Quelle  shtc1.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/* Sensirion SHTC1 humidity and temperature sensor driver
 *
 * Copyright (C) 2014 Sensirion AG, Switzerland
 * Author: Johannes Winkelmann <johannes.winkelmann@sensirion.com>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/platform_data/shtc1.h>
#include <linux/of.h>

/* commands (high precision mode) */
static const unsigned char shtc1_cmd_measure_blocking_hpm[]    = { 0x7C, 0xA2 };
static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 };

/* commands (low precision mode) */
static const unsigned char shtc1_cmd_measure_blocking_lpm[]    = { 0x64, 0x58 };
static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c };

/* command for reading the ID register */
static const unsigned char shtc1_cmd_read_id_reg[]             = { 0xef, 0xc8 };

/*
 * constants for reading the ID register
 * SHTC1: 0x0007 with mask 0x003f
 * SHTW1: 0x0007 with mask 0x003f
 * SHTC3: 0x0807 with mask 0x083f
 */
#define SHTC3_ID      0x0807
#define SHTC3_ID_MASK 0x083f
#define SHTC1_ID      0x0007
#define SHTC1_ID_MASK 0x003f

/* delays for non-blocking i2c commands, both in us */
#define SHTC1_NONBLOCKING_WAIT_TIME_HPM  14400
#define SHTC1_NONBLOCKING_WAIT_TIME_LPM   1000
#define SHTC3_NONBLOCKING_WAIT_TIME_HPM  12100
#define SHTC3_NONBLOCKING_WAIT_TIME_LPM    800

#define SHTC1_CMD_LENGTH      2
#define SHTC1_RESPONSE_LENGTH 6

enum shtcx_chips {
 shtc1,
 shtc3,
};

struct shtc1_data {
 struct i2c_client *client;
 struct mutex update_lock;
 bool valid;
 unsigned long last_updated; /* in jiffies */

 const unsigned char *command;
 unsigned int nonblocking_wait_time; /* in us */

 struct shtc1_platform_data setup;
 enum shtcx_chips chip;

 int temperature; /* 1000 * temperature in dgr C */
 int humidity; /* 1000 * relative humidity in %RH */
};

static int shtc1_update_values(struct i2c_client *client,
          struct shtc1_data *data,
          char *buf, int bufsize)
{
 int ret = i2c_master_send(client, data->command, SHTC1_CMD_LENGTH);
 if (ret != SHTC1_CMD_LENGTH) {
  dev_err(&client->dev, "failed to send command: %d\n", ret);
  return ret < 0 ? ret : -EIO;
 }

 /*
 * In blocking mode (clock stretching mode) the I2C bus
 * is blocked for other traffic, thus the call to i2c_master_recv()
 * will wait until the data is ready. For non blocking mode, we
 * have to wait ourselves.
 */
 if (!data->setup.blocking_io)
  usleep_range(data->nonblocking_wait_time,
        data->nonblocking_wait_time + 1000);

 ret = i2c_master_recv(client, buf, bufsize);
 if (ret != bufsize) {
  dev_err(&client->dev, "failed to read values: %d\n", ret);
  return ret < 0 ? ret : -EIO;
 }

 return 0;
}

/* sysfs attributes */
static struct shtc1_data *shtc1_update_client(struct device *dev)
{
 struct shtc1_data *data = dev_get_drvdata(dev);
 struct i2c_client *client = data->client;
 unsigned char buf[SHTC1_RESPONSE_LENGTH];
 int val;
 int ret = 0;

 mutex_lock(&data->update_lock);

 if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {
  ret = shtc1_update_values(client, data, buf, sizeof(buf));
  if (ret)
   goto out;

  /*
 * From datasheet:
 * T = -45 + 175 * ST / 2^16
 * RH = 100 * SRH / 2^16
 *
 * Adapted for integer fixed point (3 digit) arithmetic.
 */
  val = be16_to_cpup((__be16 *)buf);
  data->temperature = ((21875 * val) >> 13) - 45000;
  val = be16_to_cpup((__be16 *)(buf + 3));
  data->humidity = ((12500 * val) >> 13);

  data->last_updated = jiffies;
  data->valid = true;
 }

out:
 mutex_unlock(&data->update_lock);

 return ret == 0 ? data : ERR_PTR(ret);
}

static ssize_t temp1_input_show(struct device *dev,
    struct device_attribute *attr,
    char *buf)
{
 struct shtc1_data *data = shtc1_update_client(dev);
 if (IS_ERR(data))
  return PTR_ERR(data);

 return sprintf(buf, "%d\n", data->temperature);
}

static ssize_t humidity1_input_show(struct device *dev,
        struct device_attribute *attr, char *buf)
{
 struct shtc1_data *data = shtc1_update_client(dev);
 if (IS_ERR(data))
  return PTR_ERR(data);

 return sprintf(buf, "%d\n", data->humidity);
}

static DEVICE_ATTR_RO(temp1_input);
static DEVICE_ATTR_RO(humidity1_input);

static struct attribute *shtc1_attrs[] = {
 &dev_attr_temp1_input.attr,
 &dev_attr_humidity1_input.attr,
 NULL
};

