[linux-2.6-block.git] / drivers / hwmon / sht4x.c

// SPDX-License-Identifier: GPL-2.0-only

/*
 * Copyright (c) Linumiz 2021
 *
 * sht4x.c - Linux hwmon driver for SHT4x Temperature and Humidity sensor
 *
 * Author: Navin Sankar Velliangiri <navin@linumiz.com>
 */

#include <linux/crc8.h>
#include <linux/delay.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/jiffies.h>
#include <linux/module.h>

/*
 * Poll intervals (in milliseconds)
 */
#define SHT4X_MIN_POLL_INTERVAL	2000

/*
 * I2C command delays (in microseconds)
 */
#define SHT4X_MEAS_DELAY_HPM	8200	/* see t_MEAS,h in datasheet */
#define SHT4X_DELAY_EXTRA	10000

/*
 * Command Bytes
 */
#define SHT4X_CMD_MEASURE_HPM	0b11111101
#define SHT4X_CMD_RESET		0b10010100

#define SHT4X_CMD_LEN		1
#define SHT4X_CRC8_LEN		1
#define SHT4X_WORD_LEN		2
#define SHT4X_RESPONSE_LENGTH	6
#define SHT4X_CRC8_POLYNOMIAL	0x31
#define SHT4X_CRC8_INIT		0xff
#define SHT4X_MIN_TEMPERATURE	-45000
#define SHT4X_MAX_TEMPERATURE	125000
#define SHT4X_MIN_HUMIDITY	0
#define SHT4X_MAX_HUMIDITY	100000

DECLARE_CRC8_TABLE(sht4x_crc8_table);

/**
 * struct sht4x_data - All the data required to operate an SHT4X chip
 * @client: the i2c client associated with the SHT4X
 * @lock: a mutex that is used to prevent parallel access to the i2c client
 * @update_interval: the minimum poll interval
 * @last_updated: the previous time that the SHT4X was polled
 * @temperature: the latest temperature value received from the SHT4X
 * @humidity: the latest humidity value received from the SHT4X
 */
struct sht4x_data {
	struct i2c_client	*client;
	struct mutex		lock;	/* atomic read data updates */
	bool			valid;	/* validity of fields below */
	long			update_interval;	/* in milli-seconds */
	long			last_updated;	/* in jiffies */
	s32			temperature;
	s32			humidity;
};

/**
 * sht4x_read_values() - read and parse the raw data from the SHT4X
 * @sht4x_data: the struct sht4x_data to use for the lock
 * Return: 0 if successful, -ERRNO if not
 */
static int sht4x_read_values(struct sht4x_data *data)
{
	int ret = 0;
	u16 t_ticks, rh_ticks;
	unsigned long next_update;
	struct i2c_client *client = data->client;
	u8 crc;
	u8 cmd[SHT4X_CMD_LEN] = {SHT4X_CMD_MEASURE_HPM};
	u8 raw_data[SHT4X_RESPONSE_LENGTH];

	mutex_lock(&data->lock);
	next_update = data->last_updated +
		      msecs_to_jiffies(data->update_interval);

	if (data->valid && time_before_eq(jiffies, next_update))
		goto unlock;

	ret = i2c_master_send(client, cmd, SHT4X_CMD_LEN);
	if (ret < 0)
		goto unlock;

	usleep_range(SHT4X_MEAS_DELAY_HPM, SHT4X_MEAS_DELAY_HPM + SHT4X_DELAY_EXTRA);

	ret = i2c_master_recv(client, raw_data, SHT4X_RESPONSE_LENGTH);
	if (ret != SHT4X_RESPONSE_LENGTH) {
		if (ret >= 0)
			ret = -ENODATA;
		goto unlock;
	}

	t_ticks = raw_data[0] << 8 | raw_data[1];
	rh_ticks = raw_data[3] << 8 | raw_data[4];

	crc = crc8(sht4x_crc8_table, &raw_data[0], SHT4X_WORD_LEN, CRC8_INIT_VALUE);
	if (crc != raw_data[2]) {
		dev_err(&client->dev, "data integrity check failed\n");
		ret = -EIO;
		goto unlock;
	}

