]> pilppa.org Git - linux-2.6-omap-h63xx.git/blobdiff - drivers/hwmon/lm90.c
hwmon: (lm90) Support the extra resolution bits of MAX6657
[linux-2.6-omap-h63xx.git] / drivers / hwmon / lm90.c
index 6882ce75feee99b5c2ab9f4f94b5f3a78820728a..16b99e0bdff0a970a7c05fd5f7dfd62040b2cedd 100644 (file)
@@ -1,7 +1,7 @@
 /*
  * lm90.c - Part of lm_sensors, Linux kernel modules for hardware
  *          monitoring
- * Copyright (C) 2003-2006  Jean Delvare <khali@linux-fr.org>
+ * Copyright (C) 2003-2008  Jean Delvare <khali@linux-fr.org>
  *
  * Based on the lm83 driver. The LM90 is a sensor chip made by National
  * Semiconductor. It reports up to two temperatures (its own plus up to
  *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
  * Note that there is no easy way to differentiate between the three
  * variants. The extra address and features of the MAX6659 are not
- * supported by this driver.
+ * supported by this driver. These chips lack the remote temperature
+ * offset feature.
+ *
+ * This driver also supports the MAX6680 and MAX6681, two other sensor
+ * chips made by Maxim. These are quite similar to the other Maxim
+ * chips. Complete datasheet can be obtained at:
+ *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3370
+ * The MAX6680 and MAX6681 only differ in the pinout so they can be
+ * treated identically.
  *
  * This driver also supports the ADT7461 chip from Analog Devices but
  * only in its "compatability mode". If an ADT7461 chip is found but
 /*
  * Addresses to scan
  * Address is fully defined internally and cannot be changed except for
- * MAX6659.
+ * MAX6659, MAX6680 and MAX6681.
  * LM86, LM89, LM90, LM99, ADM1032, ADM1032-1, ADT7461, MAX6657 and MAX6658
  * have address 0x4c.
  * ADM1032-2, ADT7461-2, LM89-1, and LM99-1 have address 0x4d.
  * MAX6659 can have address 0x4c, 0x4d or 0x4e (unsupported).
+ * MAX6680 and MAX6681 can have address 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
+ * 0x4c, 0x4d or 0x4e.
  */
 
-static unsigned short normal_i2c[] = { 0x4c, 0x4d, I2C_CLIENT_END };
+static const unsigned short normal_i2c[] = {
+       0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b, 0x4c, 0x4d, 0x4e, I2C_CLIENT_END };
 
 /*
  * Insmod parameters
  */
 
-I2C_CLIENT_INSMOD_6(lm90, adm1032, lm99, lm86, max6657, adt7461);
+I2C_CLIENT_INSMOD_7(lm90, adm1032, lm99, lm86, max6657, adt7461, max6680);
 
 /*
  * The LM90 registers
@@ -138,6 +149,10 @@ I2C_CLIENT_INSMOD_6(lm90, adm1032, lm99, lm86, max6657, adt7461);
 #define LM90_REG_R_TCRIT_HYST          0x21
 #define LM90_REG_W_TCRIT_HYST          0x21
 
+/* MAX6657-specific registers */
+
+#define MAX6657_REG_R_LOCAL_TEMPL      0x11
+
 /*
  * Conversions and various macros
  * For local temperatures and limits, critical limits and the hysteresis
@@ -176,24 +191,44 @@ I2C_CLIENT_INSMOD_6(lm90, adm1032, lm99, lm86, max6657, adt7461);
  * Functions declaration
  */
 
-static int lm90_attach_adapter(struct i2c_adapter *adapter);
-static int lm90_detect(struct i2c_adapter *adapter, int address,
-       int kind);
+static int lm90_detect(struct i2c_client *client, int kind,
+                      struct i2c_board_info *info);
+static int lm90_probe(struct i2c_client *client,
+                     const struct i2c_device_id *id);
 static void lm90_init_client(struct i2c_client *client);
-static int lm90_detach_client(struct i2c_client *client);
+static int lm90_remove(struct i2c_client *client);
 static struct lm90_data *lm90_update_device(struct device *dev);
 
