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266 lines
7.0 KiB
266 lines
7.0 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Driver for Linear Technology LTC4215 I2C Hot Swap Controller |
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* |
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* Copyright (C) 2009 Ira W. Snyder <[email protected]> |
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* |
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* Datasheet: |
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* http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697 |
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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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/* Here are names of the chip's registers (a.k.a. commands) */ |
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enum ltc4215_cmd { |
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LTC4215_CONTROL = 0x00, /* rw */ |
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LTC4215_ALERT = 0x01, /* rw */ |
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LTC4215_STATUS = 0x02, /* ro */ |
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LTC4215_FAULT = 0x03, /* rw */ |
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LTC4215_SENSE = 0x04, /* rw */ |
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LTC4215_SOURCE = 0x05, /* rw */ |
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LTC4215_ADIN = 0x06, /* rw */ |
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}; |
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struct ltc4215_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[7]; |
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}; |
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static struct ltc4215_data *ltc4215_update_device(struct device *dev) |
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{ |
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struct ltc4215_data *data = dev_get_drvdata(dev); |
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struct i2c_client *client = data->client; |
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s32 val; |
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int i; |
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mutex_lock(&data->update_lock); |
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/* The chip's A/D updates 10 times per second */ |
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if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) { |
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dev_dbg(&client->dev, "Starting ltc4215 update\n"); |
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/* Read all registers */ |
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for (i = 0; i < ARRAY_SIZE(data->regs); i++) { |
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val = i2c_smbus_read_byte_data(client, i); |
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if (unlikely(val < 0)) |
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data->regs[i] = 0; |
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else |
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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 = 1; |
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} |
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mutex_unlock(&data->update_lock); |
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return data; |
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} |
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/* Return the voltage from the given register in millivolts */ |
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static int ltc4215_get_voltage(struct device *dev, u8 reg) |
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{ |
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struct ltc4215_data *data = ltc4215_update_device(dev); |
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const u8 regval = data->regs[reg]; |
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u32 voltage = 0; |
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switch (reg) { |
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case LTC4215_SENSE: |
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/* 151 uV per increment */ |
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voltage = regval * 151 / 1000; |
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break; |
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case LTC4215_SOURCE: |
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/* 60.5 mV per increment */ |
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voltage = regval * 605 / 10; |
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break; |
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case LTC4215_ADIN: |
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/* |
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* The ADIN input is divided by 12.5, and has 4.82 mV |
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* per increment, so we have the additional multiply |
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*/ |
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voltage = regval * 482 * 125 / 1000; |
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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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break; |
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} |
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return voltage; |
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} |
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/* Return the current from the sense resistor in mA */ |
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static unsigned int ltc4215_get_current(struct device *dev) |
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{ |
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struct ltc4215_data *data = ltc4215_update_device(dev); |
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/* |
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* The strange looking conversions that follow are fixed-point |
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* math, since we cannot do floating point in the kernel. |
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* |
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* Step 1: convert sense register to microVolts |
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* Step 2: convert voltage to milliAmperes |
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* |
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* If you play around with the V=IR equation, you come up with |
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* the following: X uV / Y mOhm == Z mA |
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* |
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* With the resistors that are fractions of a milliOhm, we multiply |
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* the voltage and resistance by 10, to shift the decimal point. |
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* Now we can use the normal division operator again. |
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*/ |
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/* Calculate voltage in microVolts (151 uV per increment) */ |
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const unsigned int voltage = data->regs[LTC4215_SENSE] * 151; |
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/* Calculate current in milliAmperes (4 milliOhm sense resistor) */ |
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const unsigned int curr = voltage / 4; |
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return curr; |
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} |
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static ssize_t ltc4215_voltage_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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const int voltage = ltc4215_get_voltage(dev, attr->index); |
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return sysfs_emit(buf, "%d\n", voltage); |
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} |
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static ssize_t ltc4215_current_show(struct device *dev, |
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struct device_attribute *da, char *buf) |
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{ |
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const unsigned int curr = ltc4215_get_current(dev); |
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return sysfs_emit(buf, "%u\n", curr); |
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} |
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static ssize_t ltc4215_power_show(struct device *dev, |
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struct device_attribute *da, char *buf) |
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{ |
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const unsigned int curr = ltc4215_get_current(dev); |
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const int output_voltage = ltc4215_get_voltage(dev, LTC4215_ADIN); |
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/* current in mA * voltage in mV == power in uW */ |
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const unsigned int power = abs(output_voltage * curr); |
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return sysfs_emit(buf, "%u\n", power); |
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} |
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static ssize_t ltc4215_alarm_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 ltc4215_data *data = ltc4215_update_device(dev); |
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const u8 reg = data->regs[LTC4215_STATUS]; |
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const u32 mask = attr->index; |
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return sysfs_emit(buf, "%u\n", !!(reg & mask)); |
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} |
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/* |
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* These macros are used below in constructing device attribute objects |
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* for use with sysfs_create_group() to make a sysfs device file |
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* for each register. |
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*/ |
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/* Construct a sensor_device_attribute structure for each register */ |
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/* Current */ |
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static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4215_current, 0); |
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static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4215_alarm, 1 << 2); |
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/* Power (virtual) */ |
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static SENSOR_DEVICE_ATTR_RO(power1_input, ltc4215_power, 0); |
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/* Input Voltage */ |
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static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4215_voltage, LTC4215_ADIN); |
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static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4215_alarm, 1 << 0); |
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static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4215_alarm, 1 << 1); |
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/* Output Voltage */ |
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static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4215_voltage, LTC4215_SOURCE); |
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static SENSOR_DEVICE_ATTR_RO(in2_min_alarm, ltc4215_alarm, 1 << 3); |
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/* |
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* Finally, construct an array of pointers to members of the above objects, |
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* as required for sysfs_create_group() |
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*/ |
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static struct attribute *ltc4215_attrs[] = { |
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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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&sensor_dev_attr_power1_input.dev_attr.attr, |
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&sensor_dev_attr_in1_input.dev_attr.attr, |
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&sensor_dev_attr_in1_max_alarm.dev_attr.attr, |
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&sensor_dev_attr_in1_min_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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NULL, |
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}; |
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ATTRIBUTE_GROUPS(ltc4215); |
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static int ltc4215_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 ltc4215_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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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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/* Initialize the LTC4215 chip */ |
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i2c_smbus_write_byte_data(client, LTC4215_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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ltc4215_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 ltc4215_id[] = { |
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{ "ltc4215", 0 }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(i2c, ltc4215_id); |
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/* This is the driver that will be inserted */ |
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static struct i2c_driver ltc4215_driver = { |
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.driver = { |
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.name = "ltc4215", |
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}, |
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.probe_new = ltc4215_probe, |
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.id_table = ltc4215_id, |
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}; |
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module_i2c_driver(ltc4215_driver); |
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MODULE_AUTHOR("Ira W. Snyder <[email protected]>"); |
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MODULE_DESCRIPTION("LTC4215 driver"); |
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MODULE_LICENSE("GPL");
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