, unsigned long offset)
 137 {
 138         return ((char *) mapping) + offset;
 139 }
 140
 141 static inline void
 142 io_mapping_unmap_atomic(void *vaddr)
 143 {
 144 }
 145
 146 /* Non-atomic map/unmap */
 147 static inline void *
 148 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 149 {
 150         return ((char *) mapping) + offset;
 151 }
 152
 153 static inline void
 154 io_mapping_unmap(void *vaddr)
 155 {
 156 }
 157
 158 #endif /* HAVE_ATOMIC_IOMAP */
 159
 160 #endif /* _LINUX_IO_MAPPING_H */