hwmon: Driver for Linear Technologies LTC4260
LTC4260 is a Positive Voltage Hot Swap Controller. The driver currently only supports voltage monitoring, not voltage control. Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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Guenter Roeck
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Documentation/hwmon/ltc4260
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56
Documentation/hwmon/ltc4260
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Kernel driver ltc4260
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=====================
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Supported chips:
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* Linear Technology LTC4260
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Prefix: 'ltc4260'
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Addresses scanned: -
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Datasheet:
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http://cds.linear.com/docs/en/datasheet/4260fc.pdf
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Author: Guenter Roeck <linux@roeck-us.net>
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Description
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-----------
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The LTC4260 Hot Swap controller allows a board to be safely inserted
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and removed from a live backplane.
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Usage Notes
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-----------
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This driver does not probe for LTC4260 devices, since there is no register
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which can be safely used to identify the chip. You will have to instantiate
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the devices explicitly.
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Example: the following will load the driver for an LTC4260 at address 0x10
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on I2C bus #1:
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$ modprobe ltc4260
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$ echo ltc4260 0x10 > /sys/bus/i2c/devices/i2c-1/new_device
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Sysfs entries
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-------------
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Voltage readings provided by this driver are reported as obtained from the ADC
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registers. If a set of voltage divider resistors is installed, calculate the
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real voltage by multiplying the reported value with (R1+R2)/R2, where R1 is the
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value of the divider resistor against the measured voltage and R2 is the value
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of the divider resistor against Ground.
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Current reading provided by this driver is reported as obtained from the ADC
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Current Sense register. The reported value assumes that a 1 mOhm sense resistor
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is installed. If a different sense resistor is installed, calculate the real
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current by dividing the reported value by the sense resistor value in mOhm.
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in1_input SOURCE voltage (mV)
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in1_min_alarm Undervoltage alarm
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in1_max_alarm Overvoltage alarm
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in2_input ADIN voltage (mV)
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in2_alarm Power bad alarm
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curr1_input SENSE current (mA)
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curr1_alarm SENSE overcurrent alarm
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@ -821,6 +821,18 @@ config SENSORS_LTC4245
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This driver can also be built as a module. If so, the module will
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be called ltc4245.
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config SENSORS_LTC4260
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tristate "Linear Technology LTC4260"
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depends on I2C
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select REGMAP_I2C
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default n
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help
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If you say yes here you get support for Linear Technology LTC4261
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Positive Voltage Hot Swap Controller I2C interface.
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This driver can also be built as a module. If so, the module will
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be called ltc4260.
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config SENSORS_LTC4261
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tristate "Linear Technology LTC4261"
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depends on I2C
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@ -99,6 +99,7 @@ obj-$(CONFIG_SENSORS_LTC4151) += ltc4151.o
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obj-$(CONFIG_SENSORS_LTC4215) += ltc4215.o
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obj-$(CONFIG_SENSORS_LTC4222) += ltc4222.o
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obj-$(CONFIG_SENSORS_LTC4245) += ltc4245.o
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obj-$(CONFIG_SENSORS_LTC4260) += ltc4260.o
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obj-$(CONFIG_SENSORS_LTC4261) += ltc4261.o
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obj-$(CONFIG_SENSORS_MAX1111) += max1111.o
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obj-$(CONFIG_SENSORS_MAX16065) += max16065.o
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200
drivers/hwmon/ltc4260.c
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drivers/hwmon/ltc4260.c
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/*
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* Driver for Linear Technology LTC4260 I2C Positive Voltage Hot Swap Controller
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*
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* Copyright (c) 2014 Guenter Roeck
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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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/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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#include <linux/regmap.h>
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/* chip registers */
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#define LTC4260_CONTROL 0x00
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#define LTC4260_ALERT 0x01
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#define LTC4260_STATUS 0x02
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#define LTC4260_FAULT 0x03
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#define LTC4260_SENSE 0x04
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#define LTC4260_SOURCE 0x05
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#define LTC4260_ADIN 0x06
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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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#define FAULT_POWER_BAD (1 << 3)
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#define FAULT_FET_SHORT (1 << 5)
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/* Return the voltage from the given register in mV or mA */
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static int ltc4260_get_value(struct device *dev, u8 reg)
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{
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struct regmap *regmap = dev_get_drvdata(dev);
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unsigned int val;
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int ret;
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ret = regmap_read(regmap, reg, &val);
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if (ret < 0)
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return ret;
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switch (reg) {
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case LTC4260_ADIN:
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/* 10 mV resolution. Convert to mV. */
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val = val * 10;
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break;
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case LTC4260_SOURCE:
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/* 400 mV resolution. Convert to mV. */
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val = val * 400;
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break;
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case LTC4260_SENSE:
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/*
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* 300 uV 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 * 300;
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break;
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default:
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return -EINVAL;
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}
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return val;
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}
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static ssize_t ltc4260_show_value(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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int value;
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value = ltc4260_get_value(dev, attr->index);
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if (value < 0)
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return value;
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return snprintf(buf, PAGE_SIZE, "%d\n", value);
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}
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static ssize_t ltc4260_show_bool(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 regmap *regmap = dev_get_drvdata(dev);
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unsigned int fault;
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int ret;
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ret = regmap_read(regmap, LTC4260_FAULT, &fault);
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if (ret < 0)
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return ret;
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fault &= attr->index;
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if (fault) /* Clear reported faults in chip register */
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regmap_update_bits(regmap, LTC4260_FAULT, attr->index, 0);
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return snprintf(buf, PAGE_SIZE, "%d\n", !!fault);
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}
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/* Voltages */
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static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4260_show_value, NULL,
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LTC4260_SOURCE);
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static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4260_show_value, NULL,
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LTC4260_ADIN);
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/*
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* Voltage alarms
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* UV/OV faults are associated with the input voltage, and the POWER BAD and
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* FET SHORT faults are associated with the output voltage.
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*/
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static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc4260_show_bool, NULL,
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FAULT_UV);
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static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc4260_show_bool, NULL,
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FAULT_OV);
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static SENSOR_DEVICE_ATTR(in2_alarm, S_IRUGO, ltc4260_show_bool, NULL,
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FAULT_POWER_BAD | FAULT_FET_SHORT);
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/* Current (via sense resistor) */
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static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4260_show_value, NULL,
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LTC4260_SENSE);
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/* Overcurrent alarm */
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static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc4260_show_bool, NULL,
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FAULT_OC);
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static struct attribute *ltc4260_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_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(ltc4260);
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static struct regmap_config ltc4260_regmap_config = {
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.reg_bits = 8,
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.val_bits = 8,
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.max_register = LTC4260_ADIN,
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};
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static int ltc4260_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct device *dev = &client->dev;
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struct device *hwmon_dev;
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struct regmap *regmap;
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regmap = devm_regmap_init_i2c(client, <c4260_regmap_config);
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if (IS_ERR(regmap)) {
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dev_err(dev, "failed to allocate register map\n");
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return PTR_ERR(regmap);
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}
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/* Clear faults */
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regmap_write(regmap, LTC4260_FAULT, 0x00);
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hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
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regmap,
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ltc4260_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 ltc4260_id[] = {
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{"ltc4260", 0},
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, ltc4260_id);
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static struct i2c_driver ltc4260_driver = {
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.driver = {
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.name = "ltc4260",
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},
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.probe = ltc4260_probe,
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.id_table = ltc4260_id,
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};
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module_i2c_driver(ltc4260_driver);
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MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
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MODULE_DESCRIPTION("LTC4260 driver");
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MODULE_LICENSE("GPL");
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