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>

15 files changed, 191 insertions, 148 deletions

diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index 35812823787b..eb8f72ca02f4 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -320,7 +320,7 @@ 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;
+        int i, ret = 0;
 
         for (i = 0; i <= retries; i++) {
                 ret = i2c_outb(i2c_adap, addr);
@@ -508,7 +508,7 @@ static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
                         addr ^= 1;
                 ret = try_address(i2c_adap, addr, retries);
                 if ((ret != 1) && !nak_ok)
-                        return -EREMOTEIO;
+                        return -ENXIO;
         }
 
         return 0;
diff --git a/drivers/i2c/busses/i2c-ali1535.c b/drivers/i2c/busses/i2c-ali1535.c
index f14372ac2fc5..c21e4d96382e 100644
--- a/drivers/i2c/busses/i2c-ali1535.c
+++ b/drivers/i2c/busses/i2c-ali1535.c
@@ -259,7 +259,7 @@ static int ali1535_transaction(struct i2c_adapter *adap)
                         dev_err(&adap->dev,
                                 "SMBus reset failed! (0x%02x) - controller or "
                                 "device on bus is probably hung\n", temp);
-                        return -1;
+                        return -EBUSY;
                 }
         } else {
                 /* check and clear done bit */
@@ -281,12 +281,12 @@ static int ali1535_transaction(struct i2c_adapter *adap)
 
         /* If the SMBus is still busy, we give up */
         if (timeout >= MAX_TIMEOUT) {
-                result = -1;
+                result = -ETIMEDOUT;
                 dev_err(&adap->dev, "SMBus Timeout!\n");
         }
 
         if (temp & ALI1535_STS_FAIL) {
-                result = -1;
+                result = -EIO;
                 dev_dbg(&adap->dev, "Error: Failed bus transaction\n");
         }
 
@@ -295,7 +295,7 @@ static int ali1535_transaction(struct i2c_adapter *adap)
          * do a printk.  This means that bus collisions go unreported.
          */
         if (temp & ALI1535_STS_BUSERR) {
-                result = -1;
+                result = -ENXIO;
                 dev_dbg(&adap->dev,
                         "Error: no response or bus collision ADD=%02x\n",
                         inb_p(SMBHSTADD));
@@ -303,13 +303,13 @@ static int ali1535_transaction(struct i2c_adapter *adap)
 
         /* haven't ever seen this */
         if (temp & ALI1535_STS_DEV) {
-                result = -1;
+                result = -EIO;
                 dev_err(&adap->dev, "Error: device error\n");
         }
 
         /* check to see if the "command complete" indication is set */
         if (!(temp & ALI1535_STS_DONE)) {
-                result = -1;
+                result = -ETIMEDOUT;
                 dev_err(&adap->dev, "Error: command never completed\n");
         }
 
@@ -332,7 +332,7 @@ static int ali1535_transaction(struct i2c_adapter *adap)
         return result;
 }
 
-/* Return -1 on error. */
+/* Return negative errno on error. */
 static s32 ali1535_access(struct i2c_adapter *adap, u16 addr,
                           unsigned short flags, char read_write, u8 command,
                           int size, union i2c_smbus_data *data)
@@ -359,7 +359,7 @@ static s32 ali1535_access(struct i2c_adapter *adap, u16 addr,
         switch (size) {
         case I2C_SMBUS_PROC_CALL:
                 dev_err(&adap->dev, "I2C_SMBUS_PROC_CALL not supported!\n");
-                result = -1;
+                result = -EOPNOTSUPP;
                 goto EXIT;
         case I2C_SMBUS_QUICK:
                 outb_p(((addr & 0x7f) << 1) | (read_write & 0x01),
@@ -420,11 +420,9 @@ static s32 ali1535_access(struct i2c_adapter *adap, u16 addr,
                 break;
         }
 
-        if (ali1535_transaction(adap)) {
-                /* Error in transaction */
-                result = -1;
+        result = ali1535_transaction(adap);
+        if (result)
                 goto EXIT;
-        }
 
         if ((read_write == I2C_SMBUS_WRITE) || (size == ALI1535_QUICK)) {
                 result = 0;
diff --git a/drivers/i2c/busses/i2c-ali1563.c b/drivers/i2c/busses/i2c-ali1563.c
index 6b68074e518a..30bd3ee70386 100644
--- a/drivers/i2c/busses/i2c-ali1563.c
+++ b/drivers/i2c/busses/i2c-ali1563.c
@@ -67,6 +67,7 @@ static int ali1563_transaction(struct i2c_adapter * a, int size)
 {
         u32 data;
         int timeout;
+        int status = -EIO;
 
         dev_dbg(&a->dev, "Transaction (pre): STS=%02x, CNTL1=%02x, "
                 "CNTL2=%02x, CMD=%02x, ADD=%02x, DAT0=%02x, DAT1=%02x\n",
@@ -103,13 +104,15 @@ static int ali1563_transaction(struct i2c_adapter * a, int size)
                 /* Issue 'kill' to host controller */
                 outb_p(HST_CNTL2_KILL,SMB_HST_CNTL2);
                 data = inb_p(SMB_HST_STS);
+                status = -ETIMEDOUT;
         }
 
