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