drivers/hwmon/shtc1.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Sensirion SHTC1 humidity and temperature sensor driver
   3  *
   4  * Copyright (C) 2014 Sensirion AG, Switzerland
   5  * Author: Johannes Winkelmann <johannes.winkelmann@sensirion.com>
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/init.h>
  10 #include <linux/slab.h>
  11 #include <linux/i2c.h>
  12 #include <linux/hwmon.h>
  13 #include <linux/hwmon-sysfs.h>
  14 #include <linux/err.h>
  15 #include <linux/delay.h>
  16 #include <linux/platform_data/shtc1.h>
  17 #include <linux/of.h>
  18
  19 /* commands (high precision mode) */
  20 static const unsigned char shtc1_cmd_measure_blocking_hpm[]    = { 0x7C, 0xA2 };
  21 static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 };
  22
  23 /* commands (low precision mode) */
  24 static const unsigned char shtc1_cmd_measure_blocking_lpm[]    = { 0x64, 0x58 };
  25 static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c };
  26
  27 /* command for reading the ID register */
  28 static const unsigned char shtc1_cmd_read_id_reg[]             = { 0xef, 0xc8 };
  29
  30 /*
  31  * constants for reading the ID register
  32  * SHTC1: 0x0007 with mask 0x003f
  33  * SHTW1: 0x0007 with mask 0x003f
  34  * SHTC3: 0x0807 with mask 0x083f
  35  */
  36 #define SHTC3_ID      0x0807
  37 #define SHTC3_ID_MASK 0x083f
  38 #define SHTC1_ID      0x0007
  39 #define SHTC1_ID_MASK 0x003f
  40
  41 /* delays for non-blocking i2c commands, both in us */
  42 #define SHTC1_NONBLOCKING_WAIT_TIME_HPM  14400
  43 #define SHTC1_NONBLOCKING_WAIT_TIME_LPM   1000
  44 #define SHTC3_NONBLOCKING_WAIT_TIME_HPM  12100
  45 #define SHTC3_NONBLOCKING_WAIT_TIME_LPM    800
  46
  47 #define SHTC1_CMD_LENGTH      2
  48 #define SHTC1_RESPONSE_LENGTH 6
  49
  50 enum shtcx_chips {
  51         shtc1,
  52         shtc3,
  53 };
  54
  55 struct shtc1_data {
  56         struct i2c_client *client;
  57         struct mutex update_lock;
  58         bool valid;
  59         unsigned long last_updated; /* in jiffies */
  60
  61         const unsigned char *command;
  62         unsigned int nonblocking_wait_time; /* in us */
  63
  64         struct shtc1_platform_data setup;
  65         enum shtcx_chips chip;
  66
  67         int temperature; /* 1000 * temperature in dgr C */
  68         int humidity; /* 1000 * relative humidity in %RH */
  69 };
  70
  71 static int shtc1_update_values(struct i2c_client *client,
  72                                struct shtc1_data *data,
  73                                char *buf, int bufsize)
  74 {
  75         int ret = i2c_master_send(client, data->command, SHTC1_CMD_LENGTH);
  76         if (ret != SHTC1_CMD_LENGTH) {
  77                 dev_err(&client->dev, "failed to send command: %d\n", ret);
  78                 return ret < 0 ? ret : -EIO;
  79         }
  80
  81         /*
  82          * In blocking mode (clock stretching mode) the I2C bus
  83          * is blocked for other traffic, thus the call to i2c_master_recv()
  84          * will wait until the data is ready. For non blocking mode, we
  85          * have to wait ourselves.
