> Add sht21 relative humidity and temperature sensor driver. There already > exists an in-kernel driver under hwmon but with limited functionality > like humidity and temperature always measured together at predefined > resolutions, etc.
comments below > New iio driver comes without limitations of predecessor, uses non-blocking i2c > communication mode and adds triggered buffer support thus is suited for more > use cases. > > Device datasheet can be found under: > > https://www.sensirion.com/fileadmin/user_upload/customers/sensirion/ \ > Dokumente/2_Humidity_Sensors/Sensirion_Humidity_Sensors_SHT21_Datasheet_V4.pdf > > Signed-off-by: Tomasz Duszynski <tdusz...@gmail.com> > --- > drivers/iio/humidity/Kconfig | 10 + > drivers/iio/humidity/Makefile | 1 + > drivers/iio/humidity/sht21.c | 519 > ++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 530 insertions(+) > create mode 100644 drivers/iio/humidity/sht21.c > > diff --git a/drivers/iio/humidity/Kconfig b/drivers/iio/humidity/Kconfig > index 866dda133336..93247ecc9324 100644 > --- a/drivers/iio/humidity/Kconfig > +++ b/drivers/iio/humidity/Kconfig > @@ -35,6 +35,16 @@ config HTU21 > This driver can also be built as a module. If so, the module will > be called htu21. > > +config SHT21 > + tristate "Sensirion SHT21 relative humidity and temperature sensor" > + depends on I2C select IIO_BUFFER select IIO_TRIGGERED_BUFFER > + help > + Say yes here to build support for the Sensirion SHT21 relative two spaces before Sensirion > + humidity and temperature sensor. > + > + To compile this driver as a module, choose M here: the module > + will be called sht21. > + > config SI7005 > tristate "SI7005 relative humidity and temperature sensor" > depends on I2C > diff --git a/drivers/iio/humidity/Makefile b/drivers/iio/humidity/Makefile > index c9f089a9a6b8..f2472fd2cc44 100644 > --- a/drivers/iio/humidity/Makefile > +++ b/drivers/iio/humidity/Makefile > @@ -5,5 +5,6 @@ > obj-$(CONFIG_DHT11) += dht11.o > obj-$(CONFIG_HDC100X) += hdc100x.o > obj-$(CONFIG_HTU21) += htu21.o > +obj-$(CONFIG_SHT21) += sht21.o > obj-$(CONFIG_SI7005) += si7005.o > obj-$(CONFIG_SI7020) += si7020.o > diff --git a/drivers/iio/humidity/sht21.c b/drivers/iio/humidity/sht21.c > new file mode 100644 > index 000000000000..199933b87297 > --- /dev/null > +++ b/drivers/iio/humidity/sht21.c > @@ -0,0 +1,519 @@ > +/* > + * Sensirion SHT21 relative humidity and temperature sensor driver > + * > + * Copyright (C) 2017 Tomasz Duszynski <tdusz...@gmail.com> > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * 7-bit I2C slave address: 0x40 > + */ > + > +#include <linux/bitops.h> > +#include <linux/delay.h> > +#include <linux/i2c.h> > +#include <linux/iio/buffer.h> > +#include <linux/iio/iio.h> > +#include <linux/iio/sysfs.h> > +#include <linux/iio/trigger_consumer.h> > +#include <linux/iio/triggered_buffer.h> > +#include <linux/module.h> > +#include <linux/mutex.h> > +#include <linux/of.h> > + > +#define SHT21_DRV_NAME "sht21" > + > +#define SHT21_TRIGGER_T_MEASUREMENT 0xF3 > +#define SHT21_TRIGGER_RH_MEASUREMENT 0xF5 > + > +#define SHT21_WRITE_USER_REG 0xE6 > +#define SHT21_READ_USER_REG 0xE7 > +#define SHT21_SOFT_RESET 0xFE > + > +#define SHT21_USER_REG_RES_8_12 