LXR linux/drivers/hwmon/tc74.c

   1/*
   2 * An hwmon driver for the Microchip TC74
   3 *
   4 * Copyright 2015 Maciej Szmigiero <mail@maciej.szmigiero.name>
   5 *
   6 * Based on ad7414.c:
   7 *      Copyright 2006 Stefan Roese, DENX Software Engineering
   8 *      Copyright 2008 Sean MacLennan, PIKA Technologies
   9 *      Copyright 2008 Frank Edelhaeuser, Spansion Inc.
  10 *
  11 * This program is free software; you can redistribute it and/or modify
  12 * it under the terms of the GNU General Public License as published by
  13 * the Free Software Foundation; either version 2 of the License, or
  14 * (at your option) any later version.
  15 */
  16
  17#include <linux/bitops.h>
  18#include <linux/err.h>
  19#include <linux/hwmon.h>
  20#include <linux/hwmon-sysfs.h>
  21#include <linux/i2c.h>
  22#include <linux/jiffies.h>
  23#include <linux/module.h>
  24#include <linux/mutex.h>
  25#include <linux/slab.h>
  26#include <linux/sysfs.h>
  27
  28/* TC74 registers */
  29#define TC74_REG_TEMP           0x00
  30#define TC74_REG_CONFIG         0x01
  31
  32struct tc74_data {
  33        struct i2c_client       *client;
  34        struct mutex            lock;   /* atomic read data updates */
  35        bool                    valid;  /* validity of fields below */
  36        unsigned long           next_update;    /* In jiffies */
  37        s8                      temp_input;     /* Temp value in dC */
  38};
  39
  40static int tc74_update_device(struct device *dev)
  41{
  42        struct tc74_data *data = dev_get_drvdata(dev);
  43        struct i2c_client *client = data->client;
  44        int ret;
  45
  46        ret = mutex_lock_interruptible(&data->lock);
  47        if (ret)
  48                return ret;
  49
  50        if (time_after(jiffies, data->next_update) || !data->valid) {
  51                s32 value;
  52
  53                value = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
  54                if (value < 0) {
  55                        dev_dbg(&client->dev, "TC74_REG_CONFIG read err %d\n",
  56                                (int)value);
  57
  58                        ret = value;
  59                        goto ret_unlock;
  60                }
  61
  62                if (!(value & BIT(6))) {
  63                        /* not ready yet */
  64
  65                        ret = -EAGAIN;
  66                        goto ret_unlock;
  67                }
  68
  69                value = i2c_smbus_read_byte_data(client, TC74_REG_TEMP);
  70                if (value < 0) {
  71                        dev_dbg(&client->dev, "TC74_REG_TEMP read err %d\n",
  72                                (int)value);
  73
  74                        ret = value;
  75                        goto ret_unlock;
  76                }
  77
  78                data->temp_input = value;
  79                data->next_update = jiffies + HZ / 4;
  80                data->valid = true;
  81        }
  82
  83ret_unlock:
  84        mutex_unlock(&data->lock);
  85
  86        return ret;
  87}
  88
  89static ssize_t show_temp_input(struct device *dev,
  90                               struct device_attribute *attr, char *buf)
  91{
  92        struct tc74_data *data = dev_get_drvdata(dev);
  93        int ret;
  94
  95        ret = tc74_update_device(dev);
  96        if (ret)
  97                return ret;
  98
  99        return sprintf(buf, "%d\n", data->temp_input * 1000);
 100}
 101static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL, 0);
 102
 103static struct attribute *tc74_attrs[] = {
 104        &sensor_dev_attr_temp1_input.dev_attr.attr,
 105        NULL
 106};
 107
 108ATTRIBUTE_GROUPS(tc74);
 109
 110static int tc74_probe(struct i2c_client *client,
 111                      const struct i2c_device_id *dev_id)
 112{
 113        struct device *dev = &client->dev;
 114        struct tc74_data *data;
 115        struct device *hwmon_dev;
 116        s32 conf;
 117
 118        if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 119                return -EOPNOTSUPP;
 120
 121        data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);
 122        if (!data)
 123                return -ENOMEM;
 124
 125        data->client = client;
 126        mutex_init(&data->lock);
 127
 128        /* Make sure the chip is powered up. */
 129        conf = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
 130        if (conf < 0) {
 131                dev_err(dev, "unable to read config register\n");
 132
 133                return conf;
 134        }
 135
 136        if (conf & 0x3f) {
 137                dev_err(dev, "invalid config register value\n");
 138
 139                return -ENODEV;
 140        }
 141
 142        if (conf & BIT(7)) {
 143                s32 ret;
 144
 145                conf &= ~BIT(7);
 146
 147                ret = i2c_smbus_write_byte_data(client, TC74_REG_CONFIG, conf);
 148                if (ret)
 149                        dev_warn(dev, "unable to disable STANDBY\n");
 150        }
 151
 152        hwmon_dev = devm_hwmon_device_register_with_groups(dev,
 153                                                           client->name,
 154                                                           data, tc74_groups);
 155        return PTR_ERR_OR_ZERO(hwmon_dev);
 156}
 157
 158static const struct i2c_device_id tc74_id[] = {
 159        { "tc74", 0 },
 160        {}
 161};
 162MODULE_DEVICE_TABLE(i2c, tc74_id);
 163
 164static struct i2c_driver tc74_driver = {
 165        .driver = {
 166                .name   = "tc74",
 167        },
 168        .probe  = tc74_probe,
 169        .id_table = tc74_id,
 170};
 171
 172module_i2c_driver(tc74_driver);
 173
 174MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");
 175
 176MODULE_DESCRIPTION("TC74 driver");
 177MODULE_LICENSE("GPL");
 178