	crc = crc8(sht4x_crc8_table, &raw_data[3], SHT4X_WORD_LEN, CRC8_INIT_VALUE);
	if (crc != raw_data[5]) {
		dev_err(&client->dev, "data integrity check failed\n");
		ret = -EIO;
		goto unlock;
	}

	data->temperature = ((21875 * (int32_t)t_ticks) >> 13) - 45000;
	data->humidity = ((15625 * (int32_t)rh_ticks) >> 13) - 6000;
	data->last_updated = jiffies;
	data->valid = true;
	ret = 0;

unlock:
	mutex_unlock(&data->lock);
	return ret;
}

static ssize_t sht4x_interval_write(struct sht4x_data *data, long val)
{
	data->update_interval = clamp_val(val, SHT4X_MIN_POLL_INTERVAL, INT_MAX);

	return 0;
}

/* sht4x_interval_read() - read the minimum poll interval in milliseconds */
static size_t sht4x_interval_read(struct sht4x_data *data, long *val)
{
	*val = data->update_interval;
	return 0;
}

/* sht4x_temperature1_read() - read the temperature in millidegrees */
static int sht4x_temperature1_read(struct sht4x_data *data, long *val)
{
	int ret;

	ret = sht4x_read_values(data);
	if (ret < 0)
		return ret;

	*val = data->temperature;

	return 0;
}

/* sht4x_humidity1_read() - read a relative humidity in millipercent */
static int sht4x_humidity1_read(struct sht4x_data *data, long *val)
{
	int ret;

	ret = sht4x_read_values(data);
	if (ret < 0)
		return ret;

	*val = data->humidity;

	return 0;
}

static umode_t sht4x_hwmon_visible(const void *data,
				   enum hwmon_sensor_types type,
				   u32 attr, int channel)
{
	switch (type) {
	case hwmon_temp:
	case hwmon_humidity:
		return 0444;
	case hwmon_chip:
		return 0644;
	default:
		return 0;
	}
}

static int sht4x_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
			    u32 attr, int channel, long *val)
{
	struct sht4x_data *data = dev_get_drvdata(dev);

	switch (type) {
	case hwmon_temp:
		return sht4x_temperature1_read(data, val);
	case hwmon_humidity:
		return sht4x_humidity1_read(data, val);
	case hwmon_chip:
		return sht4x_interval_read(data, val);
	default:
		return -EOPNOTSUPP;
	}
}

static int sht4x_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
			     u32 attr, int channel, long val)
{
	struct sht4x_data *data = dev_get_drvdata(dev);

	switch (type) {
	case hwmon_chip:
		return sht4x_interval_write(data, val);
	default:
		return -EOPNOTSUPP;
	}
}

static const struct hwmon_channel_info * const sht4x_info[] = {
	HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
	HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT),
	NULL,
};

static const struct hwmon_ops sht4x_hwmon_ops = {
	.is_visible = sht4x_hwmon_visible,
	.read = sht4x_hwmon_read,
	.write = sht4x_hwmon_write,
};

static const struct hwmon_chip_info sht4x_chip_info = {
	.ops = &sht4x_hwmon_ops,
	.info = sht4x_info,
};

static int sht4x_probe(struct i2c_client *client)
{
	struct device *device = &client->dev;
	struct device *hwmon_dev;
	struct sht4x_data *data;
	u8 cmd[] = {SHT4X_CMD_RESET};
	int ret;

	/*
	 * we require full i2c support since the sht4x uses multi-byte read and
	 * writes as well as multi-byte commands which are not supported by
	 * the smbus protocol
	 */
	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
		return -EOPNOTSUPP;

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

	data->update_interval = SHT4X_MIN_POLL_INTERVAL;
	data->client = client;

	mutex_init(&data->lock);

	crc8_populate_msb(sht4x_crc8_table, SHT4X_CRC8_POLYNOMIAL);

	ret = i2c_master_send(client, cmd, SHT4X_CMD_LEN);
	if (ret < 0)
		return ret;
	if (ret != SHT4X_CMD_LEN)
		return -EIO;

	hwmon_dev = devm_hwmon_device_register_with_info(device,
							 client->name,
							 data,
							 &sht4x_chip_info,
							 NULL);

	return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id sht4x_id[] = {
	{ "sht4x", 0 },
	{ },
};
MODULE_DEVICE_TABLE(i2c, sht4x_id);

static const struct of_device_id sht4x_of_match[] = {
	{ .compatible = "sensirion,sht4x" },
	{ }
};
MODULE_DEVICE_TABLE(of, sht4x_of_match);

static struct i2c_driver sht4x_driver = {
	.driver = {
		.name = "sht4x",
		.of_match_table = sht4x_of_match,
	},
	.probe		= sht4x_probe,
	.id_table	= sht4x_id,
};

module_i2c_driver(sht4x_driver);

