drivers/hwmon/lm77.c

   1 /*
   2  * lm77.c - Part of lm_sensors, Linux kernel modules for hardware
   3  *          monitoring
   4  *
   5  * Copyright (c) 2004  Andras BALI <drewie@freemail.hu>
   6  *
   7  * Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>.  The LM77
   8  * is a temperature sensor and thermal window comparator with 0.5 deg
   9  * resolution made by National Semiconductor.  Complete datasheet can be
  10  * obtained at their site:
  11  *      http://www.national.com/pf/LM/LM77.html
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 of the License, or
  16  * (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  */
  23
  24 #include <linux/module.h>
  25 #include <linux/init.h>
  26 #include <linux/slab.h>
  27 #include <linux/jiffies.h>
  28 #include <linux/i2c.h>
  29 #include <linux/hwmon.h>
  30 #include <linux/hwmon-sysfs.h>
  31 #include <linux/err.h>
  32 #include <linux/mutex.h>
  33
  34 /* Addresses to scan */
  35 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
  36                                                 I2C_CLIENT_END };
  37
  38 /* The LM77 registers */
  39 #define LM77_REG_TEMP           0x00
  40 #define LM77_REG_CONF           0x01
  41 #define LM77_REG_TEMP_HYST      0x02
  42 #define LM77_REG_TEMP_CRIT      0x03
  43 #define LM77_REG_TEMP_MIN       0x04
  44 #define LM77_REG_TEMP_MAX       0x05
  45
  46 enum temp_index {
  47         t_input = 0,
  48         t_crit,
  49         t_min,
  50         t_max,
  51         t_hyst,
  52         t_num_temp
  53 };
  54
  55 static const u8 temp_regs[t_num_temp] = {
  56         [t_input] = LM77_REG_TEMP,
  57         [t_min] = LM77_REG_TEMP_MIN,
  58         [t_max] = LM77_REG_TEMP_MAX,
  59         [t_crit] = LM77_REG_TEMP_CRIT,
  60         [t_hyst] = LM77_REG_TEMP_HYST,
  61 };
  62
  63 /* Each client has this additional data */
  64 struct lm77_data {
  65         struct i2c_client       *client;
  66         struct mutex            update_lock;
  67         char                    valid;
  68         unsigned long           last_updated;   /* In jiffies */
  69         int                     temp[t_num_temp]; /* index using temp_index */
  70         u8                      alarms;
  71 };
  72
  73 /* straight from the datasheet */
  74 #define LM77_TEMP_MIN (-55000)
  75 #define LM77_TEMP_MAX 125000
  76
  77 /*
  78  * In the temperature registers, the low 3 bits are not part of the
  79  * temperature values; they are the status bits.
  80  */
  81 static inline s16 LM77_TEMP_TO_REG(int temp)
  82 {
  83         int ntemp = clamp_val(temp, LM77_TEMP_MIN, LM77_TEMP_MAX);
  84         return (ntemp / 500) * 8;
  85 }
  86
  87 static inline int LM77_TEMP_FROM_REG(s16 reg)
  88 {
  89         return (reg / 8) * 500;
  90 }
  91
  92 /*
  93  * All registers are word-sized, except for the configuration register.
  94  * The LM77 uses the high-byte first convention.
