i2c: Bus drivers return -Errno not -1

Tighten error paths used by various i2c adapters (mostly x86) so
they return real fault/errno codes instead of a "-1" (which is
most often interpreted as "-EPERM").  Build tested, with eyeball
review.

One minor initial goal is to have adapters consistently return
the code "-ENXIO" when addressing a device doesn't get an ACK
response, at least in the probe paths where they are already
good at stifling related logspam.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/i2c/busses/i2c-sis5595.c

@@ -236,7 +236,7 @@ static int sis5595_transaction(struct i2c_adapter *adap)
 		sis5595_write(SMB_STS_HI, temp >> 8);
 		if ((temp = sis5595_read(SMB_STS_LO) + (sis5595_read(SMB_STS_HI) << 8)) != 0x00) {
 			dev_dbg(&adap->dev, "Failed! (%02x)\n", temp);
-			return -1;
+			return -EBUSY;
 		} else {
 			dev_dbg(&adap->dev, "Successful!\n");
 		}
@@ -254,19 +254,19 @@ static int sis5595_transaction(struct i2c_adapter *adap)
 	/* If the SMBus is still busy, we give up */
 	if (timeout >= MAX_TIMEOUT) {
 		dev_dbg(&adap->dev, "SMBus Timeout!\n");
-		result = -1;
+		result = -ETIMEDOUT;
 	}
 
 	if (temp & 0x10) {
 		dev_dbg(&adap->dev, "Error: Failed bus transaction\n");
-		result = -1;
+		result = -ENXIO;
 	}
 
 	if (temp & 0x20) {
 		dev_err(&adap->dev, "Bus collision! SMBus may be locked until "
 			"next hard reset (or not...)\n");
 		/* Clock stops and slave is stuck in mid-transmission */
-		result = -1;
+		result = -EIO;
 	}
 
 	temp = sis5595_read(SMB_STS_LO) + (sis5595_read(SMB_STS_HI) << 8);
@@ -282,11 +282,13 @@ static int sis5595_transaction(struct i2c_adapter *adap)
 	return result;
 }
 
-/* Return -1 on error. */
+/* Return negative errno on error. */
 static s32 sis5595_access(struct i2c_adapter *adap, u16 addr,
 			  unsigned short flags, char read_write,
 			  u8 command, int size, union i2c_smbus_data *data)
 {
+	int status;
+
 	switch (size) {
 	case I2C_SMBUS_QUICK:
 		sis5595_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
@@ -318,13 +320,14 @@ static s32 sis5595_access(struct i2c_adapter *adap, u16 addr,
 		break;
 	default:
 		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
-		return -1;
+		return -EOPNOTSUPP;
 	}
 
 	sis5595_write(SMB_CTL_LO, ((size & 0x0E)));
 
-	if (sis5595_transaction(adap))
-		return -1;
+	status = sis5595_transaction(adap);
+	if (status)
+		return status;
 
 	if ((size != SIS5595_PROC_CALL) &&
 	    ((read_write == I2C_SMBUS_WRITE) || (size == SIS5595_QUICK)))