drivers/hwmon/lm77.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * lm77.c - Part of lm_sensors, Linux kernel modules for hardware
   4  *          monitoring
   5  *
   6  * Copyright (c) 2004  Andras BALI <drewie@freemail.hu>
   7  *
   8  * Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>.  The LM77
   9  * is a temperature sensor and thermal window comparator with 0.5 deg
  10  * resolution made by National Semiconductor.  Complete datasheet can be
  11  * obtained at their site:
  12  *      http://www.national.com/pf/LM/LM77.html
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/init.h>
  17 #include <linux/slab.h>
  18 #include <linux/jiffies.h>
  19 #include <linux/i2c.h>
  20 #include <linux/hwmon.h>
  21 #include <linux/hwmon-sysfs.h>
  22 #include <linux/err.h>
  23 #include <linux/mutex.h>
  24
  25 /* Addresses to scan */
  26 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
  27                                                 I2C_CLIENT_END };
  28
  29 /* The LM77 registers */
  30 #define LM77_REG_TEMP           0x00
  31 #define LM77_REG_CONF           0x01
  32 #define LM77_REG_TEMP_HYST      0x02
  33 #define LM77_REG_TEMP_CRIT      0x03
  34 #define LM77_REG_TEMP_MIN       0x04
  35 #define LM77_REG_TEMP_MAX       0x05
  36
  37 enum temp_index {
  38         t_input = 0,
  39         t_crit,
  40         t_min,
  41         t_max,
  42         t_hyst,
  43         t_num_temp
  44 };
  45
  46 static const u8 temp_regs[t_num_temp] = {
  47         [t_input] = LM77_REG_TEMP,
  48         [t_min] = LM77_REG_TEMP_MIN,
  49         [t_max] = LM77_REG_TEMP_MAX,
  50         [t_crit] = LM77_REG_TEMP_CRIT,
  51         [t_hyst] = LM77_REG_TEMP_HYST,
  52 };
  53
  54 /* Each client has this additional data */
  55 struct lm77_data {
  56         struct i2c_client       *client;
  57         struct mutex            update_lock;
  58         char                    valid;
  59         unsigned long           last_updated;   /* In jiffies */
  60         int                     temp[t_num_temp]; /* index using temp_index */
  61         u8                      alarms;
  62 };
  63
  64 /* straight from the datasheet */
  65 #define LM77_TEMP_MIN (-55000)
  66 #define LM77_TEMP_MAX 125000
  67
  68 /*
  69  * In the temperature registers, the low 3 bits are not part of the
  70  * temperature values; they are the status bits.
  71  */
  72 static inline s16 LM77_TEMP_TO_REG(int temp)
  73 {
  74         return (temp / 500) * 8;
  75 }
  76
  77 static inline int LM77_TEMP_FROM_REG(s16 reg)
  78 {
  79         return (reg / 8) * 500;
  80 }
  81
  82 /*
  83  * All registers are word-sized, except for the configuration register.
  84  * The LM77 uses the high-byte first convention.
  85  */
  86 static u16 lm77_read_value(struct i2c_client *client, u8 reg)
  87 {
  88         if (reg == LM77_REG_CONF)
  89                 return i2c_smbus_read_byte_data(client, reg);
  90         else
  91                 return i2c_smbus_read_word_swapped(client, reg);
  92 }
  93
  94 static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)
  95 {
  96         if (reg == LM77_REG_CONF)
  97                 return i2c_smbus_write_byte_data(client, reg, value);
  98         else
  99                 return i2c_smbus_write_word_swapped(client, reg, value);
 100 }
 101
 102 static struct lm77_data *lm77_update_device(struct device *dev)
 103 {
 104         struct lm77_data *data = dev_get_drvdata(dev);
 105         struct i2c_client *client = data->client;
 106         int i;
 107
 108         mutex_lock(&data->update_lock);
 109
 110         if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
 111             || !data->valid) {
 112                 dev_dbg(&client->dev, "Starting lm77 update\n");
 113                 for (i = 0; i < t_num_temp; i++) {
 114                         data->temp[i] =
 115                           LM77_TEMP_FROM_REG(lm77_read_value(client,
 116                                                              temp_regs[i]));
 117                 }
 118                 data->alarms =
 119                         lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
 120                 data->last_updated = jiffies;
 121                 data->valid = 1;
 122         }
 123
 124         mutex_unlock(&data->update_lock);
 125
 126         return data;
 127 }
 128
 129 /* sysfs stuff */
 130
 131 static ssize_t temp_show(struct device *dev, struct device_attribute *devattr,
 132                          char *buf)
 133 {
 134         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 135         struct lm77_data *data = lm77_update_device(dev);
 136
 137         return sprintf(buf, "%d\n", data->temp[attr->index]);
 138 }
 139
 140 static ssize_t temp_hyst_show(struct device *dev,
 141                               struct device_attribute *devattr, char *buf)
 142 {