  95  */
  96 static u16 lm77_read_value(struct i2c_client *client, u8 reg)
  97 {
  98         if (reg == LM77_REG_CONF)
  99                 return i2c_smbus_read_byte_data(client, reg);
 100         else
 101                 return i2c_smbus_read_word_swapped(client, reg);
 102 }
 103
 104 static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)
 105 {
 106         if (reg == LM77_REG_CONF)
 107                 return i2c_smbus_write_byte_data(client, reg, value);
 108         else
 109                 return i2c_smbus_write_word_swapped(client, reg, value);
 110 }
 111
 112 static struct lm77_data *lm77_update_device(struct device *dev)
 113 {
 114         struct lm77_data *data = dev_get_drvdata(dev);
 115         struct i2c_client *client = data->client;
 116         int i;
 117
 118         mutex_lock(&data->update_lock);
 119
 120         if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
 121             || !data->valid) {
 122                 dev_dbg(&client->dev, "Starting lm77 update\n");
 123                 for (i = 0; i < t_num_temp; i++) {
 124                         data->temp[i] =
 125                           LM77_TEMP_FROM_REG(lm77_read_value(client,
 126                                                              temp_regs[i]));
 127                 }
 128                 data->alarms =
 129                         lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
 130                 data->last_updated = jiffies;
 131                 data->valid = 1;
 132         }
 133
 134         mutex_unlock(&data->update_lock);
 135
 136         return data;
 137 }
 138
 139 /* sysfs stuff */
 140
 141 static ssize_t show_temp(struct device *dev, struct device_attribute *devattr,
 142                          char *buf)
 143 {
 144         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 145         struct lm77_data *data = lm77_update_device(dev);
 146
 147         return sprintf(buf, "%d\n", data->temp[attr->index]);
 148 }
 149
 150 static ssize_t show_temp_hyst(struct device *dev,
 151                               struct device_attribute *devattr, char *buf)
 152 {
 153         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 154         struct lm77_data *data = lm77_update_device(dev);
 155         int nr = attr->index;
 156         int temp;
 157
 158         temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] :
 159                              data->temp[nr] - data->temp[t_hyst];
 160
 161         return sprintf(buf, "%d\n", temp);
 162 }
 163
 164 static ssize_t set_temp(struct device *dev, struct device_attribute *devattr,
 165                         const char *buf, size_t count)
 166 {
 167         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 168         struct lm77_data *data = dev_get_drvdata(dev);
 169         struct i2c_client *client = data->client;
 170         int nr = attr->index;
 171         long val;
 172         int err;
 173
 174         err = kstrtol(buf, 10, &val);
 175         if (err)
 176                 return err;
 177
 178         mutex_lock(&data->update_lock);
 179         data->temp[nr] = val;
 180         lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val));
 181         mutex_unlock(&data->update_lock);
 182         return count;
 183 }
 184
 185 /*
 186  * hysteresis is stored as a relative value on the chip, so it has to be
 187  * converted first.
 188  */
 189 static ssize_t set_temp_hyst(struct device *dev,
 190                              struct device_attribute *devattr,
 191                              const char *buf, size_t count)
 192 {
 193         struct lm77_data *data = dev_get_drvdata(dev);
 194         struct i2c_client *client = data->client;
 195         unsigned long val;
 196         int err;
 197
 198         err = kstrtoul(buf, 10, &val);
 199         if (err)
 200                 return err;
 201
 202         mutex_lock(&data->update_lock);
 203         data->temp[t_hyst] = data->temp[t_crit] - val;
 204         lm77_write_value(client, LM77_REG_TEMP_HYST,
 205                          LM77_TEMP_TO_REG(data->temp[t_hyst]));
 206         mutex_unlock(&data->update_lock);
 207         return count;
 208 }
 209
 210 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
 211                           char *buf)
 212 {
 213         int bitnr = to_sensor_dev_attr(attr)->index;
 214         struct lm77_data *data = lm77_update_device(dev);
 215         return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1);
 216 }
 217
 218 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, t_input);
 219 static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp, set_temp,
 220                           t_crit);
 221 static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp, set_temp,
 222                           t_min);
 223 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp, set_temp,
 224                           t_max);
 225
 226 static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp_hyst,
 227                           set_temp_hyst, t_crit);
 228 static SENSOR_DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp_hyst, NULL, t_min);
 229 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp_hyst, NULL, t_max);
 230
 231 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
 232 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
 233 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
 234
 235 static struct attribute *lm77_attrs[] = {
 236         &sensor_dev_attr_temp1_input.dev_attr.attr,
 237         &sensor_dev_attr_temp1_crit.dev_attr.attr,
 238         &sensor_dev_attr_temp1_min.dev_attr.attr,
 239         &sensor_dev_attr_temp1_max.dev_attr.attr,
 240         &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
 241         &sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
 242         &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
 243         &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
 244         &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
 245         &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
 246         NULL
 247 };
 248 ATTRIBUTE_GROUPS(lm77);
 249
 250 /* Return 0 if detection is successful, -ENODEV otherwise */
 251 static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info)
 252 {
 253         struct i2c_adapter *adapter = client->adapter;
 254         int i, cur, conf, hyst, crit, min, max;
 255
 256         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 257                                      I2C_FUNC_SMBUS_WORD_DATA))
 258                 return -ENODEV;
 259
 260         /*
 261          * Here comes the remaining detection.  Since the LM77 has no
 262          * register dedicated to identification, we have to rely on the
 263          * following tricks:
 264          *
 265          * 1. the high 4 bits represent the sign and thus they should
 266          *    always be the same
 267          * 2. the high 3 bits are unused in the configuration register
 268          * 3. addresses 0x06 and 0x07 return the last read value
 269          * 4. registers cycling over 8-address boundaries
 270          *
 271          * Word-sized registers are high-byte first.
