245 lines
6.3 KiB
C
245 lines
6.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller
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*
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* Copyright (C) 2010 Ericsson AB.
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*
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* Derived from:
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*
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* Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
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* Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
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*
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* Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/hwmon.h>
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#include <linux/hwmon-sysfs.h>
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#include <linux/jiffies.h>
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/* chip registers */
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#define LTC4261_STATUS 0x00 /* readonly */
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#define LTC4261_FAULT 0x01
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#define LTC4261_ALERT 0x02
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#define LTC4261_CONTROL 0x03
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#define LTC4261_SENSE_H 0x04
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#define LTC4261_SENSE_L 0x05
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#define LTC4261_ADIN2_H 0x06
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#define LTC4261_ADIN2_L 0x07
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#define LTC4261_ADIN_H 0x08
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#define LTC4261_ADIN_L 0x09
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/*
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* Fault register bits
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*/
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#define FAULT_OV (1<<0)
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#define FAULT_UV (1<<1)
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#define FAULT_OC (1<<2)
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struct ltc4261_data {
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struct i2c_client *client;
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struct mutex update_lock;
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bool valid;
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unsigned long last_updated; /* in jiffies */
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/* Registers */
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u8 regs[10];
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};
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static struct ltc4261_data *ltc4261_update_device(struct device *dev)
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{
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struct ltc4261_data *data = dev_get_drvdata(dev);
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struct i2c_client *client = data->client;
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struct ltc4261_data *ret = data;
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mutex_lock(&data->update_lock);
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if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) {
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int i;
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/* Read registers -- 0x00 to 0x09 */
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for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
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int val;
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val = i2c_smbus_read_byte_data(client, i);
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if (unlikely(val < 0)) {
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dev_dbg(dev,
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"Failed to read ADC value: error %d\n",
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val);
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ret = ERR_PTR(val);
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data->valid = false;
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goto abort;
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}
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data->regs[i] = val;
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}
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data->last_updated = jiffies;
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data->valid = true;
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}
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abort:
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mutex_unlock(&data->update_lock);
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return ret;
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}
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/* Return the voltage from the given register in mV or mA */
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static int ltc4261_get_value(struct ltc4261_data *data, u8 reg)
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{
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u32 val;
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val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6);
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switch (reg) {
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case LTC4261_ADIN_H:
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case LTC4261_ADIN2_H:
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/* 2.5mV resolution. Convert to mV. */
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val = val * 25 / 10;
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break;
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case LTC4261_SENSE_H:
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/*
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* 62.5uV resolution. Convert to current as measured with
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* an 1 mOhm sense resistor, in mA. If a different sense
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* resistor is installed, calculate the actual current by
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* dividing the reported current by the sense resistor value
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* in mOhm.
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*/
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val = val * 625 / 10;
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break;
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default:
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/* If we get here, the developer messed up */
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WARN_ON_ONCE(1);
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val = 0;
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break;
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}
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return val;
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}
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static ssize_t ltc4261_value_show(struct device *dev,
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struct device_attribute *da, char *buf)
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{
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struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
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struct ltc4261_data *data = ltc4261_update_device(dev);
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int value;
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if (IS_ERR(data))
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return PTR_ERR(data);
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value = ltc4261_get_value(data, attr->index);
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return sysfs_emit(buf, "%d\n", value);
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}
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static ssize_t ltc4261_bool_show(struct device *dev,
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struct device_attribute *da, char *buf)
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{
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struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
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struct ltc4261_data *data = ltc4261_update_device(dev);
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u8 fault;
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if (IS_ERR(data))
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return PTR_ERR(data);
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fault = data->regs[LTC4261_FAULT] & attr->index;
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if (fault) /* Clear reported faults in chip register */
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i2c_smbus_write_byte_data(data->client, LTC4261_FAULT, ~fault);
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return sysfs_emit(buf, "%d\n", fault ? 1 : 0);
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}
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/*
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* Input voltages.
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*/
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static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4261_value, LTC4261_ADIN_H);
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static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4261_value, LTC4261_ADIN2_H);
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/*
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* Voltage alarms. The chip has only one set of voltage alarm status bits,
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* triggered by input voltage alarms. In many designs, those alarms are
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* associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin
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* to the OV pin. ADIN2 is, however, not available on all chip variants.
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* To ensure that the alarm condition is reported to the user, report it
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* with both voltage sensors.
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*/
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static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4261_bool, FAULT_UV);
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static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4261_bool, FAULT_OV);
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static SENSOR_DEVICE_ATTR_RO(in2_min_alarm, ltc4261_bool, FAULT_UV);
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static SENSOR_DEVICE_ATTR_RO(in2_max_alarm, ltc4261_bool, FAULT_OV);
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/* Currents (via sense resistor) */
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static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4261_value, LTC4261_SENSE_H);
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/* Overcurrent alarm */
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static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4261_bool, FAULT_OC);
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static struct attribute *ltc4261_attrs[] = {
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&sensor_dev_attr_in1_input.dev_attr.attr,
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&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
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&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
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&sensor_dev_attr_in2_input.dev_attr.attr,
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&sensor_dev_attr_in2_min_alarm.dev_attr.attr,
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&sensor_dev_attr_in2_max_alarm.dev_attr.attr,
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&sensor_dev_attr_curr1_input.dev_attr.attr,
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&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(ltc4261);
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static int ltc4261_probe(struct i2c_client *client)
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{
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struct i2c_adapter *adapter = client->adapter;
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struct device *dev = &client->dev;
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struct ltc4261_data *data;
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struct device *hwmon_dev;
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if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
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return -ENODEV;
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if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) {
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dev_err(dev, "Failed to read status register\n");
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return -ENODEV;
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}
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data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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data->client = client;
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mutex_init(&data->update_lock);
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/* Clear faults */
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i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00);
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hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
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data,
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ltc4261_groups);
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return PTR_ERR_OR_ZERO(hwmon_dev);
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}
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static const struct i2c_device_id ltc4261_id[] = {
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{"ltc4261", 0},
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{}
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};
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MODULE_DEVICE_TABLE(i2c, ltc4261_id);
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/* This is the driver that will be inserted */
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static struct i2c_driver ltc4261_driver = {
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.driver = {
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.name = "ltc4261",
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},
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.probe_new = ltc4261_probe,
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.id_table = ltc4261_id,
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};
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module_i2c_driver(ltc4261_driver);
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MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
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MODULE_DESCRIPTION("LTC4261 driver");
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MODULE_LICENSE("GPL");
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