1 files changed, 125 insertions, 101 deletions

diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index a37cb6b8593c..35812823787b 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -1,7 +1,7 @@
-/* ------------------------------------------------------------------------- */
-/* i2c-algo-bit.c i2c driver algorithms for bit-shift adapters		     */
-/* ------------------------------------------------------------------------- */
-/*   Copyright (C) 1995-2000 Simon G. Vogl
+/* -------------------------------------------------------------------------
+ * 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
@@ -15,8 +15,8 @@
 
     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., 675 Mass Ave, Cambridge, MA 02139, USA.		     */
-/* ------------------------------------------------------------------------- */
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ * ------------------------------------------------------------------------- */
 
 /* With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
    <kmalkki@cc.hut.fi> and Jean Delvare <khali@linux-fr.org> */
@@ -60,26 +60,26 @@ MODULE_PARM_DESC(i2c_debug,
 
 /* --- 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)
+#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);
+	setsda(adap, 0);
 	udelay((adap->udelay + 1) / 2);
 }
 
 static inline void sdahi(struct i2c_algo_bit_data *adap)
 {
-	setsda(adap,1);
+	setsda(adap, 1);
 	udelay((adap->udelay + 1) / 2);
 }
 
 static inline void scllo(struct i2c_algo_bit_data *adap)
 {
-	setscl(adap,0);
+	setscl(adap, 0);
 	udelay(adap->udelay / 2);
 }
 
@@ -91,22 +91,21 @@ static int sclhi(struct i2c_algo_bit_data *adap)
 {
 	unsigned long start;
 
-	setscl(adap,1);
+	setscl(adap, 1);
 
 	/* Not all adapters have scl sense line... */
 	if (!adap->getscl)
 		goto done;
 
-	start=jiffies;
-	while (! getscl(adap) ) {	
- 		/* the 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
- 		 * while they are processing data internally. 
- 		 */
-		if (time_after_eq(jiffies, start+adap->timeout)) {
+	start = jiffies;
+	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 (time_after_eq(jiffies, start + adap->timeout))
 			return -ETIMEDOUT;
-		}
 		cond_resched();
 	}
 #ifdef DEBUG
@@ -118,11 +117,11 @@ static int sclhi(struct i2c_algo_bit_data *adap)
 done:
 	udelay(adap->udelay);
 	return 0;
-} 
+}
 
 
 /* --- other auxiliary functions --------------------------------------	*/
-static void i2c_start(struct i2c_algo_bit_data *adap) 
+static void i2c_start(struct i2c_algo_bit_data *adap)
 {
 	/* assert: scl, sda are high */
 	setsda(adap, 0);
@@ -130,7 +129,7 @@ static void i2c_start(struct i2c_algo_bit_data *adap)
 	scllo(adap);
 }
 
-static void i2c_repstart(struct i2c_algo_bit_data *adap) 
+static void i2c_repstart(struct i2c_algo_bit_data *adap)
 {
 	/* assert: scl is low */
 	sdahi(adap);
@@ -141,18 +140,18 @@ static void i2c_repstart(struct i2c_algo_bit_data *adap)
 }
 
 
-static void i2c_stop(struct i2c_algo_bit_data *adap) 
+static void i2c_stop(struct i2c_algo_bit_data *adap)
 {
 	/* assert: scl is low */
 	sdalo(adap);
-	sclhi(adap); 
+	sclhi(adap);
 	setsda(adap, 1);
 	udelay(adap->udelay);
 }
 
 
 
-/* send a byte without start cond., look for arbitration, 
+/* send a byte without start cond., look for arbitration,
    check ackn. from slave */
 /* returns:
  * 1 if the device acknowledged
@@ -167,27 +166,33 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
 	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 
 	/* assert: scl is low */
-	for ( i=7 ; i>=0 ; i-- ) {
+	for (i = 7; i >= 0; i--) {
 		sb = (c >> i) & 1;
-		setsda(adap,sb);
+		setsda(adap, sb);
 		udelay((adap->udelay + 1) / 2);
-		if (sclhi(adap)<0) { /* timed out */
+		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;
-		};
-		/* do arbitration here: 
-		 * if ( sb && ! getsda(adap) ) -> ouch! Get out of here.
+		}
+		/* 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 */
+	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 */
+	}
+
+	/* 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");
@@ -198,24 +203,24 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
 }
 
