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
  40 /* chip registers */
  41 #define LTC4151_SENSE_H 0x00
  42 #define LTC4151_SENSE_L 0x01
  43 #define LTC4151_VIN_H   0x02
  44 #define LTC4151_VIN_L   0x03
  45 #define LTC4151_ADIN_H  0x04
  46 #define LTC4151_ADIN_L  0x05
  47
  48 struct ltc4151_data {
  49         struct device *hwmon_dev;
  50
  51         struct mutex update_lock;
  52         bool valid;
  53         unsigned long last_updated; /* in jiffies */
  54
  55         /* Registers */
  56         u8 regs[6];
  57 };
  58
  59 static struct ltc4151_data *ltc4151_update_device(struct device *dev)
  60 {
  61         struct i2c_client *client = to_i2c_client(dev);
  62         struct ltc4151_data *data = i2c_get_clientdata(client);
  63         struct ltc4151_data *ret = data;
  64
  65         mutex_lock(&data->update_lock);
  66
  67         /*
  68          * The chip's A/D updates 6 times per second
  69          * (Conversion Rate 6 - 9 Hz)
  70          */
  71         if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) {
  72                 int i;
  73
  74                 dev_dbg(&client->dev, "Starting ltc4151 update\n");
  75
  76                 /* Read all registers */
  77                 for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
  78                         int val;
  79
  80                         val = i2c_smbus_read_byte_data(client, i);
  81                         if (unlikely(val < 0)) {
  82                                 dev_dbg(dev,
  83                                         "Failed to read ADC value: error %d\n",
  84                                         val);
  85                                 ret = ERR_PTR(val);
  86                                 goto abort;
  87                         }
  88                         data->regs[i] = val;
  89                 }
  90                 data->last_updated = jiffies;
  91                 data->valid = 1;
  92         }
  93 abort:
  94         mutex_unlock(&data->update_lock);
  95         return ret;
  96 }
  97
  98 /* Return the voltage from the given register in mV */
  99 static int ltc4151_get_value(struct ltc4151_data *data, u8 reg)
 100 {
 101         u32 val;
 102
 103         val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4);
 104
 105         switch (reg) {
 106         case LTC4151_ADIN_H:
 107                 /* 500uV resolution. Convert to mV. */
 108                 val = val * 500 / 1000;
 109                 break;
 110         case LTC4151_SENSE_H:
 111                 /*
 112                  * 20uV resolution. Convert to current as measured with
 113                  * an 1 mOhm sense resistor, in mA.
 114                  */
 115                 val = val * 20;
 116                 break;
 117         case LTC4151_VIN_H:
 118                 /* 25 mV per increment */
 119                 val = val * 25;
 120                 break;
 121         default:
 122                 /* If we get here, the developer messed up */
 123                 WARN_ON_ONCE(1);
 124                 val = 0;
 125                 break;
 126         }
 127
 128         return val;
 129 }
 130
 131 static ssize_t ltc4151_show_value(struct device *dev,
 132                                   struct device_attribute *da, char *buf)
 133 {
 134         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 135         struct ltc4151_data *data = ltc4151_update_device(dev);
 136         int value;
 137
 138         if (IS_ERR(data))
 139                 return PTR_ERR(data);
 140
 141         value = ltc4151_get_value(data, attr->index);
 142         return snprintf(buf, PAGE_SIZE, "%d\n", value);
 143 }
 144
 145 /*
 146  * Input voltages.
 147  */
 148 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, \
 149         ltc4151_show_value, NULL, LTC4151_VIN_H);
 150 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, \
 151         ltc4151_show_value, NULL, LTC4151_ADIN_H);
 152
 153 /* Currents (via sense resistor) */
 154 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, \
 155         ltc4151_show_value, NULL, LTC4151_SENSE_H);
 156
 157 /* Finally, construct an array of pointers to members of the above objects,
 158  * as required for sysfs_create_group()
 159  */
 160 static struct attribute *ltc4151_attributes[] = {
 161         &sensor_dev_attr_in1_input.dev_attr.attr,
 162         &sensor_dev_attr_in2_input.dev_attr.attr,
 163
 164         &sensor_dev_attr_curr1_input.dev_attr.attr,
 165
 166         NULL,
 167 };
 168
 169 static const struct attribute_group ltc4151_group = {
 170         .attrs = ltc4151_attributes,
 171 };
 172
 173 static int ltc4151_probe(struct i2c_client *client,
 174                          const struct i2c_device_id *id)
 175 {
 176         struct i2c_adapter *adapter = client->adapter;
 177         struct ltc4151_data *data;
 178         int ret;
 179
 180         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 181                 return -ENODEV;
 182
 183         data = kzalloc(sizeof(*data), GFP_KERNEL);
 184         if (!data) {
 185                 ret = -ENOMEM;
 186                 goto out_kzalloc;
 187         }
 188
 189         i2c_set_clientdata(client, data);
 190         mutex_init(&data->update_lock);
 191
 192         /* Register sysfs hooks */
 193         ret = sysfs_create_group(&client->dev.kobj, &ltc4151_group);
 194         if (ret)
 195                 goto out_sysfs_create_group;
 196
 197         data->hwmon_dev = hwmon_device_register(&client->dev);
 198         if (IS_ERR(data->hwmon_dev)) {
 199                 ret = PTR_ERR(data->hwmon_dev);
 200                 goto out_hwmon_device_register;
 201         }
 202
 203         return 0;
 204
 205 out_hwmon_device_register:
 206         sysfs_remove_group(&client->dev.kobj, &ltc4151_group);
 207 out_sysfs_create_group:
 208         kfree(data);
 209 out_kzalloc:
 210         return ret;
 211 }
 212
 213 static int ltc4151_remove(struct i2c_client *client)
 214 {
 215         struct ltc4151_data *data = i2c_get_clientdata(client);
 216
 217         hwmon_device_unregister(data->hwmon_dev);
 218         sysfs_remove_group(&client->dev.kobj, &ltc4151_group);
 219
 220         kfree(data);
 221
 222         return 0;
 223 }
 224
 225 static const struct i2c_device_id ltc4151_id[] = {
 226         { "ltc4151", 0 },
 227         { }
 228 };
 229 MODULE_DEVICE_TABLE(i2c, ltc4151_id);
 230
 231 /* This is the driver that will be inserted */
 232 static struct i2c_driver ltc4151_driver = {
 233         .driver = {
 234                 .name   = "ltc4151",
 235         },
 236         .probe          = ltc4151_probe,
 237         .remove         = ltc4151_remove,
 238         .id_table       = ltc4151_id,
 239 };
 240
 241 static int __init ltc4151_init(void)
 242 {
 243         return i2c_add_driver(&ltc4151_driver);
 244 }
 245
 246 static void __exit ltc4151_exit(void)
 247 {
 248         i2c_del_driver(&ltc4151_driver);
 249 }
 250
 251 MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
 252 MODULE_DESCRIPTION("LTC4151 driver");
 253 MODULE_LICENSE("GPL");
 254
 255 module_init(ltc4151_init);
 256 module_exit(ltc4151_exit);