Re: [PATCH] iio: humidity: add HDC100x support

[Matt Ranostay <mranostay@gmail.com>]

On Sun, Aug 30, 2015 at 2:43 AM, Peter Meerwald <pmeerw@pmeerw.net> wrote:
>
>> Add support for the HDC100x temperature and humidity sensors
>> including the resistive heater element.
>
> comments inline below
>
>> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
>> ---
>>  .../ABI/testing/sysfs-bus-iio-humidity-hdc100x     |   7 +
>>  drivers/iio/humidity/Kconfig                       |  10 +
>>  drivers/iio/humidity/Makefile                      |   1 +
>>  drivers/iio/humidity/hdc100x.c                     | 304 +++++++++++++++++++++
>>  4 files changed, 322 insertions(+)
>>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x
>>  create mode 100644 drivers/iio/humidity/hdc100x.c
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x b/Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x
>> new file mode 100644
>> index 0000000..7e823a8
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x
>> @@ -0,0 +1,7 @@
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_current_heater_raw
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_current_heater_raw_available
>> +KernelVersion:       4.2
>> +Contact:     linux-iio@vger.kernel.org
>> +Description:
>> +             Controls the heater device within the humidity sensor to get
>> +             rid of excess condensation.
>
> the description explains the purpose, but not what shall be actually
> written to the file; is it on/off, a current, a temperature?
>
>> diff --git a/drivers/iio/humidity/Kconfig b/drivers/iio/humidity/Kconfig
>> index 688c0d1..01906c8 100644
>> --- a/drivers/iio/humidity/Kconfig
>> +++ b/drivers/iio/humidity/Kconfig
>> @@ -12,6 +12,16 @@ config DHT11
>>         Other sensors should work as well as long as they speak the
>>         same protocol.
>>
>> +config HDC100X
>> +     tristate "TI HDC100x relative humidity and temperature sensor"
>> +     depends on I2C
>> +     help
>> +      Say yes here to build support for the TI HDC100x series of
>> +      relative humidity and temperature sensor.
>
> sensors
>
>> +
>> +      To compile this driver as a module, choose M here: the module
>> +      will be called hdc100x.
>> +
>>  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 86e2d26..3e62c0a 100644
>> --- a/drivers/iio/humidity/Makefile
>> +++ b/drivers/iio/humidity/Makefile
>> @@ -3,5 +3,6 @@
>>  #
>>
>>  obj-$(CONFIG_DHT11) += dht11.o
>> +obj-$(CONFIG_HDC100X) += hdc100x.o
>>  obj-$(CONFIG_SI7005) += si7005.o
>>  obj-$(CONFIG_SI7020) += si7020.o
>> diff --git a/drivers/iio/humidity/hdc100x.c b/drivers/iio/humidity/hdc100x.c
>> new file mode 100644
>> index 0000000..88b21c8
>> --- /dev/null
>> +++ b/drivers/iio/humidity/hdc100x.c
>> @@ -0,0 +1,304 @@
>> +/*
>> + * hdc100x.c - Support for the TI HDC100x temperature + humidity sensors
>> + *
>> + * Copyright (C) 2015 Matt Ranostay <mranostay@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.
>> + *
>> + */
>> +
>> +#include <linux/delay.h>
>> +#include <linux/module.h>
>> +#include <linux/init.h>
>> +#include <linux/i2c.h>
>> +
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/sysfs.h>
>> +
>> +#define HDC100X_REG_TEMP                     0x00
>> +#define HDC100X_REG_HUMIDITY                 0x01
>> +
>> +#define HDC100X_REG_CONFIG                   0x02
>> +#define HDC100X_REG_CONFIG_HEATER_EN         BIT(13)
>> +
>> +struct hdc100x_data {
>> +     struct i2c_client *client;
>> +     struct mutex lock;
>> +     u16 config;
>> +
>> +     /* integration time of the sensor */
>> +     int adc_int_us[2];
>> +};
>> +
>> +/* integration time in us */
>> +#define HDC100X_MAX_INT_TIME_ARRAY_SIZE              3
>> +static const int hdc100x_int_time[][HDC100X_MAX_INT_TIME_ARRAY_SIZE] = {
>> +     { 6350, 3650, 0 },      /* IIO_TEMP channel*/
>> +     { 6500, 3850, 2500 },   /* IIO_HUMIDITYRELATIVE channel */
>> +};
>> +
>> +static const int hdc100x_resolution_shift[][2] = { {10, 1}, {8, 2} };
>
> maybe a comment what the first and second element mean?