 
-static int i2c_inb(struct i2c_adapter *i2c_adap) 
+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;
+	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 */
+	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) ) 
+		if (getsda(adap))
 			indata |= 0x01;
 		setscl(adap, 0);
 		udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
@@ -228,66 +233,67 @@ static int i2c_inb(struct i2c_adapter *i2c_adap)
  * 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_algo_bit_data *adap, char* name) {
-	int scl,sda;
+static int test_bus(struct i2c_algo_bit_data *adap, char *name)
+{
+	int scl, sda;
 
-	if (adap->getscl==NULL)
+	if (adap->getscl == NULL)
 		pr_info("%s: Testing SDA only, SCL is not readable\n", name);
 
-	sda=getsda(adap);
-	scl=(adap->getscl==NULL?1:getscl(adap));
-	if (!scl || !sda ) {
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (!scl || !sda) {
 		printk(KERN_WARNING "%s: bus seems to be busy\n", name);
 		goto bailout;
 	}
 
 	sdalo(adap);
-	sda=getsda(adap);
-	scl=(adap->getscl==NULL?1:getscl(adap));
-	if ( 0 != sda ) {
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (sda) {
 		printk(KERN_WARNING "%s: SDA stuck high!\n", name);
 		goto bailout;
 	}
-	if ( 0 == scl ) {
+	if (!scl) {
 		printk(KERN_WARNING "%s: SCL unexpected low "
 		       "while pulling SDA low!\n", name);
 		goto bailout;
-	}		
+	}
 
 	sdahi(adap);
-	sda=getsda(adap);
-	scl=(adap->getscl==NULL?1:getscl(adap));
-	if ( 0 == sda ) {
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (!sda) {
 		printk(KERN_WARNING "%s: SDA stuck low!\n", name);
 		goto bailout;
 	}
-	if ( 0 == scl ) {
+	if (!scl) {
 		printk(KERN_WARNING "%s: SCL unexpected low "
 		       "while pulling SDA high!\n", name);
 		goto bailout;
 	}
 
 	scllo(adap);
-	sda=getsda(adap);
-	scl=(adap->getscl==NULL?0:getscl(adap));
-	if ( 0 != scl ) {
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 0 : getscl(adap);
+	if (scl) {
 		printk(KERN_WARNING "%s: SCL stuck high!\n", name);
 		goto bailout;
 	}
-	if ( 0 == sda ) {
+	if (!sda) {
 		printk(KERN_WARNING "%s: SDA unexpected low "
 		       "while pulling SCL low!\n", name);
 		goto bailout;
 	}
-	
+
 	sclhi(adap);
-	sda=getsda(adap);
-	scl=(adap->getscl==NULL?1:getscl(adap));
-	if ( 0 == scl ) {
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (!scl) {
 		printk(KERN_WARNING "%s: SCL stuck low!\n", name);
 		goto bailout;
 	}
-	if ( 0 == sda ) {
+	if (!sda) {
 		printk(KERN_WARNING "%s: SDA unexpected low "
 		       "while pulling SCL high!\n", name);
 		goto bailout;
@@ -314,9 +320,10 @@ 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 = -1;
-	for (i=0;i<=retries;i++) {
-		ret = i2c_outb(i2c_adap,addr);
+	int i, ret = -1;
+
+	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");
@@ -338,20 +345,38 @@ 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; 
+	unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
 	int retval;
-	int wrcount=0;
+	int wrcount = 0;
 
 	while (count > 0) {
 		retval = i2c_outb(i2c_adap, *temp);
-		if ((retval>0) || (nak_ok && (retval==0)))  { /* ok or ignored NAK */
-			count--; 
+
+		/* OK/ACK; or ignored NAK */
+		if ((retval > 0) || (nak_ok && (retval == 0))) {
+			count--;
 			temp++;
 			wrcount++;
-		} else { /* arbitration or no acknowledge */
-			dev_err(&i2c_adap->dev, "sendbytes: error - bailout.\n");
-			return (retval<0)? retval : -EFAULT;
-			        /* got a better one ?? */
+
+		/* 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;
@@ -376,14 +401,14 @@ static int acknak(struct i2c_adapter *i2c_adap, int is_ack)
 static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 {
 	int inval;
-	int rdcount=0;   	/* counts bytes read */
+	int rdcount = 0;	/* counts bytes read */
 	unsigned char *temp = msg->buf;
 	int count = msg->len;
 	const unsigned flags = msg->flags;
 
