i2c: add i2c algo bit support

This is needed for i2c-gpio support

Based on linux 3.7-rc2

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 596 insertions, 0 deletions

diff --git a/drivers/i2c/algos/Kconfig b/drivers/i2c/algos/Kconfig
new file mode 100644
index 0000000000..c74b148f5e
--- /dev/null
+++ b/drivers/i2c/algos/Kconfig
@@ -0,0 +1,6 @@
+#
+# I2C algorithm drivers configuration
+#
+
+config I2C_ALGOBIT
+	bool
diff --git a/drivers/i2c/algos/Makefile b/drivers/i2c/algos/Makefile
new file mode 100644
index 0000000000..e0a03995b5
--- /dev/null
+++ b/drivers/i2c/algos/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for the i2c algorithms
+#
+
+obj-$(CONFIG_I2C_ALGOBIT)	+= i2c-algo-bit.o
diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
new file mode 100644
index 0000000000..37af27cbb3
--- /dev/null
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -0,0 +1,585 @@
+/* -------------------------------------------------------------------------
+ * i2c-algo-bit.c i2c driver algorithms for bit-shift adapters
+ * -------------------------------------------------------------------------
+ *   Copyright (C) 1995-2000 Simon G. Vogl
+
+    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., 51 Franklin Street, Fifth Floor, Boston,
+    MA 02110-1301 USA.
+ * ------------------------------------------------------------------------- */
+
+/* With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
+   <kmalkki@cc.hut.fi> and Jean Delvare <khali@linux-fr.org> */
+
+#include <common.h>
+#include <init.h>
+#include <errno.h>
+#include <clock.h>
+#include <i2c/i2c.h>
+#include <i2c/i2c-algo-bit.h>
+
+/* ----- global defines ----------------------------------------------- */
+
+#ifdef DEBUG
+#define bit_dbg(level, dev, format, args...) \
+	do { \
+		if (i2c_debug >= level) \
+			dev_dbg(dev, format, ##args); \
+	} while (0)
+#else
+#define bit_dbg(level, dev, format, args...) \
+	do {} while (0)
+#endif /* DEBUG */
+
+/* ----- global variables ---------------------------------------------	*/
+
+static int bit_test;	/* see if the line-setting functions work	*/
+
+#ifdef DEBUG
+static int i2c_debug = 1;
+#endif
+
+/* --- setting states on the bus with the right timing: ---------------	*/
+
+#define setsda(adap, val)	adap->setsda(adap->data, val)
+#define setscl(adap, val)	adap->setscl(adap->data, val)
+#define getsda(adap)		adap->getsda(adap->data)
+#define getscl(adap)		adap->getscl(adap->data)
+
+static inline void sdalo(struct i2c_algo_bit_data *adap)
+{
+	setsda(adap, 0);
+	udelay((adap->udelay + 1) / 2);
+}
+
+static inline void sdahi(struct i2c_algo_bit_data *adap)
+{
+	setsda(adap, 1);
+	udelay((adap->udelay + 1) / 2);
+}
+
+static inline void scllo(struct i2c_algo_bit_data *adap)
+{
+	setscl(adap, 0);
+	udelay(adap->udelay / 2);
+}
+
+/*
+ * Raise scl line, and do checking for delays. This is necessary for slower
+ * devices.
+ */
+static int sclhi(struct i2c_algo_bit_data *adap)
+{
+	uint64_t start;
+
+	setscl(adap, 1);
+
+	/* Not all adapters have scl sense line... */
+	if (!adap->getscl)
+		goto done;
+
+	start = get_time_ns();
+	while (!getscl(adap)) {
+		/* This hw knows how to read the clock line, so we wait
+		 * until it actually gets high.  This is safer as some
+		 * chips may hold it low ("clock stretching") while they
+		 * are processing data internally.
+		 */
+		if (is_timeout(start, adap->timeout_ms * MSECOND)) {
+			/* Test one last time, as we may have been preempted
+			 * between last check and timeout test.
