linux/drivers/hwmon/ltc4261.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller
   4 *
   5 * Copyright (C) 2010 Ericsson AB.
   6 *
   7 * Derived from:
   8 *
   9 *  Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
  10 *  Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
  11 *
  12 * Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf
  13 */
  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   0x01
  28#define LTC4261_ALERT   0x02
  29#define LTC4261_CONTROL 0x03
  30#define LTC4261_SENSE_H 0x04
  31#define LTC4261_SENSE_L 0x05
  32#define LTC4261_ADIN2_H 0x06
  33#define LTC4261_ADIN2_L 0x07
  34#define LTC4261_ADIN_H  0x08
  35#define LTC4261_ADIN_L  0x09
  36
  37/*
  38 * Fault register bits
  39 */
  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 = 0;
  77                                goto abort;
  78                        }
  79                        data->regs[i] = val;
  80                }
  81                data->last_updated = jiffies;
  82                data->valid = 1;
  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 with
 105                 * an 1 mOhm sense resistor, in mA. If a different sense
 106                 * resistor is installed, calculate the actual current by
 107                 * dividing the reported current by the sense resistor value
 108                 * 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 snprintf(buf, PAGE_SIZE, "%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 snprintf(buf, PAGE_SIZE, "%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 are
 162 * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin
 163 * 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 it
 165 * 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                         const struct i2c_device_id *id)
 195{
 196        struct i2c_adapter *adapter = client->adapter;
 197        struct device *dev = &client->dev;
 198        struct ltc4261_data *data;
 199        struct device *hwmon_dev;
 200
 201        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 202                return -ENODEV;
 203
 204        if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) {
 205                dev_err(dev, "Failed to read status register\n");
 206                return -ENODEV;
 207        }
 208
 209        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 210        if (!data)
 211                return -ENOMEM;
 212
 213        data->client = client;
 214        mutex_init(&data->update_lock);
 215
 216        /* Clear faults */
 217        i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00);
 218
 219        hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 220                                                           data,
 221                                                           ltc4261_groups);
 222        return PTR_ERR_OR_ZERO(hwmon_dev);
 223}
 224
 225static const struct i2c_device_id ltc4261_id[] = {
 226        {"ltc4261", 0},
 227        {}
 228};
 229
 230MODULE_DEVICE_TABLE(i2c, ltc4261_id);
 231
 232/* This is the driver that will be inserted */
 233static struct i2c_driver ltc4261_driver = {
 234        .driver = {
 235                   .name = "ltc4261",
 236                   },
 237        .probe = ltc4261_probe,
 238        .id_table = ltc4261_id,
 239};
 240
 241module_i2c_driver(ltc4261_driver);
 242
 243MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
 244MODULE_DESCRIPTION("LTC4261 driver");
 245MODULE_LICENSE("GPL");
 246