 /*
  * Driver data (common to all clients)
  */
 
+static const struct i2c_device_id lm90_id[] = {
+       { "adm1032", adm1032 },
+       { "adt7461", adt7461 },
+       { "lm90", lm90 },
+       { "lm86", lm86 },
+       { "lm89", lm99 },
+       { "lm99", lm99 },       /* Missing temperature offset */
+       { "max6657", max6657 },
+       { "max6658", max6657 },
+       { "max6659", max6657 },
+       { "max6680", max6680 },
+       { "max6681", max6680 },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, lm90_id);
+
 static struct i2c_driver lm90_driver = {
+       .class          = I2C_CLASS_HWMON,
        .driver = {
                .name   = "lm90",
        },
-       .id             = I2C_DRIVERID_LM90,
-       .attach_adapter = lm90_attach_adapter,
-       .detach_client  = lm90_detach_client,
+       .probe          = lm90_probe,
+       .remove         = lm90_remove,
+       .id_table       = lm90_id,
+       .detect         = lm90_detect,
+       .address_data   = &addr_data,
 };
 
 /*
@@ -201,22 +236,22 @@ static struct i2c_driver lm90_driver = {
  */
 
 struct lm90_data {
-       struct i2c_client client;
-       struct class_device *class_dev;
+       struct device *hwmon_dev;
        struct mutex update_lock;
        char valid; /* zero until following fields are valid */
        unsigned long last_updated; /* in jiffies */
        int kind;
 
        /* registers values */
-       s8 temp8[5];    /* 0: local input
-                          1: local low limit
-                          2: local high limit
-                          3: local critical limit
-                          4: remote critical limit */
-       s16 temp11[3];  /* 0: remote input
+       s8 temp8[4];    /* 0: local low limit
+                          1: local high limit
+                          2: local critical limit
+                          3: remote critical limit */
+       s16 temp11[5];  /* 0: remote input
                           1: remote low limit
-                          2: remote high limit */
+                          2: remote high limit
+                          3: remote offset (except max6657)
+                          4: local input */
        u8 temp_hyst;
        u8 alarms; /* bitvector */
 };
@@ -254,7 +289,7 @@ static ssize_t set_temp8(struct device *dev, struct device_attribute *devattr,
                data->temp8[nr] = TEMP1_TO_REG_ADT7461(val);
        else
                data->temp8[nr] = TEMP1_TO_REG(val);
-       i2c_smbus_write_byte_data(client, reg[nr - 1], data->temp8[nr]);
+       i2c_smbus_write_byte_data(client, reg[nr], data->temp8[nr]);
        mutex_unlock(&data->update_lock);
        return count;
 }
@@ -270,11 +305,13 @@ static ssize_t show_temp11(struct device *dev, struct device_attribute *devattr,
 static ssize_t set_temp11(struct device *dev, struct device_attribute *devattr,
                          const char *buf, size_t count)
 {
-       static const u8 reg[4] = {
+       static const u8 reg[6] = {
                LM90_REG_W_REMOTE_LOWH,
                LM90_REG_W_REMOTE_LOWL,
                LM90_REG_W_REMOTE_HIGHH,
                LM90_REG_W_REMOTE_HIGHL,
+               LM90_REG_W_REMOTE_OFFSH,
+               LM90_REG_W_REMOTE_OFFSL,
        };
 
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
@@ -314,7 +351,7 @@ static ssize_t set_temphyst(struct device *dev, struct device_attribute *dummy,
        long hyst;
 
        mutex_lock(&data->update_lock);
-       hyst = TEMP1_FROM_REG(data->temp8[3]) - val;
+       hyst = TEMP1_FROM_REG(data->temp8[2]) - val;
        i2c_smbus_write_byte_data(client, LM90_REG_W_TCRIT_HYST,
                                  HYST_TO_REG(hyst));
        mutex_unlock(&data->update_lock);
@@ -338,28 +375,30 @@ static ssize_t show_alarm(struct device *dev, struct device_attribute
        return sprintf(buf, "%d\n", (data->alarms >> bitnr) & 1);
 }
 