 	while (count > 0) {
 		inval = i2c_inb(i2c_adap);
-		if (inval>=0) {
+		if (inval >= 0) {
 			*temp = inval;
 			rdcount++;
 		} else {   /* read timed out */
@@ -431,7 +456,7 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
  * returns:
  *  0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
  * -x an error occurred (like: -EREMOTEIO if the device did not answer, or
- *	-ETIMEDOUT, for example if the lines are stuck...) 
+ *	-ETIMEDOUT, for example if the lines are stuck...)
  */
 static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 {
@@ -443,10 +468,10 @@ static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 	int ret, retries;
 
 	retries = nak_ok ? 0 : i2c_adap->retries;
-	
-	if ( (flags & I2C_M_TEN)  ) { 
+
+	if (flags & I2C_M_TEN) {
 		/* a ten bit address */
-		addr = 0xf0 | (( msg->addr >> 7) & 0x03);
+		addr = 0xf0 | ((msg->addr >> 7) & 0x03);
 		bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
 		/* try extended address code...*/
 		ret = try_address(i2c_adap, addr, retries);
@@ -456,33 +481,33 @@ static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 			return -EREMOTEIO;
 		}
 		/* the remaining 8 bit address */
-		ret = i2c_outb(i2c_adap,msg->addr & 0x7f);
+		ret = i2c_outb(i2c_adap, msg->addr & 0x7f);
 		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 -EREMOTEIO;
 		}
-		if ( flags & I2C_M_RD ) {
+		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) {
+			if ((ret != 1) && !nak_ok) {
 				dev_err(&i2c_adap->dev,
 					"died at repeated address code\n");
 				return -EREMOTEIO;
 			}
 		}
 	} else {		/* normal 7bit address	*/
-		addr = ( msg->addr << 1 );
-		if (flags & I2C_M_RD )
+		addr = msg->addr << 1;
+		if (flags & I2C_M_RD)
 			addr |= 1;
-		if (flags & I2C_M_REV_DIR_ADDR )
+		if (flags & I2C_M_REV_DIR_ADDR)
 			addr ^= 1;
 		ret = try_address(i2c_adap, addr, retries);
-		if ((ret!=1) && !nak_ok)
+		if ((ret != 1) && !nak_ok)
 			return -EREMOTEIO;
 	}
 
@@ -494,15 +519,14 @@ static int bit_xfer(struct i2c_adapter *i2c_adap,
 {
 	struct i2c_msg *pmsg;
 	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
-	
-	int i,ret;
+	int i, ret;
 	unsigned short nak_ok;
 
 	bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
 	i2c_start(adap);
-	for (i=0;i<num;i++) {
+	for (i = 0; i < num; i++) {
 		pmsg = &msgs[i];
-		nak_ok = pmsg->flags & I2C_M_IGNORE_NAK; 
+		nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
 		if (!(pmsg->flags & I2C_M_NOSTART)) {
 			if (i) {
 				bit_dbg(3, &i2c_adap->dev, "emitting "
@@ -517,7 +541,7 @@ static int bit_xfer(struct i2c_adapter *i2c_adap,
 				goto bailout;
 			}
 		}
-		if (pmsg->flags & I2C_M_RD ) {
+		if (pmsg->flags & I2C_M_RD) {
 			/* read bytes into buffer*/
 			ret = readbytes(i2c_adap, pmsg);
 			if (ret >= 1)
@@ -551,7 +575,7 @@ bailout:
 
 static u32 bit_func(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | 
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
 	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
 	       I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
@@ -565,8 +589,8 @@ static const struct i2c_algorithm i2c_bit_algo = {
 	.functionality	= bit_func,
 };
 
-/* 
- * registering functions to load algorithms at runtime 
+/*
+ * registering functions to load algorithms at runtime
  */
 static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
 {
@@ -574,7 +598,7 @@ static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
 
 	if (bit_test) {
 		int ret = test_bus(bit_adap, adap->name);
-		if (ret<0)
+		if (ret < 0)
 			return -ENODEV;
 	}