linux/drivers/hwmon/ltc4151.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Driver for Linear Technology LTC4151 High Voltage I2C Current
   4 * and Voltage Monitor
   5 *
   6 * Copyright (C) 2011 AppearTV AS
   7 *
   8 * Derived from:
   9 *
  10 *  Driver for Linear Technology LTC4261 I2C Negative Voltage Hot
  11 *  Swap Controller
  12 *  Copyright (C) 2010 Ericsson AB.
  13 *
  14 * Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf
  15 */
  16
  17#include <linux/kernel.h>
  18#include <linux/module.h>
  19#include <linux/of.h>
  20#include <linux/init.h>
  21#include <linux/err.h>
  22#include <linux/slab.h>
  23#include <linux/i2c.h>
  24#include <linux/hwmon.h>
  25#include <linux/hwmon-sysfs.h>
  26#include <linux/jiffies.h>
  27
  28/* chip registers */
  29#define LTC4151_SENSE_H 0x00
  30#define LTC4151_SENSE_L 0x01
  31#define LTC4151_VIN_H   0x02
  32#define LTC4151_VIN_L   0x03
  33#define LTC4151_ADIN_H  0x04
  34#define LTC4151_ADIN_L  0x05
  35
  36struct ltc4151_data {
  37        struct i2c_client *client;
  38
  39        struct mutex update_lock;
  40        bool valid;
  41        unsigned long last_updated; /* in jiffies */
  42        unsigned int shunt; /* in micro ohms */
  43
  44        /* Registers */
  45        u8 regs[6];
  46};
  47
  48static struct ltc4151_data *ltc4151_update_device(struct device *dev)
  49{
  50        struct ltc4151_data *data = dev_get_drvdata(dev);
  51        struct i2c_client *client = data->client;
  52        struct ltc4151_data *ret = data;
  53
  54        mutex_lock(&data->update_lock);
  55
  56        /*
  57         * The chip's A/D updates 6 times per second
  58         * (Conversion Rate 6 - 9 Hz)
  59         */
  60        if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) {
  61                int i;
  62
  63                dev_dbg(&client->dev, "Starting ltc4151 update\n");
  64
  65                /* Read all registers */
  66                for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
  67                        int val;
  68
  69                        val = i2c_smbus_read_byte_data(client, i);
  70                        if (unlikely(val < 0)) {
  71                                dev_dbg(dev,
  72                                        "Failed to read ADC value: error %d\n",
  73                                        val);
  74                                ret = ERR_PTR(val);
  75                                goto abort;
  76                        }
  77                        data->regs[i] = val;
  78                }
  79                data->last_updated = jiffies;
  80                data->valid = 1;
  81        }
  82abort:
  83        mutex_unlock(&data->update_lock);
  84        return ret;
  85}
  86
  87/* Return the voltage from the given register in mV */
  88static int ltc4151_get_value(struct ltc4151_data *data, u8 reg)
  89{
  90        u32 val;
  91
  92        val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4);
  93
  94        switch (reg) {
  95        case LTC4151_ADIN_H:
  96                /* 500uV resolution. Convert to mV. */
  97                val = val * 500 / 1000;
  98                break;
  99        case LTC4151_SENSE_H:
 100                /*
 101                 * 20uV resolution. Convert to current as measured with
 102                 * a given sense resistor, in mA.
 103                 */
 104                val = val * 20 * 1000 / data->shunt;
 105                break;
 106        case LTC4151_VIN_H:
 107                /* 25 mV per increment */
 108                val = val * 25;
 109                break;
 110        default:
 111                /* If we get here, the developer messed up */
 112                WARN_ON_ONCE(1);
 113                val = 0;
 114                break;
 115        }
 116
 117        return val;
 118}
 119
 120static ssize_t ltc4151_value_show(struct device *dev,
 121                                  struct device_attribute *da, char *buf)
 122{
 123        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 124        struct ltc4151_data *data = ltc4151_update_device(dev);
 125        int value;
 126
 127        if (IS_ERR(data))
 128                return PTR_ERR(data);
 129
 130        value = ltc4151_get_value(data, attr->index);
 131        return snprintf(buf, PAGE_SIZE, "%d\n", value);
 132}
 133
 134/*
 135 * Input voltages.
 136 */
 137static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4151_value, LTC4151_VIN_H);
 138static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4151_value, LTC4151_ADIN_H);
 139
 140/* Currents (via sense resistor) */
 141static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4151_value, LTC4151_SENSE_H);
 142
 143/*
 144 * Finally, construct an array of pointers to members of the above objects,
 145 * as required for sysfs_create_group()
 146 */
 147static struct attribute *ltc4151_attrs[] = {
 148        &sensor_dev_attr_in1_input.dev_attr.attr,
 149        &sensor_dev_attr_in2_input.dev_attr.attr,
 150
 151        &sensor_dev_attr_curr1_input.dev_attr.attr,
 152
 153        NULL,
 154};
 155ATTRIBUTE_GROUPS(ltc4151);
 156
 157static int ltc4151_probe(struct i2c_client *client,
 158                         const struct i2c_device_id *id)
 159{
 160        struct i2c_adapter *adapter = client->adapter;
 161        struct device *dev = &client->dev;
 162        struct ltc4151_data *data;
 163        struct device *hwmon_dev;
 164        u32 shunt;
 165
 166        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 167                return -ENODEV;
 168
 169        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 170        if (!data)
 171                return -ENOMEM;
 172
 173        if (of_property_read_u32(client->dev.of_node,
 174                                 "shunt-resistor-micro-ohms", &shunt))
 175                shunt = 1000; /* 1 mOhm if not set via DT */
 176
 177        if (shunt == 0)
 178                return -EINVAL;
 179
 180        data->shunt = shunt;
 181
 182        data->client = client;
 183        mutex_init(&data->update_lock);
 184
 185        hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 186                                                           data,
 187                                                           ltc4151_groups);
 188        return PTR_ERR_OR_ZERO(hwmon_dev);
 189}
 190
 191static const struct i2c_device_id ltc4151_id[] = {
 192        { "ltc4151", 0 },
 193        { }
 194};
 195MODULE_DEVICE_TABLE(i2c, ltc4151_id);
 196
 197static const struct of_device_id __maybe_unused ltc4151_match[] = {
 198        { .compatible = "lltc,ltc4151" },
 199        {},
 200};
 201MODULE_DEVICE_TABLE(of, ltc4151_match);
 202
 203/* This is the driver that will be inserted */
 204static struct i2c_driver ltc4151_driver = {
 205        .driver = {
 206                .name   = "ltc4151",
 207                .of_match_table = of_match_ptr(ltc4151_match),
 208        },
 209        .probe          = ltc4151_probe,
 210        .id_table       = ltc4151_id,
 211};
 212
 213module_i2c_driver(ltc4151_driver);
 214
 215MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
 216MODULE_DESCRIPTION("LTC4151 driver");
 217MODULE_LICENSE("GPL");
 218