         /* device error - no response, ignore the autodetection case */
-        if ((data & HST_STS_DEVERR) && (size != HST_CNTL2_QUICK)) {
-                dev_err(&a->dev, "Device error!\n");
+        if (data & HST_STS_DEVERR) {
+                if (size != HST_CNTL2_QUICK)
+                        dev_err(&a->dev, "Device error!\n");
+                status = -ENXIO;
         }
-
         /* bus collision */
         if (data & HST_STS_BUSERR) {
                 dev_err(&a->dev, "Bus collision!\n");
@@ -122,13 +125,14 @@ static int ali1563_transaction(struct i2c_adapter * a, int size)
                 outb_p(0x0,SMB_HST_CNTL2);
         }
 
-        return -1;
+        return status;
 }
 
 static int ali1563_block_start(struct i2c_adapter * a)
 {
         u32 data;
         int timeout;
+        int status = -EIO;
 
         dev_dbg(&a->dev, "Block (pre): STS=%02x, CNTL1=%02x, "
                 "CNTL2=%02x, CMD=%02x, ADD=%02x, DAT0=%02x, DAT1=%02x\n",
@@ -164,13 +168,20 @@ static int ali1563_block_start(struct i2c_adapter * a)
 
         if (timeout && !(data & HST_STS_BAD))
                 return 0;
+
+        if (timeout == 0)
+                status = -ETIMEDOUT;
+
+        if (data & HST_STS_DEVERR)
+                status = -ENXIO;
+
         dev_err(&a->dev, "SMBus Error: %s%s%s%s%s\n",
-                timeout ? "Timeout " : "",
+                timeout ? "" : "Timeout ",
                 data & HST_STS_FAIL ? "Transaction Failed " : "",
                 data & HST_STS_BUSERR ? "No response or Bus Collision " : "",
                 data & HST_STS_DEVERR ? "Device Error " : "",
                 !(data & HST_STS_DONE) ? "Transaction Never Finished " : "");
-        return -1;
+        return status;
 }
 
 static int ali1563_block(struct i2c_adapter * a, union i2c_smbus_data * data, u8 rw)
diff --git a/drivers/i2c/busses/i2c-ali15x3.c b/drivers/i2c/busses/i2c-ali15x3.c
index 93bf87d70961..3d752561dc37 100644
--- a/drivers/i2c/busses/i2c-ali15x3.c
+++ b/drivers/i2c/busses/i2c-ali15x3.c
@@ -282,7 +282,7 @@ static int ali15x3_transaction(struct i2c_adapter *adap)
                         dev_err(&adap->dev, "SMBus reset failed! (0x%02x) - "
                                 "controller or device on bus is probably hung\n",
                                 temp);
-                        return -1;
+                        return -EBUSY;
                 }
         } else {
                 /* check and clear done bit */
@@ -304,12 +304,12 @@ static int ali15x3_transaction(struct i2c_adapter *adap)
 
         /* If the SMBus is still busy, we give up */
         if (timeout >= MAX_TIMEOUT) {
-                result = -1;
+                result = -ETIMEDOUT;
                 dev_err(&adap->dev, "SMBus Timeout!\n");
         }
 
         if (temp & ALI15X3_STS_TERM) {
-                result = -1;
+                result = -EIO;
                 dev_dbg(&adap->dev, "Error: Failed bus transaction\n");
         }
 
@@ -320,7 +320,7 @@ static int ali15x3_transaction(struct i2c_adapter *adap)
           This means that bus collisions go unreported.
         */
         if (temp & ALI15X3_STS_COLL) {
-                result = -1;
+                result = -ENXIO;
                 dev_dbg(&adap->dev,
                         "Error: no response or bus collision ADD=%02x\n",
                         inb_p(SMBHSTADD));
@@ -328,7 +328,7 @@ static int ali15x3_transaction(struct i2c_adapter *adap)
 
         /* haven't ever seen this */
         if (temp & ALI15X3_STS_DEV) {
-                result = -1;
+                result = -EIO;
                 dev_err(&adap->dev, "Error: device error\n");
         }
         dev_dbg(&adap->dev, "Transaction (post): STS=%02x, CNT=%02x, CMD=%02x, "
@@ -338,7 +338,7 @@ static int ali15x3_transaction(struct i2c_adapter *adap)
         return result;
 }
 
-/* Return -1 on error. */
+/* Return negative errno on error. */
 static s32 ali15x3_access(struct i2c_adapter * adap, u16 addr,
                    unsigned short flags, char read_write, u8 command,
                    int size, union i2c_smbus_data * data)
@@ -364,7 +364,7 @@ static s32 ali15x3_access(struct i2c_adapter * adap, u16 addr,
         switch (size) {
         case I2C_SMBUS_PROC_CALL:
                 dev_err(&adap->dev, "I2C_SMBUS_PROC_CALL not supported!\n");
-                return -1;
+                return -EOPNOTSUPP;
         case I2C_SMBUS_QUICK:
                 outb_p(((addr & 0x7f) << 1) | (read_write & 0x01),
                        SMBHSTADD);
@@ -421,8 +421,9 @@ static s32 ali15x3_access(struct i2c_adapter * adap, u16 addr,
 
         outb_p(size, SMBHSTCNT);        /* output command */
 
-        if (ali15x3_transaction(adap))  /* Error in transaction */
-                return -1;
+        temp = ali15x3_transaction(adap);
+        if (temp)
+                return temp;
 
         if ((read_write == I2C_SMBUS_WRITE) || (size == ALI15X3_QUICK))
                 return 0;
diff --git a/drivers/i2c/busses/i2c-amd756-s4882.c b/drivers/i2c/busses/i2c-amd756-s4882.c
index c38a0a112208..2f150e33c74c 100644
--- a/drivers/i2c/busses/i2c-amd756-s4882.c
+++ b/drivers/i2c/busses/i2c-amd756-s4882.c
@@ -58,7 +58,7 @@ static s32 amd756_access_virt0(struct i2c_adapter * adap, u16 addr,
         /* We exclude the multiplexed addresses */
         if (addr == 0x4c || (addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30
          || addr == 0x18)
-                return -1;
+                return -ENXIO;
 
         mutex_lock(&amd756_lock);
 
