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/err.h>
  28 #include <linux/mutex.h>
  29 #include "lm75.h"
  30
  31
  32 /* Addresses to scan */
  33 static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
  34                                         0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
  35
  36 /* Insmod parameters */
  37 I2C_CLIENT_INSMOD_1(lm75);
  38
  39 /* Many LM75 constants specified below */
  40
  41 /* The LM75 registers */
  42 #define LM75_REG_TEMP           0x00
  43 #define LM75_REG_CONF           0x01
  44 #define LM75_REG_TEMP_HYST      0x02
  45 #define LM75_REG_TEMP_OS        0x03
  46
  47 /* Each client has this additional data */
  48 struct lm75_data {
  49         struct i2c_client       client;
  50         struct class_device *class_dev;
  51         struct mutex            update_lock;
  52         char                    valid;          /* !=0 if following fields are valid */
  53         unsigned long           last_updated;   /* In jiffies */
  54         u16                     temp_input;     /* Register values */
  55         u16                     temp_max;
  56         u16                     temp_hyst;
  57 };
  58
  59 static int lm75_attach_adapter(struct i2c_adapter *adapter);
  60 static int lm75_detect(struct i2c_adapter *adapter, int address, int kind);
  61 static void lm75_init_client(struct i2c_client *client);
  62 static int lm75_detach_client(struct i2c_client *client);
  63 static int lm75_read_value(struct i2c_client *client, u8 reg);
  64 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
  65 static struct lm75_data *lm75_update_device(struct device *dev);
  66
  67
  68 /* This is the driver that will be inserted */
  69 static struct i2c_driver lm75_driver = {
  70         .driver = {
  71                 .name   = "lm75",
  72         },
  73         .id             = I2C_DRIVERID_LM75,
  74         .attach_adapter = lm75_attach_adapter,
  75         .detach_client  = lm75_detach_client,
  76 };
  77
  78 #define show(value)     \
  79 static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)               \
  80 {                                                                       \
  81         struct lm75_data *data = lm75_update_device(dev);               \
  82         return sprintf(buf, "%d\n", LM75_TEMP_FROM_REG(data->value));   \
  83 }
  84 show(temp_max);
  85 show(temp_hyst);
  86 show(temp_input);
  87
  88 #define set(value, reg) \
  89 static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)    \
  90 {                                                               \
  91         struct i2c_client *client = to_i2c_client(dev);         \
  92         struct lm75_data *data = i2c_get_clientdata(client);    \
  93         int temp = simple_strtoul(buf, NULL, 10);               \
  94                                                                 \
  95         mutex_lock(&data->update_lock);                         \
  96         data->value = LM75_TEMP_TO_REG(temp);                   \
  97         lm75_write_value(client, reg, data->value);             \
  98         mutex_unlock(&data->update_lock);                                       \
  99         return count;                                           \
 100 }
 101 set(temp_max, LM75_REG_TEMP_OS);
 102 set(temp_hyst, LM75_REG_TEMP_HYST);
 103
 104 static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp_max, set_temp_max);
 105 static DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO, show_temp_hyst, set_temp_hyst);
 106 static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL);
 107
 108 static int lm75_attach_adapter(struct i2c_adapter *adapter)
 109 {
 110         if (!(adapter->class & I2C_CLASS_HWMON))
 111                 return 0;
 112         return i2c_probe(adapter, &addr_data, lm75_detect);
 113 }
 114
 115 static struct attribute *lm75_attributes[] = {
 116         &dev_attr_temp1_input.attr,
 117         &dev_attr_temp1_max.attr,
 118         &dev_attr_temp1_max_hyst.attr,
 119
 120         NULL
 121 };
 122
 123 static const struct attribute_group lm75_group = {
 124         .attrs = lm75_attributes,
 125 };
 126
 127 /* This function is called by i2c_probe */
 128 static int lm75_detect(struct i2c_adapter *adapter, int address, int kind)
 129 {
 130         int i;
 131         struct i2c_client *new_client;
 132         struct lm75_data *data;
 133         int err = 0;
 134         const char *name = "";
 135
 136         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 137                                      I2C_FUNC_SMBUS_WORD_DATA))
 138                 goto exit;
 139
 140         /* OK. For now, we presume we have a valid client. We now create the
 141            client structure, even though we cannot fill it completely yet.
 142            But it allows us to access lm75_{read,write}_value. */
 143         if (!(data = kzalloc(sizeof(struct lm75_data), GFP_KERNEL))) {
 144                 err = -ENOMEM;
 145                 goto exit;
 146         }
 147
 148         new_client = &data->client;
 149         i2c_set_clientdata(new_client, data);
 150         new_client->addr = address;
 151         new_client->adapter = adapter;
 152         new_client->driver = &lm75_driver;
 153         new_client->flags = 0;
 154
 155         /* Now, we do the remaining detection. There is no identification-
 156            dedicated register so we have to rely on several tricks:
 157            unused bits, registers cycling over 8-address boundaries,
 158            addresses 0x04-0x07 returning the last read value.