-static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp8, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp11, NULL, 4);
 static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, show_temp11, NULL, 0);
 static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp8,
-       set_temp8, 1);
+       set_temp8, 0);
 static SENSOR_DEVICE_ATTR(temp2_min, S_IWUSR | S_IRUGO, show_temp11,
        set_temp11, 1);
 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp8,
-       set_temp8, 2);
+       set_temp8, 1);
 static SENSOR_DEVICE_ATTR(temp2_max, S_IWUSR | S_IRUGO, show_temp11,
        set_temp11, 2);
 static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp8,
-       set_temp8, 3);
+       set_temp8, 2);
 static SENSOR_DEVICE_ATTR(temp2_crit, S_IWUSR | S_IRUGO, show_temp8,
-       set_temp8, 4);
+       set_temp8, 3);
 static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temphyst,
-       set_temphyst, 3);
-static SENSOR_DEVICE_ATTR(temp2_crit_hyst, S_IRUGO, show_temphyst, NULL, 4);
+       set_temphyst, 2);
+static SENSOR_DEVICE_ATTR(temp2_crit_hyst, S_IRUGO, show_temphyst, NULL, 3);
+static SENSOR_DEVICE_ATTR(temp2_offset, S_IWUSR | S_IRUGO, show_temp11,
+       set_temp11, 3);
 
 /* Individual alarm files */
 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 0);
 static SENSOR_DEVICE_ATTR(temp2_crit_alarm, S_IRUGO, show_alarm, NULL, 1);
-static SENSOR_DEVICE_ATTR(temp2_input_fault, S_IRUGO, show_alarm, NULL, 2);
+static SENSOR_DEVICE_ATTR(temp2_fault, S_IRUGO, show_alarm, NULL, 2);
 static SENSOR_DEVICE_ATTR(temp2_min_alarm, S_IRUGO, show_alarm, NULL, 3);
 static SENSOR_DEVICE_ATTR(temp2_max_alarm, S_IRUGO, show_alarm, NULL, 4);
 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 5);
@@ -381,7 +420,7 @@ static struct attribute *lm90_attributes[] = {
 
        &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
        &sensor_dev_attr_temp2_crit_alarm.dev_attr.attr,
-       &sensor_dev_attr_temp2_input_fault.dev_attr.attr,
+       &sensor_dev_attr_temp2_fault.dev_attr.attr,
        &sensor_dev_attr_temp2_min_alarm.dev_attr.attr,
        &sensor_dev_attr_temp2_max_alarm.dev_attr.attr,
        &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
@@ -429,7 +468,7 @@ static DEVICE_ATTR(pec, S_IWUSR | S_IRUGO, show_pec, set_pec);
  */
 
 /* The ADM1032 supports PEC but not on write byte transactions, so we need
-   to explicitely ask for a transaction without PEC. */
+   to explicitly ask for a transaction without PEC. */
 static inline s32 adm1032_write_byte(struct i2c_client *client, u8 value)
 {
        return i2c_smbus_xfer(client->adapter, client->addr,
@@ -462,40 +501,16 @@ static int lm90_read_reg(struct i2c_client* client, u8 reg, u8 *value)
        return 0;
 }
 
-static int lm90_attach_adapter(struct i2c_adapter *adapter)
-{
-       if (!(adapter->class & I2C_CLASS_HWMON))
-               return 0;
-       return i2c_probe(adapter, &addr_data, lm90_detect);
-}
-
-/*
- * The following function does more than just detection. If detection
- * succeeds, it also registers the new chip.
- */
-static int lm90_detect(struct i2c_adapter *adapter, int address, int kind)
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int lm90_detect(struct i2c_client *new_client, int kind,
+                      struct i2c_board_info *info)
 {
-       struct i2c_client *new_client;
-       struct lm90_data *data;
-       int err = 0;
+       struct i2c_adapter *adapter = new_client->adapter;
+       int address = new_client->addr;
        const char *name = "";
 
