include/asm-generic/io.h

   1 /*
   2  * Generic I/O functions.
   3  *
   4  * Copyright (c) 2016 Imagination Technologies Ltd.
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #ifndef __ASM_GENERIC_IO_H__
  10 #define __ASM_GENERIC_IO_H__
  11
  12 /*
  13  * This file should be included at the end of each architecture-specific
  14  * asm/io.h such that we may provide generic implementations without
  15  * conflicting with architecture-specific code.
  16  */
  17
  18 #ifndef __ASSEMBLY__
  19
  20 /**
  21  * phys_to_virt() - Return a virtual address mapped to a given physical address
  22  * @paddr: the physical address
  23  *
  24  * Returns a virtual address which the CPU can access that maps to the physical
  25  * address @paddr. This should only be used where it is known that no dynamic
  26  * mapping is required. In general, map_physmem should be used instead.
  27  *
  28  * Returns: a virtual address which maps to @paddr
  29  */
  30 #ifndef phys_to_virt
  31 static inline void *phys_to_virt(phys_addr_t paddr)
  32 {
  33         return (void *)(unsigned long)paddr;
  34 }
  35 #endif
  36
  37 /**
  38  * virt_to_phys() - Return the physical address that a virtual address maps to
  39  * @vaddr: the virtual address
  40  *
  41  * Returns the physical address which the CPU-accessible virtual address @vaddr
  42  * maps to.
  43  *
  44  * Returns: the physical address which @vaddr maps to
  45  */
  46 #ifndef virt_to_phys
  47 static inline phys_addr_t virt_to_phys(void *vaddr)
  48 {
  49         return (phys_addr_t)((unsigned long)vaddr);
  50 }
  51 #endif
  52
  53 /*
  54  * Flags for use with map_physmem() & unmap_physmem(). Architectures need not
  55  * support all of these, in which case they will be defined as zero here &
  56  * ignored. Callers that may run on multiple architectures should therefore
  57  * treat them as hints rather than requirements.
  58  */
  59 #ifndef MAP_NOCACHE
  60 # define MAP_NOCACHE    0       /* Produce an uncached mapping */
  61 #endif
  62 #ifndef MAP_WRCOMBINE
  63 # define MAP_WRCOMBINE  0       /* Allow write-combining on the mapping */
  64 #endif
  65 #ifndef MAP_WRBACK
  66 # define MAP_WRBACK     0       /* Map using write-back caching */
  67 #endif
  68 #ifndef MAP_WRTHROUGH
  69 # define MAP_WRTHROUGH  0       /* Map using write-through caching */
  70 #endif
  71
  72 /**
  73  * map_physmem() - Return a virtual address mapped to a given physical address
  74  * @paddr: the physical address
  75  * @len: the length of the required mapping
  76  * @flags: flags affecting the type of mapping
  77  *
  78  * Return a virtual address through which the CPU may access the memory at
  79  * physical address @paddr. The mapping will be valid for at least @len bytes,
  80  * and may be affected by flags passed to the @flags argument. This function
  81  * may create new mappings, so should generally be paired with a matching call
  82  * to unmap_physmem once the caller is finished with the memory in question.
  83  *
  84  * Returns: a virtual address suitably mapped to @paddr
  85  */
  86 #ifndef map_physmem
  87 static inline void *map_physmem(phys_addr_t paddr, unsigned long len,
  88                                 unsigned long flags)
  89 {
  90         return phys_to_virt(paddr);
  91 }
  92 #endif
  93
  94 /**
  95  * unmap_physmem() - Remove mappings created by a prior call to map_physmem()
  96  * @vaddr: the virtual address which map_physmem() previously returned
  97  * @flags: flags matching those originally passed to map_physmem()
  98  *
  99  * Unmap memory which was previously mapped by a call to map_physmem(). If
 100  * map_physmem() dynamically created a mapping for the memory in question then
 101  * unmap_physmem() will remove that mapping.
 102  */
 103 #ifndef unmap_physmem
 104 static inline void unmap_physmem(void *vaddr, unsigned long flags)
 105 {
 106 }
 107 #endif
 108
 109 #endif /* !__ASSEMBLY__ */
 110 #endif /* __ASM_GENERIC_IO_H__ */