MODULE_AUTHOR("Navin Sankar Velliangiri <navin@linumiz.com>");
MODULE_DESCRIPTION("Sensirion SHT4x humidity and temperature sensor driver");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
505c2549 NSV	1	// SPDX-License-Identifier: GPL-2.0-only
	2
	3	/*
	4	* Copyright (c) Linumiz 2021
	5	*
	6	* sht4x.c - Linux hwmon driver for SHT4x Temperature and Humidity sensor
	7	*
	8	* Author: Navin Sankar Velliangiri <navin@linumiz.com>
	9	*/
	10
	11	#include <linux/crc8.h>
	12	#include <linux/delay.h>
	13	#include <linux/hwmon.h>
	14	#include <linux/i2c.h>
	15	#include <linux/jiffies.h>
	16	#include <linux/module.h>
	17
	18	/*
	19	* Poll intervals (in milliseconds)
	20	*/
	21	#define SHT4X_MIN_POLL_INTERVAL 2000
	22
	23	/*
	24	* I2C command delays (in microseconds)
	25	*/
0e4190d7	26	#define SHT4X_MEAS_DELAY_HPM 8200 /* see t_MEAS,h in datasheet */
505c2549 NSV	27	#define SHT4X_DELAY_EXTRA 10000
	28
	29	/*
	30	* Command Bytes
	31	*/
	32	#define SHT4X_CMD_MEASURE_HPM 0b11111101
	33	#define SHT4X_CMD_RESET 0b10010100
	34
	35	#define SHT4X_CMD_LEN 1
	36	#define SHT4X_CRC8_LEN 1
	37	#define SHT4X_WORD_LEN 2
	38	#define SHT4X_RESPONSE_LENGTH 6
	39	#define SHT4X_CRC8_POLYNOMIAL 0x31
	40	#define SHT4X_CRC8_INIT 0xff
	41	#define SHT4X_MIN_TEMPERATURE -45000
	42	#define SHT4X_MAX_TEMPERATURE 125000
	43	#define SHT4X_MIN_HUMIDITY 0
	44	#define SHT4X_MAX_HUMIDITY 100000
	45
	46	DECLARE_CRC8_TABLE(sht4x_crc8_table);
	47
	48	/**
	49	* struct sht4x_data - All the data required to operate an SHT4X chip
	50	* @client: the i2c client associated with the SHT4X
	51	* @lock: a mutex that is used to prevent parallel access to the i2c client
	52	* @update_interval: the minimum poll interval
	53	* @last_updated: the previous time that the SHT4X was polled
	54	* @temperature: the latest temperature value received from the SHT4X
	55	* @humidity: the latest humidity value received from the SHT4X
	56	*/
	57	struct sht4x_data {
	58	struct i2c_client *client;
	59	struct mutex lock; /* atomic read data updates */
	60	bool valid; /* validity of fields below */
	61	long update_interval; /* in milli-seconds */
	62	long last_updated; /* in jiffies */
	63	s32 temperature;
	64	s32 humidity;
	65	};
	66
	67	/**
	68	* sht4x_read_values() - read and parse the raw data from the SHT4X
	69	* @sht4x_data: the struct sht4x_data to use for the lock
07c6621a	70	* Return: 0 if successful, -ERRNO if not
505c2549 NSV	71	*/
	72	static int sht4x_read_values(struct sht4x_data *data)
	73	{
	74	int ret = 0;
	75	u16 t_ticks, rh_ticks;
	76	unsigned long next_update;
	77	struct i2c_client *client = data->client;
07c6621a JP	78	u8 crc;
	79	u8 cmd[SHT4X_CMD_LEN] = {SHT4X_CMD_MEASURE_HPM};
	80	u8 raw_data[SHT4X_RESPONSE_LENGTH];
505c2549 NSV	81
	82	mutex_lock(&data->lock);
	83	next_update = data->last_updated +
	84	msecs_to_jiffies(data->update_interval);
07c6621a JP	85
	86	if (data->valid && time_before_eq(jiffies, next_update))
	87	goto unlock;
	88
	89	ret = i2c_master_send(client, cmd, SHT4X_CMD_LEN);