        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
-               goto exit;
-
-       if (!(data = kzalloc(sizeof(struct lm90_data), GFP_KERNEL))) {
-               err = -ENOMEM;
-               goto exit;
-       }
-
-       /* The common I2C client data is placed right before the
-          LM90-specific data. */
-       new_client = &data->client;
-       i2c_set_clientdata(new_client, data);
-       new_client->addr = address;
-       new_client->adapter = adapter;
-       new_client->driver = &lm90_driver;
-       new_client->flags = 0;
+               return -ENODEV;
 
        /*
         * Now we do the remaining detection. A negative kind means that
@@ -513,24 +528,25 @@ static int lm90_detect(struct i2c_adapter *adapter, int address, int kind)
                kind = lm90;
 
        if (kind < 0) { /* detection and identification */
-               u8 man_id, chip_id, reg_config1, reg_convrate;
-
-               if (lm90_read_reg(new_client, LM90_REG_R_MAN_ID,
-                                 &man_id) < 0
-                || lm90_read_reg(new_client, LM90_REG_R_CHIP_ID,
-                                 &chip_id) < 0
-                || lm90_read_reg(new_client, LM90_REG_R_CONFIG1,
-                                 &reg_config1) < 0
-                || lm90_read_reg(new_client, LM90_REG_R_CONVRATE,
-                                 &reg_convrate) < 0)
-                       goto exit_free;
+               int man_id, chip_id, reg_config1, reg_convrate;
+
+               if ((man_id = i2c_smbus_read_byte_data(new_client,
+                                               LM90_REG_R_MAN_ID)) < 0
+                || (chip_id = i2c_smbus_read_byte_data(new_client,
+                                               LM90_REG_R_CHIP_ID)) < 0
+                || (reg_config1 = i2c_smbus_read_byte_data(new_client,
+                                               LM90_REG_R_CONFIG1)) < 0
+                || (reg_convrate = i2c_smbus_read_byte_data(new_client,
+                                               LM90_REG_R_CONVRATE)) < 0)
+                       return -ENODEV;
                
-               if (man_id == 0x01) { /* National Semiconductor */
-                       u8 reg_config2;
+               if ((address == 0x4C || address == 0x4D)
+                && man_id == 0x01) { /* National Semiconductor */
+                       int reg_config2;
 
-                       if (lm90_read_reg(new_client, LM90_REG_R_CONFIG2,
-                                         &reg_config2) < 0)
-                               goto exit_free;
+                       if ((reg_config2 = i2c_smbus_read_byte_data(new_client,
+                                               LM90_REG_R_CONFIG2)) < 0)
+                               return -ENODEV;
 
                        if ((reg_config1 & 0x2A) == 0x00
                         && (reg_config2 & 0xF8) == 0x00
@@ -548,7 +564,8 @@ static int lm90_detect(struct i2c_adapter *adapter, int address, int kind)
                                }
                        }
                } else
-               if (man_id == 0x41) { /* Analog Devices */
+               if ((address == 0x4C || address == 0x4D)
+                && man_id == 0x41) { /* Analog Devices */
                        if ((chip_id & 0xF0) == 0x40 /* ADM1032 */
                         && (reg_config1 & 0x3F) == 0x00
                         && reg_convrate <= 0x0A) {
@@ -562,18 +579,30 @@ static int lm90_detect(struct i2c_adapter *adapter, int address, int kind)
                } else
                if (man_id == 0x4D) { /* Maxim */
                        /*
-                        * The Maxim variants do NOT have a chip_id register.
-                        * Reading from that address will return the last read
-                        * value, which in our case is those of the man_id
-                        * register. Likewise, the config1 register seems to
-                        * lack a low nibble, so the value will be those of the
-                        * previous read, so in our case those of the man_id
-                        * register.
+                        * The MAX6657, MAX6658 and MAX6659 do NOT have a
+                        * chip_id register. Reading from that address will
+                        * return the last read value, which in our case is
+                        * those of the man_id register. Likewise, the config1
+                        * register seems to lack a low nibble, so the value
+                        * will be those of the previous read, so in our case
+                        * those of the man_id register.
                         */
                        if (chip_id == man_id
+                        && (address == 0x4C || address == 0x4D)
                         && (reg_config1 & 0x1F) == (man_id & 0x0F)
                         && reg_convrate <= 0x09) {
                                kind = max6657;
+                       } else
+                       /* The chip_id register of the MAX6680 and MAX6681
+                        * holds the revision of the chip.
+                        * the lowest bit of the config1 register is unused
+                        * and should return zero when read, so should the
+                        * second to last bit of config1 (software reset)
+                        */
+                       if (chip_id == 0x01
+                        && (reg_config1 & 0x03) == 0x00
+                        && reg_convrate <= 0x07) {
+                               kind = max6680;
                        }
                }
 