BIT(0) > +#define SHT21_USER_REG_RES_10_13 BIT(7) > +#define SHT21_USER_REG_RES_11_11 (BIT(7) | BIT(0)) > + > +#define SHT21_USER_REG_ENABLE_HEATER BIT(2) > + > +enum { > + RES_12_14, I'd prefix these as well > + RES_8_12, > + RES_10_13, > + RES_11_11, > +}; > + > +/* > + * Combined sampling frequency i.e measuring RH and T together, which seems i.e. > + * to be common case for pressure/humidity sensors, was chosen so that sensor > + * is active for only 10% of time thus avoiding self-heating effect. > + * > + * Note that sampling frequencies are higher when measuring RH or T > separately. > + * > + * Following table shows how available resolutions, combined sampling > frequency > + * and frequencies for RH and T when measured separately are related. > + * > + * +-------------------+-------------+---------+--------+ > + * | RH / T resolution | RH + T [Hz] | RH [Hz] | T [Hz] | > + * +-------------------+-------------+---------+--------+ > + * | 12 / 14 | 0.88 | 3.45 | 1.18 | > + * +-------------------+-------------+---------+--------+ > + * | 8 / 12 | 3.85 | 25 | 4.55 | > + * +-------------------+-------------+---------+--------+ > + * | 10 / 13 | 1.93 | 11.11 | 2.33 | > + * +-------------------+-------------+---------+--------+ > + * | 11 / 11 | 2.28 | 6.67 | 9.09 | > + * +-------------------+-------------+---------+--------+ > + */ > +static const struct { > + int freq; > + int freq2; > + > + int rh_meas_time; > + int t_meas_time; > +} sht21_freq_meas_time_tbl[] = { > + [RES_12_14] = { 0, 880000, 29000, 85000 }, > + [RES_8_12] = { 3, 850000, 4000, 22000 }, > + [RES_10_13] = { 1, 930000, 9000, 43000 }, > + [RES_11_11] = { 2, 280000, 15000, 11000 } > +}; > + > +struct sht21_state { > + struct i2c_client *client; > + struct mutex lock; > + int res; > +}; > + > +static int sht21_verify_crc(const u8 *data, int len) returns bool? > +{ > + int i, j; > + u8 crc = 0; > + > + for (i = 0; i < len; i++) { > + crc ^= data[i]; > + > + for (j = 0; j < 8; j++) { > + if (crc & 0x80) > + crc = (crc << 1) ^ 0x31; > + else > + crc = crc << 1; > + } > + } > + > + return crc == 0; > +} > + > +/* every chunk of data read from sensor has crc byte appended */ > +static int sht21_read_data(struct sht21_state *state, int cmd, int *data) > +{ > + int delay, ret = 0; ret initialization not needed > + __be32 tmp = 0; > + > + switch (cmd) { > + case SHT21_READ_USER_REG: > + ret = i2c_smbus_read_i2c_block_data(state->client, cmd, > + 2, (u8 *)&tmp); > + break; > + case SHT21_TRIGGER_RH_MEASUREMENT: > + case SHT21_TRIGGER_T_MEASUREMENT: > + ret = i2c_smbus_write_byte(state->client, cmd); > + if (ret) > + break; > + > + delay = cmd == SHT21_TRIGGER_RH_MEASUREMENT ? > + sht21_freq_meas_time_tbl[state->res].rh_meas_time : > + sht21_freq_meas_time_tbl[state->res].t_meas_time; > + > + usleep_range(delay, delay + 1000); > + > + ret = i2c_master_recv(state->client, (u8 *)&tmp, 3); > + if (ret < 0) > + break; > + > + /* > + * Sensor should not be active more that 10% of time > + * otherwise it heats up and returns biased measurements. > + */ > + delay *= 9; > + usleep_range(delay, delay + 1000); > + > + break; default: return -EINVAL; ? > + } > + > + if (ret < 0) > + return ret; > + > + if (!sht21_verify_crc((u8 *)&tmp, ret)) { > + dev_err(&state->client->dev, "Data integrity check failed\n"); > + return -EINVAL; > + } > + > + /* crc byte no longer needed so drop it here */ > + *data = be32_to_cpu(tmp) >> ((sizeof(tmp) - ret + 1) * 8); wondering if negative values are properly sign-extended? I'd prefer a bit of code duplication if the ugliness above can be avoided > + > + return 0; > +} > + > +static int sht21_write_data(struct sht21_state *state, int cmd, int *data) > +{ > + int ret; > + > + if (!data) > + ret = i2c_smbus_write_byte(state->client, cmd); > + else > + ret = i2c_smbus_write_byte_data(state->client, cmd, *data); > + > + return ret; > +} > + > +static int sht21_trigger_measurement(struct sht21_state *state, int cmd, int > *data) > +{ > + int ret; > + > + mutex_lock(&state->lock); > + ret = sht21_read_data(state, cmd, data); simplify, just mutex_unlock(&state->lock); return ret; > + if (ret) { > + mutex_unlock(&state->lock); > + return ret; > + } > + mutex_unlock(&state->lock); > + > + return 0; > +} > + > +static int sht21_trigger_rh_measurement(struct sht21_state *state, int *data) > +{ > + int ret = sht21_trigger_measurement(state, > SHT21_TRIGGER_RH_MEASUREMENT, data); > + if (ret) > + return ret; > + > + *data >>= 2; > + *data = (((s64)*data * 125000) >> 14) - 6000; can't this be expressed using _SCALE and _OFFSET? I think that is the preferred way > + > + return 0; > +} > + > +static int sht21_trigger_t_measurement(struct sht21_state *state, int *data) > +{ > + int ret = sht21_trigger_measurement(state, SHT21_TRIGGER_T_MEASUREMENT, > data); > + if (ret) > + return ret; > + > + *data >>= 2; > + *data = (((s64)*data * 175720) >> 14) - 46850; > + > + return 0; > +} > + > +static int sht21_set_resolution(struct sht21_state *state, int res) > +{ > + int ret, data; > + > + ret = sht21_read_data(state, SHT21_READ_USER_REG, &data); > + if (ret) > + return ret; > + > + data &= ~SHT21_USER_REG_RES_11_11; > + > + switch (res) { > + case RES_12_14: > + break; > + case RES_8_12: > + data |= SHT21_USER_REG_RES_8_12; > + break; > + case RES_10_13: > + data |= SHT21_USER_REG_RES_10_13; > + break; > + case RES_11_11: > + data |= SHT21_USER_REG_RES_11_11; > + break; > + } > + > + ret = sht21_write_data(state, SHT21_WRITE_USER_REG, &data); > + if (ret) > + return ret; > + > + state->res = res; > + > + return 0; > +} > + > +static int sht21_soft_reset(struct sht21_state *state) > +{ > + int ret = sht21_write_data(state, SHT21_SOFT_RESET, NULL); > + if (ret) { > + dev_err(&state->client->dev, "Failed to reset device\n"); > + return ret; > + } > + > + msleep(15); this should raise a checkpatch warning... 20ms should be fine > + > + return 0; > +} > + > +static irqreturn_t sht21_trigger_handler(int irq, void *p) > +{ > + struct iio_poll_func *pf = p; > + struct iio_dev *indio_dev = pf->indio_dev; > + struct sht21_state *state = iio_priv(indio_dev); > + int buf[4], ret, i, j = 0; > + > + for_each_set_bit(i, indio_dev->active_scan_mask, indio_dev->masklength) > { > + ret = i == 0 ? sht21_trigger_rh_measurement(state, &buf[j++]) : > + sht21_trigger_t_measurement(state, &buf[j++]); > + if (ret) > + goto