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 struct io_mapping {
  35         resource_size_t base;
  36         unsigned long size;
  37         pgprot_t prot;
  38         void __iomem *iomem;
  39 };
  40
  41 #ifdef CONFIG_HAVE_ATOMIC_IOMAP
  42
  43 #include <asm/iomap.h>
  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_init_wc(struct io_mapping *iomap,
  53                    resource_size_t base,
  54                    unsigned long size)
  55 {
  56         pgprot_t prot;
  57
  58         if (iomap_create_wc(base, size, &prot))
  59                 return NULL;
  60
  61         iomap->base = base;
  62         iomap->size = size;
  63         iomap->prot = prot;
  64         return iomap;
  65 }
  66
  67 static inline void
  68 io_mapping_fini(struct io_mapping *mapping)
  69 {
  70         iomap_free(mapping->base, mapping->size);
  71 }
  72
  73 /* Atomic map/unmap */
  74 static inline void __iomem *
  75 io_mapping_map_atomic_wc(struct io_mapping *mapping,
  76                          unsigned long offset)
  77 {
  78         resource_size_t phys_addr;
  79         unsigned long pfn;
  80
  81         BUG_ON(offset >= mapping->size);
  82         phys_addr = mapping->base + offset;
  83         pfn = (unsigned long) (phys_addr >> PAGE_SHIFT);
  84         return iomap_atomic_prot_pfn(pfn, mapping->prot);
  85 }
  86
  87 static inline void
  88 io_mapping_unmap_atomic(void __iomem *vaddr)
  89 {
  90         iounmap_atomic(vaddr);
  91 }
  92
  93 static inline void __iomem *
  94 io_mapping_map_wc(struct io_mapping *mapping,
  95                   unsigned long offset,
  96                   unsigned long size)
  97 {
  98         resource_size_t phys_addr;
  99
 100         BUG_ON(offset >= mapping->size);
 101         phys_addr = mapping->base + offset;
 102
 103         return ioremap_wc(phys_addr, size);
 104 }
 105
 106 static inline void
 107 io_mapping_unmap(void __iomem *vaddr)
 108 {
 109         iounmap(vaddr);
 110 }
 111
 112 #else
 113
 114 #include <linux/uaccess.h>
 115 #include <asm/pgtable.h>
 116
 117 /* Create the io_mapping object*/
 118 static inline struct io_mapping *
 119 io_mapping_init_wc(struct io_mapping *iomap,
 120                    resource_size_t base,
 121                    unsigned long size)
 122 {
 123         iomap->base = base;
 124         iomap->size = size;
 125         iomap->iomem = ioremap_wc(base, size);
 126 #if defined(pgprot_noncached_wc) /* archs can't agree on a name ... */
 127         iomap->prot = pgprot_noncached_wc(PAGE_KERNEL);
 128 #elif defined(pgprot_writecombine)
 129         iomap->prot = pgprot_writecombine(PAGE_KERNEL);
 130 #else
 131         iomap->prot = pgprot_noncached(PAGE_KERNEL);
 132 #endif
 133
 134         return iomap;
 135 }
 136
 137 static inline void
 138 io_mapping_fini(struct io_mapping *mapping)
 139 {
 140         iounmap(mapping->iomem);
 141 }
 142
 143 /* Non-atomic map/unmap */
 144 static inline void __iomem *
 145 io_mapping_map_wc(struct io_mapping *mapping,
 146                   unsigned long offset,
 147                   unsigned long size)
 148 {
 149         return mapping->iomem + offset;
 150 }
 151
 152 static inline void
 153 io_mapping_unmap(void __iomem *vaddr)
 154 {
 155 }
 156
 157 /* Atomic map/unmap */
 158 static inline void __iomem *
 159 io_mapping_map_atomic_wc(struct io_mapping *mapping,
 160                          unsigned long offset)
 161 {
 162         preempt_disable();
 163         pagefault_disable();
 164         return io_mapping_map_wc(mapping, offset, PAGE_SIZE);
 165 }
 166
 167 static inline void
 168 io_mapping_unmap_atomic(void __iomem *vaddr)
 169 {
 170         io_mapping_unmap(vaddr);
 171         pagefault_enable();
 172         preempt_enable();
 173 }
 174
 175 #endif /* HAVE_ATOMIC_IOMAP */
 176
 177 static inline struct io_mapping *
 178 io_mapping_create_wc(resource_size_t base,
 179                      unsigned long size)
 180 {
 181         struct io_mapping *iomap;
 182
 183         iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
 184         if (!iomap)
 185                 return NULL;
 186
 187         if (!io_mapping_init_wc(iomap, base, size)) {
 188                 kfree(iomap);
 189                 return NULL;
 190         }
 191
 192         return iomap;
 193 }
 194
 195 static inline void
 196 io_mapping_free(struct io_mapping *iomap)
 197 {
 198         io_mapping_fini(iomap);
 199         kfree(iomap);
 200 }
 201
 202 #endif /* _LINUX_IO_MAPPING_H */