@@ -581,10 +610,11 @@ static int lm90_detect(struct i2c_adapter *adapter, int address, int kind)
                        dev_info(&adapter->dev,
                            "Unsupported chip (man_id=0x%02X, "
                            "chip_id=0x%02X).\n", man_id, chip_id);
-                       goto exit_free;
+                       return -ENODEV;
                }
        }
 
+       /* Fill the i2c board info */
        if (kind == lm90) {
                name = "lm90";
        } else if (kind == adm1032) {
@@ -592,42 +622,65 @@ static int lm90_detect(struct i2c_adapter *adapter, int address, int kind)
                /* The ADM1032 supports PEC, but only if combined
                   transactions are not used. */
                if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
-                       new_client->flags |= I2C_CLIENT_PEC;
+                       info->flags |= I2C_CLIENT_PEC;
        } else if (kind == lm99) {
                name = "lm99";
        } else if (kind == lm86) {
                name = "lm86";
        } else if (kind == max6657) {
                name = "max6657";
+       } else if (kind == max6680) {
+               name = "max6680";
        } else if (kind == adt7461) {
                name = "adt7461";
        }
+       strlcpy(info->type, name, I2C_NAME_SIZE);
+
+       return 0;
+}
 
-       /* We can fill in the remaining client fields */
-       strlcpy(new_client->name, name, I2C_NAME_SIZE);
-       data->valid = 0;
-       data->kind = kind;
+static int lm90_probe(struct i2c_client *new_client,
+                     const struct i2c_device_id *id)
+{
+       struct i2c_adapter *adapter = to_i2c_adapter(new_client->dev.parent);
+       struct lm90_data *data;
+       int err;
+
+       data = kzalloc(sizeof(struct lm90_data), GFP_KERNEL);
+       if (!data) {
+               err = -ENOMEM;
+               goto exit;
+       }
+       i2c_set_clientdata(new_client, data);
        mutex_init(&data->update_lock);
 
-       /* Tell the I2C layer a new client has arrived */
-       if ((err = i2c_attach_client(new_client)))
-               goto exit_free;
+       /* Set the device type */
+       data->kind = id->driver_data;
+       if (data->kind == adm1032) {
+               if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
+                       new_client->flags &= ~I2C_CLIENT_PEC;
+       }
 
        /* Initialize the LM90 chip */
        lm90_init_client(new_client);
 
        /* Register sysfs hooks */
        if ((err = sysfs_create_group(&new_client->dev.kobj, &lm90_group)))
-               goto exit_detach;
+               goto exit_free;
        if (new_client->flags & I2C_CLIENT_PEC) {
                if ((err = device_create_file(&new_client->dev,
                                              &dev_attr_pec)))
                        goto exit_remove_files;
        }
+       if (data->kind != max6657) {
+               if ((err = device_create_file(&new_client->dev,
+                               &sensor_dev_attr_temp2_offset.dev_attr)))
+                       goto exit_remove_files;
+       }
 
-       data->class_dev = hwmon_device_register(&new_client->dev);
-       if (IS_ERR(data->class_dev)) {
-               err = PTR_ERR(data->class_dev);
+       data->hwmon_dev = hwmon_device_register(&new_client->dev);
+       if (IS_ERR(data->hwmon_dev)) {
+               err = PTR_ERR(data->hwmon_dev);
                goto exit_remove_files;
        }
 
