linux/drivers/hwmon/ltc4151.c
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   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
  48struct 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
  59static 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        }
  93abort:
  94        mutex_unlock(&data->update_lock);
  95        return ret;
  96}
  97
  98/* Return the voltage from the given register in mV */
  99static 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
 131static 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 */
 148static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, \
 149        ltc4151_show_value, NULL, LTC4151_VIN_H);
 150static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, \
 151        ltc4151_show_value, NULL, LTC4151_ADIN_H);
 152
 153/* Currents (via sense resistor) */
 154static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, \
 155        ltc4151_show_value, NULL, LTC4151_SENSE_H);
 156
 157/*
 158 * Finally, construct an array of pointers to members of the above objects,
 159 * as required for sysfs_create_group()
 160 */
 161static struct attribute *ltc4151_attributes[] = {
 162        &sensor_dev_attr_in1_input.dev_attr.attr,
 163        &sensor_dev_attr_in2_input.dev_attr.attr,
 164
 165        &sensor_dev_attr_curr1_input.dev_attr.attr,
 166
 167        NULL,
 168};
 169
 170static const struct attribute_group ltc4151_group = {
 171        .attrs = ltc4151_attributes,
 172};
 173
 174static int ltc4151_probe(struct i2c_client *client,
 175                         const struct i2c_device_id *id)
 176{
 177        struct i2c_adapter *adapter = client->adapter;
 178        struct ltc4151_data *data;
 179        int ret;
 180
 181        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 182                return -ENODEV;
 183
 184        data = kzalloc(sizeof(*data), GFP_KERNEL);
 185        if (!data) {
 186                ret = -ENOMEM;
 187                goto out_kzalloc;
 188        }
 189
 190        i2c_set_clientdata(client, data);
 191        mutex_init(&data->update_lock);
 192
 193        /* Register sysfs hooks */
 194        ret = sysfs_create_group(&client->dev.kobj, &ltc4151_group);
 195        if (ret)
 196                goto out_sysfs_create_group;
 197
 198        data->hwmon_dev = hwmon_device_register(&client->dev);
 199        if (IS_ERR(data->hwmon_dev)) {
 200                ret = PTR_ERR(data->hwmon_dev);
 201                goto out_hwmon_device_register;
 202        }
 203
 204        return 0;
 205
 206out_hwmon_device_register:
 207        sysfs_remove_group(&client->dev.kobj, &ltc4151_group);
 208out_sysfs_create_group:
 209        kfree(data);
 210out_kzalloc:
 211        return ret;
 212}
 213
 214static int ltc4151_remove(struct i2c_client *client)
 215{
 216        struct ltc4151_data *data = i2c_get_clientdata(client);
 217
 218        hwmon_device_unregister(data->hwmon_dev);
 219        sysfs_remove_group(&client->dev.kobj, &ltc4151_group);
 220
 221        kfree(data);
 222
 223        return 0;
 224}
 225
 226static const struct i2c_device_id ltc4151_id[] = {
 227        { "ltc4151", 0 },
 228        { }
 229};
 230MODULE_DEVICE_TABLE(i2c, ltc4151_id);
 231
 232/* This is the driver that will be inserted */
 233static struct i2c_driver ltc4151_driver = {
 234        .driver = {
 235                .name   = "ltc4151",
 236        },
 237        .probe          = ltc4151_probe,
 238        .remove         = ltc4151_remove,
 239        .id_table       = ltc4151_id,
 240};
 241
 242module_i2c_driver(ltc4151_driver);
 243
 244MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
 245MODULE_DESCRIPTION("LTC4151 driver");
 246MODULE_LICENSE("GPL");
 247
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