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>

diff --git a/Makefile b/Makefile
index 1cce381f611a4257ffc3c8229e3771d2a63b7142..b6fb939f691bf530d52d32d6cfae400f8b974323 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -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

diff --git a/drivers/twserial/Makefile b/drivers/twserial/Makefile
new file mode 100644 (file)
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 (file)
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;
+}

diff --git a/include/tws.h b/include/tws.h
new file mode 100644 (file)
index 0000000..9dcc4b1
--- /dev/null
+++ b/include/tws.h
@@ -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_ */