@@ -86,7 +86,7 @@ static inline s32 amd756_access_channel(struct i2c_adapter * adap, u16 addr,
 
         /* We exclude the non-multiplexed addresses */
         if (addr != 0x4c && (addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30)
-                return -1;
+                return -ENXIO;
 
         mutex_lock(&amd756_lock);
 
diff --git a/drivers/i2c/busses/i2c-amd756.c b/drivers/i2c/busses/i2c-amd756.c
index 43508d61eb7c..3d5bcb65e9e0 100644
--- a/drivers/i2c/busses/i2c-amd756.c
+++ b/drivers/i2c/busses/i2c-amd756.c
@@ -151,17 +151,17 @@ static int amd756_transaction(struct i2c_adapter *adap)
         }
 
         if (temp & GS_PRERR_STS) {
-                result = -1;
+                result = -ENXIO;
                 dev_dbg(&adap->dev, "SMBus Protocol error (no response)!\n");
         }
 
         if (temp & GS_COL_STS) {
-                result = -1;
+                result = -EIO;
                 dev_warn(&adap->dev, "SMBus collision!\n");
         }
 
         if (temp & GS_TO_STS) {
-                result = -1;
+                result = -ETIMEDOUT;
                 dev_dbg(&adap->dev, "SMBus protocol timeout!\n");
         }
 
@@ -189,22 +189,23 @@ static int amd756_transaction(struct i2c_adapter *adap)
         outw_p(inw(SMB_GLOBAL_ENABLE) | GE_ABORT, SMB_GLOBAL_ENABLE);
         msleep(100);
         outw_p(GS_CLEAR_STS, SMB_GLOBAL_STATUS);
-        return -1;
+        return -EIO;
 }
 
-/* Return -1 on error. */
+/* Return negative errno on error. */
 static s32 amd756_access(struct i2c_adapter * adap, u16 addr,
                   unsigned short flags, char read_write,
                   u8 command, int size, union i2c_smbus_data * data)
 {
         int i, len;
+        int status;
 
         /** TODO: Should I supporte the 10-bit transfers? */
         switch (size) {
         case I2C_SMBUS_PROC_CALL:
                 dev_dbg(&adap->dev, "I2C_SMBUS_PROC_CALL not supported!\n");
                 /* TODO: Well... It is supported, I'm just not sure what to do here... */
-                return -1;
+                return -EOPNOTSUPP;
         case I2C_SMBUS_QUICK:
                 outw_p(((addr & 0x7f) << 1) | (read_write & 0x01),
                        SMB_HOST_ADDRESS);
@@ -256,8 +257,9 @@ static s32 amd756_access(struct i2c_adapter * adap, u16 addr,
         /* How about enabling interrupts... */
         outw_p(size & GE_CYC_TYPE_MASK, SMB_GLOBAL_ENABLE);
 
-        if (amd756_transaction(adap))   /* Error in transaction */
-                return -1;
+        status = amd756_transaction(adap);
+        if (status)
+                return status;
 
         if ((read_write == I2C_SMBUS_WRITE) || (size == AMD756_QUICK))
                 return 0;
diff --git a/drivers/i2c/busses/i2c-amd8111.c b/drivers/i2c/busses/i2c-amd8111.c
index 5d1a27ef2504..a4f687915de1 100644
--- a/drivers/i2c/busses/i2c-amd8111.c
+++ b/drivers/i2c/busses/i2c-amd8111.c
@@ -77,7 +77,7 @@ static unsigned int amd_ec_wait_write(struct amd_smbus *smbus)
         if (!timeout) {
                 dev_warn(&smbus->dev->dev,
                          "Timeout while waiting for IBF to clear\n");
-                return -1;
+                return -ETIMEDOUT;
         }
 
         return 0;
@@ -93,7 +93,7 @@ static unsigned int amd_ec_wait_read(struct amd_smbus *smbus)
         if (!timeout) {
                 dev_warn(&smbus->dev->dev,
                          "Timeout while waiting for OBF to set\n");
-                return -1;
+                return -ETIMEDOUT;
         }
 
         return 0;
@@ -102,16 +102,21 @@ static unsigned int amd_ec_wait_read(struct amd_smbus *smbus)
 static unsigned int amd_ec_read(struct amd_smbus *smbus, unsigned char address,
                 unsigned char *data)
 {
-        if (amd_ec_wait_write(smbus))
-                return -1;
+        int status;
+
+        status = amd_ec_wait_write(smbus);
+        if (status)
+                return status;
         outb(AMD_EC_CMD_RD, smbus->base + AMD_EC_CMD);
 
-        if (amd_ec_wait_write(smbus))
-                return -1;
+        status = amd_ec_wait_write(smbus);
+        if (status)
+                return status;
         outb(address, smbus->base + AMD_EC_DATA);
 
-        if (amd_ec_wait_read(smbus))
-                return -1;
+        status = amd_ec_wait_read(smbus);
+        if (status)
+                return status;
         *data = inb(smbus->base + AMD_EC_DATA);
 
         return 0;
@@ -120,16 +125,21 @@ static unsigned int amd_ec_read(struct amd_smbus *smbus, unsigned char address,
 static unsigned int amd_ec_write(struct amd_smbus *smbus, unsigned char address,
                 unsigned char data)
 {
-        if (amd_ec_wait_write(smbus))
-                return -1;
+        int status;
+
+        status = amd_ec_wait_write(smbus);
+        if (status)
+                return status;
         outb(AMD_EC_CMD_WR, smbus->base + AMD_EC_CMD);
 
