drivers/hwmon/ltc4151.c

   1 /*
   2  * Driver for Linear Technology LTC4151 High Voltage I2C Current
   3  * and Voltage Monitor
   4  *
   5  * Copyright (C) 2011 AppearTV AS
   6  *
   7  * Derived from:
   8  *
   9  *  Driver for Linear Technology LTC4261 I2C Negative Voltage Hot
  10  *  Swap Controller
  11  *  Copyright (C) 2010 Ericsson AB.
  12  *
  13  * Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf
  14  *
  15  * This program is free software; you can redistribute it and/or modify
  16  * it under the terms of the GNU General Public License as published by
  17  * the Free Software Foundation; either version 2 of the License, or
  18  * (at your option) any later version.
  19  *
  20  * This program is distributed in the hope that it will be useful,
  21  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  * GNU General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program; if not, write to the Free Software
  27  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  28  *
  29  */
  30
  31 #include <linux/kernel.h>
  32 #include <linux/module.h>
  33 #include <linux/init.h>
  34 #include <linux/err.h>
  35 #include <linux/slab.h>
  36 #include <linux/i2c.h>
  37 #include <linux/hwmon.h>
  38 #include <linux/hwmon-sysfs.h>
  39 #include <linux/jiffies.h>
  40
  41 /* chip registers */
  42 #define LTC4151_SENSE_H 0x00
  43 #define LTC4151_SENSE_L 0x01
  44 #define LTC4151_VIN_H   0x02
  45 #define LTC4151_VIN_L   0x03
  46 #define LTC4151_ADIN_H  0x04
  47 #define LTC4151_ADIN_L  0x05
  48
  49 struct ltc4151_data {
  50         struct i2c_client *client;
  51
  52         struct mutex update_lock;
  53         bool valid;
  54         unsigned long last_updated; /* in jiffies */
  55
  56         /* Registers */
  57         u8 regs[6];
  58 };
  59
  60 static struct ltc4151_data *ltc4151_update_device(struct device *dev)
  61 {
  62         struct ltc4151_data *data = dev_get_drvdata(dev);
  63         struct i2c_client *client = data->client;
  64         struct ltc4151_data *ret = data;
  65
  66         mutex_lock(&data->update_lock);
  67
  68         /*
  69          * The chip's A/D updates 6 times per second
  70          * (Conversion Rate 6 - 9 Hz)
  71          */
  72         if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) {
  73                 int i;
  74
  75                 dev_dbg(&client->dev, "Starting ltc4151 update\n");
  76
  77                 /* Read all registers */
  78                 for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
  79                         int val;
  80
  81                         val = i2c_smbus_read_byte_data(client, i);
  82                         if (unlikely(val < 0)) {
  83                                 dev_dbg(dev,
  84                                         "Failed to read ADC value: error %d\n",
  85                                         val);
  86                                 ret = ERR_PTR(val);
  87                                 goto abort;
  88                         }
  89                         data->regs[i] = val;
  90                 }
  91                 data->last_updated = jiffies;
  92                 data->valid = 1;
  93         }
  94 abort:
  95         mutex_unlock(&data->update_lock);
  96         return ret;
  97 }
  98
  99 /* Return the voltage from the given register in mV */
 100 static int ltc4151_get_value(struct ltc4151_data *data, u8 reg)
 101 {
 102         u32 val;
 103
 104         val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4);
 105
 106         switch (reg) {
 107         case LTC4151_ADIN_H:
 108                 /* 500uV resolution. Convert to mV. */
 109                 val = val * 500 / 1000;
 110                 break;
 111         case LTC4151_SENSE_H:
 112                 /*
 113                  * 20uV resolution. Convert to current as measured with
 114                  * an 1 mOhm sense resistor, in mA.
 115                  */
 116                 val = val * 20;
 117                 break;
 118         case LTC4151_VIN_H:
 119                 /* 25 mV per increment */
 120                 val = val * 25;
 121                 break;
 122         default:
 123                 /* If we get here, the developer messed up */
 124                 WARN_ON_ONCE(1);
 125                 val = 0;
 126                 break;
 127         }
 128
 129         return val;
 130 }
 131
 132 static ssize_t ltc4151_show_value(struct device *dev,
 133                                   struct device_attribute *da, char *buf)
 134 {
 135         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 136         struct ltc4151_data *data = ltc4151_update_device(dev);
 137         int value;
 138
 139         if (IS_ERR(data))
 140                 return PTR_ERR(data);
 141
 142         value = ltc4151_get_value(data, attr->index);
 143         return snprintf(buf, PAGE_SIZE, "%d\n", value);
 144 }
 145
 146 /*
 147  * Input voltages.
 148  */
 149 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4151_show_value, NULL,
 150                           LTC4151_VIN_H);
 151 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4151_show_value, NULL,
 152                           LTC4151_ADIN_H);
 153
 154 /* Currents (via sense resistor) */
 155 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4151_show_value, NULL,
 156                           LTC4151_SENSE_H);
 157
 158 /*
 159  * Finally, construct an array of pointers to members of the above objects,
 160  * as required for sysfs_create_group()
 161  */
 162 static struct attribute *ltc4151_attrs[] = {
 163         &sensor_dev_attr_in1_input.dev_attr.attr,
 164         &sensor_dev_attr_in2_input.dev_attr.attr,
 165
 166         &sensor_dev_attr_curr1_input.dev_attr.attr,
 167
 168         NULL,
 169 };
 170 ATTRIBUTE_GROUPS(ltc4151);
 171
 172 static int ltc4151_probe(struct i2c_client *client,
 173                          const struct i2c_device_id *id)
 174 {
 175         struct i2c_adapter *adapter = client->adapter;
 176         struct device *dev = &client->dev;
 177         struct ltc4151_data *data;
 178         struct device *hwmon_dev;
 179
 180         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 181                 return -ENODEV;
 182
 183         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 184         if (!data)
 185                 return -ENOMEM;
 186
 187         data->client = client;
 188         mutex_init(&data->update_lock);
 189
 190         hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 191                                                            data,
 192                                                            ltc4151_groups);
 193         return PTR_ERR_OR_ZERO(hwmon_dev);
 194 }
 195
 196 static const struct i2c_device_id ltc4151_id[] = {
 197         { "ltc4151", 0 },
 198         { }
 199 };
 200 MODULE_DEVICE_TABLE(i2c, ltc4151_id);
 201
 202 /* This is the driver that will be inserted */
 203 static struct i2c_driver ltc4151_driver = {
 204         .driver = {
 205                 .name   = "ltc4151",
 206         },
 207         .probe          = ltc4151_probe,
 208         .id_table       = ltc4151_id,
 209 };
 210
 211 module_i2c_driver(ltc4151_driver);
 212
 213 MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
 214 MODULE_DESCRIPTION("LTC4151 driver");
 215 MODULE_LICENSE("GPL");