Commit d2abcb5c authored by Kirill Yatsenko's avatar Kirill Yatsenko Committed by Guenter Roeck
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hwmon: (aht10) Add support for compatible aht20 



Add support for compatible AHT20 temperature/humidity sensor. The only
difference between the two is that AHT20 has additional crc8 byte.

It seems like AHT15 is also supported by the driver but it wasn't
verified and tested yet.

Tested on Beaglebone black rev C.

Signed-off-by: default avatarKirill Yatsenko <kiriyatsenko@gmail.com>
Link: https://lore.kernel.org/r/20230524201912.815993-1-kiriyatsenko@gmail.com


Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 7d0c2c61

Documentation/hwmon/aht10.rst

+15 −5
Original line number Diff line number Diff line
@@ -5,32 +5,42 @@ Kernel driver aht10 


Supported chips:



  * Aosong AHT10

  * Aosong AHT10/AHT20



    Prefix: 'aht10'



    Addresses scanned: None



    Datasheet:

    Datasheet(AHT10):



      Chinese: http://www.aosong.com/userfiles/files/media/AHT10%E4%BA%A7%E5%93%81%E6%89%8B%E5%86%8C%20A3%2020201210.pdf

      English: https://server4.eca.ir/eshop/AHT10/Aosong_AHT10_en_draft_0c.pdf



    Datasheet(AHT20):



      English: http://www.aosong.com/userfiles/files/media/Data%20Sheet%20AHT20.pdf



Author: Johannes Cornelis Draaijer <jcdra1@gmail.com>





Description

-----------



The AHT10 is a Temperature and Humidity sensor

The AHT10/AHT20 is a Temperature and Humidity sensor



The address of this i2c device may only be 0x38



Special Features

----------------



AHT20 has additional CRC8 support which is sent as the last byte of the sensor

values.



Usage Notes

-----------



This driver does not probe for AHT10 devices, as there is no reliable

way to determine if an i2c chip is or isn't an AHT10. The device has

This driver does not probe for AHT10/ATH20 devices, as there is no reliable

way to determine if an i2c chip is or isn't an AHT10/AHT20. The device has

to be instantiated explicitly with the address 0x38. See

Documentation/i2c/instantiating-devices.rst for details.

drivers/hwmon/Kconfig

+3 −2
Original line number Diff line number Diff line
@@ -255,10 +255,11 @@ config SENSORS_ADT7475 
	  will be called adt7475.



config SENSORS_AHT10

	tristate "Aosong AHT10"

	tristate "Aosong AHT10, AHT20"

	depends on I2C

	select CRC8

	help

	  If you say yes here, you get support for the Aosong AHT10

	  If you say yes here, you get support for the Aosong AHT10 and AHT20

	  temperature and humidity sensors



	  This driver can also be built as a module. If so, the module

drivers/hwmon/aht10.c

+65 −19
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only



/*

 * aht10.c - Linux hwmon driver for AHT10 Temperature and Humidity sensor

 * aht10.c - Linux hwmon driver for AHT10/AHT20 Temperature and Humidity sensors

 * Copyright (C) 2020 Johannes Cornelis Draaijer

 */
@@ -10,9 +10,13 @@ 
#include <linux/i2c.h>

#include <linux/ktime.h>

#include <linux/module.h>

#include <linux/crc8.h>



#define AHT10_MEAS_SIZE		6



#define AHT20_MEAS_SIZE		7

#define AHT20_CRC8_POLY		0x31



/*

 * Poll intervals (in milliseconds)

 */
@@ -44,9 +48,18 @@ 


#define AHT10_MAX_POLL_INTERVAL_LEN	30



enum aht10_variant { aht10, aht20 };



static const struct i2c_device_id aht10_id[] = {

	{ "aht10", aht10 },

	{ "aht20", aht20 },

	{ },

};

MODULE_DEVICE_TABLE(i2c, aht10_id);



/**

 *   struct aht10_data - All the data required to operate an AHT10 chip

 *   @client: the i2c client associated with the AHT10

 *   struct aht10_data - All the data required to operate an AHT10/AHT20 chip

 *   @client: the i2c client associated with the AHT10/AHT20

 *   @lock: a mutex that is used to prevent parallel access to the

 *          i2c client

 *   @min_poll_interval: the minimum poll interval
@@ -56,12 +69,14 @@ 
 *                   the chip from warming up due to the heat it generates.

