Disintegrate asm/system.h for PA-RISC

Disintegrate asm/system.h for PA-RISC.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-parisc@vger.kernel.org

1 files changed, 35 insertions, 0 deletions

diff --git a/arch/parisc/include/asm/barrier.h b/arch/parisc/include/asm/barrier.h
new file mode 100644
index 00000000000..e77d834aa80
--- /dev/null
+++ b/arch/parisc/include/asm/barrier.h
@@ -0,0 +1,35 @@
+#ifndef __PARISC_BARRIER_H
+#define __PARISC_BARRIER_H
+
+/*
+** 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 */