+			 */
+			if (getscl(adap))
+				break;
+			return -ETIMEDOUT;
+		}
+	}
+#ifdef DEBUG
+	if (jiffies != start && i2c_debug >= 3)
+		pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go "
+			 "high\n", jiffies - start);
+#endif
+
+done:
+	udelay(adap->udelay);
+	return 0;
+}
+
+
+/* --- other auxiliary functions --------------------------------------	*/
+static void i2c_start(struct i2c_algo_bit_data *adap)
+{
+	/* assert: scl, sda are high */
+	setsda(adap, 0);
+	udelay(adap->udelay);
+	scllo(adap);
+}
+
+static void i2c_repstart(struct i2c_algo_bit_data *adap)
+{
+	/* assert: scl is low */
+	sdahi(adap);
+	sclhi(adap);
+	setsda(adap, 0);
+	udelay(adap->udelay);
+	scllo(adap);
+}
+
+
+static void i2c_stop(struct i2c_algo_bit_data *adap)
+{
+	/* assert: scl is low */
+	sdalo(adap);
+	sclhi(adap);
+	setsda(adap, 1);
+	udelay(adap->udelay);
+}
+
+
+
+/* send a byte without start cond., look for arbitration,
+   check ackn. from slave */
+/* returns:
+ * 1 if the device acknowledged
+ * 0 if the device did not ack
+ * -ETIMEDOUT if an error occurred (while raising the scl line)
+ */
+static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
+{
+	int i;
+	int sb;
+	int ack;
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+	/* assert: scl is low */
+	for (i = 7; i >= 0; i--) {
+		sb = (c >> i) & 1;
+		setsda(adap, sb);
+		udelay((adap->udelay + 1) / 2);
+		if (sclhi(adap) < 0) { /* timed out */
+			bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
+				"timeout at bit #%d\n", (int)c, i);
+			return -ETIMEDOUT;
+		}
+		/* FIXME do arbitration here:
+		 * if (sb && !getsda(adap)) -> ouch! Get out of here.
+		 *
+		 * Report a unique code, so higher level code can retry
+		 * the whole (combined) message and *NOT* issue STOP.
+		 */
+		scllo(adap);
+	}
+	sdahi(adap);
+	if (sclhi(adap) < 0) { /* timeout */
+		bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
+			"timeout at ack\n", (int)c);
+		return -ETIMEDOUT;
+	}
+
+	/* read ack: SDA should be pulled down by slave, or it may
+	 * NAK (usually to report problems with the data we wrote).
+	 */
+	ack = !getsda(adap);    /* ack: sda is pulled low -> success */
+	bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
+		ack ? "A" : "NA");
+
+	scllo(adap);
+	return ack;
+	/* assert: scl is low (sda undef) */
+}
+
+
+static int i2c_inb(struct i2c_adapter *i2c_adap)
+{
+	/* read byte via i2c port, without start/stop sequence	*/
+	/* acknowledge is sent in i2c_read.			*/
+	int i;
+	unsigned char indata = 0;
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+	/* assert: scl is low */
+	sdahi(adap);
+	for (i = 0; i < 8; i++) {
+		if (sclhi(adap) < 0) { /* timeout */
+			bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit "
+				"#%d\n", 7 - i);
+			return -ETIMEDOUT;
+		}
+		indata *= 2;
+		if (getsda(adap))
+			indata |= 0x01;
+		setscl(adap, 0);
+		udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
+	}
+	/* assert: scl is low */
+	return indata;
+}
+
+/*
+ * Sanity check for the adapter hardware - check the reaction of
+ * the bus lines only if it seems to be idle.
+ */
+static int test_bus(struct i2c_adapter *i2c_adap)
+{
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+	struct device_d *dev = &i2c_adap->dev;
+	int scl, sda, ret;
+
+	if (adap->pre_xfer) {
+		ret = adap->pre_xfer(i2c_adap);
+		if (ret < 0)
+			return -ENODEV;
+	}
+
+	if (adap->getscl == NULL)
+		dev_info(dev, "Testing SDA only, SCL is not readable\n");
+
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (!scl || !sda) {
+		dev_warn(dev, "bus seems to be busy (scl=%d, sda=%d)\n", scl, sda);
+		goto bailout;
+	}
+
+	sdalo(adap);
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (sda) {
+		dev_warn(dev, "SDA stuck high!\n");
+		goto bailout;
+	}
+	if (!scl) {
+		dev_warn(dev, "SCL unexpected low while pulling SDA low!\n");
+		goto bailout;
+	}
+
+	sdahi(adap);
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (!sda) {
+		dev_warn(dev, "SDA stuck low!\n");
+		goto bailout;
+	}
+	if (!scl) {
+		dev_warn(dev, "SCL unexpected low while pulling SDA high!\n");
+		goto bailout;
+	}
+
+	scllo(adap);
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 0 : getscl(adap);
+	if (scl) {
+		dev_warn(dev, "SCL stuck high!\n");
+		goto bailout;
+	}
+	if (!sda) {
+		dev_warn(dev, "SDA unexpected low while pulling SCL low!\n");
+		goto bailout;
+	}
+
+	sclhi(adap);
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (!scl) {
+		dev_warn(dev, "SCL stuck low!\n");
+		goto bailout;
+	}
+	if (!sda) {
+		dev_warn(dev, "SDA unexpected low while pulling SCL high!\n");
+		goto bailout;
+	}
+
+	if (adap->post_xfer)
+		adap->post_xfer(i2c_adap);
+
+	dev_info(dev, "Test OK\n");
+	return 0;
+bailout:
+	sdahi(adap);
+	sclhi(adap);
+
+	if (adap->post_xfer)
+		adap->post_xfer(i2c_adap);
+
+	return -ENODEV;
+}
+
+/* ----- Utility functions
+ */
+
+/* try_address tries to contact a chip for a number of
+ * times before it gives up.