 159            The cycling+unused addresses combination is not tested,
 160            since it would significantly slow the detection down and would
 161            hardly add any value. */
 162         if (kind < 0) {
 163                 int cur, conf, hyst, os;
 164
 165                 /* Unused addresses */
 166                 cur = i2c_smbus_read_word_data(new_client, 0);
 167                 conf = i2c_smbus_read_byte_data(new_client, 1);
 168                 hyst = i2c_smbus_read_word_data(new_client, 2);
 169                 if (i2c_smbus_read_word_data(new_client, 4) != hyst
 170                  || i2c_smbus_read_word_data(new_client, 5) != hyst
 171                  || i2c_smbus_read_word_data(new_client, 6) != hyst
 172                  || i2c_smbus_read_word_data(new_client, 7) != hyst)
 173                         goto exit_free;
 174                 os = i2c_smbus_read_word_data(new_client, 3);
 175                 if (i2c_smbus_read_word_data(new_client, 4) != os
 176                  || i2c_smbus_read_word_data(new_client, 5) != os
 177                  || i2c_smbus_read_word_data(new_client, 6) != os
 178                  || i2c_smbus_read_word_data(new_client, 7) != os)
 179                         goto exit_free;
 180
 181                 /* Unused bits */
 182                 if (conf & 0xe0)
 183                         goto exit_free;
 184
 185                 /* Addresses cycling */
 186                 for (i = 8; i < 0xff; i += 8)
 187                         if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
 188                          || i2c_smbus_read_word_data(new_client, i + 2) != hyst
 189                          || i2c_smbus_read_word_data(new_client, i + 3) != os)
 190                                 goto exit_free;
 191         }
 192
 193         /* Determine the chip type - only one kind supported! */
 194         if (kind <= 0)
 195                 kind = lm75;
 196
 197         if (kind == lm75) {
 198                 name = "lm75";
 199         }
 200
 201         /* Fill in the remaining client fields and put it into the global list */
 202         strlcpy(new_client->name, name, I2C_NAME_SIZE);
 203         data->valid = 0;
 204         mutex_init(&data->update_lock);
 205
 206         /* Tell the I2C layer a new client has arrived */
 207         if ((err = i2c_attach_client(new_client)))
 208                 goto exit_free;
 209
 210         /* Initialize the LM75 chip */
 211         lm75_init_client(new_client);
 212
 213         /* Register sysfs hooks */
 214         if ((err = sysfs_create_group(&new_client->dev.kobj, &lm75_group)))
 215                 goto exit_detach;
 216
 217         data->class_dev = hwmon_device_register(&new_client->dev);
 218         if (IS_ERR(data->class_dev)) {
 219                 err = PTR_ERR(data->class_dev);
 220                 goto exit_remove;
 221         }
 222
 223         return 0;
 224
 225 exit_remove:
 226         sysfs_remove_group(&new_client->dev.kobj, &lm75_group);
 227 exit_detach:
 228         i2c_detach_client(new_client);
 229 exit_free:
 230         kfree(data);
 231 exit:
 232         return err;
 233 }
 234
 235 static int lm75_detach_client(struct i2c_client *client)
 236 {
 237         struct lm75_data *data = i2c_get_clientdata(client);
 238         hwmon_device_unregister(data->class_dev);
 239         sysfs_remove_group(&client->dev.kobj, &lm75_group);
 240         i2c_detach_client(client);
 241         kfree(data);
 242         return 0;
 243 }
 244
 245 /* All registers are word-sized, except for the configuration register.
 246    LM75 uses a high-byte first convention, which is exactly opposite to
 247    the usual practice. */
 248 static int lm75_read_value(struct i2c_client *client, u8 reg)
 249 {
 250         if (reg == LM75_REG_CONF)
 251                 return i2c_smbus_read_byte_data(client, reg);
 252         else
 253                 return swab16(i2c_smbus_read_word_data(client, reg));
 254 }
 255
 256 /* All registers are word-sized, except for the configuration register.
 257    LM75 uses a high-byte first convention, which is exactly opposite to
 258    the usual practice. */
 259 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
 260 {
 261         if (reg == LM75_REG_CONF)
 262                 return i2c_smbus_write_byte_data(client, reg, value);
 263         else
 264                 return i2c_smbus_write_word_data(client, reg, swab16(value));
 265 }
 266
 267 static void lm75_init_client(struct i2c_client *client)
 268 {
 269         int reg;
 270
 271         /* Enable if in shutdown mode */
 272         reg = lm75_read_value(client, LM75_REG_CONF);
 273         if (reg >= 0 && (reg & 0x01))
 274                 lm75_write_value(client, LM75_REG_CONF, reg & 0xfe);
 275 }
 276
 277 static struct lm75_data *lm75_update_device(struct device *dev)
 278 {
 279         struct i2c_client *client = to_i2c_client(dev);
 280         struct lm75_data *data = i2c_get_clientdata(client);
 281
 282         mutex_lock(&data->update_lock);
 283
 284         if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
 285             || !data->valid) {
 286                 dev_dbg(&client->dev, "Starting lm75 update\n");
 287
 288                 data->temp_input = lm75_read_value(client, LM75_REG_TEMP);
 289                 data->temp_max = lm75_read_value(client, LM75_REG_TEMP_OS);
 290                 data->temp_hyst = lm75_read_value(client, LM75_REG_TEMP_HYST);
 291                 data->last_updated = jiffies;
 292                 data->valid = 1;
 293         }
 294
 295         mutex_unlock(&data->update_lock);
 296
 297         return data;
 298 }
 299
 300 static int __init sensors_lm75_init(void)
 301 {
 302         return i2c_add_driver(&lm75_driver);
 303 }
 304
 305 static void __exit sensors_lm75_exit(void)
 306 {
 307         i2c_del_driver(&lm75_driver);
 308 }
 309
 310 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
 311 MODULE_DESCRIPTION("LM75 driver");
 312 MODULE_LICENSE("GPL");
 313
 314 module_init(sensors_lm75_init);
 315 module_exit(sensors_lm75_exit);