forked from luck/tmp_suning_uos_patched
hwmon: (lm73) Add 'update_interval' attribute
The LM73 supports four A/D conversion resolutions. The default used by the existing lm73 driver is the chip's default, 11-bit (0.25 C/LSB). This patch enables changing of this resolution from userspace via the update_interval sysfs attribute. Full details on usage are included in Documentation/hwmon/lm73. Signed-off-by: Chris Verges <kg4ysn@gmail.com> [linux@roeck-us.net: cleanup] Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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Documentation/hwmon/lm73
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79
Documentation/hwmon/lm73
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Kernel driver lm73
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==================
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Supported chips:
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* Texas Instruments LM73
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Prefix: 'lm73'
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Addresses scanned: I2C 0x48, 0x49, 0x4a, 0x4c, 0x4d, and 0x4e
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Datasheet: Publicly available at the Texas Instruments website
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http://www.ti.com/product/lm73
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Author: Guillaume Ligneul <guillaume.ligneul@gmail.com>
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Documentation: Chris Verges <kg4ysn@gmail.com>
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Description
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-----------
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The LM73 is a digital temperature sensor. All temperature values are
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given in degrees Celsius.
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Measurement Resolution Support
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------------------------------
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The LM73 supports four resolutions, defined in terms of degrees C per
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LSB: 0.25, 0.125, 0.0625, and 0.3125. Changing the resolution mode
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affects the conversion time of the LM73's analog-to-digital converter.
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From userspace, the desired resolution can be specified as a function of
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conversion time via the 'update_interval' sysfs attribute for the
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device. This attribute will normalize ranges of input values to the
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maximum times defined for the resolution in the datasheet.
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Resolution Conv. Time Input Range
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(C/LSB) (msec) (msec)
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--------------------------------------
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0.25 14 0..14
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0.125 28 15..28
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0.0625 56 29..56
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0.03125 112 57..infinity
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--------------------------------------
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The following examples show how the 'update_interval' attribute can be
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used to change the conversion time:
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$ echo 0 > update_interval
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$ cat update_interval
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14
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$ cat temp1_input
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24250
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$ echo 22 > update_interval
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$ cat update_interval
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28
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$ cat temp1_input
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24125
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$ echo 56 > update_interval
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$ cat update_interval
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56
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$ cat temp1_input
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24062
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$ echo 85 > update_interval
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$ cat update_interval
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112
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$ cat temp1_input
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24031
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As shown here, the lm73 driver automatically adjusts any user input for
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'update_interval' via a step function. Reading back the
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'update_interval' value after a write operation will confirm the
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conversion time actively in use.
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Mathematically, the resolution can be derived from the conversion time
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via the following function:
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g(x) = 0.250 * [log(x/14) / log(2)]
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where 'x' is the output from 'update_interval' and 'g(x)' is the
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resolution in degrees C per LSB.
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@ -39,8 +39,24 @@ static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4c,
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#define LM73_TEMP_MIN (-256000 / 250)
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#define LM73_TEMP_MAX (255750 / 250)
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/*-----------------------------------------------------------------------*/
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#define LM73_CTRL_RES_SHIFT 5
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#define LM73_CTRL_RES_MASK (BIT(5) | BIT(6))
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#define LM73_CTRL_TO_MASK BIT(7)
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static const unsigned short lm73_convrates[] = {
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14, /* 11-bits (0.25000 C/LSB): RES1 Bit = 0, RES0 Bit = 0 */
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28, /* 12-bits (0.12500 C/LSB): RES1 Bit = 0, RES0 Bit = 1 */
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56, /* 13-bits (0.06250 C/LSB): RES1 Bit = 1, RES0 Bit = 0 */
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112, /* 14-bits (0.03125 C/LSB): RES1 Bit = 1, RES0 Bit = 1 */
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};
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struct lm73_data {
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struct device *hwmon_dev;
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struct mutex lock;
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u8 ctrl; /* control register value */
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};
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/*-----------------------------------------------------------------------*/
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static ssize_t set_temp(struct device *dev, struct device_attribute *da,
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const char *buf, size_t count)
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@ -78,6 +94,51 @@ static ssize_t show_temp(struct device *dev, struct device_attribute *da,
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return scnprintf(buf, PAGE_SIZE, "%d\n", temp);
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}
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static ssize_t set_convrate(struct device *dev, struct device_attribute *da,
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const char *buf, size_t count)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct lm73_data *data = i2c_get_clientdata(client);
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unsigned long convrate;
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s32 err;
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int res = 0;
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err = kstrtoul(buf, 10, &convrate);
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if (err < 0)
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return err;
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/*
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* Convert the desired conversion rate into register bits.
