Currently the compiler picks up the definition in machine/cpufunc.h.
Add compiler memory barriers to read* and write*. The Linux x86
implementation of these functions uses inline asm with "memory" clobber.
The Linux x86 implementation of read_relaxed* and write_relaxed* uses the
same inline asm without "memory" clobber.
Implement ioread* and iowrite* in terms of read* and write* so they also
have memory barriers.
Qualify the addr parameter in write* as volatile.
Like Linux, define macros with the same name as the inline functions.
Only define 64-bit versions on 64-bit architectures because generally
32-bit architectures can't do atomic 64-bit loads and stores.
Regroup the functions a bit and add brief comments explaining what they do:
- __raw_read*, __raw_write*: atomic, no barriers, no byte swapping
- read_relaxed*, write_relaxed*: atomic, no barriers, little-endian
- read*, write*: atomic, with barriers, little-endian
Add a comment that says our implementation of ioread* and iowrite*
only handles MMIO and does not support port IO.
Reviewed by: hselasky
MFC after: 3 days
642909fdfb