drivers/hwmon/lm75.c

   1 /*
   2     lm75.c - Part of lm_sensors, Linux kernel modules for hardware
   3              monitoring
   4     Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/slab.h>
  24 #include <linux/jiffies.h>
  25 #include <linux/i2c.h>
  26 #include <linux/hwmon.h>
  27 #include <linux/hwmon-sysfs.h>
  28 #include <linux/err.h>
  29 #include <linux/mutex.h>
  30 #include "lm75.h"
  31
  32
  33 /* Addresses to scan */
  34 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
  35                                         0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
  36
  37 /* Insmod parameters */
  38 I2C_CLIENT_INSMOD_1(lm75);
  39
  40 /* Many LM75 constants specified below */
  41
  42 /* The LM75 registers */
  43 #define LM75_REG_CONF           0x01
  44 static const u8 LM75_REG_TEMP[3] = {
  45         0x00,           /* input */
  46         0x03,           /* max */
  47         0x02,           /* hyst */
  48 };
  49
  50 /* Each client has this additional data */
  51 struct lm75_data {
  52         struct i2c_client       client;
  53         struct device *hwmon_dev;
  54         struct mutex            update_lock;
  55         char                    valid;          /* !=0 if following fields are valid */
  56         unsigned long           last_updated;   /* In jiffies */
  57         u16                     temp[3];        /* Register values,
  58                                                    0 = input
  59                                                    1 = max
  60                                                    2 = hyst */
  61 };
  62
  63 static int lm75_attach_adapter(struct i2c_adapter *adapter);
  64 static int lm75_detect(struct i2c_adapter *adapter, int address, int kind);
  65 static void lm75_init_client(struct i2c_client *client);
  66 static int lm75_detach_client(struct i2c_client *client);
  67 static int lm75_read_value(struct i2c_client *client, u8 reg);
  68 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
  69 static struct lm75_data *lm75_update_device(struct device *dev);
  70
  71
  72 /* This is the driver that will be inserted */
  73 static struct i2c_driver lm75_driver = {
  74         .driver = {
  75                 .name   = "lm75",
  76         },
  77         .attach_adapter = lm75_attach_adapter,
  78         .detach_client  = lm75_detach_client,
  79 };
  80
  81 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
  82                          char *buf)
  83 {
  84         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  85         struct lm75_data *data = lm75_update_device(dev);
  86         return sprintf(buf, "%d\n",
  87                        LM75_TEMP_FROM_REG(data->temp[attr->index]));
  88 }
  89
  90 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
  91                         const char *buf, size_t count)
  92 {
  93         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  94         struct i2c_client *client = to_i2c_client(dev);
  95         struct lm75_data *data = i2c_get_clientdata(client);
  96         int nr = attr->index;
  97         long temp = simple_strtol(buf, NULL, 10);
  98
  99         mutex_lock(&data->update_lock);
 100         data->temp[nr] = LM75_TEMP_TO_REG(temp);
 101         lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
 102         mutex_unlock(&data->update_lock);
 103         return count;
 104 }
 105
 106 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
 107                         show_temp, set_temp, 1);
 108 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
 109                         show_temp, set_temp, 2);
 110 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
 111
 112 static int lm75_attach_adapter(struct i2c_adapter *adapter)
 113 {
 114         if (!(adapter->class & I2C_CLASS_HWMON))
 115                 return 0;
 116         return i2c_probe(adapter, &addr_data, lm75_detect);
 117 }
 118
 119 static struct attribute *lm75_attributes[] = {
 120         &sensor_dev_attr_temp1_input.dev_attr.attr,
 121         &sensor_dev_attr_temp1_max.dev_attr.attr,
 122         &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
 123
 124         NULL
 125 };
 126
 127 static const struct attribute_group lm75_group = {
 128         .attrs = lm75_attributes,
 129 };
 130
 131 /* This function is called by i2c_probe */
 132 static int lm75_detect(struct i2c_adapter *adapter, int address, int kind)
 133 {
 134         int i;
 135         struct i2c_client *new_client;
 136         struct lm75_data *data;
 137         int err = 0;
 138         const char *name = "";
 139
 140         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 141                                      I2C_FUNC_SMBUS_WORD_DATA))
 142                 goto exit;
 143
 144         /* OK. For now, we presume we have a valid client. We now create the
 145            client structure, even though we cannot fill it completely yet.
 146            But it allows us to access lm75_{read,write}_value. */
 147         if (!(data = kzalloc(sizeof(struct lm75_data), GFP_KERNEL))) {
 148                 err = -ENOMEM;
 149                 goto exit;
 150         }
 151
 152         new_client = &data->client;
 153         i2c_set_clientdata(new_client, data);
 154         new_client->addr = address;
 155         new_client->adapter = adapter;
 156         new_client->driver = &lm75_driver;
 157         new_client->flags = 0;
 158
 159         /* Now, we do the remaining detection. There is no identification-
 160            dedicated register so we have to rely on several tricks:
 161            unused bits, registers cycling over 8-address boundaries,
 162            addresses 0x04-0x07 returning the last read value.