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* res is already initialized, and everything past the second-to-last
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* value in the array is treated as belonging to the last value
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* in the array.
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*/
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while (res < (ARRAY_SIZE(lm73_convrates) - 1) &&
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convrate > lm73_convrates[res])
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res++;
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mutex_lock(&data->lock);
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data->ctrl &= LM73_CTRL_TO_MASK;
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data->ctrl |= res << LM73_CTRL_RES_SHIFT;
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err = i2c_smbus_write_byte_data(client, LM73_REG_CTRL, data->ctrl);
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mutex_unlock(&data->lock);
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if (err < 0)
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return err;
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return count;
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}
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static ssize_t show_convrate(struct device *dev, struct device_attribute *da,
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char *buf)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct lm73_data *data = i2c_get_clientdata(client);
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int res;
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res = (data->ctrl & LM73_CTRL_RES_MASK) >> LM73_CTRL_RES_SHIFT;
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return scnprintf(buf, PAGE_SIZE, "%hu\n", lm73_convrates[res]);
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}
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/*-----------------------------------------------------------------------*/
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@ -89,13 +150,14 @@ static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO,
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show_temp, set_temp, LM73_REG_MIN);
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static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
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show_temp, NULL, LM73_REG_INPUT);
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static SENSOR_DEVICE_ATTR(update_interval, S_IWUSR | S_IRUGO,
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show_convrate, set_convrate, 0);
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static struct attribute *lm73_attributes[] = {
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&sensor_dev_attr_temp1_input.dev_attr.attr,
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&sensor_dev_attr_temp1_max.dev_attr.attr,
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&sensor_dev_attr_temp1_min.dev_attr.attr,
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&sensor_dev_attr_update_interval.dev_attr.attr,
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NULL
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};
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@ -110,23 +172,36 @@ static const struct attribute_group lm73_group = {
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static int
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lm73_probe(struct i2c_client *client, const struct i2c_device_id *id)
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{
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struct device *hwmon_dev;
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int status;
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struct lm73_data *data;
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int ctrl;
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data = devm_kzalloc(&client->dev, sizeof(struct lm73_data),
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GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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i2c_set_clientdata(client, data);
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mutex_init(&data->lock);
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ctrl = i2c_smbus_read_byte_data(client, LM73_REG_CTRL);
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if (ctrl < 0)
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return ctrl;
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data->ctrl = ctrl;
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/* Register sysfs hooks */
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status = sysfs_create_group(&client->dev.kobj, &lm73_group);
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if (status)
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return status;
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hwmon_dev = hwmon_device_register(&client->dev);
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if (IS_ERR(hwmon_dev)) {
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status = PTR_ERR(hwmon_dev);
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data->hwmon_dev = hwmon_device_register(&client->dev);
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if (IS_ERR(data->hwmon_dev)) {
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status = PTR_ERR(data->hwmon_dev);
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goto exit_remove;
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}
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i2c_set_clientdata(client, hwmon_dev);
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dev_info(&client->dev, "%s: sensor '%s'\n",
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dev_name(hwmon_dev), client->name);
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dev_name(data->hwmon_dev), client->name);
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return 0;
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@ -137,9 +212,9 @@ lm73_probe(struct i2c_client *client, const struct i2c_device_id *id)
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static int lm73_remove(struct i2c_client *client)
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{
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struct device *hwmon_dev = i2c_get_clientdata(client);
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struct lm73_data *data = i2c_get_clientdata(client);
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hwmon_device_unregister(hwmon_dev);
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hwmon_device_unregister(data->hwmon_dev);
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sysfs_remove_group(&client->dev.kobj, &lm73_group);
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return 0;
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}
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