 272          */
 273
 274         /* addresses cycling */
 275         cur = i2c_smbus_read_word_data(client, 0);
 276         conf = i2c_smbus_read_byte_data(client, 1);
 277         hyst = i2c_smbus_read_word_data(client, 2);
 278         crit = i2c_smbus_read_word_data(client, 3);
 279         min = i2c_smbus_read_word_data(client, 4);
 280         max = i2c_smbus_read_word_data(client, 5);
 281         for (i = 8; i <= 0xff; i += 8) {
 282                 if (i2c_smbus_read_byte_data(client, i + 1) != conf
 283                  || i2c_smbus_read_word_data(client, i + 2) != hyst
 284                  || i2c_smbus_read_word_data(client, i + 3) != crit
 285                  || i2c_smbus_read_word_data(client, i + 4) != min
 286                  || i2c_smbus_read_word_data(client, i + 5) != max)
 287                         return -ENODEV;
 288         }
 289
 290         /* sign bits */
 291         if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)
 292          || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)
 293          || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)
 294          || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)
 295          || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))
 296                 return -ENODEV;
 297
 298         /* unused bits */
 299         if (conf & 0xe0)
 300                 return -ENODEV;
 301
 302         /* 0x06 and 0x07 return the last read value */
 303         cur = i2c_smbus_read_word_data(client, 0);
 304         if (i2c_smbus_read_word_data(client, 6) != cur
 305          || i2c_smbus_read_word_data(client, 7) != cur)
 306                 return -ENODEV;
 307         hyst = i2c_smbus_read_word_data(client, 2);
 308         if (i2c_smbus_read_word_data(client, 6) != hyst
 309          || i2c_smbus_read_word_data(client, 7) != hyst)
 310                 return -ENODEV;
 311         min = i2c_smbus_read_word_data(client, 4);
 312         if (i2c_smbus_read_word_data(client, 6) != min
 313          || i2c_smbus_read_word_data(client, 7) != min)
 314                 return -ENODEV;
 315
 316         strlcpy(info->type, "lm77", I2C_NAME_SIZE);
 317
 318         return 0;
 319 }
 320
 321 static void lm77_init_client(struct i2c_client *client)
 322 {
 323         /* Initialize the LM77 chip - turn off shutdown mode */
 324         int conf = lm77_read_value(client, LM77_REG_CONF);
 325         if (conf & 1)
 326                 lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);
 327 }
 328
 329 static int lm77_probe(struct i2c_client *client, const struct i2c_device_id *id)
 330 {
 331         struct device *dev = &client->dev;
 332         struct device *hwmon_dev;
 333         struct lm77_data *data;
 334
 335         data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL);
 336         if (!data)
 337                 return -ENOMEM;
 338
 339         data->client = client;
 340         mutex_init(&data->update_lock);
 341
 342         /* Initialize the LM77 chip */
 343         lm77_init_client(client);
 344
 345         hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 346                                                            data, lm77_groups);
 347         return PTR_ERR_OR_ZERO(hwmon_dev);
 348 }
 349
 350 static const struct i2c_device_id lm77_id[] = {
 351         { "lm77", 0 },
 352         { }
 353 };
 354 MODULE_DEVICE_TABLE(i2c, lm77_id);
 355
 356 /* This is the driver that will be inserted */
 357 static struct i2c_driver lm77_driver = {
 358         .class          = I2C_CLASS_HWMON,
 359         .driver = {
 360                 .name   = "lm77",
 361         },
 362         .probe          = lm77_probe,
 363         .id_table       = lm77_id,
 364         .detect         = lm77_detect,
 365         .address_list   = normal_i2c,
 366 };
 367
 368 module_i2c_driver(lm77_driver);
 369
 370 MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");
 371 MODULE_DESCRIPTION("LM77 driver");
 372 MODULE_LICENSE("GPL");