+ * return values:
+ * 1 chip answered
+ * 0 chip did not answer
+ * -x transmission error
+ */
+static int try_address(struct i2c_adapter *i2c_adap,
+		       unsigned char addr, int retries)
+{
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+	int i, ret = 0;
+
+	for (i = 0; i <= retries; i++) {
+		ret = i2c_outb(i2c_adap, addr);
+		if (ret == 1 || i == retries)
+			break;
+		bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
+		i2c_stop(adap);
+		udelay(adap->udelay);
+		bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
+		i2c_start(adap);
+	}
+	if (i && ret)
+		bit_dbg(1, &i2c_adap->dev, "Used %d tries to %s client at "
+			"0x%02x: %s\n", i + 1,
+			addr & 1 ? "read from" : "write to", addr >> 1,
+			ret == 1 ? "success" : "failed, timeout?");
+	return ret;
+}
+
+static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
+{
+	const unsigned char *temp = msg->buf;
+	int count = msg->len;
+	unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
+	int retval;
+	int wrcount = 0;
+
+	while (count > 0) {
+		retval = i2c_outb(i2c_adap, *temp);
+
+		/* OK/ACK; or ignored NAK */
+		if ((retval > 0) || (nak_ok && (retval == 0))) {
+			count--;
+			temp++;
+			wrcount++;
+
+		/* A slave NAKing the master means the slave didn't like
+		 * something about the data it saw.  For example, maybe
+		 * the SMBus PEC was wrong.
+		 */
+		} else if (retval == 0) {
+			dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n");
+			return -EIO;
+
+		/* Timeout; or (someday) lost arbitration
+		 *
+		 * FIXME Lost ARB implies retrying the transaction from
+		 * the first message, after the "winning" master issues
+		 * its STOP.  As a rule, upper layer code has no reason
+		 * to know or care about this ... it is *NOT* an error.
+		 */
+		} else {
+			dev_err(&i2c_adap->dev, "sendbytes: error %d\n",
+					retval);
+			return retval;
+		}
+	}
+	return wrcount;
+}
+
+static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
+{
+	int inval;
+	int rdcount = 0;	/* counts bytes read */
+	unsigned char *temp = msg->buf;
+	int count = msg->len;
+
+	while (count > 0) {
+		inval = i2c_inb(i2c_adap);
+		if (inval >= 0) {
+			*temp = inval;
+			rdcount++;
+		} else {   /* read timed out */
+			break;
+		}
+
+		temp++;
+		count--;
+
+		bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n",
+			inval,
+			(flags & I2C_M_NO_RD_ACK)
+				? "(no ack/nak)"
+				: (count ? "A" : "NA"));
+	}
+	return rdcount;
+}
+
+/* doAddress initiates the transfer by generating the start condition (in
+ * try_address) and transmits the address in the necessary format to handle
+ * reads, writes as well as 10bit-addresses.
+ * returns:
+ *  0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
+ * -x an error occurred (like: -ENXIO if the device did not answer, or
+ *	-ETIMEDOUT, for example if the lines are stuck...)
