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authorDetlev Zundel <dzu@denx.de>2009-03-29 22:31:32 (GMT)
committerWolfgang Denk <wd@denx.de>2009-03-30 07:38:36 (GMT)
commit572e6179adb5447ff42ec2aa5cf3a26decf97583 (patch)
tree1246758c58c67dac35f1adbf4e2b0cfe56b630af /drivers/twserial
parent88685b5f62274167ad2ba8a58e108d89ff71955b (diff)
downloadu-boot-572e6179adb5447ff42ec2aa5cf3a26decf97583.tar.xz
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>
Diffstat (limited to 'drivers/twserial')
-rw-r--r--drivers/twserial/Makefile46
-rw-r--r--drivers/twserial/soft_tws.c111
2 files changed, 157 insertions, 0 deletions
diff --git a/drivers/twserial/Makefile b/drivers/twserial/Makefile
new file mode 100644
index 0000000..0b059f3
--- /dev/null
+++ b/drivers/twserial/Makefile
@@ -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
+
+#########################################################################
diff --git a/drivers/twserial/soft_tws.c b/drivers/twserial/soft_tws.c
new file mode 100644
index 0000000..0b50e1d
--- /dev/null
+++ b/drivers/twserial/soft_tws.c
@@ -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;
+}