hwmon: Add AHT10 Temperature and Humidity Sensor Driver
This patch adds a hwmon driver for the AHT10 Temperature and Humidity sensor. It has a maximum sample rate, as the datasheet states that the chip may heat up if it is sampled more than once every two seconds. Has been tested a to work on a raspberrypi0w Signed-off-by: Johannes Cornelis Draaijer (datdenkikniet) <jcdra1@gmail.com> Link: https://lore.kernel.org/r/20210107194014.GA88780@desktop [groeck: dropped AHT10_ADDR (unused) and use AHT10_MEAS_SIZE where appropriate; dropped change log] Signed-off-by: Guenter Roeck <linux@roeck-us.net>master
Johannes Cornelis Draaijer (datdenkikniet)
Guenter Roeck
parent
0bf6a1e85d
commit
8c78f0dee4
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@ -0,0 +1,46 @@
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.. SPDX-License-Identifier: GPL-2.0
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Kernel driver aht10
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=====================
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Supported chips:
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* Aosong AHT10
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Prefix: 'aht10'
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Addresses scanned: None
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Datasheet:
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Chinese: http://www.aosong.com/userfiles/files/media/AHT10%E4%BA%A7%E5%93%81%E6%89%8B%E5%86%8C%20A3%2020201210.pdf
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English: https://server4.eca.ir/eshop/AHT10/Aosong_AHT10_en_draft_0c.pdf
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Author: Johannes Cornelis Draaijer <jcdra1@gmail.com>
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Description
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-----------
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The AHT10 is a Temperature and Humidity sensor
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The address of this i2c device may only be 0x38
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Usage Notes
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-----------
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This driver does not probe for AHT10 devices, as there is no reliable
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way to determine if an i2c chip is or isn't an AHT10. The device has
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to be instantiated explicitly with the address 0x38. See
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Documentation/i2c/instantiating-devices.rst for details.
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Sysfs entries
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-------------
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=============== ============================================
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temp1_input Measured temperature in millidegrees Celcius
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humidity1_input Measured humidity in %H
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update_interval The minimum interval for polling the sensor,
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in milliseconds. Writable. Must be at
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least 2000.
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=============== ============================================
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@ -37,6 +37,7 @@ Hardware Monitoring Kernel Drivers
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adt7462
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adt7470
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adt7475
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aht10
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amc6821
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amd_energy
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asb100
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@ -244,6 +244,16 @@ config SENSORS_ADT7475
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This driver can also be built as a module. If so, the module
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will be called adt7475.
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config SENSORS_AHT10
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tristate "Aosong AHT10"
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depends on I2C
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help
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If you say yes here, you get support for the Aosong AHT10
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temperature and humidity sensors
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This driver can also be built as a module. If so, the module
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will be called aht10.
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config SENSORS_AS370
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tristate "Synaptics AS370 SoC hardware monitoring driver"
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help
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@ -44,6 +44,7 @@ obj-$(CONFIG_SENSORS_ADT7411) += adt7411.o
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obj-$(CONFIG_SENSORS_ADT7462) += adt7462.o
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obj-$(CONFIG_SENSORS_ADT7470) += adt7470.o
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obj-$(CONFIG_SENSORS_ADT7475) += adt7475.o
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obj-$(CONFIG_SENSORS_AHT10) += aht10.o
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obj-$(CONFIG_SENSORS_AMD_ENERGY) += amd_energy.o
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obj-$(CONFIG_SENSORS_APPLESMC) += applesmc.o
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obj-$(CONFIG_SENSORS_ARM_SCMI) += scmi-hwmon.o
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@ -0,0 +1,346 @@
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* aht10.c - Linux hwmon driver for AHT10 Temperature and Humidity sensor
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* Copyright (C) 2020 Johannes Cornelis Draaijer
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*/
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#include <linux/delay.h>
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#include <linux/hwmon.h>
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#include <linux/i2c.h>
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#include <linux/ktime.h>
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#include <linux/module.h>
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#define AHT10_MEAS_SIZE 6
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/*
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* Poll intervals (in milliseconds)
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*/
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#define AHT10_DEFAULT_MIN_POLL_INTERVAL 2000
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#define AHT10_MIN_POLL_INTERVAL 2000
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/*
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* I2C command delays (in microseconds)
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*/
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#define AHT10_MEAS_DELAY 80000
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#define AHT10_CMD_DELAY 350000
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#define AHT10_DELAY_EXTRA 100000
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/*
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* Command bytes
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*/
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#define AHT10_CMD_INIT 0b11100001
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#define AHT10_CMD_MEAS 0b10101100
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#define AHT10_CMD_RST 0b10111010
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/*
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* Flags in the answer byte/command
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*/
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#define AHT10_CAL_ENABLED BIT(3)
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#define AHT10_BUSY BIT(7)
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#define AHT10_MODE_NOR (BIT(5) | BIT(6))
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#define AHT10_MODE_CYC BIT(5)
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#define AHT10_MODE_CMD BIT(6)
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#define AHT10_MAX_POLL_INTERVAL_LEN 30
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/**
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* struct aht10_data - All the data required to operate an AHT10 chip
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* @client: the i2c client associated with the AHT10
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* @lock: a mutex that is used to prevent parallel access to the
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* i2c client
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* @min_poll_interval: the minimum poll interval
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* While the poll rate limit is not 100% necessary,
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* the datasheet recommends that a measurement
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* is not performed too often to prevent
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* the chip from warming up due to the heat it generates.