-        if (amd_ec_wait_write(smbus))
-                return -1;
+        status = amd_ec_wait_write(smbus);
+        if (status)
+                return status;
         outb(address, smbus->base + AMD_EC_DATA);
 
-        if (amd_ec_wait_write(smbus))
-                return -1;
+        status = amd_ec_wait_write(smbus);
+        if (status)
+                return status;
         outb(data, smbus->base + AMD_EC_DATA);
 
         return 0;
@@ -267,12 +277,17 @@ static s32 amd8111_access(struct i2c_adapter * adap, u16 addr,
 
                 default:
                         dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
-                        return -1;
+                        return -EOPNOTSUPP;
         }
 
         amd_ec_write(smbus, AMD_SMB_ADDR, addr << 1);
         amd_ec_write(smbus, AMD_SMB_PRTCL, protocol);
 
+        /* FIXME this discards status from ec_read(); so temp[0] will
+         * hold stack garbage ... the rest of this routine will act
+         * nonsensically.  Ignored ec_write() status might explain
+         * some such failures...
+         */
         amd_ec_read(smbus, AMD_SMB_STS, temp + 0);
 
         if (~temp[0] & AMD_SMB_STS_DONE) {
@@ -286,7 +301,7 @@ static s32 amd8111_access(struct i2c_adapter * adap, u16 addr,
         }
 
         if ((~temp[0] & AMD_SMB_STS_DONE) || (temp[0] & AMD_SMB_STS_STATUS))
-                return -1;
+                return -EIO;
 
         if (read_write == I2C_SMBUS_WRITE)
                 return 0;
diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index b0f771fe4326..7d6d9dfcc58a 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -151,7 +151,7 @@ static int i801_transaction(int xact)
                 outb_p(temp, SMBHSTSTS);
                 if ((temp = (0x1f & inb_p(SMBHSTSTS))) != 0x00) {
                         dev_dbg(&I801_dev->dev, "Failed! (%02x)\n", temp);
-                        return -1;
+                        return -EBUSY;
                 } else {
                         dev_dbg(&I801_dev->dev, "Successful!\n");
                 }
@@ -170,7 +170,7 @@ static int i801_transaction(int xact)
         /* If the SMBus is still busy, we give up */
         if (timeout >= MAX_TIMEOUT) {
                 dev_dbg(&I801_dev->dev, "SMBus Timeout!\n");
-                result = -1;
+                result = -ETIMEDOUT;
                 /* try to stop the current command */
                 dev_dbg(&I801_dev->dev, "Terminating the current operation\n");
                 outb_p(inb_p(SMBHSTCNT) | SMBHSTCNT_KILL, SMBHSTCNT);
@@ -179,19 +179,19 @@ static int i801_transaction(int xact)
         }
 
         if (temp & SMBHSTSTS_FAILED) {
-                result = -1;
+                result = -EIO;
                 dev_dbg(&I801_dev->dev, "Error: Failed bus transaction\n");
         }
 
         if (temp & SMBHSTSTS_BUS_ERR) {
-                result = -1;
+                result = -EIO;
                 dev_err(&I801_dev->dev, "Bus collision! SMBus may be locked "
                         "until next hard reset. (sorry!)\n");
                 /* Clock stops and slave is stuck in mid-transmission */
         }
 
         if (temp & SMBHSTSTS_DEV_ERR) {
-                result = -1;
+                result = -ENXIO;
                 dev_dbg(&I801_dev->dev, "Error: no response!\n");
         }
 
@@ -231,6 +231,7 @@ static int i801_block_transaction_by_block(union i2c_smbus_data *data,
                                            char read_write, int hwpec)
 {
         int i, len;
+        int status;
 
         inb_p(SMBHSTCNT); /* reset the data buffer index */
 
@@ -242,14 +243,15 @@ static int i801_block_transaction_by_block(union i2c_smbus_data *data,
                         outb_p(data->block[i+1], SMBBLKDAT);
         }
 
-        if (i801_transaction(I801_BLOCK_DATA | ENABLE_INT9 |
-                             I801_PEC_EN * hwpec))
-                return -1;
+        status = i801_transaction(I801_BLOCK_DATA | ENABLE_INT9 |
+                                  I801_PEC_EN * hwpec);
+        if (status)
+                return status;
 
         if (read_write == I2C_SMBUS_READ) {
                 len = inb_p(SMBHSTDAT0);
                 if (len < 1 || len > I2C_SMBUS_BLOCK_MAX)
-                        return -1;
+                        return -EPROTO;
 
                 data->block[0] = len;
                 for (i = 0; i < len; i++)
@@ -314,11 +316,11 @@ static int i801_block_transaction_byte_by_byte(union i2c_smbus_data *data,
                         if (((temp = inb_p(SMBHSTSTS)) & errmask) != 0x00) {
                                 dev_err(&I801_dev->dev,
                                         "Reset failed! (%02x)\n", temp);
-                                return -1;
+                                return -EBUSY;
                         }
                         if (i != 1)
                                 /* if die in middle of block transaction, fail */
-                                return -1;
+                                return -EIO;
                 }
 