@@ -636,8 +689,6 @@ static int lm90_detect(struct i2c_adapter *adapter, int address, int kind)
 exit_remove_files:
        sysfs_remove_group(&new_client->dev.kobj, &lm90_group);
        device_remove_file(&new_client->dev, &dev_attr_pec);
-exit_detach:
-       i2c_detach_client(new_client);
 exit_free:
        kfree(data);
 exit:
@@ -646,7 +697,8 @@ exit:
 
 static void lm90_init_client(struct i2c_client *client)
 {
-       u8 config;
+       u8 config, config_orig;
+       struct lm90_data *data = i2c_get_clientdata(client);
 
        /*
         * Start the conversions.
@@ -657,24 +709,66 @@ static void lm90_init_client(struct i2c_client *client)
                dev_warn(&client->dev, "Initialization failed!\n");
                return;
        }
-       if (config & 0x40)
-               i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1,
-                                         config & 0xBF); /* run */
+       config_orig = config;
+
+       /*
+        * Put MAX6680/MAX8881 into extended resolution (bit 0x10,
+        * 0.125 degree resolution) and range (0x08, extend range
+        * to -64 degree) mode for the remote temperature sensor.
+        */
+       if (data->kind == max6680) {
+               config |= 0x18;
+       }
+
+       config &= 0xBF; /* run */
+       if (config != config_orig) /* Only write if changed */
+               i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1, config);
 }
 
-static int lm90_detach_client(struct i2c_client *client)
+static int lm90_remove(struct i2c_client *client)
 {
        struct lm90_data *data = i2c_get_clientdata(client);
-       int err;
 
-       hwmon_device_unregister(data->class_dev);
+       hwmon_device_unregister(data->hwmon_dev);
        sysfs_remove_group(&client->dev.kobj, &lm90_group);
        device_remove_file(&client->dev, &dev_attr_pec);
+       if (data->kind != max6657)
+               device_remove_file(&client->dev,
+                                  &sensor_dev_attr_temp2_offset.dev_attr);
+
+       kfree(data);
+       return 0;
+}
+
+static int lm90_read16(struct i2c_client *client, u8 regh, u8 regl, u16 *value)
+{
+       int err;
+       u8 oldh, newh, l;
 
-       if ((err = i2c_detach_client(client)))
+       /*
+        * There is a trick here. We have to read two registers to have the
+        * sensor temperature, but we have to beware a conversion could occur
+        * inbetween the readings. The datasheet says we should either use
+        * the one-shot conversion register, which we don't want to do
+        * (disables hardware monitoring) or monitor the busy bit, which is
+        * impossible (we can't read the values and monitor that bit at the
+        * exact same time). So the solution used here is to read the high
+        * byte once, then the low byte, then the high byte again. If the new
+        * high byte matches the old one, then we have a valid reading. Else
+        * we have to read the low byte again, and now we believe we have a
+        * correct reading.
+        */
+       if ((err = lm90_read_reg(client, regh, &oldh))
+        || (err = lm90_read_reg(client, regl, &l))
+        || (err = lm90_read_reg(client, regh, &newh)))
                return err;
+       if (oldh != newh) {
+               err = lm90_read_reg(client, regl, &l);
+               if (err)
+                       return err;
+       }
+       *value = (newh << 8) | l;
 
-       kfree(data);
        return 0;
 }
 
@@ -686,43 +780,40 @@ static struct lm90_data *lm90_update_device(struct device *dev)
        mutex_lock(&data->update_lock);
 
        if (time_after(jiffies, data->last_updated + HZ * 2) || !data->valid) {
-               u8 oldh, newh, l;
+               u8 h, l;
 