out; > + } > + > + iio_push_to_buffers_with_timestamp(indio_dev, buf, > + iio_get_time_ns(indio_dev)); > +out: > + iio_trigger_notify_done(indio_dev->trig); > + > + return IRQ_HANDLED; > +} > + > +static int sht21_read_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *channel, int *val, > + int *val2, long mask) > +{ > + struct sht21_state *state = iio_priv(indio_dev); > + int ret; > + > + switch (mask) { > + case IIO_CHAN_INFO_PROCESSED: > + if (iio_buffer_enabled(indio_dev)) use iio_device_claim_direct_mode() > + return -EBUSY; > + > + switch (channel->type) { > + case IIO_HUMIDITYRELATIVE: > + ret = sht21_trigger_rh_measurement(state, val); > + if (ret) > + return ret; > + > + return IIO_VAL_INT; > + case IIO_TEMP: > + ret = sht21_trigger_t_measurement(state, val); > + if (ret) > + return ret; > + > + return IIO_VAL_INT; > + default: > + return -EINVAL; > + } > + case IIO_CHAN_INFO_SAMP_FREQ: > + *val = sht21_freq_meas_time_tbl[state->res].freq; > + *val2 = sht21_freq_meas_time_tbl[state->res].freq2; > + > + return IIO_VAL_INT_PLUS_MICRO; > + default: > + return -EINVAL; > + } > +} > + > +static int sht21_write_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, > + int val, int val2, long mask) > +{ > + struct sht21_state *state = iio_priv(indio_dev); > + int i, ret; > + > + switch (mask) { > + case IIO_CHAN_INFO_SAMP_FREQ: > + for (i = 0; i < ARRAY_SIZE(sht21_freq_meas_time_tbl); i++) > + if (val == sht21_freq_meas_time_tbl[i].freq && > + val2 == sht21_freq_meas_time_tbl[i].freq2) > + break; > + > + if (i == ARRAY_SIZE(sht21_freq_meas_time_tbl)) > + return -EINVAL; > + > + ret = iio_device_claim_direct_mode(indio_dev); > + if (ret) > + return ret; > + > + mutex_lock(&state->lock); > + ret = sht21_set_resolution(state, i); > + mutex_unlock(&state->lock); > + > + iio_device_release_direct_mode(indio_dev); > + > + return ret; > + default: > + return -EINVAL; > + } > +} > + > +static ssize_t sht21_show_heater(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct iio_dev *indio_dev = dev_to_iio_dev(dev); > + struct sht21_state *state = iio_priv(indio_dev); > + int data, ret; > + > + ret = sht21_read_data(state, SHT21_READ_USER_REG, &data); > + if (ret) > + return ret; > + > + return sprintf(buf, "%d\n", !!(data & SHT21_USER_REG_ENABLE_HEATER)); > +} > + > +static ssize_t sht21_write_heater(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t len) > +{ > + struct iio_dev *indio_dev = dev_to_iio_dev(dev); > + struct sht21_state *state = iio_priv(indio_dev); > + int val, data, ret; > + > + ret = kstrtoint(buf, 10, &val); > + if (ret) > + return ret; > + if (val != 0 && val != 1) > + return -EINVAL; > + > + mutex_lock(&state->lock); > + ret = sht21_read_data(state, SHT21_READ_USER_REG, &data); > + if (ret) { > + mutex_unlock(&state->lock); > + return ret; > + } > + > + if (val) > + data |= SHT21_USER_REG_ENABLE_HEATER; > + else > + data &= ~SHT21_USER_REG_ENABLE_HEATER; > + > + ret = sht21_write_data(state, SHT21_WRITE_USER_REG, &data); > + mutex_unlock(&state->lock); > + > + return ret ? ret : len; > +} > + > +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("0.88 1.93 2.28 3.85"); > +static IIO_DEVICE_ATTR(heater_enable, S_IRUGO | S_IWUSR, > + sht21_show_heater, sht21_write_heater, 