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* If it's unwanted, it can be ignored setting it to
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* it to 0. Default value is 2000 ms
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* @previous_poll_time: the previous time that the AHT10
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* was polled
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* @temperature: the latest temperature value received from
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* the AHT10
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* @humidity: the latest humidity value received from the
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* AHT10
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*/
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struct aht10_data {
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struct i2c_client *client;
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/*
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* Prevent simultaneous access to the i2c
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* client and previous_poll_time
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*/
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struct mutex lock;
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ktime_t min_poll_interval;
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ktime_t previous_poll_time;
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int temperature;
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int humidity;
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};
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/**
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* aht10_init() - Initialize an AHT10 chip
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* @client: the i2c client associated with the AHT10
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* @data: the data associated with this AHT10 chip
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* Return: 0 if succesfull, 1 if not
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*/
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static int aht10_init(struct aht10_data *data)
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{
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const u8 cmd_init[] = {AHT10_CMD_INIT, AHT10_CAL_ENABLED | AHT10_MODE_CYC,
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0x00};
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int res;
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u8 status;
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struct i2c_client *client = data->client;
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res = i2c_master_send(client, cmd_init, 3);
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if (res < 0)
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return res;
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usleep_range(AHT10_CMD_DELAY, AHT10_CMD_DELAY +
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AHT10_DELAY_EXTRA);
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res = i2c_master_recv(client, &status, 1);
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if (res != 1)
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return -ENODATA;
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if (status & AHT10_BUSY)
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return -EBUSY;
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return 0;
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}
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/**
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* aht10_polltime_expired() - check if the minimum poll interval has
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* expired
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* @data: the data containing the time to compare
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* Return: 1 if the minimum poll interval has expired, 0 if not
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*/
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static int aht10_polltime_expired(struct aht10_data *data)
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{
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ktime_t current_time = ktime_get_boottime();
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ktime_t difference = ktime_sub(current_time, data->previous_poll_time);
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return ktime_after(difference, data->min_poll_interval);
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}
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/**
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* aht10_read_values() - read and parse the raw data from the AHT10
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* @aht10_data: the struct aht10_data to use for the lock
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* Return: 0 if succesfull, 1 if not
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*/
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static int aht10_read_values(struct aht10_data *data)
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{
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const u8 cmd_meas[] = {AHT10_CMD_MEAS, 0x33, 0x00};
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u32 temp, hum;
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int res;
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u8 raw_data[AHT10_MEAS_SIZE];
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struct i2c_client *client = data->client;
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mutex_lock(&data->lock);
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if (aht10_polltime_expired(data)) {
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res = i2c_master_send(client, cmd_meas, sizeof(cmd_meas));
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if (res < 0)
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return res;
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usleep_range(AHT10_MEAS_DELAY,
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AHT10_MEAS_DELAY + AHT10_DELAY_EXTRA);
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res = i2c_master_recv(client, raw_data, AHT10_MEAS_SIZE);
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if (res != AHT10_MEAS_SIZE) {
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mutex_unlock(&data->lock);
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if (res >= 0)
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return -ENODATA;
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else
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return res;
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}
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hum = ((u32)raw_data[1] << 12u) |
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((u32)raw_data[2] << 4u) |
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((raw_data[3] & 0xF0u) >> 4u);
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temp = ((u32)(raw_data[3] & 0x0Fu) << 16u) |
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((u32)raw_data[4] << 8u) |
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raw_data[5];
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temp = ((temp * 625) >> 15u) * 10;
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hum = ((hum * 625) >> 16u) * 10;
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data->temperature = (int)temp - 50000;
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data->humidity = hum;
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data->previous_poll_time = ktime_get_boottime();
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}
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mutex_unlock(&data->lock);
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return 0;
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}
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/**
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* aht10_interval_write() - store the given minimum poll interval.