                dev_dbg(&client->dev, "Updating lm90 data.\n");
-               lm90_read_reg(client, LM90_REG_R_LOCAL_TEMP, &data->temp8[0]);
-               lm90_read_reg(client, LM90_REG_R_LOCAL_LOW, &data->temp8[1]);
-               lm90_read_reg(client, LM90_REG_R_LOCAL_HIGH, &data->temp8[2]);
-               lm90_read_reg(client, LM90_REG_R_LOCAL_CRIT, &data->temp8[3]);
-               lm90_read_reg(client, LM90_REG_R_REMOTE_CRIT, &data->temp8[4]);
+               lm90_read_reg(client, LM90_REG_R_LOCAL_LOW, &data->temp8[0]);
+               lm90_read_reg(client, LM90_REG_R_LOCAL_HIGH, &data->temp8[1]);
+               lm90_read_reg(client, LM90_REG_R_LOCAL_CRIT, &data->temp8[2]);
+               lm90_read_reg(client, LM90_REG_R_REMOTE_CRIT, &data->temp8[3]);
                lm90_read_reg(client, LM90_REG_R_TCRIT_HYST, &data->temp_hyst);
 
-               /*
-                * There is a trick here. We have to read two registers to
-                * have the remote sensor temperature, but we have to beware
-                * a conversion could occur inbetween the readings. The
-                * datasheet says we should either use the one-shot
-                * conversion register, which we don't want to do (disables
-                * hardware monitoring) or monitor the busy bit, which is
-                * impossible (we can't read the values and monitor that bit
-                * at the exact same time). So the solution used here is to
-                * read the high byte once, then the low byte, then the high
-                * byte again. If the new high byte matches the old one,
-                * then we have a valid reading. Else we have to read the low
-                * byte again, and now we believe we have a correct reading.
-                */
-               if (lm90_read_reg(client, LM90_REG_R_REMOTE_TEMPH, &oldh) == 0
-                && lm90_read_reg(client, LM90_REG_R_REMOTE_TEMPL, &l) == 0
-                && lm90_read_reg(client, LM90_REG_R_REMOTE_TEMPH, &newh) == 0
-                && (newh == oldh
-                 || lm90_read_reg(client, LM90_REG_R_REMOTE_TEMPL, &l) == 0))
-                       data->temp11[0] = (newh << 8) | l;
-
-               if (lm90_read_reg(client, LM90_REG_R_REMOTE_LOWH, &newh) == 0
+               if (data->kind == max6657) {
+                       lm90_read16(client, LM90_REG_R_LOCAL_TEMP,
+                                   MAX6657_REG_R_LOCAL_TEMPL,
+                                   &data->temp11[4]);
+               } else {
+                       if (lm90_read_reg(client, LM90_REG_R_LOCAL_TEMP,
+                                         &h) == 0)
+                               data->temp11[4] = h << 8;
+               }
+               lm90_read16(client, LM90_REG_R_REMOTE_TEMPH,
+                           LM90_REG_R_REMOTE_TEMPL, &data->temp11[0]);
+
+               if (lm90_read_reg(client, LM90_REG_R_REMOTE_LOWH, &h) == 0
                 && lm90_read_reg(client, LM90_REG_R_REMOTE_LOWL, &l) == 0)
-                       data->temp11[1] = (newh << 8) | l;
-               if (lm90_read_reg(client, LM90_REG_R_REMOTE_HIGHH, &newh) == 0
+                       data->temp11[1] = (h << 8) | l;
+               if (lm90_read_reg(client, LM90_REG_R_REMOTE_HIGHH, &h) == 0
                 && lm90_read_reg(client, LM90_REG_R_REMOTE_HIGHL, &l) == 0)
-                       data->temp11[2] = (newh << 8) | l;
+                       data->temp11[2] = (h << 8) | l;
+               if (data->kind != max6657) {
+                       if (lm90_read_reg(client, LM90_REG_R_REMOTE_OFFSH,
+                                         &h) == 0
+                        && lm90_read_reg(client, LM90_REG_R_REMOTE_OFFSL,
+                                         &l) == 0)
+                               data->temp11[3] = (h << 8) | l;
+               }
                lm90_read_reg(client, LM90_REG_R_STATUS, &data->alarms);
 
                data->last_updated = jiffies;