	90	if (ret < 0)
	91	goto unlock;
	92
0e4190d7	93	usleep_range(SHT4X_MEAS_DELAY_HPM, SHT4X_MEAS_DELAY_HPM + SHT4X_DELAY_EXTRA);
07c6621a JP	94
	95	ret = i2c_master_recv(client, raw_data, SHT4X_RESPONSE_LENGTH);
	96	if (ret != SHT4X_RESPONSE_LENGTH) {
	97	if (ret >= 0)
	98	ret = -ENODATA;
	99	goto unlock;
505c2549 NSV	100	}
505c2549 NSV	101
07c6621a JP	102	t_ticks = raw_data[0] << 8 \| raw_data[1];
	103	rh_ticks = raw_data[3] << 8 \| raw_data[4];
	104
	105	crc = crc8(sht4x_crc8_table, &raw_data[0], SHT4X_WORD_LEN, CRC8_INIT_VALUE);
	106	if (crc != raw_data[2]) {
	107	dev_err(&client->dev, "data integrity check failed\n");
	108	ret = -EIO;
	109	goto unlock;
	110	}
	111
	112	crc = crc8(sht4x_crc8_table, &raw_data[3], SHT4X_WORD_LEN, CRC8_INIT_VALUE);
	113	if (crc != raw_data[5]) {
	114	dev_err(&client->dev, "data integrity check failed\n");
	115	ret = -EIO;
	116	goto unlock;
	117	}
	118
	119	data->temperature = ((21875 * (int32_t)t_ticks) >> 13) - 45000;
	120	data->humidity = ((15625 * (int32_t)rh_ticks) >> 13) - 6000;
	121	data->last_updated = jiffies;
	122	data->valid = true;
	123	ret = 0;
	124
505c2549 NSV	125	unlock:
	126	mutex_unlock(&data->lock);
	127	return ret;
	128	}
	129
	130	static ssize_t sht4x_interval_write(struct sht4x_data *data, long val)
	131	{
f9c0cf8f	132	data->update_interval = clamp_val(val, SHT4X_MIN_POLL_INTERVAL, INT_MAX);
505c2549 NSV	133
	134	return 0;
	135	}
	136
07c6621a	137	/* sht4x_interval_read() - read the minimum poll interval in milliseconds */
505c2549 NSV	138	static size_t sht4x_interval_read(struct sht4x_data data, long val)
	139	{
	140	*val = data->update_interval;
	141	return 0;
	142	}
	143
07c6621a	144	/* sht4x_temperature1_read() - read the temperature in millidegrees */
505c2549 NSV	145	static int sht4x_temperature1_read(struct sht4x_data data, long val)
	146	{
	147	int ret;
	148
	149	ret = sht4x_read_values(data);
	150	if (ret < 0)
	151	return ret;
	152
	153	*val = data->temperature;
	154
	155	return 0;
	156	}
	157
07c6621a	158	/* sht4x_humidity1_read() - read a relative humidity in millipercent */
505c2549 NSV	159	static int sht4x_humidity1_read(struct sht4x_data data, long val)
	160	{
	161	int ret;
	162
	163	ret = sht4x_read_values(data);
	164	if (ret < 0)
	165	return ret;
	166
	167	*val = data->humidity;
	168
	169	return 0;
	170	}
	171
	172	static umode_t sht4x_hwmon_visible(const void *data,
	173	enum hwmon_sensor_types type,
	174	u32 attr, int channel)
	175	{
	176	switch (type) {
	177	case hwmon_temp:
	178	case hwmon_humidity:
	179	return 0444;
	180	case hwmon_chip:
	181	return 0644;
	182	default:
	183	return 0;
	184	}
	185	}
	186
	187	static int sht4x_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
	188	u32 attr, int channel, long *val)
	189	{
	190	struct sht4x_data *data = dev_get_drvdata(dev);
	191
	192	switch (type) {
	193	case hwmon_temp:
	194	return sht4x_temperature1_read(data, val);
	195	case hwmon_humidity:
	196	return sht4x_humidity1_read(data, val);