                 if (i == 1)
@@ -342,19 +344,19 @@ static int i801_block_transaction_byte_by_byte(union i2c_smbus_data *data,
                         msleep(1);
                         outb_p(inb_p(SMBHSTCNT) & (~SMBHSTCNT_KILL),
                                 SMBHSTCNT);
-                        result = -1;
+                        result = -ETIMEDOUT;
                         dev_dbg(&I801_dev->dev, "SMBus Timeout!\n");
                 }
 
                 if (temp & SMBHSTSTS_FAILED) {
-                        result = -1;
+                        result = -EIO;
                         dev_dbg(&I801_dev->dev,
                                 "Error: Failed bus transaction\n");
                 } else if (temp & SMBHSTSTS_BUS_ERR) {
-                        result = -1;
+                        result = -EIO;
                         dev_err(&I801_dev->dev, "Bus collision!\n");
                 } else if (temp & SMBHSTSTS_DEV_ERR) {
-                        result = -1;
+                        result = -ENXIO;
                         dev_dbg(&I801_dev->dev, "Error: no response!\n");
                 }
 
@@ -362,7 +364,7 @@ static int i801_block_transaction_byte_by_byte(union i2c_smbus_data *data,
                  && command != I2C_SMBUS_I2C_BLOCK_DATA) {
                         len = inb_p(SMBHSTDAT0);
                         if (len < 1 || len > I2C_SMBUS_BLOCK_MAX)
-                                return -1;
+                                return -EPROTO;
                         data->block[0] = len;
                 }
 
@@ -394,7 +396,7 @@ static int i801_set_block_buffer_mode(void)
 {
         outb_p(inb_p(SMBAUXCTL) | SMBAUXCTL_E32B, SMBAUXCTL);
         if ((inb_p(SMBAUXCTL) & SMBAUXCTL_E32B) == 0)
-                return -1;
+                return -EIO;
         return 0;
 }
 
@@ -414,7 +416,7 @@ static int i801_block_transaction(union i2c_smbus_data *data, char read_write,
                 } else if (!(i801_features & FEATURE_I2C_BLOCK_READ)) {
                         dev_err(&I801_dev->dev,
                                 "I2C block read is unsupported!\n");
-                        return -1;
+                        return -EOPNOTSUPP;
                 }
         }
 
@@ -449,7 +451,7 @@ static int i801_block_transaction(union i2c_smbus_data *data, char read_write,
         return result;
 }
 
-/* Return -1 on error. */
+/* Return negative errno on error. */
 static s32 i801_access(struct i2c_adapter * adap, u16 addr,
                        unsigned short flags, char read_write, u8 command,
                        int size, union i2c_smbus_data * data)
@@ -514,7 +516,7 @@ static s32 i801_access(struct i2c_adapter * adap, u16 addr,
         case I2C_SMBUS_PROC_CALL:
         default:
                 dev_err(&I801_dev->dev, "Unsupported transaction %d\n", size);
-                return -1;
+                return -EOPNOTSUPP;
         }
 
         if (hwpec)      /* enable/disable hardware PEC */
@@ -537,7 +539,7 @@ static s32 i801_access(struct i2c_adapter * adap, u16 addr,
         if(block)
                 return ret;
         if(ret)
-                return -1;
+                return ret;
         if ((read_write == I2C_SMBUS_WRITE) || (xact == I801_QUICK))
                 return 0;
 
diff --git a/drivers/i2c/busses/i2c-nforce2.c b/drivers/i2c/busses/i2c-nforce2.c
index f95efff9b3d1..081fdf3393f4 100644
--- a/drivers/i2c/busses/i2c-nforce2.c
+++ b/drivers/i2c/busses/i2c-nforce2.c
@@ -172,16 +172,16 @@ static int nforce2_check_status(struct i2c_adapter *adap)
                 dev_dbg(&adap->dev, "SMBus Timeout!\n");
                 if (smbus->can_abort)
                         nforce2_abort(adap);
-                return -1;
+                return -ETIMEDOUT;
         }
         if (!(temp & NVIDIA_SMB_STS_DONE) || (temp & NVIDIA_SMB_STS_STATUS)) {
                 dev_dbg(&adap->dev, "Transaction failed (0x%02x)!\n", temp);
-                return -1;
+                return -EIO;
         }
         return 0;
 }
 
-/* Return -1 on error */
+/* Return negative errno on error */
 static s32 nforce2_access(struct i2c_adapter * adap, u16 addr,
                 unsigned short flags, char read_write,
                 u8 command, int size, union i2c_smbus_data * data)
@@ -189,7 +189,7 @@ static s32 nforce2_access(struct i2c_adapter * adap, u16 addr,
         struct nforce2_smbus *smbus = adap->algo_data;
         unsigned char protocol, pec;
         u8 len;
-        int i;
+        int i, status;
 
         protocol = (read_write == I2C_SMBUS_READ) ? NVIDIA_SMB_PRTCL_READ :
                 NVIDIA_SMB_PRTCL_WRITE;
@@ -233,7 +233,7 @@ static s32 nforce2_access(struct i2c_adapter * adap, u16 addr,
                                                 "Transaction failed "
                                                 "(requested block size: %d)\n",
                                                 len);
-                                        return -1;
+                                        return -EINVAL;
                                 }
                                 outb_p(len, NVIDIA_SMB_BCNT);
                                 for (i = 0; i < I2C_SMBUS_BLOCK_MAX; i++)
@@ -245,14 +245,15 @@ static s32 nforce2_access(struct i2c_adapter * adap, u16 addr,
 
                 default:
                         dev_err(&adap->dev, "Unsupported transaction %d\n", size);
-                        return -1;
+                        return -EOPNOTSUPP;
         }
 
         outb_p((addr & 0x7f) << 1, NVIDIA_SMB_ADDR);
         outb_p(protocol, NVIDIA_SMB_PRTCL);
 