 143         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 144         struct lm77_data *data = lm77_update_device(dev);
 145         int nr = attr->index;
 146         int temp;
 147
 148         temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] :
 149                              data->temp[nr] - data->temp[t_hyst];
 150
 151         return sprintf(buf, "%d\n", temp);
 152 }
 153
 154 static ssize_t temp_store(struct device *dev,
 155                           struct device_attribute *devattr, const char *buf,
 156                           size_t count)
 157 {
 158         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 159         struct lm77_data *data = dev_get_drvdata(dev);
 160         struct i2c_client *client = data->client;
 161         int nr = attr->index;
 162         long val;
 163         int err;
 164
 165         err = kstrtol(buf, 10, &val);
 166         if (err)
 167                 return err;
 168
 169         val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX);
 170         mutex_lock(&data->update_lock);
 171         data->temp[nr] = val;
 172         lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val));
 173         mutex_unlock(&data->update_lock);
 174         return count;
 175 }
 176
 177 /*
 178  * hysteresis is stored as a relative value on the chip, so it has to be
 179  * converted first.
 180  */
 181 static ssize_t temp_hyst_store(struct device *dev,
 182                                struct device_attribute *devattr,
 183                                const char *buf, size_t count)
 184 {
 185         struct lm77_data *data = dev_get_drvdata(dev);
 186         struct i2c_client *client = data->client;
 187         long val;
 188         int err;
 189
 190         err = kstrtol(buf, 10, &val);
 191         if (err)
 192                 return err;
 193
 194         mutex_lock(&data->update_lock);
 195         val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX);
 196         data->temp[t_hyst] = val;
 197         lm77_write_value(client, LM77_REG_TEMP_HYST,
 198                          LM77_TEMP_TO_REG(data->temp[t_hyst]));
 199         mutex_unlock(&data->update_lock);
 200         return count;
 201 }
 202
 203 static ssize_t alarm_show(struct device *dev, struct device_attribute *attr,
 204                           char *buf)
 205 {
 206         int bitnr = to_sensor_dev_attr(attr)->index;
 207         struct lm77_data *data = lm77_update_device(dev);
 208         return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1);
 209 }
 210
 211 static SENSOR_DEVICE_ATTR_RO(temp1_input, temp, t_input);
 212 static SENSOR_DEVICE_ATTR_RW(temp1_crit, temp, t_crit);
 213 static SENSOR_DEVICE_ATTR_RW(temp1_min, temp, t_min);
 214 static SENSOR_DEVICE_ATTR_RW(temp1_max, temp, t_max);
 215
 216 static SENSOR_DEVICE_ATTR_RW(temp1_crit_hyst, temp_hyst, t_crit);
 217 static SENSOR_DEVICE_ATTR_RO(temp1_min_hyst, temp_hyst, t_min);
 218 static SENSOR_DEVICE_ATTR_RO(temp1_max_hyst, temp_hyst, t_max);
 219
 220 static SENSOR_DEVICE_ATTR_RO(temp1_crit_alarm, alarm, 2);
 221 static SENSOR_DEVICE_ATTR_RO(temp1_min_alarm, alarm, 0);
 222 static SENSOR_DEVICE_ATTR_RO(temp1_max_alarm, alarm, 1);
 223
 224 static struct attribute *lm77_attrs[] = {
 225         &sensor_dev_attr_temp1_input.dev_attr.attr,
 226         &sensor_dev_attr_temp1_crit.dev_attr.attr,
 227         &sensor_dev_attr_temp1_min.dev_attr.attr,
 228         &sensor_dev_attr_temp1_max.dev_attr.attr,
 229         &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
 230         &sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
 231         &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
 232         &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
 233         &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
 234         &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
 235         NULL
 236 };
 237 ATTRIBUTE_GROUPS(lm77);
 238
 239 /* Return 0 if detection is successful, -ENODEV otherwise */
 240 static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info)
 241 {
 242         struct i2c_adapter *adapter = client->adapter;
 243         int i, cur, conf, hyst, crit, min, max;
 244
 245         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 246                                      I2C_FUNC_SMBUS_WORD_DATA))
 247                 return -ENODEV;
 248
 249         /*
 250          * Here comes the remaining detection.  Since the LM77 has no
 251          * register dedicated to identification, we have to rely on the
 252          * following tricks:
 253          *
 254          * 1. the high 4 bits represent the sign and thus they should
 255          *    always be the same
 256          * 2. the high 3 bits are unused in the configuration register
 257          * 3. addresses 0x06 and 0x07 return the last read value
 258          * 4. registers cycling over 8-address boundaries
 259          *
 260          * Word-sized registers are high-byte first.