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* Return: 0 on success, -EINVAL if a value lower than the
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* AHT10_MIN_POLL_INTERVAL is given
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*/
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static ssize_t aht10_interval_write(struct aht10_data *data,
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long val)
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{
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data->min_poll_interval = ms_to_ktime(clamp_val(val, 2000, LONG_MAX));
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return 0;
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}
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/**
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* aht10_interval_read() - read the minimum poll interval
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* in milliseconds
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*/
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static ssize_t aht10_interval_read(struct aht10_data *data,
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long *val)
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{
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*val = ktime_to_ms(data->min_poll_interval);
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return 0;
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}
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/**
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* aht10_temperature1_read() - read the temperature in millidegrees
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*/
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static int aht10_temperature1_read(struct aht10_data *data, long *val)
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{
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int res;
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res = aht10_read_values(data);
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if (res < 0)
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return res;
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*val = data->temperature;
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return 0;
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}
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/**
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* aht10_humidity1_read() - read the relative humidity in millipercent
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*/
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static int aht10_humidity1_read(struct aht10_data *data, long *val)
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{
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int res;
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res = aht10_read_values(data);
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if (res < 0)
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return res;
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*val = data->humidity;
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return 0;
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}
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static umode_t aht10_hwmon_visible(const void *data, enum hwmon_sensor_types type,
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u32 attr, int channel)
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{
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switch (type) {
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case hwmon_temp:
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case hwmon_humidity:
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return 0444;
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case hwmon_chip:
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return 0644;
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default:
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return 0;
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}
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}
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static int aht10_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
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u32 attr, int channel, long *val)
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{
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struct aht10_data *data = dev_get_drvdata(dev);
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switch (type) {
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case hwmon_temp:
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return aht10_temperature1_read(data, val);
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case hwmon_humidity:
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return aht10_humidity1_read(data, val);
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case hwmon_chip:
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return aht10_interval_read(data, val);
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default:
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return -EOPNOTSUPP;
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}
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}
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static int aht10_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
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u32 attr, int channel, long val)
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{
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struct aht10_data *data = dev_get_drvdata(dev);
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switch (type) {
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case hwmon_chip:
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return aht10_interval_write(data, val);
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default:
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return -EOPNOTSUPP;
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}
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}
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static const struct hwmon_channel_info *aht10_info[] = {
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HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
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HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
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HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT),
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NULL,
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};
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static const struct hwmon_ops aht10_hwmon_ops = {
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.is_visible = aht10_hwmon_visible,
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.read = aht10_hwmon_read,
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.write = aht10_hwmon_write,
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};
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static const struct hwmon_chip_info aht10_chip_info = {
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.ops = &aht10_hwmon_ops,
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.info = aht10_info,
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};
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static int aht10_probe(struct i2c_client *client,
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const struct i2c_device_id *aht10_id)
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{
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struct device *device = &client->dev;
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struct device *hwmon_dev;
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struct aht10_data *data;
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int res;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
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return -ENOENT;
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data = devm_kzalloc(device, sizeof(*data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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data->min_poll_interval = ms_to_ktime(AHT10_DEFAULT_MIN_POLL_INTERVAL);
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data->client = client;
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mutex_init(&data->lock);
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res = aht10_init(data);
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if (res < 0)
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return res;
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res = aht10_read_values(data);
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if (res < 0)
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return res;
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hwmon_dev = devm_hwmon_device_register_with_info(device,
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client->name,
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data,
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&aht10_chip_info,
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NULL);
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return PTR_ERR_OR_ZERO(hwmon_dev);
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}
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static const struct i2c_device_id aht10_id[] = {
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{ "aht10", 0 },
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{ },
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};
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MODULE_DEVICE_TABLE(i2c, aht10_id);
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static struct i2c_driver aht10_driver = {
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.driver = {
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.name = "aht10",
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},
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.probe = aht10_probe,
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.id_table = aht10_id,
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};
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module_i2c_driver(aht10_driver);
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MODULE_AUTHOR("Johannes Cornelis Draaijer <jcdra1@gmail.com>");
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MODULE_DESCRIPTION("AHT10 Temperature and Humidity sensor driver");
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MODULE_VERSION("1.0");
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MODULE_LICENSE("GPL v2");
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Loading…
Reference in New Issue