  86          */
  87         if (!data->setup.blocking_io)
  88                 usleep_range(data->nonblocking_wait_time,
  89                              data->nonblocking_wait_time + 1000);
  90
  91         ret = i2c_master_recv(client, buf, bufsize);
  92         if (ret != bufsize) {
  93                 dev_err(&client->dev, "failed to read values: %d\n", ret);
  94                 return ret < 0 ? ret : -EIO;
  95         }
  96
  97         return 0;
  98 }
  99
 100 /* sysfs attributes */
 101 static struct shtc1_data *shtc1_update_client(struct device *dev)
 102 {
 103         struct shtc1_data *data = dev_get_drvdata(dev);
 104         struct i2c_client *client = data->client;
 105         unsigned char buf[SHTC1_RESPONSE_LENGTH];
 106         int val;
 107         int ret = 0;
 108
 109         mutex_lock(&data->update_lock);
 110
 111         if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {
 112                 ret = shtc1_update_values(client, data, buf, sizeof(buf));
 113                 if (ret)
 114                         goto out;
 115
 116                 /*
 117                  * From datasheet:
 118                  * T = -45 + 175 * ST / 2^16
 119                  * RH = 100 * SRH / 2^16
 120                  *
 121                  * Adapted for integer fixed point (3 digit) arithmetic.
 122                  */
 123                 val = be16_to_cpup((__be16 *)buf);
 124                 data->temperature = ((21875 * val) >> 13) - 45000;
 125                 val = be16_to_cpup((__be16 *)(buf + 3));
 126                 data->humidity = ((12500 * val) >> 13);
 127
 128                 data->last_updated = jiffies;
 129                 data->valid = true;
 130         }
 131
 132 out:
 133         mutex_unlock(&data->update_lock);
 134
 135         return ret == 0 ? data : ERR_PTR(ret);
 136 }
 137
 138 static ssize_t temp1_input_show(struct device *dev,
 139                                 struct device_attribute *attr,
 140                                 char *buf)
 141 {
 142         struct shtc1_data *data = shtc1_update_client(dev);
 143         if (IS_ERR(data))
 144                 return PTR_ERR(data);
 145
 146         return sprintf(buf, "%d\n", data->temperature);
 147 }
 148
 149 static ssize_t humidity1_input_show(struct device *dev,
 150                                     struct device_attribute *attr, char *buf)
 151 {
 152         struct shtc1_data *data = shtc1_update_client(dev);
 153         if (IS_ERR(data))
 154                 return PTR_ERR(data);
 155
 156         return sprintf(buf, "%d\n", data->humidity);
 157 }
 158
 159 static DEVICE_ATTR_RO(temp1_input);
 160 static DEVICE_ATTR_RO(humidity1_input);
 161
 162 static struct attribute *shtc1_attrs[] = {
 163         &dev_attr_temp1_input.attr,
 164         &dev_attr_humidity1_input.attr,
 165         NULL
 166 };
 167
 168 ATTRIBUTE_GROUPS(shtc1);
 169
 170 static void shtc1_select_command(struct shtc1_data *data)
 171 {
 172         if (data->setup.high_precision) {
 173                 data->command = data->setup.blocking_io ?
 174                                 shtc1_cmd_measure_blocking_hpm :
 175                                 shtc1_cmd_measure_nonblocking_hpm;
 176                 data->nonblocking_wait_time = (data->chip == shtc1) ?
 177                                 SHTC1_NONBLOCKING_WAIT_TIME_HPM :
 178                                 SHTC3_NONBLOCKING_WAIT_TIME_HPM;
 179         } else {
 180                 data->command = data->setup.blocking_io ?
 181                                 shtc1_cmd_measure_blocking_lpm :
 182                                 shtc1_cmd_measure_nonblocking_lpm;
 183                 data->nonblocking_wait_time = (data->chip == shtc1) ?
