io.h
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/*
* Generic I/O functions.
*
* Copyright (c) 2016 Imagination Technologies Ltd.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef __ASM_GENERIC_IO_H__
#define __ASM_GENERIC_IO_H__
/*
* This file should be included at the end of each architecture-specific
* asm/io.h such that we may provide generic implementations without
* conflicting with architecture-specific code.
*/
#ifndef __ASSEMBLY__
/**
* phys_to_virt() - Return a virtual address mapped to a given physical address
* @paddr: the physical address
*
* Returns a virtual address which the CPU can access that maps to the physical
* address @paddr. This should only be used where it is known that no dynamic
* mapping is required. In general, map_physmem should be used instead.
*
* Returns: a virtual address which maps to @paddr
*/
#ifndef phys_to_virt
static inline void *phys_to_virt(phys_addr_t paddr)
{
return (void *)(unsigned long)paddr;
}
#endif
/**
* virt_to_phys() - Return the physical address that a virtual address maps to
* @vaddr: the virtual address
*
* Returns the physical address which the CPU-accessible virtual address @vaddr
* maps to.
*
* Returns: the physical address which @vaddr maps to
*/
#ifndef virt_to_phys
static inline phys_addr_t virt_to_phys(void *vaddr)
{
return (phys_addr_t)((unsigned long)vaddr);
}
#endif
/*
* Flags for use with map_physmem() & unmap_physmem(). Architectures need not
* support all of these, in which case they will be defined as zero here &
* ignored. Callers that may run on multiple architectures should therefore
* treat them as hints rather than requirements.
*/
#ifndef MAP_NOCACHE
# define MAP_NOCACHE 0 /* Produce an uncached mapping */
#endif
#ifndef MAP_WRCOMBINE
# define MAP_WRCOMBINE 0 /* Allow write-combining on the mapping */
#endif
#ifndef MAP_WRBACK
# define MAP_WRBACK 0 /* Map using write-back caching */
#endif
#ifndef MAP_WRTHROUGH
# define MAP_WRTHROUGH 0 /* Map using write-through caching */
#endif
/**
* map_physmem() - Return a virtual address mapped to a given physical address
* @paddr: the physical address
* @len: the length of the required mapping
* @flags: flags affecting the type of mapping
*
* Return a virtual address through which the CPU may access the memory at
* physical address @paddr. The mapping will be valid for at least @len bytes,
* and may be affected by flags passed to the @flags argument. This function
* may create new mappings, so should generally be paired with a matching call
* to unmap_physmem once the caller is finished with the memory in question.
*
* Returns: a virtual address suitably mapped to @paddr
*/
#ifndef map_physmem
static inline void *map_physmem(phys_addr_t paddr, unsigned long len,
unsigned long flags)
{
return phys_to_virt(paddr);
}
#endif
/**
* unmap_physmem() - Remove mappings created by a prior call to map_physmem()
* @vaddr: the virtual address which map_physmem() previously returned
* @flags: flags matching those originally passed to map_physmem()
*
* Unmap memory which was previously mapped by a call to map_physmem(). If
* map_physmem() dynamically created a mapping for the memory in question then
* unmap_physmem() will remove that mapping.
*/
#ifndef unmap_physmem
static inline void unmap_physmem(void *vaddr, unsigned long flags)
{
}
#endif
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_GENERIC_IO_H__ */