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/i2c-sensor.h>
  27 #include "lm75.h"
  28
  29
  30 /* Addresses to scan */
  31 static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
  32                                         0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
  33 static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END };
  34
  35 /* Insmod parameters */
  36 SENSORS_INSMOD_1(lm75);
  37
  38 /* Many LM75 constants specified below */
  39
  40 /* The LM75 registers */
  41 #define LM75_REG_TEMP           0x00
  42 #define LM75_REG_CONF           0x01
  43 #define LM75_REG_TEMP_HYST      0x02
  44 #define LM75_REG_TEMP_OS        0x03
  45
  46 /* Each client has this additional data */
  47 struct lm75_data {
  48         struct i2c_client       client;
  49         struct semaphore        update_lock;
  50         char                    valid;          /* !=0 if following fields are valid */
  51         unsigned long           last_updated;   /* In jiffies */
  52         u16                     temp_input;     /* Register values */
  53         u16                     temp_max;
  54         u16                     temp_hyst;
  55 };
  56
  57 static int lm75_attach_adapter(struct i2c_adapter *adapter);
  58 static int lm75_detect(struct i2c_adapter *adapter, int address, int kind);
  59 static void lm75_init_client(struct i2c_client *client);
  60 static int lm75_detach_client(struct i2c_client *client);
  61 static int lm75_read_value(struct i2c_client *client, u8 reg);
  62 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
  63 static struct lm75_data *lm75_update_device(struct device *dev);
  64
  65
  66 /* This is the driver that will be inserted */
  67 static struct i2c_driver lm75_driver = {
  68         .owner          = THIS_MODULE,
  69         .name           = "lm75",
  70         .id             = I2C_DRIVERID_LM75,
  71         .flags          = I2C_DF_NOTIFY,
  72         .attach_adapter = lm75_attach_adapter,
  73         .detach_client  = lm75_detach_client,
  74 };
  75
  76 #define show(value)     \
  77 static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)               \
  78 {                                                                       \
  79         struct lm75_data *data = lm75_update_device(dev);               \
  80         return sprintf(buf, "%d\n", LM75_TEMP_FROM_REG(data->value));   \
  81 }
  82 show(temp_max);
  83 show(temp_hyst);
  84 show(temp_input);
  85
  86 #define set(value, reg) \
  87 static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)    \
  88 {                                                               \
  89         struct i2c_client *client = to_i2c_client(dev);         \
  90         struct lm75_data *data = i2c_get_clientdata(client);    \
  91         int temp = simple_strtoul(buf, NULL, 10);               \
  92                                                                 \
  93         down(&data->update_lock);                               \
  94         data->value = LM75_TEMP_TO_REG(temp);                   \
  95         lm75_write_value(client, reg, data->value);             \
  96         up(&data->update_lock);                                 \
  97         return count;                                           \
  98 }
  99 set(temp_max, LM75_REG_TEMP_OS);
 100 set(temp_hyst, LM75_REG_TEMP_HYST);
 101
 102 static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp_max, set_temp_max);
 103 static DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO, show_temp_hyst, set_temp_hyst);
 104 static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL);
 105
 106 static int lm75_attach_adapter(struct i2c_adapter *adapter)
 107 {
 108         if (!(adapter->class & I2C_CLASS_HWMON))
 109                 return 0;
 110         return i2c_detect(adapter, &addr_data, lm75_detect);
 111 }
 112
 113 /* This function is called by i2c_detect */
 114 static int lm75_detect(struct i2c_adapter *adapter, int address, int kind)
 115 {
 116         int i;
 117         struct i2c_client *new_client;
 118         struct lm75_data *data;
 119         int err = 0;
 120         const char *name = "";
 121
 122         /* Make sure we aren't probing the ISA bus!! This is just a safety check
 123            at this moment; i2c_detect really won't call us. */
 124 #ifdef DEBUG
 125         if (i2c_is_isa_adapter(adapter)) {
 126                 dev_dbg(&adapter->dev,
 127                         "lm75_detect called for an ISA bus adapter?!?\n");
 128                 goto exit;
 129         }
 130 #endif
 131
 132         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 133                                      I2C_FUNC_SMBUS_WORD_DATA))
 134                 goto exit;
 135
 136         /* OK. For now, we presume we have a valid client. We now create the
 137            client structure, even though we cannot fill it completely yet.
 138            But it allows us to access lm75_{read,write}_value. */
 139         if (!(data = kmalloc(sizeof(struct lm75_data), GFP_KERNEL))) {
 140                 err = -ENOMEM;
 141                 goto exit;
 142         }
 143         memset(data, 0, sizeof(struct lm75_data));
 144
 145         new_client = &data->client;
 146         i2c_set_clientdata(new_client, data);
 147         new_client->addr = address;
 148         new_client->adapter = adapter;
 149         new_client->driver = &lm75_driver;
 150         new_client->flags = 0;
 151
 152         /* Now, we do the remaining detection. There is no identification-
 153            dedicated register so we have to rely on several tricks:
 154            unused bits, registers cycling over 8-address boundaries,
 155            addresses 0x04-0x07 returning the last read value.