 184                                 SHTC1_NONBLOCKING_WAIT_TIME_LPM :
 185                                 SHTC3_NONBLOCKING_WAIT_TIME_LPM;
 186         }
 187 }
 188
 189 static const struct i2c_device_id shtc1_id[];
 190
 191 static int shtc1_probe(struct i2c_client *client)
 192 {
 193         int ret;
 194         u16 id_reg;
 195         char id_reg_buf[2];
 196         struct shtc1_data *data;
 197         struct device *hwmon_dev;
 198         enum shtcx_chips chip = i2c_match_id(shtc1_id, client)->driver_data;
 199         struct i2c_adapter *adap = client->adapter;
 200         struct device *dev = &client->dev;
 201         struct device_node *np = dev->of_node;
 202
 203         if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
 204                 dev_err(dev, "plain i2c transactions not supported\n");
 205                 return -ENODEV;
 206         }
 207
 208         ret = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH);
 209         if (ret != SHTC1_CMD_LENGTH) {
 210                 dev_err(dev, "could not send read_id_reg command: %d\n", ret);
 211                 return ret < 0 ? ret : -ENODEV;
 212         }
 213         ret = i2c_master_recv(client, id_reg_buf, sizeof(id_reg_buf));
 214         if (ret != sizeof(id_reg_buf)) {
 215                 dev_err(dev, "could not read ID register: %d\n", ret);
 216                 return -ENODEV;
 217         }
 218
 219         id_reg = be16_to_cpup((__be16 *)id_reg_buf);
 220         if (chip == shtc3) {
 221                 if ((id_reg & SHTC3_ID_MASK) != SHTC3_ID) {
 222                         dev_err(dev, "SHTC3 ID register does not match\n");
 223                         return -ENODEV;
 224                 }
 225         } else if ((id_reg & SHTC1_ID_MASK) != SHTC1_ID) {
 226                 dev_err(dev, "SHTC1 ID register does not match\n");
 227                 return -ENODEV;
 228         }
 229
 230         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 231         if (!data)
 232                 return -ENOMEM;
 233
 234         data->setup.blocking_io = false;
 235         data->setup.high_precision = true;
 236         data->client = client;
 237         data->chip = chip;
 238
 239         if (np) {
 240                 data->setup.blocking_io = of_property_read_bool(np, "sensirion,blocking-io");
 241                 data->setup.high_precision = !of_property_read_bool(np, "sensicon,low-precision");
 242         } else {
 243                 if (client->dev.platform_data)
 244                         data->setup = *(struct shtc1_platform_data *)dev->platform_data;
 245         }
 246
 247         shtc1_select_command(data);
 248         mutex_init(&data->update_lock);
 249
 250         hwmon_dev = devm_hwmon_device_register_with_groups(dev,
 251                                                            client->name,
 252                                                            data,
 253                                                            shtc1_groups);
 254         if (IS_ERR(hwmon_dev))
 255                 dev_dbg(dev, "unable to register hwmon device\n");
 256
 257         return PTR_ERR_OR_ZERO(hwmon_dev);
 258 }
 259
 260 /* device ID table */
 261 static const struct i2c_device_id shtc1_id[] = {
 262         { "shtc1", shtc1 },
 263         { "shtw1", shtc1 },
 264         { "shtc3", shtc3 },
 265         { }
 266 };
 267 MODULE_DEVICE_TABLE(i2c, shtc1_id);
 268
 269 static const struct of_device_id shtc1_of_match[] = {
 270         { .compatible = "sensirion,shtc1" },
 271         { .compatible = "sensirion,shtw1" },
 272         { .compatible = "sensirion,shtc3" },
 273         { }
 274 };
 275 MODULE_DEVICE_TABLE(of, shtc1_of_match);
 276
 277 static struct i2c_driver shtc1_i2c_driver = {
 278         .driver = {
 279                 .name = "shtc1",
 280                 .of_match_table = shtc1_of_match,
 281         },
 282         .probe        = shtc1_probe,
 283         .id_table     = shtc1_id,
 284 };
 285
 286 module_i2c_driver(shtc1_i2c_driver);
 287
 288 MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@sensirion.com>");
 289 MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
 290 MODULE_LICENSE("GPL");