diff options
Diffstat (limited to 'include/asm-generic/io.h')
| -rw-r--r-- | include/asm-generic/io.h | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h index f56094cfdeff..eed3bbe88c8a 100644 --- a/include/asm-generic/io.h +++ b/include/asm-generic/io.h @@ -736,6 +736,35 @@ static inline void *phys_to_virt(unsigned long address) } #endif +/** + * DOC: ioremap() and ioremap_*() variants + * + * If you have an IOMMU your architecture is expected to have both ioremap() + * and iounmap() implemented otherwise the asm-generic helpers will provide a + * direct mapping. + * + * There are ioremap_*() call variants, if you have no IOMMU we naturally will + * default to direct mapping for all of them, you can override these defaults. + * If you have an IOMMU you are highly encouraged to provide your own + * ioremap variant implementation as there currently is no safe architecture + * agnostic default. To avoid possible improper behaviour default asm-generic + * ioremap_*() variants all return NULL when an IOMMU is available. If you've + * defined your own ioremap_*() variant you must then declare your own + * ioremap_*() variant as defined to itself to avoid the default NULL return. + */ + +#ifdef CONFIG_MMU + +#ifndef ioremap_uc +#define ioremap_uc ioremap_uc +static inline void __iomem *ioremap_uc(phys_addr_t offset, size_t size) +{ + return NULL; +} +#endif + +#else /* !CONFIG_MMU */ + /* * Change "struct page" to physical address. * @@ -743,7 +772,6 @@ static inline void *phys_to_virt(unsigned long address) * you'll need to provide your own definitions. */ -#ifndef CONFIG_MMU #ifndef ioremap #define ioremap ioremap static inline void __iomem *ioremap(phys_addr_t offset, size_t size) |