-        if (nforce2_check_status(adap))
-                return -1;
+        status = nforce2_check_status(adap);
+        if (status)
+                return status;
 
         if (read_write == I2C_SMBUS_WRITE)
                 return 0;
@@ -274,7 +275,7 @@ static s32 nforce2_access(struct i2c_adapter * adap, u16 addr,
                                 dev_err(&adap->dev, "Transaction failed "
                                         "(received block size: 0x%02x)\n",
                                         len);
-                                return -1;
+                                return -EPROTO;
                         }
                         for (i = 0; i < len; i++)
                                 data->block[i+1] = inb_p(NVIDIA_SMB_DATA + i);
@@ -335,7 +336,7 @@ static int __devinit nforce2_probe_smb (struct pci_dev *dev, int bar,
                     != PCIBIOS_SUCCESSFUL) {
                         dev_err(&dev->dev, "Error reading PCI config for %s\n",
                                 name);
-                        return -1;
+                        return -EIO;
                 }
 
                 smbus->base = iobase & PCI_BASE_ADDRESS_IO_MASK;
@@ -345,7 +346,7 @@ static int __devinit nforce2_probe_smb (struct pci_dev *dev, int bar,
         if (!request_region(smbus->base, smbus->size, nforce2_driver.name)) {
                 dev_err(&smbus->adapter.dev, "Error requesting region %02x .. %02X for %s\n",
                         smbus->base, smbus->base+smbus->size-1, name);
-                return -1;
+                return -EBUSY;
         }
         smbus->adapter.owner = THIS_MODULE;
         smbus->adapter.id = I2C_HW_SMBUS_NFORCE2;
@@ -360,7 +361,7 @@ static int __devinit nforce2_probe_smb (struct pci_dev *dev, int bar,
         if (error) {
                 dev_err(&smbus->adapter.dev, "Failed to register adapter.\n");
                 release_region(smbus->base, smbus->size);
-                return -1;
+                return error;
         }
         dev_info(&smbus->adapter.dev, "nForce2 SMBus adapter at %#x\n", smbus->base);
         return 0;
diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index ac9165968587..dc76c0e2dc65 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -253,7 +253,7 @@ static int piix4_transaction(void)
                 outb_p(temp, SMBHSTSTS);
                 if ((temp = inb_p(SMBHSTSTS)) != 0x00) {
                         dev_err(&piix4_adapter.dev, "Failed! (%02x)\n", temp);
-                        return -1;
+                        return -EBUSY;
                 } else {
                         dev_dbg(&piix4_adapter.dev, "Successful!\n");
                 }
@@ -275,23 +275,23 @@ static int piix4_transaction(void)
         /* If the SMBus is still busy, we give up */
         if (timeout >= MAX_TIMEOUT) {
                 dev_err(&piix4_adapter.dev, "SMBus Timeout!\n");
-                result = -1;
+                result = -ETIMEDOUT;
         }
 
         if (temp & 0x10) {
-                result = -1;
+                result = -EIO;
                 dev_err(&piix4_adapter.dev, "Error: Failed bus transaction\n");
         }
 
         if (temp & 0x08) {
-                result = -1;
+                result = -EIO;
                 dev_dbg(&piix4_adapter.dev, "Bus collision! SMBus may be "
                         "locked until next hard reset. (sorry!)\n");
                 /* Clock stops and slave is stuck in mid-transmission */
         }
 
         if (temp & 0x04) {
-                result = -1;
+                result = -ENXIO;
                 dev_dbg(&piix4_adapter.dev, "Error: no response!\n");
         }
 
@@ -309,17 +309,18 @@ static int piix4_transaction(void)
         return result;
 }
 
-/* Return -1 on error. */
+/* Return negative errno on error. */
 static s32 piix4_access(struct i2c_adapter * adap, u16 addr,
                  unsigned short flags, char read_write,
                  u8 command, int size, union i2c_smbus_data * data)
 {
         int i, len;
+        int status;
 
         switch (size) {
         case I2C_SMBUS_PROC_CALL:
                 dev_err(&adap->dev, "I2C_SMBUS_PROC_CALL not supported!\n");
-                return -1;
+                return -EOPNOTSUPP;
         case I2C_SMBUS_QUICK:
                 outb_p(((addr & 0x7f) << 1) | (read_write & 0x01),
                        SMBHSTADD);
@@ -371,8 +372,9 @@ static s32 piix4_access(struct i2c_adapter * adap, u16 addr,
 
         outb_p((size & 0x1C) + (ENABLE_INT9 & 1), SMBHSTCNT);
 
