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#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
  49struct ltc4151_data {
  50        struct device *hwmon_dev;
  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
  60static struct ltc4151_data *ltc4151_update_device(struct device *dev)
  61{
  62        struct i2c_client *client = to_i2c_client(dev);
  63        struct ltc4151_data *data = i2c_get_clientdata(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        }
  94abort:
  95        mutex_unlock(&data->update_lock);
  96        return ret;
  97}
  98
  99/* Return the voltage from the given register in mV */
 100static 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
 132static 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 */
 149static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, \
 150        ltc4151_show_value, NULL, LTC4151_VIN_H);
 151static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, \
 152        ltc4151_show_value, NULL, LTC4151_ADIN_H);
 153
 154/* Currents (via sense resistor) */
 155static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, \
 156        ltc4151_show_value, NULL, 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 */
 162static struct attribute *ltc4151_attributes[] = {
 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
 171static const struct attribute_group ltc4151_group = {
 172        .attrs = ltc4151_attributes,
 173};
 174
 175static int ltc4151_probe(struct i2c_client *client,
 176                         const struct i2c_device_id *id)
 177{
 178        struct i2c_adapter *adapter = client->adapter;
 179        struct ltc4151_data *data;
 180        int ret;
 181
 182        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 183                return -ENODEV;
 184
 185        data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
 186        if (!data)
 187                return -ENOMEM;
 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                return ret;
 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
 205out_hwmon_device_register:
 206        sysfs_remove_group(&client->dev.kobj, &ltc4151_group);
 207        return ret;
 208}
 209
 210static int ltc4151_remove(struct i2c_client *client)
 211{
 212        struct ltc4151_data *data = i2c_get_clientdata(client);
 213
 214        hwmon_device_unregister(data->hwmon_dev);
 215        sysfs_remove_group(&client->dev.kobj, &ltc4151_group);
 216
 217        return 0;
 218}
 219
 220static const struct i2c_device_id ltc4151_id[] = {
 221        { "ltc4151", 0 },
 222        { }
 223};
 224MODULE_DEVICE_TABLE(i2c, ltc4151_id);
 225
 226/* This is the driver that will be inserted */
 227static struct i2c_driver ltc4151_driver = {
 228        .driver = {
 229                .name   = "ltc4151",
 230        },
 231        .probe          = ltc4151_probe,
 232        .remove         = ltc4151_remove,
 233        .id_table       = ltc4151_id,
 234};
 235
 236module_i2c_driver(ltc4151_driver);
 237
 238MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
 239MODULE_DESCRIPTION("LTC4151 driver");
 240MODULE_LICENSE("GPL");
 241
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