linux/drivers/hwmon/sht21.c
Stephen Kitt 6748703856 hwmon: use simple i2c probe function
Many hwmon drivers don't use the id information provided by the old
i2c probe function, and the remainder can easily be adapted to the new
form ("probe_new") by calling i2c_match_id explicitly.

This avoids scanning the identifier tables during probes.

Drivers which didn't use the id are converted as-is; drivers which did
are modified as follows:

* if the information in i2c_client is sufficient, that's used instead
  (client->name);
* anything else is handled by calling i2c_match_id() with the same
  level of error-handling (if any) as before.

A few drivers aren't included in this patch because they have a
different set of maintainers. They will be covered by other patches.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200813160222.1503401-1-steve@sk2.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2020-09-23 09:42:39 -07:00

297 lines
7.4 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* Sensirion SHT21 humidity and temperature sensor driver
*
* Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com>
*
* Data sheet available at https://www.sensirion.com/file/datasheet_sht21
*/
#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/mutex.h>
#include <linux/device.h>
#include <linux/jiffies.h>
/* I2C command bytes */
#define SHT21_TRIG_T_MEASUREMENT_HM 0xe3
#define SHT21_TRIG_RH_MEASUREMENT_HM 0xe5
#define SHT21_READ_SNB_CMD1 0xFA
#define SHT21_READ_SNB_CMD2 0x0F
#define SHT21_READ_SNAC_CMD1 0xFC
#define SHT21_READ_SNAC_CMD2 0xC9
/**
* struct sht21 - SHT21 device specific data
* @client: I2C client device
* @lock: mutex to protect measurement values
* @last_update: time of last update (jiffies)
* @temperature: cached temperature measurement value
* @humidity: cached humidity measurement value
* @valid: only 0 before first measurement is taken
* @eic: cached electronic identification code text
*/
struct sht21 {
struct i2c_client *client;
struct mutex lock;
unsigned long last_update;
int temperature;
int humidity;
char valid;
char eic[18];
};
/**
* sht21_temp_ticks_to_millicelsius() - convert raw temperature ticks to
* milli celsius
* @ticks: temperature ticks value received from sensor
*/
static inline int sht21_temp_ticks_to_millicelsius(int ticks)
{
ticks &= ~0x0003; /* clear status bits */
/*
* Formula T = -46.85 + 175.72 * ST / 2^16 from data sheet 6.2,
* optimized for integer fixed point (3 digits) arithmetic
*/
return ((21965 * ticks) >> 13) - 46850;
}
/**
* sht21_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to
* one-thousandths of a percent relative humidity
* @ticks: humidity ticks value received from sensor
*/
static inline int sht21_rh_ticks_to_per_cent_mille(int ticks)
{
ticks &= ~0x0003; /* clear status bits */
/*
* Formula RH = -6 + 125 * SRH / 2^16 from data sheet 6.1,
* optimized for integer fixed point (3 digits) arithmetic
*/
return ((15625 * ticks) >> 13) - 6000;
}
/**
* sht21_update_measurements() - get updated measurements from device
* @dev: device
*
* Returns 0 on success, else negative errno.
*/
static int sht21_update_measurements(struct device *dev)
{
int ret = 0;
struct sht21 *sht21 = dev_get_drvdata(dev);
struct i2c_client *client = sht21->client;
mutex_lock(&sht21->lock);
/*
* Data sheet 2.4:
* SHT2x should not be active for more than 10% of the time - e.g.
* maximum two measurements per second at 12bit accuracy shall be made.
*/
if (time_after(jiffies, sht21->last_update + HZ / 2) || !sht21->valid) {
ret = i2c_smbus_read_word_swapped(client,
SHT21_TRIG_T_MEASUREMENT_HM);
if (ret < 0)
goto out;
sht21->temperature = sht21_temp_ticks_to_millicelsius(ret);
ret = i2c_smbus_read_word_swapped(client,
SHT21_TRIG_RH_MEASUREMENT_HM);
if (ret < 0)
goto out;
sht21->humidity = sht21_rh_ticks_to_per_cent_mille(ret);
sht21->last_update = jiffies;
sht21->valid = 1;
}
out:
mutex_unlock(&sht21->lock);
return ret >= 0 ? 0 : ret;
}
/**