ATTRIBUTE_GROUPS(shtc1);

static void shtc1_select_command(struct shtc1_data *data)
{
 if (data->setup.high_precision) {
  data->command = data->setup.blocking_io ?
    shtc1_cmd_measure_blocking_hpm :
    shtc1_cmd_measure_nonblocking_hpm;
  data->nonblocking_wait_time = (data->chip == shtc1) ?
    SHTC1_NONBLOCKING_WAIT_TIME_HPM :
    SHTC3_NONBLOCKING_WAIT_TIME_HPM;
 } else {
  data->command = data->setup.blocking_io ?
    shtc1_cmd_measure_blocking_lpm :
    shtc1_cmd_measure_nonblocking_lpm;
  data->nonblocking_wait_time = (data->chip == shtc1) ?
    SHTC1_NONBLOCKING_WAIT_TIME_LPM :
    SHTC3_NONBLOCKING_WAIT_TIME_LPM;
 }
}

static int shtc1_probe(struct i2c_client *client)
{
 int ret;
 u16 id_reg;
 char id_reg_buf[2];
 struct shtc1_data *data;
 struct device *hwmon_dev;
 enum shtcx_chips chip = (uintptr_t)i2c_get_match_data(client);
 struct i2c_adapter *adap = client->adapter;
 struct device *dev = &client->dev;
 struct device_node *np = dev->of_node;

 if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
  dev_err(dev, "plain i2c transactions not supported\n");
  return -ENODEV;
 }

 ret = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH);
 if (ret != SHTC1_CMD_LENGTH) {
  dev_err(dev, "could not send read_id_reg command: %d\n", ret);
  return ret < 0 ? ret : -ENODEV;
 }
 ret = i2c_master_recv(client, id_reg_buf, sizeof(id_reg_buf));
 if (ret != sizeof(id_reg_buf)) {
  dev_err(dev, "could not read ID register: %d\n", ret);
  return -ENODEV;
 }

 id_reg = be16_to_cpup((__be16 *)id_reg_buf);
 if (chip == shtc3) {
  if ((id_reg & SHTC3_ID_MASK) != SHTC3_ID) {
   dev_err(dev, "SHTC3 ID register does not match\n");
   return -ENODEV;
  }
 } else if ((id_reg & SHTC1_ID_MASK) != SHTC1_ID) {
  dev_err(dev, "SHTC1 ID register does not match\n");
  return -ENODEV;
 }

 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 if (!data)
  return -ENOMEM;

 data->setup.blocking_io = false;
 data->setup.high_precision = true;
 data->client = client;
 data->chip = chip;

 if (np) {
  data->setup.blocking_io = of_property_read_bool(np, "sensirion,blocking-io");
  data->setup.high_precision = !of_property_read_bool(np, "sensirion,low-precision");
 } else {
  if (client->dev.platform_data)
   data->setup = *(struct shtc1_platform_data *)dev->platform_data;
 }

 shtc1_select_command(data);
 mutex_init(&data->update_lock);

 hwmon_dev = devm_hwmon_device_register_with_groups(dev,
          client->name,
          data,
          shtc1_groups);
 if (IS_ERR(hwmon_dev))
  dev_dbg(dev, "unable to register hwmon device\n");

 return PTR_ERR_OR_ZERO(hwmon_dev);
}

/* device ID table */
static const struct i2c_device_id shtc1_id[] = {
 { "shtc1", shtc1 },
 { "shtw1", shtc1 },
 { "shtc3", shtc3 },
 { }
};
MODULE_DEVICE_TABLE(i2c, shtc1_id);

static const struct of_device_id shtc1_of_match[] = {
 { .compatible = "sensirion,shtc1" },
 { .compatible = "sensirion,shtw1" },
 { .compatible = "sensirion,shtc3" },
 { }
};
MODULE_DEVICE_TABLE(of, shtc1_of_match);

static struct i2c_driver shtc1_i2c_driver = {
 .driver = {
  .name = "shtc1",
  .of_match_table = shtc1_of_match,
 },
 .probe        = shtc1_probe,
 .id_table     = shtc1_id,
};

module_i2c_driver(shtc1_i2c_driver);

MODULE_AUTHOR("Johannes Winkelmann ");
MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
MODULE_LICENSE("GPL");