 261          */
 262
 263         /* addresses cycling */
 264         cur = i2c_smbus_read_word_data(client, 0);
 265         conf = i2c_smbus_read_byte_data(client, 1);
 266         hyst = i2c_smbus_read_word_data(client, 2);
 267         crit = i2c_smbus_read_word_data(client, 3);
 268         min = i2c_smbus_read_word_data(client, 4);
 269         max = i2c_smbus_read_word_data(client, 5);
 270         for (i = 8; i <= 0xff; i += 8) {
 271                 if (i2c_smbus_read_byte_data(client, i + 1) != conf
 272                  || i2c_smbus_read_word_data(client, i + 2) != hyst
 273                  || i2c_smbus_read_word_data(client, i + 3) != crit
 274                  || i2c_smbus_read_word_data(client, i + 4) != min
 275                  || i2c_smbus_read_word_data(client, i + 5) != max)
 276                         return -ENODEV;
 277         }
 278
 279         /* sign bits */
 280         if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)
 281          || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)
 282          || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)
 283          || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)
 284          || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))
 285                 return -ENODEV;
 286
 287         /* unused bits */
 288         if (conf & 0xe0)
 289                 return -ENODEV;
 290
 291         /* 0x06 and 0x07 return the last read value */
 292         cur = i2c_smbus_read_word_data(client, 0);
 293         if (i2c_smbus_read_word_data(client, 6) != cur
 294          || i2c_smbus_read_word_data(client, 7) != cur)
 295                 return -ENODEV;
 296         hyst = i2c_smbus_read_word_data(client, 2);
 297         if (i2c_smbus_read_word_data(client, 6) != hyst
 298          || i2c_smbus_read_word_data(client, 7) != hyst)
 299                 return -ENODEV;
 300         min = i2c_smbus_read_word_data(client, 4);
 301         if (i2c_smbus_read_word_data(client, 6) != min
 302          || i2c_smbus_read_word_data(client, 7) != min)
 303                 return -ENODEV;
 304
 305         strlcpy(info->type, "lm77", I2C_NAME_SIZE);
 306
 307         return 0;
 308 }
 309
 310 static void lm77_init_client(struct i2c_client *client)
 311 {
 312         /* Initialize the LM77 chip - turn off shutdown mode */
 313         int conf = lm77_read_value(client, LM77_REG_CONF);
 314         if (conf & 1)
 315                 lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);
 316 }
 317
 318 static int lm77_probe(struct i2c_client *client, const struct i2c_device_id *id)
 319 {
 320         struct device *dev = &client->dev;
 321         struct device *hwmon_dev;
 322         struct lm77_data *data;
 323
 324         data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL);
 325         if (!data)
 326                 return -ENOMEM;
 327
 328         data->client = client;
 329         mutex_init(&data->update_lock);
 330
 331         /* Initialize the LM77 chip */
 332         lm77_init_client(client);
 333
 334         hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 335                                                            data, lm77_groups);
 336         return PTR_ERR_OR_ZERO(hwmon_dev);
 337 }
 338
 339 static const struct i2c_device_id lm77_id[] = {
 340         { "lm77", 0 },
 341         { }
 342 };
 343 MODULE_DEVICE_TABLE(i2c, lm77_id);
 344
 345 /* This is the driver that will be inserted */
 346 static struct i2c_driver lm77_driver = {
 347         .class          = I2C_CLASS_HWMON,
 348         .driver = {
 349                 .name   = "lm77",
 350         },
 351         .probe          = lm77_probe,
 352         .id_table       = lm77_id,
 353         .detect         = lm77_detect,
 354         .address_list   = normal_i2c,
 355 };
 356
 357 module_i2c_driver(lm77_driver);
 358
 359 MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");
 360 MODULE_DESCRIPTION("LM77 driver");
 361 MODULE_LICENSE("GPL");