0); > + > +static struct attribute *sht21_attributes[] = { > + &iio_const_attr_sampling_frequency_available.dev_attr.attr, > + &iio_dev_attr_heater_enable.dev_attr.attr, > + NULL > +}; > + > +static const struct attribute_group sht21_attribute_group = { > + .attrs = sht21_attributes, > +}; > + > +static const struct iio_info sht21_info = { > + .driver_module = THIS_MODULE, > + .read_raw = sht21_read_raw, > + .write_raw = sht21_write_raw, > + .attrs = &sht21_attribute_group, > +}; > + > +#define SHT21_CHANNEL(_type, _index) { \ > + .type = _type, \ > + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \ > + .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), \ > + .scan_index = _index, \ > + .scan_type = { \ > + .sign = 's', \ > + .realbits = 32, \ > + .storagebits = 32, \ > + .endianness = IIO_CPU, \ > + }, \ > +} > + > +static const struct iio_chan_spec sht21_channels[] = { > + SHT21_CHANNEL(IIO_HUMIDITYRELATIVE, 0), > + SHT21_CHANNEL(IIO_TEMP, 1), > + IIO_CHAN_SOFT_TIMESTAMP(2), > +}; > + > +static int sht21_probe(struct i2c_client *client, const struct i2c_device_id > *id) > +{ > + struct iio_dev *indio_dev; > + struct sht21_state *data; > + int ret; > + > + if (!i2c_check_functionality(client->adapter, > + I2C_FUNC_SMBUS_WRITE_BYTE | > + I2C_FUNC_SMBUS_BYTE_DATA | > + I2C_FUNC_SMBUS_READ_I2C_BLOCK)) > + return -ENODEV; > + > + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); > + if (!indio_dev) > + return -ENOMEM; > + > + data = iio_priv(indio_dev); > + i2c_set_clientdata(client, indio_dev); > + data->client = client; > + mutex_init(&data->lock); > + > + indio_dev->dev.parent = &client->dev; > + indio_dev->name = id->name; > + indio_dev->modes = INDIO_DIRECT_MODE; > + indio_dev->info = &sht21_info; > + indio_dev->channels = sht21_channels; > + indio_dev->num_channels = ARRAY_SIZE(sht21_channels); > + > + ret = sht21_soft_reset(data); > + if (ret) > + return ret; > + > + ret = iio_triggered_buffer_setup(indio_dev, NULL, > + sht21_trigger_handler, NULL); > + if (ret) > + return ret; > + > + ret = iio_device_register(indio_dev); > + if (ret) > + iio_triggered_buffer_cleanup(indio_dev); > + > + return ret; > +} > + > +static int sht21_remove(struct i2c_client *client) > +{ > + struct iio_dev *indio_dev = i2c_get_clientdata(client); > + > + iio_device_unregister(indio_dev); > + iio_triggered_buffer_cleanup(indio_dev); > + > + return 0; > +} > + > +static const struct i2c_device_id sht21_id[] = { > + { "sht21", 0 }, > + { } > +}; > +MODULE_DEVICE_TABLE(i2c, sht21_id); > + > +static const struct of_device_id sht21_of_match[] = { > + { .compatible = "sensirion,sht21" }, > + { } > +}; > +MODULE_DEVICE_TABLE(of, sht21_of_match); > + > +static struct i2c_driver sht21_driver = { > + .driver = { > + .name = SHT21_DRV_NAME, > + .of_match_table = of_match_ptr(sht21_of_match), > + }, > + .id_table = sht21_id, > + .probe = sht21_probe, > + .remove = sht21_remove, > +}; > +module_i2c_driver(sht21_driver); > + > +MODULE_DESCRIPTION("Sensirion SHT21 relative humidity and temperature sensor > driver"); > +MODULE_AUTHOR("Tomasz Duszynski <tdusz...@gmail.com>"); > +MODULE_LICENSE("GPL v2"); > -- > 2.11.1 > -- Peter Meerwald-Stadler +43-664-2444418 (mobile)
