drivers/hwmon/ltc4151.c

   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
  36 struct 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
  48 static 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         }
  82 abort:
  83         mutex_unlock(&data->update_lock);
  84         return ret;
  85 }
  86
  87 /* Return the voltage from the given register in mV */
  88 static 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
 120 static 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  */
 137 static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4151_value, LTC4151_VIN_H);
 138 static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4151_value, LTC4151_ADIN_H);
 139
 140 /* Currents (via sense resistor) */
 141 static 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  */
 147 static 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 };
 155 ATTRIBUTE_GROUPS(ltc4151);
 156
 157 static 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
 191 static const struct i2c_device_id ltc4151_id[] = {
 192         { "ltc4151", 0 },
 193         { }
 194 };
 195 MODULE_DEVICE_TABLE(i2c, ltc4151_id);
 196
 197 static const struct of_device_id __maybe_unused ltc4151_match[] = {
 198         { .compatible = "lltc,ltc4151" },
 199         {},
 200 };
 201 MODULE_DEVICE_TABLE(of, ltc4151_match);
 202
 203 /* This is the driver that will be inserted */
 204 static 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
 213 module_i2c_driver(ltc4151_driver);
 214
 215 MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
 216 MODULE_DESCRIPTION("LTC4151 driver");
 217 MODULE_LICENSE("GPL");