[U-Boot] [PATCH 04/11] powerpc/ppc4xx: Add bitbang i2c interface for gdsys boards

Dirk Eibach
2013-04-22T11:16:05Z

This adds an i2c bitbang interface that can coexist with processor i2c.

Signed-off-by: Dirk Eibach <eibach@gdsys.de>
---
board/gdsys/common/Makefile | 2 +-
board/gdsys/common/bb_i2c.c | 304 +++++++++++++++++++++++++++++++++++++++++++
board/gdsys/common/bb_i2c.h | 76 +++++++++++
3 files changed, 381 insertions(+), 1 deletion(-)
create mode 100644 board/gdsys/common/bb_i2c.c
create mode 100644 board/gdsys/common/bb_i2c.h

diff --git a/board/gdsys/common/Makefile b/board/gdsys/common/Makefile
index aa15c15..b217d97 100644
--- a/board/gdsys/common/Makefile
+++ b/board/gdsys/common/Makefile
@@ -31,7 +31,7 @@ LIB = $(obj)lib$(VENDOR).o

COBJS-$(CONFIG_IO) += miiphybb.o
COBJS-$(CONFIG_IO64) += miiphybb.o
-COBJS-$(CONFIG_IOCON) += osd.o mclink.o cmd_fpga.o
+COBJS-$(CONFIG_IOCON) += osd.o mclink.o cmd_fpga.o bb_i2c.o
COBJS-$(CONFIG_DLVISION_10G) += osd.o