-        if (piix4_transaction())        /* Error in transaction */
-                return -1;
+        status = piix4_transaction();
+        if (status)
+                return status;
 
         if ((read_write == I2C_SMBUS_WRITE) || (size == PIIX4_QUICK))
                 return 0;
diff --git a/drivers/i2c/busses/i2c-sis5595.c b/drivers/i2c/busses/i2c-sis5595.c
index 9ca8f9155f95..328441bb5470 100644
--- a/drivers/i2c/busses/i2c-sis5595.c
+++ b/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)))
diff --git a/drivers/i2c/busses/i2c-sis630.c b/drivers/i2c/busses/i2c-sis630.c
index 3765dd7f450f..c4cc5eddf50d 100644
--- a/drivers/i2c/busses/i2c-sis630.c
+++ b/drivers/i2c/busses/i2c-sis630.c
@@ -134,7 +134,7 @@ static int sis630_transaction_start(struct i2c_adapter *adap, int size, u8 *oldc
 
                 if ((temp = sis630_read(SMB_CNT) & 0x03) != 0x00) {
                         dev_dbg(&adap->dev, "Failed! (%02x)\n", temp);
-                        return -1;
+                        return -EBUSY;
                 } else {
                         dev_dbg(&adap->dev, "Successful!\n");
                 }
@@ -177,17 +177,17 @@ static int sis630_transaction_wait(struct i2c_adapter *adap, int size)
         /* 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 & 0x02) {
                 dev_dbg(&adap->dev, "Error: Failed bus transaction\n");
-                result = -1;
+                result = -ENXIO;
         }
 
         if (temp & 0x04) {
                 dev_err(&adap->dev, "Bus collision!\n");
-                result = -1;
+                result = -EIO;
                 /*
                   TBD: Datasheet say:
                   the software should clear this bit and restart SMBUS operation.
@@ -250,8 +250,10 @@ static int sis630_block_data(struct i2c_adapter *adap, union i2c_smbus_data *dat
                         if (i==8 || (len<8 && i==len)) {
                                 dev_dbg(&adap->dev, "start trans len=%d i=%d\n",len ,i);
                                 /* first transaction */
-                                if (sis630_transaction_start(adap, SIS630_BLOCK_DATA, &oldclock))
-                                        return -1;
+                                rc = sis630_transaction_start(adap,
+                                                SIS630_BLOCK_DATA, &oldclock);
+                                if (rc)
+                                        return rc;
                         }
                         else if ((i-1)%8 == 7 || i==len) {
                                 dev_dbg(&adap->dev, "trans_wait len=%d i=%d\n",len,i);
@@ -264,9 +266,10 @@ static int sis630_block_data(struct i2c_adapter *adap, union i2c_smbus_data *dat
                                         */
                                         sis630_write(SMB_STS,0x10);
                                 }
-                                if (sis630_transaction_wait(adap, SIS630_BLOCK_DATA)) {
+                                rc = sis630_transaction_wait(adap,
+                                                SIS630_BLOCK_DATA);
+                                if (rc) {
                                         dev_dbg(&adap->dev, "trans_wait failed\n");
-                                        rc = -1;
                                         break;
                                 }
                         }
@@ -275,13 +278,14 @@ static int sis630_block_data(struct i2c_adapter *adap, union i2c_smbus_data *dat
         else {
                 /* read request */
                 data->block[0] = len = 0;
-                if (sis630_transaction_start(adap, SIS630_BLOCK_DATA, &oldclock)) {
-                        return -1;
-                }
+                rc = sis630_transaction_start(adap,
+                                SIS630_BLOCK_DATA, &oldclock);
+                if (rc)
+                        return rc;
                 do {
-                        if (sis630_transaction_wait(adap, SIS630_BLOCK_DATA)) {
+                        rc = sis630_transaction_wait(adap, SIS630_BLOCK_DATA);
+                        if (rc) {
                                 dev_dbg(&adap->dev, "trans_wait failed\n");
-                                rc = -1;
                                 break;
                         }
                         /* if this first transaction then read byte count */
@@ -311,11 +315,13 @@ static int sis630_block_data(struct i2c_adapter *adap, union i2c_smbus_data *dat
         return rc;
 }
 
-/* Return -1 on error. */
+/* Return negative errno on error. */
 static s32 sis630_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:
                         sis630_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
@@ -350,13 +356,13 @@ static s32 sis630_access(struct i2c_adapter *adap, u16 addr,
                         size = SIS630_BLOCK_DATA;
                         return sis630_block_data(adap, data, read_write);
                 default:
-                        printk("Unsupported I2C size\n");
-                        return -1;
-                        break;
+                        printk("Unsupported SMBus operation\n");
+                        return -EOPNOTSUPP;
         }
 
-        if (sis630_transaction(adap, size))
-                return -1;
+        status = sis630_transaction(adap, size);
+        if (status)
+                return status;
 
         if ((size != SIS630_PCALL) &&
                 ((read_write == I2C_SMBUS_WRITE) || (size == SIS630_QUICK))) {
@@ -373,8 +379,7 @@ static s32 sis630_access(struct i2c_adapter *adap, u16 addr,
                         data->word = sis630_read(SMB_BYTE) + (sis630_read(SMB_BYTE + 1) << 8);
                         break;
                 default:
-                        return -1;
-                        break;
+                        return -EOPNOTSUPP;
         }
 
         return 0;
diff --git a/drivers/i2c/busses/i2c-sis96x.c b/drivers/i2c/busses/i2c-sis96x.c
index dc235bb8e24d..29757b2e11dd 100644
--- a/drivers/i2c/busses/i2c-sis96x.c
+++ b/drivers/i2c/busses/i2c-sis96x.c
@@ -111,7 +111,7 @@ static int sis96x_transaction(int size)
                 /* check it again */
                 if (((temp = sis96x_read(SMB_CNT)) & 0x03) != 0x00) {
                         dev_dbg(&sis96x_adapter.dev, "Failed (0x%02x)\n", temp);
-                        return -1;
+                        return -EBUSY;
                 } else {
                         dev_dbg(&sis96x_adapter.dev, "Successful\n");
                 }
@@ -136,19 +136,19 @@ static int sis96x_transaction(int size)
         /* If the SMBus is still busy, we give up */
         if (timeout >= MAX_TIMEOUT) {
                 dev_dbg(&sis96x_adapter.dev, "SMBus Timeout! (0x%02x)\n", temp);
-                result = -1;
+                result = -ETIMEDOUT;
         }
 
