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 <linux/bug.h>
  24 #include <linux/io.h>
  25 #include <asm/page.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 #include <asm/iomap.h>
  37
  38 struct io_mapping {
  39         resource_size_t base;
  40         unsigned long size;
  41         pgprot_t prot;
  42 };
  43
  44 /*
  45  * For small address space machines, mapping large objects
  46  * into the kernel virtual space isn't practical. Where
  47  * available, use fixmap support to dynamically map pages
  48  * of the object at run time.
  49  */
  50
  51 static inline struct io_mapping *
  52 io_mapping_create_wc(resource_size_t base, unsigned long size)
  53 {
  54         struct io_mapping *iomap;
  55         pgprot_t prot;
  56
  57         iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
  58         if (!iomap)
  59                 goto out_err;
  60
  61         if (iomap_create_wc(base, size, &prot))
  62                 goto out_free;
  63
  64         iomap->base = base;
  65         iomap->size = size;
  66         iomap->prot = prot;
  67         return iomap;
  68
  69 out_free:
  70         kfree(iomap);
  71 out_err:
  72         return NULL;
  73 }
  74
  75 static inline void
  76 io_mapping_free(struct io_mapping *mapping)
  77 {
  78         iomap_free(mapping->base, mapping->size);
  79         kfree(mapping);
  80 }
  81
  82 /* Atomic map/unmap */
  83 static inline void __iomem *
  84 io_mapping_map_atomic_wc(struct io_mapping *mapping,
  85                          unsigned long offset)
  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, mapping->prot);
  94 }
  95
  96 static inline void
  97 io_mapping_unmap_atomic(void __iomem *vaddr)
  98 {
  99         iounmap_atomic(vaddr);
 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 #include <linux/uaccess.h>
 122
 123 /* this struct isn't actually defined anywhere */
 124 struct io_mapping;
 125
 126 /* Create the io_mapping object*/
 127 static inline struct io_mapping *
 128 io_mapping_create_wc(resource_size_t base, unsigned long size)
 129 {
 130         return (struct io_mapping __force *) ioremap_wc(base, size);
 131 }
 132
 133 static inline void
 134 io_mapping_free(struct io_mapping *mapping)
 135 {
 136         iounmap((void __force __iomem *) mapping);
 137 }
 138
 139 /* Atomic map/unmap */
 140 static inline void __iomem *
 141 io_mapping_map_atomic_wc(struct io_mapping *mapping,
 142                          unsigned long offset)
 143 {
 144         preempt_disable();
 145         pagefault_disable();
 146         return ((char __force __iomem *) mapping) + offset;
 147 }
 148
 149 static inline void
 150 io_mapping_unmap_atomic(void __iomem *vaddr)
 151 {
 152         pagefault_enable();
 153         preempt_enable();
 154 }
 155
 156 /* Non-atomic map/unmap */
 157 static inline void __iomem *
 158 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 159 {
 160         return ((char __force __iomem *) mapping) + offset;
 161 }
 162
 163 static inline void
 164 io_mapping_unmap(void __iomem *vaddr)
 165 {
 166 }
 167
 168 #endif /* HAVE_ATOMIC_IOMAP */
 169
 170 #endif /* _LINUX_IO_MAPPING_H */