COBJS := $(COBJS-y)
diff --git a/board/gdsys/common/bb_i2c.c b/board/gdsys/common/bb_i2c.c
new file mode 100644
index 0000000..a816514
--- /dev/null
+++ b/board/gdsys/common/bb_i2c.c
@@ -0,0 +1,304 @@
+/*
+ * (C) Copyright 2012
+ * Dirk Eibach, Guntermann & Drunck GmbH, eibach at gdsys.de
+ *
+ * based on soft_i2c.c
+ * (C) Copyright 2001, 2002
+ * Wolfgang Denk, DENX Software Engineering, wd at 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
+ *
+ * This has been changed substantially by Gerald Van Baren, Custom IDEAS,
+ * vanbaren at cideas.com. It was heavily influenced by LiMon, written by
+ * Neil Russell.
+ */
+
+#include <common.h>
+
+/*-----------------------------------------------------------------------
+ * Definitions
+ */
+
+#define RETRIES 0
+
+#define BB_I2C_ACK 0 /* PD_SDA level to ack a byte */
+#define BB_I2C_NOACK 1 /* PD_SDA level to noack a byte */
+
+/*-----------------------------------------------------------------------
+ * Local functions
+ */
+static void send_reset(unsigned int bus);
+static void send_start(unsigned int bus);
+static void send_stop(unsigned int bus);
+static void send_ack(unsigned int bus, int ack);
+static int write_byte(unsigned int bus, uchar byte);
+static uchar read_byte(unsigned int bus, int ack);
+
+/*-----------------------------------------------------------------------
+ * Send a reset sequence consisting of 9 clocks with the data signal high
+ * to clock any confused device back into an idle state. Also send a
+ * <stop> at the end of the sequence for belts & suspenders.
+ */
+static void send_reset(unsigned int bus)
+{
+ BB_I2C_SOFT_DECLARATIONS(bus) /* intentional without ';' */
+ int j;
+
+ BB_I2C_SCL(bus, 1);
+ BB_I2C_SDA(bus, 1);
+ BB_I2C_TRISTATE(bus);
+ for (j = 0; j < 9; j++) {
+ BB_I2C_SCL(bus, 0);
+ BB_I2C_DELAY(bus);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SCL(bus, 1);
+ BB_I2C_DELAY(bus);
+ BB_I2C_DELAY(bus);
+ }
+ send_stop(bus);
+ BB_I2C_TRISTATE(bus);
+}
+
+/*-----------------------------------------------------------------------
+ * START: High -> Low on SDA while SCL is High
+ */
+static void send_start(unsigned int bus)
+{
+ BB_I2C_SOFT_DECLARATIONS(bus) /* intentional without ';' */
+
+ BB_I2C_DELAY(bus);
+ BB_I2C_SDA(bus, 1);
+ BB_I2C_ACTIVE(bus);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SCL(bus, 1);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SDA(bus, 0);
+ BB_I2C_DELAY(bus);
+}
+
+/*-----------------------------------------------------------------------
+ * STOP: Low -> High on SDA while SCL is High
+ */
+static void send_stop(unsigned int bus)
+{
+ BB_I2C_SOFT_DECLARATIONS(bus) /* intentional without ';' */
+
+ BB_I2C_SCL(bus, 0);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SDA(bus, 0);
+ BB_I2C_ACTIVE(bus);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SCL(bus, 1);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SDA(bus, 1);
+ BB_I2C_DELAY(bus);
+ BB_I2C_TRISTATE(bus);
+}
+
+/*-----------------------------------------------------------------------
+ * ack should be BB_I2C_ACK or BB_I2C_NOACK
+ */
+static void send_ack(unsigned int bus, int ack)
+{
+ BB_I2C_SOFT_DECLARATIONS(bus) /* intentional without ';' */
+
+ BB_I2C_SCL(bus, 0);
+ BB_I2C_DELAY(bus);
+ BB_I2C_ACTIVE(bus);
+ BB_I2C_SDA(bus, ack);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SCL(bus, 1);
+ BB_I2C_DELAY(bus);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SCL(bus, 0);
+ BB_I2C_DELAY(bus);
+}
+
+/*-----------------------------------------------------------------------
+ * Send 8 bits and look for an acknowledgement.
+ */
+static int write_byte(unsigned int bus, uchar data)
+{
+ BB_I2C_SOFT_DECLARATIONS(bus) /* intentional without ';' */
+ int j;
+ int nack;
+
+ BB_I2C_ACTIVE(bus);
+ for (j = 0; j < 8; j++) {
+ BB_I2C_SCL(bus, 0);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SDA(bus, data & 0x80);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SCL(bus, 1);
+ BB_I2C_DELAY(bus);
+ BB_I2C_DELAY(bus);
+
+ data <<= 1;
+ }
+
+ /*
+ * Look for an <ACK>(negative logic) and return it.
+ */
+ BB_I2C_SCL(bus, 0);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SDA(bus, 1);
+ BB_I2C_TRISTATE(bus);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SCL(bus, 1);
+ BB_I2C_DELAY(bus);
+ BB_I2C_DELAY(bus);
+ nack = BB_I2C_READ(bus);
+ BB_I2C_SCL(bus, 0);
+ BB_I2C_DELAY(bus);
+ BB_I2C_ACTIVE(bus);
+
+ return nack; /* not a nack is an ack */
+}
+
+/*-----------------------------------------------------------------------
+ * if ack == BB_I2C_ACK, ACK the byte so can continue reading, else
+ * send BB_I2C_NOACK to end the read.
+ */
+static uchar read_byte(unsigned int bus, int ack)