+ */
+static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
+{
+	unsigned short flags = msg->flags;
+	unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+	unsigned char addr;
+	int ret, retries;
+
+	retries = nak_ok ? 0 : i2c_adap->retries;
+
+	if (flags & I2C_M_TEN) {
+		/* a ten bit address */
+		addr = 0xf0 | ((msg->addr >> 7) & 0x06);
+		bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
+		/* try extended address code...*/
+		ret = try_address(i2c_adap, addr, retries);
+		if ((ret != 1) && !nak_ok)  {
+			dev_err(&i2c_adap->dev,
+				"died at extended address code\n");
+			return -ENXIO;
+		}
+		/* the remaining 8 bit address */
+		ret = i2c_outb(i2c_adap, msg->addr & 0xff);
+		if ((ret != 1) && !nak_ok) {
+			/* the chip did not ack / xmission error occurred */
+			dev_err(&i2c_adap->dev, "died at 2nd address code\n");
+			return -ENXIO;
+		}
+		if (flags & I2C_M_RD) {
+			bit_dbg(3, &i2c_adap->dev, "emitting repeated "
+				"start condition\n");
+			i2c_repstart(adap);
+			/* okay, now switch into reading mode */
+			addr |= 0x01;
+			ret = try_address(i2c_adap, addr, retries);
+			if ((ret != 1) && !nak_ok) {
+				dev_err(&i2c_adap->dev,
+					"died at repeated address code\n");
+				return -EIO;
+			}
+		}
+	} else {		/* normal 7bit address	*/
+		addr = msg->addr << 1;
+		if (flags & I2C_M_RD)
+			addr |= 1;
+		ret = try_address(i2c_adap, addr, retries);
+		if ((ret != 1) && !nak_ok)
+			return -ENXIO;
+	}
+
+	return 0;
+}
+
+static int bit_xfer(struct i2c_adapter *i2c_adap,
+		    struct i2c_msg msgs[], int num)
+{
+	struct i2c_msg *pmsg;
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+	int i, ret;
+	unsigned short nak_ok;
+
+	if (adap->pre_xfer) {
+		ret = adap->pre_xfer(i2c_adap);
+		if (ret < 0)
+			return ret;
+	}
+
+	bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
+	i2c_start(adap);
+	for (i = 0; i < num; i++) {
+		pmsg = &msgs[i];
+		nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
+		if (i) {
+			bit_dbg(3, &i2c_adap->dev, "emitting "
+				"repeated start condition\n");
+			i2c_repstart(adap);
+		}
+		ret = bit_doAddress(i2c_adap, pmsg);
+		if ((ret != 0) && !nak_ok) {
+			bit_dbg(1, &i2c_adap->dev, "NAK from "
+				"device addr 0x%02x msg #%d\n",
+				msgs[i].addr, i);
+			goto bailout;
+		}
+		if (pmsg->flags & I2C_M_RD) {
+			/* read bytes into buffer*/
+			ret = readbytes(i2c_adap, pmsg);
+			if (ret >= 1)
+				bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
+					ret, ret == 1 ? "" : "s");
+			if (ret < pmsg->len) {
+				if (ret >= 0)
+					ret = -EIO;
+				goto bailout;
+			}
+		} else {
+			/* write bytes from buffer */
+			ret = sendbytes(i2c_adap, pmsg);
+			if (ret >= 1)
+				bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
+					ret, ret == 1 ? "" : "s");
+			if (ret < pmsg->len) {
+				if (ret >= 0)
+					ret = -EIO;
+				goto bailout;
+			}
+		}
+	}
+	ret = i;
+
+bailout:
+	bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
+	i2c_stop(adap);
+
+	if (adap->post_xfer)
+		adap->post_xfer(i2c_adap);
+	return ret;
+}
+
+/*
+ * registering functions to load algorithms at runtime
+ */
+static int __i2c_bit_add_bus(struct i2c_adapter *adap,
+			     int (*add_adapter)(struct i2c_adapter *))
+{
+	struct i2c_algo_bit_data *bit_adap = adap->algo_data;
+	int ret;
+
+	if (bit_test) {
+		ret = test_bus(adap);
+		if (bit_test >= 2 && ret < 0)
+			return -ENODEV;
+	}
+
+	/* register new adapter to i2c module... */
+	//adap->algo = &i2c_bit_algo;
+	adap->retries = 3;
+	adap->master_xfer = bit_xfer;
+
+	ret = add_adapter(adap);
+	if (ret < 0)
+		return ret;
+
+	/* Complain if SCL can't be read */
+	if (bit_adap->getscl == NULL) {
+		dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");
+		dev_warn(&adap->dev, "Bus may be unreliable\n");
+	}
+	return 0;
+}
+
+int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
+{
+	return __i2c_bit_add_bus(adap, i2c_add_numbered_adapter);
+}
+EXPORT_SYMBOL(i2c_bit_add_numbered_bus);