> above you have a CONSTANT for the number of elements
> (HDC100X_MAX_INT_TIME_ARRAY_SIZE), but not here
>
>> +
>> +static IIO_CONST_ATTR(temp_integration_time_available,
>> +             "0.00365 0.00635");
>> +
>> +static IIO_CONST_ATTR(humidity_integration_time_available,
>> +             "0.0025 0.00385 0.0065");
>> +
>> +static IIO_CONST_ATTR(out_current_heater_raw_available,
>> +             "0 1");
>> +
>> +static struct attribute *hdc100x_attributes[] = {
>> +     &iio_const_attr_temp_integration_time_available.dev_attr.attr,
>> +     &iio_const_attr_humidity_integration_time_available.dev_attr.attr,
>> +     &iio_const_attr_out_current_heater_raw_available.dev_attr.attr,
>> +     NULL
>> +};
>> +
>> +static struct attribute_group hdc100x_attribute_group = {
>> +     .attrs = hdc100x_attributes,
>> +};
>> +
>> +static const struct iio_chan_spec hdc100x_channels[] = {
>> +     {
>> +             .type = IIO_TEMP,
>> +             .channel = 0,
>
> channel is not needed (no plurality of channels of the same type)
>
>> +             .address = HDC100X_REG_TEMP,
>> +             .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
>> +                     BIT(IIO_CHAN_INFO_SCALE) |
>> +                     BIT(IIO_CHAN_INFO_INT_TIME) |
>> +                     BIT(IIO_CHAN_INFO_OFFSET),
>> +     },
>> +     {
>> +             .type = IIO_HUMIDITYRELATIVE,
>> +             .channel = 1,
>> +             .address = HDC100X_REG_HUMIDITY,
>> +             .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
>> +                     BIT(IIO_CHAN_INFO_SCALE) |
>> +                     BIT(IIO_CHAN_INFO_INT_TIME)
>> +     },
>> +
>> +     {
>> +             .type = IIO_CURRENT,
>> +             .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>> +             .extend_name = "heater",
>> +             .output = 1,
>> +     },
>> +};
>> +
>> +static int hdc100x_update_config(struct hdc100x_data *data, int mask, int val)
>> +{
>> +     data->config = (~mask & data->config) | val;
>> +
>> +     return i2c_smbus_write_word_data(data->client, HDC100X_REG_CONFIG,
>> +                                      cpu_to_be16(data->config));
>
> use i2c_smbus_write_word_swapped(), drop cpu_to_be16()
>
> strictly, data->config should be updated after having successfully written
> to register
>
>> +}
>> +
>> +static int hdc100x_set_it_time(struct hdc100x_data *data, int chan, int val2)
>> +{
>> +     const int *int_time = (const int *) &hdc100x_int_time[chan];
>> +     int shift = hdc100x_resolution_shift[chan][0];
>> +     int ret = -EINVAL;
>> +     int i;
>> +
>> +     for (i = 0; i < HDC100X_MAX_INT_TIME_ARRAY_SIZE; i++) {
>> +             if (val2 && val2 == int_time[i]) {
>> +                     ret = hdc100x_update_config(data,
>> +                             hdc100x_resolution_shift[chan][1] << shift,
>> +                             i << shift);
>> +                     data->adc_int_us[chan] = val2;
>> +                     break;
>> +             }
>> +     }
>> +
>> +     return ret;
>> +}
>> +
>> +static int hdc100x_get_measurement(struct hdc100x_data *data,
>> +                                struct iio_chan_spec const *chan,
>> +                                int *val)
>> +{
>> +     struct i2c_client *client = data->client;
>> +     int delay = data->adc_int_us[chan->channel];
>> +     int ret;
>> +
>> +     /* start measurement */
>> +     ret = i2c_smbus_write_byte(client, chan->address);
>> +     if (ret < 0) {
>> +             dev_err(&client->dev, "cannot start measurement");
>> +             return ret;
>> +     }
>> +
>> +     /* wait for integration time to pass */
>> +     usleep_range(delay, delay + 1000);
>> +
>> +     if (ret < 0) {
>
> huh? is there a _read_byte() missing?
> could a word transfer be used?
