blob: e77d834aa803e07c249a1edfc9a03bce876cecf5 [file] [log] [blame]
** This is simply the barrier() macro from linux/kernel.h but when serial.c
** uses tqueue.h uses smp_mb() defined using barrier(), linux/kernel.h
** hasn't yet been included yet so it fails, thus repeating the macro here.
** PA-RISC architecture allows for weakly ordered memory accesses although
** none of the processors use it. There is a strong ordered bit that is
** set in the O-bit of the page directory entry. Operating systems that
** can not tolerate out of order accesses should set this bit when mapping
** pages. The O-bit of the PSW should also be set to 1 (I don't believe any
** of the processor implemented the PSW O-bit). The PCX-W ERS states that
** the TLB O-bit is not implemented so the page directory does not need to
** have the O-bit set when mapping pages (section 3.1). This section also
** states that the PSW Y, Z, G, and O bits are not implemented.
** So it looks like nothing needs to be done for parisc-linux (yet).
** (thanks to chada for the above comment -ggg)
** The __asm__ op below simple prevents gcc/ld from reordering
** instructions across the mb() "call".
#define mb() __asm__ __volatile__("":::"memory") /* barrier() */
#define rmb() mb()
#define wmb() mb()
#define smp_mb() mb()
#define smp_rmb() mb()
#define smp_wmb() mb()
#define smp_read_barrier_depends() do { } while(0)
#define read_barrier_depends() do { } while(0)
#define set_mb(var, value) do { var = value; mb(); } while (0)
#endif /* __PARISC_BARRIER_H */