[src/trunk]: src/sys/dev/ic Revert part of changes in rev 1.298:

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

details:   https://anonhg.NetBSD.org/src/rev/3f448a4492e6
branches:  trunk
changeset: 761269:3f448a4492e6
user:      tsutsui <tsutsui%NetBSD.org@localhost>
date:      Sat Jan 22 16:59:26 2011 +0000

description:
Revert part of changes in rev 1.298:
 - it breaks cobalt's serial console as mentioned in PR port-cobalt/44292
 - MCR_PRESCALE doesn't affect unless EFR_EFCR is set in the EFR register
 - even if MCR_PRESCALE is enabled we should define appropriate sc_type
   variants and BRG values should be adjusted in comspeed() per sc_type
 - sc_frequency should be adjusted in MD attachment if necessary
Tested on cobalt by several people, ok from jklos@

diffstat:

 sys/dev/ic/com.c |  6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)

diffs (27 lines):

diff -r 20929981cece -r 3f448a4492e6 sys/dev/ic/com.c
--- a/sys/dev/ic/com.c  Sat Jan 22 16:54:48 2011 +0000
+++ b/sys/dev/ic/com.c  Sat Jan 22 16:59:26 2011 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: com.c,v 1.298 2010/07/20 06:17:20 jklos Exp $ */
+/* $NetBSD: com.c,v 1.299 2011/01/22 16:59:26 tsutsui Exp $ */
 
 /*-
  * Copyright (c) 1998, 1999, 2004, 2008 The NetBSD Foundation, Inc.
@@ -66,7 +66,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: com.c,v 1.298 2010/07/20 06:17:20 jklos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: com.c,v 1.299 2011/01/22 16:59:26 tsutsui Exp $");
 
 #include "opt_com.h"
 #include "opt_ddb.h"
@@ -465,8 +465,6 @@
                                        sc->sc_fifolen = 0;
                                } else {
                                        SET(sc->sc_hwflags, COM_HW_FLOW);
-                                       SET(sc->sc_mcr, MCR_PRESCALE);
-                                       sc->sc_frequency /= 4;
                                        sc->sc_fifolen = 32;
                                }
                        } else