 156            The cycling+unused addresses combination is not tested,
 157            since it would significantly slow the detection down and would
 158            hardly add any value. */
 159         if (kind < 0) {
 160                 int cur, conf, hyst, os;
 161
 162                 /* Unused addresses */
 163                 cur = i2c_smbus_read_word_data(new_client, 0);
 164                 conf = i2c_smbus_read_byte_data(new_client, 1);
 165                 hyst = i2c_smbus_read_word_data(new_client, 2);
 166                 if (i2c_smbus_read_word_data(new_client, 4) != hyst
 167                  || i2c_smbus_read_word_data(new_client, 5) != hyst
 168                  || i2c_smbus_read_word_data(new_client, 6) != hyst
 169                  || i2c_smbus_read_word_data(new_client, 7) != hyst)
 170                         goto exit_free;
 171                 os = i2c_smbus_read_word_data(new_client, 3);
 172                 if (i2c_smbus_read_word_data(new_client, 4) != os
 173                  || i2c_smbus_read_word_data(new_client, 5) != os
 174                  || i2c_smbus_read_word_data(new_client, 6) != os
 175                  || i2c_smbus_read_word_data(new_client, 7) != os)
 176                         goto exit_free;
 177
 178                 /* Unused bits */
 179                 if (conf & 0xe0)
 180                         goto exit_free;
 181
 182                 /* Addresses cycling */
 183                 for (i = 8; i < 0xff; i += 8)
 184                         if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
 185                          || i2c_smbus_read_word_data(new_client, i + 2) != hyst
 186                          || i2c_smbus_read_word_data(new_client, i + 3) != os)
 187                                 goto exit_free;
 188         }
 189
 190         /* Determine the chip type - only one kind supported! */
 191         if (kind <= 0)
 192                 kind = lm75;
 193
 194         if (kind == lm75) {
 195                 name = "lm75";
 196         }
 197
 198         /* Fill in the remaining client fields and put it into the global list */
 199         strlcpy(new_client->name, name, I2C_NAME_SIZE);
 200         data->valid = 0;
 201         init_MUTEX(&data->update_lock);
 202
 203         /* Tell the I2C layer a new client has arrived */
 204         if ((err = i2c_attach_client(new_client)))
 205                 goto exit_free;
 206
 207         /* Initialize the LM75 chip */
 208         lm75_init_client(new_client);
 209
 210         /* Register sysfs hooks */
 211         device_create_file(&new_client->dev, &dev_attr_temp1_max);
 212         device_create_file(&new_client->dev, &dev_attr_temp1_max_hyst);
 213         device_create_file(&new_client->dev, &dev_attr_temp1_input);
 214
 215         return 0;
 216
 217 exit_free:
 218         kfree(data);
 219 exit:
 220         return err;
 221 }
 222
 223 static int lm75_detach_client(struct i2c_client *client)
 224 {
 225         i2c_detach_client(client);
 226         kfree(i2c_get_clientdata(client));
 227         return 0;
 228 }
 229
 230 /* All registers are word-sized, except for the configuration register.
 231    LM75 uses a high-byte first convention, which is exactly opposite to
 232    the usual practice. */
 233 static int lm75_read_value(struct i2c_client *client, u8 reg)
 234 {
 235         if (reg == LM75_REG_CONF)
 236                 return i2c_smbus_read_byte_data(client, reg);
 237         else
 238                 return swab16(i2c_smbus_read_word_data(client, reg));
 239 }
 240
 241 /* All registers are word-sized, except for the configuration register.
 242    LM75 uses a high-byte first convention, which is exactly opposite to
 243    the usual practice. */
 244 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
 245 {
 246         if (reg == LM75_REG_CONF)
 247                 return i2c_smbus_write_byte_data(client, reg, value);
 248         else
 249                 return i2c_smbus_write_word_data(client, reg, swab16(value));
 250 }
 251
 252 static void lm75_init_client(struct i2c_client *client)
 253 {
 254         /* Initialize the LM75 chip */
 255         lm75_write_value(client, LM75_REG_CONF, 0);
 256 }
 257
 258 static struct lm75_data *lm75_update_device(struct device *dev)
 259 {
 260         struct i2c_client *client = to_i2c_client(dev);
 261         struct lm75_data *data = i2c_get_clientdata(client);
 262
 263         down(&data->update_lock);
 264
 265         if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
 266             || !data->valid) {
 267                 dev_dbg(&client->dev, "Starting lm75 update\n");
 268
 269                 data->temp_input = lm75_read_value(client, LM75_REG_TEMP);
 270                 data->temp_max = lm75_read_value(client, LM75_REG_TEMP_OS);
 271                 data->temp_hyst = lm75_read_value(client, LM75_REG_TEMP_HYST);
 272                 data->last_updated = jiffies;
 273                 data->valid = 1;
 274         }
 275
 276         up(&data->update_lock);
 277
 278         return data;
 279 }
 280
 281 static int __init sensors_lm75_init(void)
 282 {
 283         return i2c_add_driver(&lm75_driver);
 284 }
 285
 286 static void __exit sensors_lm75_exit(void)
 287 {
 288         i2c_del_driver(&lm75_driver);
 289 }
 290
 291 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
 292 MODULE_DESCRIPTION("LM75 driver");
 293 MODULE_LICENSE("GPL");
 294
 295 module_init(sensors_lm75_init);
 296 module_exit(sensors_lm75_exit);