>
>> +             dev_err(&client->dev, "cannot read low byte measurement");
>> +             return ret;
>> +     }
>> +     *val = ret >> 2;
>> +
>> +     ret = i2c_smbus_read_byte(client);
>> +     if (ret < 0) {
>> +             dev_err(&client->dev, "cannot read high byte measurement");
>> +             return ret;
>> +     }
>> +     *val |= ret << 6;
>> +
>> +     return 0;
>> +}
>> +
>> +static inline int get_heater_status(struct hdc100x_data *data)
>
> no hdc100xx_ prefix
>
> drop inline, let the compiler figure out
>
>> +{
>> +     return !!(data->config & HDC100X_REG_CONFIG_HEATER_EN);
>> +}
>> +
>> +static int hdc100x_read_raw(struct iio_dev *indio_dev,
>> +                         struct iio_chan_spec const *chan, int *val,
>> +                         int *val2, long mask)
>> +{
>> +     struct hdc100x_data *data = iio_priv(indio_dev);
>> +     int ret = -EINVAL;
>> +
>> +     switch (mask) {
>> +     case IIO_CHAN_INFO_RAW:
>> +             mutex_lock(&data->lock);
>> +             if (chan->type != IIO_CURRENT) {
>> +                     ret = hdc100x_get_measurement(data, chan, val);
>> +                     if (!ret)
>> +                             ret = IIO_VAL_INT;
>
> ret < 0 would be an error condition, don't overwrite with VAL_INT

Sorry not sure I follow. If ret is 0 it sets IIO_VAL_INT
>
>> +             } else {
>> +                     *val = get_heater_status(data);
>> +                     ret = IIO_VAL_INT;
>> +             }
>> +             mutex_unlock(&data->lock);
>> +             break;
>> +     case IIO_CHAN_INFO_INT_TIME:
>> +             mutex_lock(&data->lock);
>
> the lock could probably be dropped
>
>> +             *val = 0;
>> +             *val2 = data->adc_int_us[chan->channel];
>> +             mutex_unlock(&data->lock);
>> +             return IIO_VAL_INT_PLUS_MICRO;
>> +     case IIO_CHAN_INFO_SCALE:
>> +             if (chan->type == IIO_TEMP) {
>> +                     *val = 165;
>> +                     *val2 = 65536 >> 2;
>> +                     ret = IIO_VAL_FRACTIONAL;
>> +             } else {
>> +                     *val = 0;
>> +                     *val2 = 10000;
>> +                     ret = IIO_VAL_INT_PLUS_MICRO;
>> +             }
>> +             break;
>> +     case IIO_CHAN_INFO_OFFSET:
>> +             *val = -40;
>> +             return IIO_VAL_INT;
>> +     default:
>> +             break;
>> +     }
>> +
>> +     return ret;
>> +}
>> +
>> +static int hdc100x_write_raw(struct iio_dev *indio_dev,
>> +                          struct iio_chan_spec const *chan,
>> +                          int val, int val2, long mask)
>> +{
>> +     struct hdc100x_data *data = iio_priv(indio_dev);
>> +     int ret = -EINVAL;
>> +
>> +     switch (mask) {
>> +     case IIO_CHAN_INFO_INT_TIME:
>> +             if (val != 0)
>> +                     return -EINVAL;
>> +
>> +             mutex_lock(&data->lock);
>> +             ret = hdc100x_set_it_time(data, chan->channel, val2);
>> +             mutex_unlock(&data->lock);
>> +             break;
>> +     case IIO_CHAN_INFO_RAW:
>> +             if (chan->type == IIO_CURRENT) {
>> +                     if (val2 != 0)
>> +                             return -EINVAL;
>> +
>> +                     mutex_lock(&data->lock);
>> +                     ret = hdc100x_update_config(data,
>> +                                     HDC100X_REG_CONFIG_HEATER_EN,
>> +                                     val ? 0 : HDC100X_REG_CONFIG_HEATER_EN);
>> +
>> +                     if (!ret)
>> +                             ret = IIO_VAL_INT;
>
> no, drop this; this is _write, not _read
>
>> +                     mutex_unlock(&data->lock);
>> +             }
>> +             /* fall-thru */
>
> just return ret and avoid the fall-thru
>
>> +     }
>> +
>> +     return ret;
>> +}
>> +
>> +static const struct iio_info hdc100x_info = {
>> +     .read_raw = hdc100x_read_raw,
>> +     .write_raw = hdc100x_write_raw,
>> +     .attrs = &hdc100x_attribute_group,
>> +     .driver_module = THIS_MODULE,
>> +};
>> +
>> +static int hdc100x_probe(struct i2c_client *client,
>> +                      const struct i2c_device_id *id)
>> +{
>> +     struct iio_dev *indio_dev;
>> +     struct hdc100x_data *data;
>> +
>> +     if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
>> +             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 = dev_name(&client->dev);
>> +     indio_dev->modes = INDIO_DIRECT_MODE;
>> +     indio_dev->info = &hdc100x_info;
>> +
>> +     indio_dev->channels = hdc100x_channels;
>> +     indio_dev->num_channels = ARRAY_SIZE(hdc100x_channels);
>> +
>> +     /* be sure we are in a known state */
>> +     hdc100x_set_it_time(data, 0, 6350);
>
> probably use hdc100x_int_time[0][0] instead of the redundant value
>
>> +     hdc100x_set_it_time(data, 1, 6500);
>> +
>> +     return devm_iio_device_register(&client->dev, indio_dev);
>> +}
>> +
>> +static const struct i2c_device_id hdc100x_id[] = {
>> +     { "hdc100x", 0 },
>> +     { }
>> +};
>> +MODULE_DEVICE_TABLE(i2c, hdc100x_id);
>> +
>> +static struct i2c_driver hdc100x_driver = {
>> +     .driver = {
>> +             .name   = "hdc100x",
>> +     },
>> +     .probe = hdc100x_probe,
>> +     .id_table = hdc100x_id,
>> +};
>> +module_i2c_driver(hdc100x_driver);
>> +
>> +MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
>> +MODULE_DESCRIPTION("TI HDC100x humidity and temperature sensor driver");
>> +MODULE_LICENSE("GPL");
>>
>
> --
>
> Peter Meerwald
> +43-664-2444418 (mobile)