[src/trunk]: src/sys/sys Add BUS_ADDR_{LO, HI}32() macros to correctly extract...

[thorpej <thorpej%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/47bfb38841ff
branches:  trunk
changeset: 745617:47bfb38841ff
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Sun Mar 08 02:42:00 2020 +0000

description:
Add BUS_ADDR_{LO,HI}32() macros to correctly extract the lower and
upper halves of 64-bit DMA addresses for 32-bit and 64-bit bus_addr_t.
This is a common pattern in modern drivers, so it's a good idea to provide
a common correct definition.

This particular implementation suggested by riastradh@.

diffstat:

 sys/sys/bus.h |  10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diffs (22 lines):

diff -r 1fd6e9280984 -r 47bfb38841ff sys/sys/bus.h
--- a/sys/sys/bus.h     Sun Mar 08 00:53:12 2020 +0000
+++ b/sys/sys/bus.h     Sun Mar 08 02:42:00 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: bus.h,v 1.12 2018/04/19 21:19:07 christos Exp $        */
+/*     $NetBSD: bus.h,v 1.13 2020/03/08 02:42:00 thorpej Exp $ */
 
 /*-
  * Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -245,4 +245,12 @@
 } *bus_dmamap_t;
 #endif /* __HAVE_NO_BUS_DMA */
 
+/*
+ * Convenience macros to correctly extract the upper and lower
+ * 32 bits of a bus_addr_t (which may be a 32-bit or 64-bit
+ * value).
+ */
+#define        BUS_ADDR_HI32(a)        ((uint32_t) __SHIFTOUT(a, __BITS(32,63)))
+#define        BUS_ADDR_LO32(a)        ((uint32_t) __SHIFTOUT(a, __BITS(0,31)))
+
 #endif /* _SYS_BUS_H_ */