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