	197	case hwmon_chip:
	198	return sht4x_interval_read(data, val);
	199	default:
	200	return -EOPNOTSUPP;
	201	}
	202	}
	203
	204	static int sht4x_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
	205	u32 attr, int channel, long val)
	206	{
	207	struct sht4x_data *data = dev_get_drvdata(dev);
	208
	209	switch (type) {
	210	case hwmon_chip:
	211	return sht4x_interval_write(data, val);
	212	default:
	213	return -EOPNOTSUPP;
	214	}
	215	}
	216
11c1dff5	217	static const struct hwmon_channel_info * const sht4x_info[] = {
505c2549 NSV	218	HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
	219	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
	220	HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT),
	221	NULL,
	222	};
	223
	224	static const struct hwmon_ops sht4x_hwmon_ops = {
	225	.is_visible = sht4x_hwmon_visible,
	226	.read = sht4x_hwmon_read,
	227	.write = sht4x_hwmon_write,
	228	};
	229
	230	static const struct hwmon_chip_info sht4x_chip_info = {
	231	.ops = &sht4x_hwmon_ops,
	232	.info = sht4x_info,
	233	};
	234
deeab9ea	235	static int sht4x_probe(struct i2c_client *client)
505c2549 NSV	236	{
	237	struct device *device = &client->dev;
	238	struct device *hwmon_dev;
	239	struct sht4x_data *data;
	240	u8 cmd[] = {SHT4X_CMD_RESET};
	241	int ret;
	242
	243	/*
	244	* we require full i2c support since the sht4x uses multi-byte read and
	245	* writes as well as multi-byte commands which are not supported by
	246	* the smbus protocol
	247	*/
	248	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	249	return -EOPNOTSUPP;
	250
	251	data = devm_kzalloc(device, sizeof(*data), GFP_KERNEL);
	252	if (!data)
	253	return -ENOMEM;
	254
	255	data->update_interval = SHT4X_MIN_POLL_INTERVAL;
	256	data->client = client;
	257
	258	mutex_init(&data->lock);
	259
	260	crc8_populate_msb(sht4x_crc8_table, SHT4X_CRC8_POLYNOMIAL);
	261
	262	ret = i2c_master_send(client, cmd, SHT4X_CMD_LEN);
	263	if (ret < 0)
	264	return ret;
	265	if (ret != SHT4X_CMD_LEN)
	266	return -EIO;
	267
	268	hwmon_dev = devm_hwmon_device_register_with_info(device,
	269	client->name,
	270	data,
	271	&sht4x_chip_info,
	272	NULL);
	273
	274	return PTR_ERR_OR_ZERO(hwmon_dev);
	275	}
	276
	277	static const struct i2c_device_id sht4x_id[] = {
	278	{ "sht4x", 0 },
	279	{ },
	280	};
	281	MODULE_DEVICE_TABLE(i2c, sht4x_id);
	282
62cfc057 DMT	283	static const struct of_device_id sht4x_of_match[] = {
	284	{ .compatible = "sensirion,sht4x" },
	285	{ }
	286	};
	287	MODULE_DEVICE_TABLE(of, sht4x_of_match);
	288
505c2549 NSV	289	static struct i2c_driver sht4x_driver = {
	290	.driver = {
	291	.name = "sht4x",
62cfc057	292	.of_match_table = sht4x_of_match,
505c2549	293	},
1975d167	294	.probe = sht4x_probe,
505c2549 NSV	295	.id_table = sht4x_id,
	296	};
	297
	298	module_i2c_driver(sht4x_driver);
	299
	300	MODULE_AUTHOR("Navin Sankar Velliangiri <navin@linumiz.com>");
	301	MODULE_DESCRIPTION("Sensirion SHT4x humidity and temperature sensor driver");
	302	MODULE_LICENSE("GPL v2");