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 {
  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, mapping->prot);
  93 }
  94
  95 static inline void
  96 io_mapping_unmap_atomic(void __iomem *vaddr)
  97 {
  98         iounmap_atomic(vaddr);
  99 }
 100
 101 static inline void __iomem *
 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 __iomem *vaddr)
 114 {
 115         iounmap(vaddr);
 116 }
 117
 118 #else
 119
 120 #include <linux/uaccess.h>
 121
 122 /* this struct isn't actually defined anywhere */
 123 struct io_mapping;
 124
 125 /* Create the io_mapping object*/
 126 static inline struct io_mapping *
 127 io_mapping_create_wc(resource_size_t base, unsigned long size)
 128 {
 129         return (struct io_mapping __force *) ioremap_wc(base, size);
 130 }
 131
 132 static inline void
 133 io_mapping_free(struct io_mapping *mapping)
 134 {
 135         iounmap((void __force __iomem *) mapping);
 136 }
 137
 138 /* Atomic map/unmap */
 139 static inline void __iomem *
 140 io_mapping_map_atomic_wc(struct io_mapping *mapping,
 141                          unsigned long offset)
 142 {
 143         pagefault_disable();
 144         return ((char __force __iomem *) mapping) + offset;
 145 }
 146
 147 static inline void
 148 io_mapping_unmap_atomic(void __iomem *vaddr)
 149 {
 150         pagefault_enable();
 151 }
 152
 153 /* Non-atomic map/unmap */
 154 static inline void __iomem *
 155 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 156 {
 157         return ((char __force __iomem *) mapping) + offset;
 158 }
 159
 160 static inline void
 161 io_mapping_unmap(void __iomem *vaddr)
 162 {
 163 }
 164
 165 #endif /* HAVE_ATOMIC_IOMAP */
 166
 167 #endif /* _LINUX_IO_MAPPING_H */