* sht21_show_temperature() - show temperature measurement value in sysfs
* @dev: device
* @attr: device attribute
* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
*
* Will be called on read access to temp1_input sysfs attribute.
* Returns number of bytes written into buffer, negative errno on error.
*/
static ssize_t sht21_temperature_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct sht21 *sht21 = dev_get_drvdata(dev);
int ret;
ret = sht21_update_measurements(dev);
if (ret < 0)
return ret;
return sprintf(buf, "%d\n", sht21->temperature);
}
/**
* sht21_show_humidity() - show humidity measurement value in sysfs
* @dev: device
* @attr: device attribute
* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
*
* Will be called on read access to humidity1_input sysfs attribute.
* Returns number of bytes written into buffer, negative errno on error.
*/
static ssize_t sht21_humidity_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct sht21 *sht21 = dev_get_drvdata(dev);
int ret;
ret = sht21_update_measurements(dev);
if (ret < 0)
return ret;
return sprintf(buf, "%d\n", sht21->humidity);
}
static ssize_t eic_read(struct sht21 *sht21)
{
struct i2c_client *client = sht21->client;
u8 tx[2];
u8 rx[8];
u8 eic[8];
struct i2c_msg msgs[2] = {
{
.addr = client->addr,
.flags = 0,
.len = 2,
.buf = tx,
},
{
.addr = client->addr,
.flags = I2C_M_RD,
.len = 8,
.buf = rx,
},
};
int ret;
tx[0] = SHT21_READ_SNB_CMD1;
tx[1] = SHT21_READ_SNB_CMD2;
ret = i2c_transfer(client->adapter, msgs, 2);
if (ret < 0)
goto out;
eic[2] = rx[0];
eic[3] = rx[2];
eic[4] = rx[4];
eic[5] = rx[6];
tx[0] = SHT21_READ_SNAC_CMD1;
tx[1] = SHT21_READ_SNAC_CMD2;
msgs[1].len = 6;
ret = i2c_transfer(client->adapter, msgs, 2);
if (ret < 0)
goto out;
eic[0] = rx[3];
eic[1] = rx[4];
eic[6] = rx[0];
eic[7] = rx[1];
ret = snprintf(sht21->eic, sizeof(sht21->eic),
"%02x%02x%02x%02x%02x%02x%02x%02x\n",
eic[0], eic[1], eic[2], eic[3],
eic[4], eic[5], eic[6], eic[7]);
out:
if (ret < 0)
sht21->eic[0] = 0;
return ret;
}
/**
* eic_show() - show Electronic Identification Code in sysfs
* @dev: device
* @attr: device attribute
* @buf: sysfs buffer (PAGE_SIZE) where EIC is written
*
* Will be called on read access to eic sysfs attribute.
* Returns number of bytes written into buffer, negative errno on error.
*/
static ssize_t eic_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct sht21 *sht21 = dev_get_drvdata(dev);
int ret;
ret = sizeof(sht21->eic) - 1;
mutex_lock(&sht21->lock);
if (!sht21->eic[0])
ret = eic_read(sht21);
if (ret > 0)
memcpy(buf, sht21->eic, ret);
mutex_unlock(&sht21->lock);
return ret;
}
/* sysfs attributes */
static SENSOR_DEVICE_ATTR_RO(temp1_input, sht21_temperature, 0);
static SENSOR_DEVICE_ATTR_RO(humidity1_input, sht21_humidity, 0);
static DEVICE_ATTR_RO(eic);
static struct attribute *sht21_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
&sensor_dev_attr_humidity1_input.dev_attr.attr,
&dev_attr_eic.attr,
NULL
};
ATTRIBUTE_GROUPS(sht21);
static int sht21_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct device *hwmon_dev;
struct sht21 *sht21;
if (!i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WORD_DATA)) {
dev_err(&client->dev,
"adapter does not support SMBus word transactions\n");
return -ENODEV;
}
sht21 = devm_kzalloc(dev, sizeof(*sht21), GFP_KERNEL);
if (!sht21)
return -ENOMEM;
sht21->client = client;
mutex_init(&sht21->lock);
hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
sht21, sht21_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
/* Device ID table */
static const struct i2c_device_id sht21_id[] = {
{ "sht21", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, sht21_id);
static struct i2c_driver sht21_driver = {
.driver.name = "sht21",
.probe_new = sht21_probe,
.id_table = sht21_id,
};
module_i2c_driver(sht21_driver);
MODULE_AUTHOR("Urs Fleisch <urs.fleisch@sensirion.com>");
MODULE_DESCRIPTION("Sensirion SHT21 humidity and temperature sensor driver");
MODULE_LICENSE("GPL");