         /* device error - probably missing ACK */
         if (temp & 0x02) {
                 dev_dbg(&sis96x_adapter.dev, "Failed bus transaction!\n");
-                result = -1;
+                result = -ENXIO;
         }
 
         /* bus collision */
         if (temp & 0x04) {
                 dev_dbg(&sis96x_adapter.dev, "Bus collision!\n");
-                result = -1;
+                result = -EIO;
         }
 
         /* Finish up by resetting the bus */
@@ -161,11 +161,12 @@ static int sis96x_transaction(int size)
         return result;
 }
 
-/* Return -1 on error. */
+/* Return negative errno on error. */
 static s32 sis96x_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:
@@ -203,17 +204,17 @@ static s32 sis96x_access(struct i2c_adapter * adap, u16 addr,
         case I2C_SMBUS_BLOCK_DATA:
                 /* TO DO: */
                 dev_info(&adap->dev, "SMBus block not implemented!\n");
-                return -1;
+                return -EOPNOTSUPP;
                 break;
 
         default:
-                dev_info(&adap->dev, "Unsupported I2C size\n");
-                return -1;
-                break;
+                dev_info(&adap->dev, "Unsupported SMBus operation\n");
+                return -EOPNOTSUPP;
         }
 
-        if (sis96x_transaction(size))
-                return -1;
+        status = sis96x_transaction(size);
+        if (status)
+                return status;
 
         if ((size != SIS96x_PROC_CALL) &&
                 ((read_write == I2C_SMBUS_WRITE) || (size == SIS96x_QUICK)))
diff --git a/drivers/i2c/busses/i2c-stub.c b/drivers/i2c/busses/i2c-stub.c
index d08eeec53913..e37ccd80f77a 100644
--- a/drivers/i2c/busses/i2c-stub.c
+++ b/drivers/i2c/busses/i2c-stub.c
@@ -43,7 +43,7 @@ struct stub_chip {
 
 static struct stub_chip *stub_chips;
 
-/* Return -1 on error. */
+/* Return negative errno on error. */
 static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
         char read_write, u8 command, int size, union i2c_smbus_data * data)
 {
@@ -120,7 +120,7 @@ static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
 
         default:
                 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
-                ret = -1;
+                ret = -EOPNOTSUPP;
                 break;
         } /* switch (size) */
 
diff --git a/drivers/i2c/busses/i2c-viapro.c b/drivers/i2c/busses/i2c-viapro.c
index 77b13d027f86..7628fe8e0946 100644
--- a/drivers/i2c/busses/i2c-viapro.c
+++ b/drivers/i2c/busses/i2c-viapro.c
@@ -152,7 +152,7 @@ static int vt596_transaction(u8 size)
                 if ((temp = inb_p(SMBHSTSTS)) & 0x1F) {
                         dev_err(&vt596_adapter.dev, "SMBus reset failed! "
                                 "(0x%02x)\n", temp);
-                        return -1;
+                        return -EBUSY;
                 }
         }
 
@@ -167,24 +167,24 @@ static int vt596_transaction(u8 size)
 
         /* If the SMBus is still busy, we give up */
         if (timeout >= MAX_TIMEOUT) {
-                result = -1;
+                result = -ETIMEDOUT;
                 dev_err(&vt596_adapter.dev, "SMBus timeout!\n");
         }
 
         if (temp & 0x10) {
-                result = -1;
+                result = -EIO;
                 dev_err(&vt596_adapter.dev, "Transaction failed (0x%02x)\n",
                         size);
         }
 
         if (temp & 0x08) {
-                result = -1;
+                result = -EIO;
                 dev_err(&vt596_adapter.dev, "SMBus collision!\n");
         }
 
         if (temp & 0x04) {
                 int read = inb_p(SMBHSTADD) & 0x01;
-                result = -1;
+                result = -ENXIO;
                 /* The quick and receive byte commands are used to probe
                    for chips, so errors are expected, and we don't want
                    to frighten the user. */
@@ -202,12 +202,13 @@ static int vt596_transaction(u8 size)
         return result;
 }
 
-/* Return -1 on error, 0 on success */
+/* Return negative errno on error, 0 on success */
 static s32 vt596_access(struct i2c_adapter *adap, u16 addr,
                 unsigned short flags, char read_write, u8 command,
                 int size, union i2c_smbus_data *data)
 {
         int i;
+        int status;
 
         switch (size) {
         case I2C_SMBUS_QUICK:
@@ -258,8 +259,9 @@ static s32 vt596_access(struct i2c_adapter *adap, u16 addr,
 
         outb_p(((addr & 0x7f) << 1) | read_write, SMBHSTADD);
 
-        if (vt596_transaction(size)) /* Error in transaction */
-                return -1;
+        status = vt596_transaction(size);
+        if (status)
+                return status;
 
         if ((read_write == I2C_SMBUS_WRITE) || (size == VT596_QUICK))
                 return 0;
@@ -287,7 +289,7 @@ static s32 vt596_access(struct i2c_adapter *adap, u16 addr,
 exit_unsupported:
         dev_warn(&vt596_adapter.dev, "Unsupported command invoked! (0x%02x)\n",
                  size);
-        return -1;
+        return -EOPNOTSUPP;
 }
 
 static u32 vt596_func(struct i2c_adapter *adapter)