hwmon: (ds1621) Clean up register access

Fix a few oddities in how the ds1621 driver accesses the registers:
* We don't need a wrapper to access the configuration register.
* Check for error before calling swab16. Error checking isn't
  complete yet, but that's a start.
* Device-specific read functions should never be called during
  detection, as by definition we don't know what device we are talking
  to at that point.
* Likewise, don't assume that register reads succeed during detection.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Aurelien Jarno <aurelien@aurel32.net>

1 files changed, 24 insertions, 24 deletions

diff --git a/drivers/hwmon/ds1621.c b/drivers/hwmon/ds1621.c
index e688798e115f..fe160c54b959 100644
--- a/drivers/hwmon/ds1621.c
+++ b/drivers/hwmon/ds1621.c
@@ -81,28 +81,27 @@ struct ds1621_data {
         u8 conf;                        /* Register encoding, combined */
 };
 
-/* All registers are word-sized, except for the configuration register.
+/* Temperature registers are word-sized.
    DS1621 uses a high-byte first convention, which is exactly opposite to
    the SMBus standard. */
-static int ds1621_read_value(struct i2c_client *client, u8 reg)
+static int ds1621_read_temp(struct i2c_client *client, u8 reg)
 {
-        if (reg == DS1621_REG_CONF)
-                return i2c_smbus_read_byte_data(client, reg);
-        else
-                return swab16(i2c_smbus_read_word_data(client, reg));
+        int ret;
+
+        ret = i2c_smbus_read_word_data(client, reg);
+        if (ret < 0)
+                return ret;
+        return swab16(ret);
 }
 
-static int ds1621_write_value(struct i2c_client *client, u8 reg, u16 value)
+static int ds1621_write_temp(struct i2c_client *client, u8 reg, u16 value)
 {
-        if (reg == DS1621_REG_CONF)
-                return i2c_smbus_write_byte_data(client, reg, value);
-        else
-                return i2c_smbus_write_word_data(client, reg, swab16(value));
+        return i2c_smbus_write_word_data(client, reg, swab16(value));
 }
 
 static void ds1621_init_client(struct i2c_client *client)
 {
-        int reg = ds1621_read_value(client, DS1621_REG_CONF);
+        int reg = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);
         /* switch to continuous conversion mode */
         reg &= ~ DS1621_REG_CONFIG_1SHOT;
 
@@ -112,7 +111,7 @@ static void ds1621_init_client(struct i2c_client *client)
         else if (polarity == 1)
                 reg |= DS1621_REG_CONFIG_POLARITY;
         
-        ds1621_write_value(client, DS1621_REG_CONF, reg);
+        i2c_smbus_write_byte_data(client, DS1621_REG_CONF, reg);
         
         /* start conversion */
         i2c_smbus_write_byte(client, DS1621_COM_START);
@@ -132,11 +131,11 @@ static struct ds1621_data *ds1621_update_client(struct device *dev)
 
                 dev_dbg(&client->dev, "Starting ds1621 update\n");
 
-                data->conf = ds1621_read_value(client, DS1621_REG_CONF);
+                data->conf = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);
 
                 for (i = 0; i < ARRAY_SIZE(data->temp); i++)
-                        data->temp[i] = ds1621_read_value(client,
-                                                          DS1621_REG_TEMP[i]);
+                        data->temp[i] = ds1621_read_temp(client,
+                                                         DS1621_REG_TEMP[i]);
 
                 /* reset alarms if necessary */
                 new_conf = data->conf;
@@ -145,8 +144,8 @@ static struct ds1621_data *ds1621_update_client(struct device *dev)
                 if (data->temp[0] < data->temp[2])      /* input < max */
                         new_conf &= ~DS1621_ALARM_TEMP_HIGH;
                 if (data->conf != new_conf)
-                        ds1621_write_value(client, DS1621_REG_CONF,
-                                           new_conf);
+                        i2c_smbus_write_byte_data(client, DS1621_REG_CONF,
+                                                  new_conf);
 
                 data->last_updated = jiffies;
                 data->valid = 1;
@@ -176,8 +175,8 @@ static ssize_t set_temp(struct device *dev, struct device_attribute *da,
 
         mutex_lock(&data->update_lock);
         data->temp[attr->index] = val;
-        ds1621_write_value(client, DS1621_REG_TEMP[attr->index],
-                           data->temp[attr->index]);
+        ds1621_write_temp(client, DS1621_REG_TEMP[attr->index],
+                          data->temp[attr->index]);
         mutex_unlock(&data->update_lock);
         return count;
 }
@@ -239,13 +238,14 @@ static int ds1621_detect(struct i2c_client *client, int kind,
                 /* The NVB bit should be low if no EEPROM write has been 
                    requested during the latest 10ms, which is highly 
                    improbable in our case. */
-                conf = ds1621_read_value(client, DS1621_REG_CONF);
-                if (conf & DS1621_REG_CONFIG_NVB)
+                conf = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);
+                if (conf < 0 || conf & DS1621_REG_CONFIG_NVB)
                         return -ENODEV;
                 /* The 7 lowest bits of a temperature should always be 0. */
                 for (i = 0; i < ARRAY_SIZE(DS1621_REG_TEMP); i++) {
-                        temp = ds1621_read_value(client, DS1621_REG_TEMP[i]);
-                        if (temp & 0x007f)
+                        temp = i2c_smbus_read_word_data(client,
+                                                        DS1621_REG_TEMP[i]);
+                        if (temp < 0 || (temp & 0x7f00))
                                 return -ENODEV;
                 }
         }