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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller4 *5 * Copyright (C) 2010 Ericsson AB.6 *7 * Derived from:8 *9 * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller10 * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>11 *12 * Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf13 */14 15#include <linux/kernel.h>16#include <linux/module.h>17#include <linux/init.h>18#include <linux/err.h>19#include <linux/slab.h>20#include <linux/i2c.h>21#include <linux/hwmon.h>22#include <linux/hwmon-sysfs.h>23#include <linux/jiffies.h>24 25/* chip registers */26#define LTC4261_STATUS 0x00 /* readonly */27#define LTC4261_FAULT 0x0128#define LTC4261_ALERT 0x0229#define LTC4261_CONTROL 0x0330#define LTC4261_SENSE_H 0x0431#define LTC4261_SENSE_L 0x0532#define LTC4261_ADIN2_H 0x0633#define LTC4261_ADIN2_L 0x0734#define LTC4261_ADIN_H 0x0835#define LTC4261_ADIN_L 0x0936 37/*38 * Fault register bits39 */40#define FAULT_OV (1<<0)41#define FAULT_UV (1<<1)42#define FAULT_OC (1<<2)43 44struct ltc4261_data {45 struct i2c_client *client;46 47 struct mutex update_lock;48 bool valid;49 unsigned long last_updated; /* in jiffies */50 51 /* Registers */52 u8 regs[10];53};54 55static struct ltc4261_data *ltc4261_update_device(struct device *dev)56{57 struct ltc4261_data *data = dev_get_drvdata(dev);58 struct i2c_client *client = data->client;59 struct ltc4261_data *ret = data;60 61 mutex_lock(&data->update_lock);62 63 if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) {64 int i;65 66 /* Read registers -- 0x00 to 0x09 */67 for (i = 0; i < ARRAY_SIZE(data->regs); i++) {68 int val;69 70 val = i2c_smbus_read_byte_data(client, i);71 if (unlikely(val < 0)) {72 dev_dbg(dev,73 "Failed to read ADC value: error %d\n",74 val);75 ret = ERR_PTR(val);76 data->valid = false;77 goto abort;78 }79 data->regs[i] = val;80 }81 data->last_updated = jiffies;82 data->valid = true;83 }84abort:85 mutex_unlock(&data->update_lock);86 return ret;87}88 89/* Return the voltage from the given register in mV or mA */90static int ltc4261_get_value(struct ltc4261_data *data, u8 reg)91{92 u32 val;93 94 val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6);95 96 switch (reg) {97 case LTC4261_ADIN_H:98 case LTC4261_ADIN2_H:99 /* 2.5mV resolution. Convert to mV. */100 val = val * 25 / 10;101 break;102 case LTC4261_SENSE_H:103 /*104 * 62.5uV resolution. Convert to current as measured with105 * an 1 mOhm sense resistor, in mA. If a different sense106 * resistor is installed, calculate the actual current by107 * dividing the reported current by the sense resistor value108 * in mOhm.109 */110 val = val * 625 / 10;111 break;112 default:113 /* If we get here, the developer messed up */114 WARN_ON_ONCE(1);115 val = 0;116 break;117 }118 119 return val;120}121 122static ssize_t ltc4261_value_show(struct device *dev,123 struct device_attribute *da, char *buf)124{125 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);126 struct ltc4261_data *data = ltc4261_update_device(dev);127 int value;128 129 if (IS_ERR(data))130 return PTR_ERR(data);131 132 value = ltc4261_get_value(data, attr->index);133 return sysfs_emit(buf, "%d\n", value);134}135 136static ssize_t ltc4261_bool_show(struct device *dev,137 struct device_attribute *da, char *buf)138{139 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);140 struct ltc4261_data *data = ltc4261_update_device(dev);141 u8 fault;142 143 if (IS_ERR(data))144 return PTR_ERR(data);145 146 fault = data->regs[LTC4261_FAULT] & attr->index;147 if (fault) /* Clear reported faults in chip register */148 i2c_smbus_write_byte_data(data->client, LTC4261_FAULT, ~fault);149 150 return sysfs_emit(buf, "%d\n", fault ? 1 : 0);151}152 153/*154 * Input voltages.155 */156static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4261_value, LTC4261_ADIN_H);157static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4261_value, LTC4261_ADIN2_H);158 159/*160 * Voltage alarms. The chip has only one set of voltage alarm status bits,161 * triggered by input voltage alarms. In many designs, those alarms are162 * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin163 * to the OV pin. ADIN2 is, however, not available on all chip variants.164 * To ensure that the alarm condition is reported to the user, report it165 * with both voltage sensors.166 */167static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4261_bool, FAULT_UV);168static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4261_bool, FAULT_OV);169static SENSOR_DEVICE_ATTR_RO(in2_min_alarm, ltc4261_bool, FAULT_UV);170static SENSOR_DEVICE_ATTR_RO(in2_max_alarm, ltc4261_bool, FAULT_OV);171 172/* Currents (via sense resistor) */173static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4261_value, LTC4261_SENSE_H);174 175/* Overcurrent alarm */176static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4261_bool, FAULT_OC);177 178static struct attribute *ltc4261_attrs[] = {179 &sensor_dev_attr_in1_input.dev_attr.attr,180 &sensor_dev_attr_in1_min_alarm.dev_attr.attr,181 &sensor_dev_attr_in1_max_alarm.dev_attr.attr,182 &sensor_dev_attr_in2_input.dev_attr.attr,183 &sensor_dev_attr_in2_min_alarm.dev_attr.attr,184 &sensor_dev_attr_in2_max_alarm.dev_attr.attr,185 186 &sensor_dev_attr_curr1_input.dev_attr.attr,187 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,188 189 NULL,190};191ATTRIBUTE_GROUPS(ltc4261);192 193static int ltc4261_probe(struct i2c_client *client)194{195 struct i2c_adapter *adapter = client->adapter;196 struct device *dev = &client->dev;197 struct ltc4261_data *data;198 struct device *hwmon_dev;199 200 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))201 return -ENODEV;202 203 if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) {204 dev_err(dev, "Failed to read status register\n");205 return -ENODEV;206 }207 208 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);209 if (!data)210 return -ENOMEM;211 212 data->client = client;213 mutex_init(&data->update_lock);214 215 /* Clear faults */216 i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00);217 218 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,219 data,220 ltc4261_groups);221 return PTR_ERR_OR_ZERO(hwmon_dev);222}223 224static const struct i2c_device_id ltc4261_id[] = {225 {"ltc4261"},226 {}227};228 229MODULE_DEVICE_TABLE(i2c, ltc4261_id);230 231/* This is the driver that will be inserted */232static struct i2c_driver ltc4261_driver = {233 .driver = {234 .name = "ltc4261",235 },236 .probe = ltc4261_probe,237 .id_table = ltc4261_id,238};239 240module_i2c_driver(ltc4261_driver);241 242MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");243MODULE_DESCRIPTION("LTC4261 driver");244MODULE_LICENSE("GPL");245