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drivers/twserial: Add protocol driver for "three wire serial" interface. 

This pretty unintelligent interface is used on some RTC chips.

Signed-off-by: Detlev Zundel <dzu@denx.de>
This commit is contained in:
Detlev Zundel 2009-03-30 00:31:32 +02:00 committed by Wolfgang Denk
parent 88685b5f62
commit 572e6179ad
4 changed files with 197 additions and 1 deletions
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3
Makefile
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@ -1,5 +1,5 @@
#
# (C) Copyright 2000-2008
# (C) Copyright 2000-2009
# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
#
# See file CREDITS for list of people who contributed to this
@ -262,6 +262,7 @@ TAG_SUBDIRS += cpu/mpc8xxx
endif
LIBS += drivers/rtc/librtc.a
LIBS += drivers/serial/libserial.a
LIBS += drivers/twserial/libtws.a
LIBS += drivers/usb/libusb.a
LIBS += drivers/video/libvideo.a
LIBS += common/libcommon.a

46
drivers/twserial/Makefile Normal file
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@ -0,0 +1,46 @@
#
# (C) Copyright 2009
# Detlev Zundel, DENX Software Engineering, dzu@denx.de.
#
# See file CREDITS for list of people who contributed to this
# project.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2 of
# the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
include $(TOPDIR)/config.mk
LIB := $(obj)libtws.a
COBJS-$(CONFIG_SOFT_TWS) += soft_tws.o
COBJS := $(COBJS-y)
SRCS := $(COBJS:.o=.c)
OBJS := $(addprefix $(obj),$(COBJS))
all: $(LIB)
$(LIB): $(obj).depend $(OBJS)
$(AR) $(ARFLAGS) $@ $(OBJS)
#########################################################################
# defines $(obj).depend target
include $(SRCTREE)/rules.mk
sinclude $(obj).depend
#########################################################################

111
drivers/twserial/soft_tws.c Normal file
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@ -0,0 +1,111 @@
/*
* (C) Copyright 2009
* Detlev Zundel, DENX Software Engineering, dzu@denx.de.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*
*/
#define TWS_IMPLEMENTATION
#include <common.h>
/*=====================================================================*/
/* Public Functions */
/*=====================================================================*/
/*-----------------------------------------------------------------------
* Read bits
*/
int tws_read(uchar *buffer, int len)
{
int rem = len;
uchar accu, shift;
debug("tws_read: buffer %p len %d\n", buffer, len);
/* Configure the data pin for input */
tws_data_config_output(0);
/* Disable WR, i.e. setup a read */
tws_wr(0);
udelay(1);
/* Rise CE */
tws_ce(1);
udelay(1);
for (; rem > 0; ) {
for (shift = 0, accu = 0;
(rem > 0) && (shift < 8);
rem--, shift++) {
tws_clk(1);
udelay(10);
accu |= (tws_data_read() << shift); /* LSB first */
tws_clk(0);
udelay(10);
}
*buffer++ = accu;
}
/* Lower CE */
tws_ce(0);
return len - rem;
}
/*-----------------------------------------------------------------------
* Write bits
*/
int tws_write(uchar *buffer, int len)
{
int rem = len;
uchar accu, shift;
debug("tws_write: buffer %p len %d\n", buffer, len);
/* Configure the data pin for output */
tws_data_config_output(1);
/* Enable WR, i.e. setup a write */
tws_wr(1);
udelay(1);
/* Rise CE */
tws_ce(1);
udelay(1);
for (; rem > 0; ) {
for (shift = 0, accu = *buffer++;
(rem > 0) && (shift < 8);
rem--, shift++) {
tws_data(accu & 0x01); /* LSB first */
tws_clk(1);
udelay(10);
tws_clk(0);
udelay(10);
accu >>= 1;
}
}
/* Lower CE */
tws_ce(0);
return len - rem;
}

38
include/tws.h Normal file
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@ -0,0 +1,38 @@
/*
* (C) Copyright 2009
* Detlev Zundel, DENX Software Engineering, dzu@denx.de.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*
*/
#ifndef _TWS_H_
#define _TWS_H_
/*
* Read/Write interface:
* buffer: Where to read/write the data
* len: How many bits to read/write
*
* Returns: 0 on success, not 0 on failure
*/
int tws_read(uchar *buffer, int len);
int tws_write(uchar *buffer, int len);
#endif /* _TWS_H_ */