 163            The cycling+unused addresses combination is not tested,
 164            since it would significantly slow the detection down and would
 165            hardly add any value. */
 166         if (kind < 0) {
 167                 int cur, conf, hyst, os;
 168
 169                 /* Unused addresses */
 170                 cur = i2c_smbus_read_word_data(new_client, 0);
 171                 conf = i2c_smbus_read_byte_data(new_client, 1);
 172                 hyst = i2c_smbus_read_word_data(new_client, 2);
 173                 if (i2c_smbus_read_word_data(new_client, 4) != hyst
 174                  || i2c_smbus_read_word_data(new_client, 5) != hyst
 175                  || i2c_smbus_read_word_data(new_client, 6) != hyst
 176                  || i2c_smbus_read_word_data(new_client, 7) != hyst)
 177                         goto exit_free;
 178                 os = i2c_smbus_read_word_data(new_client, 3);
 179                 if (i2c_smbus_read_word_data(new_client, 4) != os
 180                  || i2c_smbus_read_word_data(new_client, 5) != os
 181                  || i2c_smbus_read_word_data(new_client, 6) != os
 182                  || i2c_smbus_read_word_data(new_client, 7) != os)
 183                         goto exit_free;
 184
 185                 /* Unused bits */
 186                 if (conf & 0xe0)
 187                         goto exit_free;
 188
 189                 /* Addresses cycling */
 190                 for (i = 8; i < 0xff; i += 8)
 191                         if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
 192                          || i2c_smbus_read_word_data(new_client, i + 2) != hyst
 193                          || i2c_smbus_read_word_data(new_client, i + 3) != os)
 194                                 goto exit_free;
 195         }
 196
 197         /* Determine the chip type - only one kind supported! */
 198         if (kind <= 0)
 199                 kind = lm75;
 200
 201         if (kind == lm75) {
 202                 name = "lm75";
 203         }
 204
 205         /* Fill in the remaining client fields and put it into the global list */
 206         strlcpy(new_client->name, name, I2C_NAME_SIZE);
 207         data->valid = 0;
 208         mutex_init(&data->update_lock);
 209
 210         /* Tell the I2C layer a new client has arrived */
 211         if ((err = i2c_attach_client(new_client)))
 212                 goto exit_free;
 213
 214         /* Initialize the LM75 chip */
 215         lm75_init_client(new_client);
 216
 217         /* Register sysfs hooks */
 218         if ((err = sysfs_create_group(&new_client->dev.kobj, &lm75_group)))
 219                 goto exit_detach;
 220
 221         data->hwmon_dev = hwmon_device_register(&new_client->dev);
 222         if (IS_ERR(data->hwmon_dev)) {
 223                 err = PTR_ERR(data->hwmon_dev);
 224                 goto exit_remove;
 225         }
 226
 227         return 0;
 228
 229 exit_remove:
 230         sysfs_remove_group(&new_client->dev.kobj, &lm75_group);
 231 exit_detach:
 232         i2c_detach_client(new_client);
 233 exit_free:
 234         kfree(data);
 235 exit:
 236         return err;
 237 }
 238
 239 static int lm75_detach_client(struct i2c_client *client)
 240 {
 241         struct lm75_data *data = i2c_get_clientdata(client);
 242         hwmon_device_unregister(data->hwmon_dev);
 243         sysfs_remove_group(&client->dev.kobj, &lm75_group);
 244         i2c_detach_client(client);
 245         kfree(data);
 246         return 0;
 247 }
 248
 249 /* All registers are word-sized, except for the configuration register.
 250    LM75 uses a high-byte first convention, which is exactly opposite to
 251    the SMBus standard. */
 252 static int lm75_read_value(struct i2c_client *client, u8 reg)
 253 {
 254         if (reg == LM75_REG_CONF)
 255                 return i2c_smbus_read_byte_data(client, reg);
 256         else
 257                 return swab16(i2c_smbus_read_word_data(client, reg));
 258 }
 259
 260 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
 261 {
 262         if (reg == LM75_REG_CONF)
 263                 return i2c_smbus_write_byte_data(client, reg, value);
 264         else
 265                 return i2c_smbus_write_word_data(client, reg, swab16(value));
 266 }
 267
 268 static void lm75_init_client(struct i2c_client *client)
 269 {
 270         int reg;
 271
 272         /* Enable if in shutdown mode */
 273         reg = lm75_read_value(client, LM75_REG_CONF);
 274         if (reg >= 0 && (reg & 0x01))
 275                 lm75_write_value(client, LM75_REG_CONF, reg & 0xfe);
 276 }
 277
 278 static struct lm75_data *lm75_update_device(struct device *dev)
 279 {
 280         struct i2c_client *client = to_i2c_client(dev);
 281         struct lm75_data *data = i2c_get_clientdata(client);
 282
 283         mutex_lock(&data->update_lock);
 284
 285         if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
 286             || !data->valid) {
 287                 int i;
 288                 dev_dbg(&client->dev, "Starting lm75 update\n");
 289
 290                 for (i = 0; i < ARRAY_SIZE(data->temp); i++)
 291                         data->temp[i] = lm75_read_value(client,
 292                                                         LM75_REG_TEMP[i]);
 293                 data->last_updated = jiffies;
 294                 data->valid = 1;
 295         }
 296
 297         mutex_unlock(&data->update_lock);
 298
 299         return data;
 300 }
 301
 302 static int __init sensors_lm75_init(void)
 303 {
 304         return i2c_add_driver(&lm75_driver);
 305 }
 306
 307 static void __exit sensors_lm75_exit(void)
 308 {
 309         i2c_del_driver(&lm75_driver);
 310 }
 311
 312 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
 313 MODULE_DESCRIPTION("LM75 driver");
 314 MODULE_LICENSE("GPL");
 315
 316 module_init(sensors_lm75_init);
 317 module_exit(sensors_lm75_exit);