+{
+ BB_I2C_SOFT_DECLARATIONS(bus) /* intentional without ';' */
+ int data;
+ int j;
+
+ /*
+ * Read 8 bits, MSB first.
+ */
+ BB_I2C_TRISTATE(bus);
+ BB_I2C_SDA(bus, 1);
+ data = 0;
+ for (j = 0; j < 8; j++) {
+ BB_I2C_SCL(bus, 0);
+ BB_I2C_DELAY(bus);
+ BB_I2C_SCL(bus, 1);
+ BB_I2C_DELAY(bus);
+ data <<= 1;
+ data |= BB_I2C_READ(bus);
+ BB_I2C_DELAY(bus);
+ }
+ send_ack(bus, ack);
+
+ return data;
+}
+
+/*=====================================================================*/
+/* Public Functions */
+/*=====================================================================*/
+
+/*-----------------------------------------------------------------------
+ * Initialization
+ */
+void bb_i2c_init(unsigned int bus, int speed, int slaveaddr)
+{
+ send_reset(bus);
+}
+
+/*-----------------------------------------------------------------------
+ * Probe to see if a chip is present. Also good for checking for the
+ * completion of EEPROM writes since the chip stops responding until
+ * the write completes (typically 10mSec).
+ */
+int bb_i2c_probe(unsigned int bus, uchar addr)
+{
+ int rc;
+
+ /*
+ * perform 1 byte write transaction with just address byte
+ * (fake write)
+ */
+ send_start(bus);
+ rc = write_byte(bus, (addr << 1) | 0);
+ send_stop(bus);
+
+ return rc ? 1 : 0;
+}
+
+/*-----------------------------------------------------------------------
+ * Read bytes
+ */
+int bb_i2c_read(unsigned int bus, uchar chip, uint addr, int alen,
+ uchar *buffer, int len)
+{
+ int shift;
+
+ /*
+ * Do the addressing portion of a write cycle to set the
+ * chip's address pointer. If the address length is zero,
+ * don't do the normal write cycle to set the address pointer,
+ * there is no address pointer in this chip.
+ */
+ send_start(bus);
+ if (alen > 0) {
+ if (write_byte(bus, chip << 1)) { /* write cycle */
+ send_stop(bus);
+ return 1;
+ }
+ shift = (alen-1) * 8;
+ while (alen-- > 0) {
+ if (write_byte(bus, addr >> shift))
+ return 1;
+ shift -= 8;
+ }
+
+ send_stop(bus);
+ send_start(bus);
+ }
+ /*
+ * Send the chip address again, this time for a read cycle.
+ * Then read the data. On the last byte, we do a NACK instead
+ * of an ACK(len == 0) to terminate the read.
+ */
+ write_byte(bus, (chip << 1) | 1); /* read cycle */
+ while (len-- > 0)
+ *buffer++ = read_byte(bus, len == 0);
+ send_stop(bus);
+ return 0;
+}
+
+/*-----------------------------------------------------------------------
+ * Write bytes
+ */
+int bb_i2c_write(unsigned int bus, uchar chip, uint addr, int alen,
+ uchar *buffer, int len)
+{
+ int shift, failures = 0;
+
+ send_start(bus);
+ if (write_byte(bus, chip << 1)) { /* write cycle */
+ send_stop(bus);
+ return 1;
+ }
+ shift = (alen-1) * 8;
+ while (alen-- > 0) {
+ if (write_byte(bus, addr >> shift))
+ return 1;
+ shift -= 8;
+ }
+
+ while (len-- > 0) {
+ if (write_byte(bus, *buffer++))
+ failures++;
+ }
+ send_stop(bus);
+ return failures;
+}
diff --git a/board/gdsys/common/bb_i2c.h b/board/gdsys/common/bb_i2c.h
new file mode 100644
index 0000000..34f4c0f
--- /dev/null
+++ b/board/gdsys/common/bb_i2c.h
@@ -0,0 +1,76 @@
+/*
+ * (C) Copyright 2012
+ * Dirk Eibach, Guntermann & Drunck GmbH, eibach at gdsys.de
+ *
+ * based on i2c.h
+ * (C) Copyright 2001
+ * Gerald Van Baren, Custom IDEAS, vanbaren at cideas.com.
+ *
+ * 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
+ *
+ * The original I2C interface was
+ * (C) 2000 by Paolo Scaffardi (arsenio at tin.it)
+ * AIRVENT SAM s.p.a - RIMINI(ITALY)
+ * but has been changed substantially.
+ */
+
+#ifndef _BB_I2C_H_
+#define _BB_I2C_H_
+
+/*
+ * Probe the given I2C chip address. Returns 0 if a chip responded,
+ * not 0 on failure.
+ */
+int bb_i2c_probe(unsigned int bus, uchar chip);
+
+/*
+ * Read/Write interface:
+ * chip: I2C chip address, range 0..127
+ * addr: Memory (register) address within the chip
+ * alen: Number of bytes to use for addr (typically 1, 2 for larger
+ * memories, 0 for register type devices with only one
+ * register)
+ * buffer: Where to read/write the data
+ * len: How many bytes to read/write
+ *
+ * Returns: 0 on success, not 0 on failure
+ */
+int bb_i2c_read(unsigned int bus, uchar chip, uint addr, int alen,
+ uchar *buffer, int len);
+int bb_i2c_write(unsigned int bus, uchar chip, uint addr, int alen,
+ uchar *buffer, int len);
+
+/*
+ * Utility routines to read/write registers.
+ */
+static inline u8 bb_i2c_reg_read(unsigned int bus, u8 addr, u8 reg)
+{
+ u8 buf;
+
+ bb_i2c_read(bus, addr, reg, 1, &buf, 1);
+
+ return buf;
+}
+
+static inline void bb_i2c_reg_write(unsigned int bus, u8 addr, u8 reg, u8 val)
+{
+ bb_i2c_write(bus, addr, reg, 1, &val, 1);
+}
+
+#endif /* _BB_I2C_H_ */
--
1.7.10.4