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>

diff --git a/drivers/hwmon/ds1621.c b/drivers/hwmon/ds1621.c
index e688798e115fddfa79ba223b8ae562662df0ef96..fe160c54b959a03a2df4d997a961e1fc9e29dc69 100644 (file)
--- 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;
                }
        }