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
  32 struct 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
  40 static 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
  83 ret_unlock:
  84         mutex_unlock(&data->lock);
  85
  86         return ret;
  87 }
  88
  89 static ssize_t temp_input_show(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 }
 101 static SENSOR_DEVICE_ATTR_RO(temp1_input, temp_input, 0);
 102
 103 static struct attribute *tc74_attrs[] = {
 104         &sensor_dev_attr_temp1_input.dev_attr.attr,
 105         NULL
 106 };
 107
 108 ATTRIBUTE_GROUPS(tc74);
 109
 110 static 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
 158 static const struct i2c_device_id tc74_id[] = {
 159         { "tc74", 0 },
 160         {}
 161 };
 162 MODULE_DEVICE_TABLE(i2c, tc74_id);
 163
 164 static struct i2c_driver tc74_driver = {
 165         .driver = {
 166                 .name   = "tc74",
 167         },
 168         .probe  = tc74_probe,
 169         .id_table = tc74_id,
 170 };
 171
 172 module_i2c_driver(tc74_driver);
 173
 174 MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");
 175
 176 MODULE_DESCRIPTION("TC74 driver");
 177 MODULE_LICENSE("GPL");