 *                   If it's unwanted, it can be ignored setting it to

 *                   it to 0. Default value is 2000 ms

 *   @previous_poll_time: the previous time that the AHT10

 *   @previous_poll_time: the previous time that the AHT10/AHT20

 *                        was polled

 *   @temperature: the latest temperature value received from

 *                 the AHT10

 *                 the AHT10/AHT20

 *   @humidity: the latest humidity value received from the

 *              AHT10

 *              AHT10/AHT20

 *   @crc8: crc8 support flag

 *   @meas_size: measurements data size

 */



struct aht10_data {
@@ -75,11 +90,13 @@ struct aht10_data { 
	ktime_t previous_poll_time;

	int temperature;

	int humidity;

	bool crc8;

	unsigned int meas_size;

};



/**

 * aht10_init() - Initialize an AHT10 chip

 * @data: the data associated with this AHT10 chip

 * aht10_init() - Initialize an AHT10/AHT20 chip

 * @data: the data associated with this AHT10/AHT20 chip

 * Return: 0 if successful, 1 if not

 */

static int aht10_init(struct aht10_data *data)
@@ -121,8 +138,25 @@ static int aht10_polltime_expired(struct aht10_data *data) 
	return ktime_after(difference, data->min_poll_interval);

}



DECLARE_CRC8_TABLE(crc8_table);



/**

 * aht10_read_values() - read and parse the raw data from the AHT10

 * crc8_check() - check crc of the sensor's measurements

 * @raw_data: data frame received from sensor(including crc as the last byte)

 * @count: size of the data frame

 * Return: 0 if successful, 1 if not

 */

static int crc8_check(u8 *raw_data, int count)

{

	/*

	 * crc calculated on the whole frame(including crc byte) should yield

	 * zero in case of correctly received bytes

	 */

	return crc8(crc8_table, raw_data, count, CRC8_INIT_VALUE);

}



/**

 * aht10_read_values() - read and parse the raw data from the AHT10/AHT20

 * @data: the struct aht10_data to use for the lock

 * Return: 0 if successful, 1 if not

 */
@@ -131,7 +165,7 @@ static int aht10_read_values(struct aht10_data *data) 
	const u8 cmd_meas[] = {AHT10_CMD_MEAS, 0x33, 0x00};

	u32 temp, hum;

	int res;

	u8 raw_data[AHT10_MEAS_SIZE];

	u8 raw_data[AHT20_MEAS_SIZE];

	struct i2c_client *client = data->client;



	mutex_lock(&data->lock);
@@ -148,14 +182,19 @@ static int aht10_read_values(struct aht10_data *data) 


	usleep_range(AHT10_MEAS_DELAY, AHT10_MEAS_DELAY + AHT10_DELAY_EXTRA);



	res = i2c_master_recv(client, raw_data, AHT10_MEAS_SIZE);

	if (res != AHT10_MEAS_SIZE) {

	res = i2c_master_recv(client, raw_data, data->meas_size);

	if (res != data->meas_size) {

		mutex_unlock(&data->lock);

		if (res >= 0)

			return -ENODATA;

		return res;

	}



	if (data->crc8 && crc8_check(raw_data, data->meas_size)) {

		mutex_unlock(&data->lock);

		return -EIO;

	}



	hum =   ((u32)raw_data[1] << 12u) |

		((u32)raw_data[2] << 4u) |

		((raw_data[3] & 0xF0u) >> 4u);
@@ -292,6 +331,8 @@ static const struct hwmon_chip_info aht10_chip_info = { 


static int aht10_probe(struct i2c_client *client)

{

	const struct i2c_device_id *id = i2c_match_id(aht10_id, client);

	enum aht10_variant variant = id->driver_data;

	struct device *device = &client->dev;

	struct device *hwmon_dev;

	struct aht10_data *data;
@@ -307,6 +348,17 @@ static int aht10_probe(struct i2c_client *client) 
	data->min_poll_interval = ms_to_ktime(AHT10_DEFAULT_MIN_POLL_INTERVAL);

	data->client = client;



	switch (variant) {

	case aht20:

		data->meas_size = AHT20_MEAS_SIZE;

		data->crc8 = true;

		crc8_populate_msb(crc8_table, AHT20_CRC8_POLY);

		break;

	default:

		data->meas_size = AHT10_MEAS_SIZE;

		break;

	}



	mutex_init(&data->lock);



	res = aht10_init(data);
@@ -326,12 +378,6 @@ static int aht10_probe(struct i2c_client *client) 
	return PTR_ERR_OR_ZERO(hwmon_dev);

}



static const struct i2c_device_id aht10_id[] = {

	{ "aht10", 0 },

	{ },

};

MODULE_DEVICE_TABLE(i2c, aht10_id);



static struct i2c_driver aht10_driver = {

	.driver = {

		.name = "aht10",
@@ -343,6 +389,6 @@ static struct i2c_driver aht10_driver = { 
module_i2c_driver(aht10_driver);



MODULE_AUTHOR("Johannes Cornelis Draaijer <jcdra1@gmail.com>");

MODULE_DESCRIPTION("AHT10 Temperature and Humidity sensor driver");

MODULE_DESCRIPTION("AHT10/AHT20 Temperature and Humidity sensor driver");

MODULE_VERSION("1.0");

MODULE_LICENSE("GPL v2");