| Message ID | 20210804154641.GA3237@arbad (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | iio: chemical: Add support for sgp40 gas sensor | expand |
Hi Andreas,
I love your patch! Perhaps something to improve:
[auto build test WARNING on iio/togreg]
[also build test WARNING on robh/for-next linus/master v5.14-rc4 next-20210804]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Andreas-Klinger/iio-chemical-Add-support-for-sgp40-gas-sensor/20210804-234955
base: https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg
config: x86_64-buildonly-randconfig-r001-20210804 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 4f71f59bf3d9914188a11d0c41bedbb339d36ff5)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/c122fa429b69b2cf1d2546043c4ba21c715fa3cb
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Andreas-Klinger/iio-chemical-Add-support-for-sgp40-gas-sensor/20210804-234955
git checkout c122fa429b69b2cf1d2546043c4ba21c715fa3cb
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> drivers/iio/chemical/sgp40.c:186:68: warning: format specifies type 'int' but the argument has type 'unsigned long' [-Wformat]
dev_warn(data->dev, "i2c_master_send ret: %d sizeof: %d\n", ret, sizeof(tg));
~~ ^~~~~~~~~~
%lu
include/linux/dev_printk.h:114:33: note: expanded from macro 'dev_warn'
_dev_warn(dev, dev_fmt(fmt), ##__VA_ARGS__)
~~~ ^~~~~~~~~~~
drivers/iio/chemical/sgp40.c:195:68: warning: format specifies type 'int' but the argument has type 'unsigned long' [-Wformat]
dev_warn(data->dev, "i2c_master_recv ret: %d sizeof: %d\n", ret, sizeof(tgres));
~~ ^~~~~~~~~~~~~
%lu
include/linux/dev_printk.h:114:33: note: expanded from macro 'dev_warn'
_dev_warn(dev, dev_fmt(fmt), ##__VA_ARGS__)
~~~ ^~~~~~~~~~~
2 warnings generated.
vim +186 drivers/iio/chemical/sgp40.c
159
160 static int sgp40_measure_resistance_raw(struct sgp40_data *data, u16 *resistance_raw)
161 {
162 int ret;
163 struct i2c_client *client = data->client;
164 u32 ticks;
165 u16 ticks16;
166 u8 crc;
167 struct sgp40_tg_measure tg = {.command = {0x26, 0x0F}};
168 struct sgp40_tg_result tgres;
169
170 mutex_lock(&data->lock);
171
172 ticks = (data->rht / 10) * 65535 / 10000;
173 ticks16 = (u16)clamp(ticks, 0u, 65535u); /* clamp between 0 .. 100 %rH */
174 tg.rht_ticks = cpu_to_be16(ticks16);
175 tg.rht_crc = crc8(sgp40_crc8_table, (u8 *)&tg.rht_ticks, 2, SGP40_CRC8_INIT);
176
177 ticks = ((data->temp + 45000) / 10 ) * 65535 / 17500;
178 ticks16 = (u16)clamp(ticks, 0u, 65535u); /* clamp between -45 .. +130 °C */
179 tg.temp_ticks = cpu_to_be16(ticks16);
180 tg.temp_crc = crc8(sgp40_crc8_table, (u8 *)&tg.temp_ticks, 2, SGP40_CRC8_INIT);
181
182 mutex_unlock(&data->lock);
183
184 ret = i2c_master_send(client, (const char *)&tg, sizeof(tg));
185 if (ret != sizeof(tg)) {
> 186 dev_warn(data->dev, "i2c_master_send ret: %d sizeof: %d\n", ret, sizeof(tg));
187 return -EIO;
188 }
189 msleep(30);
190
191 ret = i2c_master_recv(client, (u8 *)&tgres, sizeof(tgres));
192 if (ret < 0)
193 return ret;
194 if (ret != sizeof(tgres)) {
195 dev_warn(data->dev, "i2c_master_recv ret: %d sizeof: %d\n", ret, sizeof(tgres));
196 return -EIO;
197 }
198
199 crc = crc8(sgp40_crc8_table, (u8 *)&tgres.res_ticks, 2, SGP40_CRC8_INIT);
200 if (crc != tgres.res_crc) {
201 dev_err(data->dev, "CRC error while measure-raw\n");
202 return -EIO;
203 }
204
205 *resistance_raw = be16_to_cpu(tgres.res_ticks);
206
207 return 0;
208 }
209
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
On Wed, 4 Aug 2021 17:46:42 +0200 Andreas Klinger <ak@it-klinger.de> wrote: > sgp40 is a gas sensor used for measuring the air quality. > > This driver is reading the raw resistance value which can be passed to > an userspace algorithm for further calculation. > > The raw value is also used to calculate an estimated absolute voc index > in the range from 0 to 500. For this purpose the raw_mean value of the > resistance for which the index value is 250 might be set up as a > calibration step. This can be done with in_resistance_calibbias. > > Compensation of relative humidity and temperature is supported and can > be used by writing to output values of out_humidityrelative_raw and > out_temp_raw. > > There is a predecesor sensor type (sgp30) already existing. This driver > module was not extended because the new sensor is quite different in its > i2c telegrams. > > Signed-off-by: Andreas Klinger <ak@it-klinger.de> Hi Andreas, Along with the 0-day build warnings email, there were some additional things in here that I've tweaked (including some whitespace at end of lines). As it's all minor stuff I've applied the patches and made the changes I wanted to see. Printk issue resolved using the %zu format and other tweaks as mentioned below, Please take a look and check I haven't messed anything up. Applied to the togreg branch of iio.git and pushed out as testing for 0-day to take another poke at it. Thanks, Jonathan > --- > .../ABI/testing/sysfs-bus-iio-chemical-sgp40 | 31 ++ > MAINTAINERS | 6 + > drivers/iio/chemical/Kconfig | 11 + > drivers/iio/chemical/Makefile | 1 + > drivers/iio/chemical/sgp40.c | 372 ++++++++++++++++++ > 5 files changed, 421 insertions(+) > create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-chemical-sgp40 > create mode 100644 drivers/iio/chemical/sgp40.c > > diff --git a/Documentation/ABI/testing/sysfs-bus-iio-chemical-sgp40 b/Documentation/ABI/testing/sysfs-bus-iio-chemical-sgp40 > new file mode 100644 > index 000000000000..469a7c00fad4 > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-bus-iio-chemical-sgp40 > @@ -0,0 +1,31 @@ > +What: /sys/bus/iio/devices/iio:deviceX/out_temp_raw > +Date: August 2021 > +KernelVersion: 5.15 > +Contact: Andreas Klinger <ak@it-klinger.de> > +Description: > + Set the temperature. This value is sent to the sensor for > + temperature compensation. > + Default value: 25000 (25 °C) > + > +What: /sys/bus/iio/devices/iio:deviceX/out_humidityrelative_raw > +Date: August 2021 > +KernelVersion: 5.15 > +Contact: Andreas Klinger <ak@it-klinger.de> > +Description: > + Set the relative humidity. This value is sent to the sensor for > + humidity compensation. > + Default value: 50000 (50 % relative humidity) > + > +What: /sys/bus/iio/devices/iio:deviceX/in_resistance_calibbias This may bite us in future. A 'limitation' or deliberate restriction of the ABI docs format is we can't have repeats. Right now, these three are unique to this file, so we are fine. It seems unlikely they will remain so long term. When we move them to a unified location it becomes harder to maintain the level of detail you have here. Still, a problem for another day. > +Date: August 2021 > +KernelVersion: 5.15 > +Contact: Andreas Klinger <ak@it-klinger.de> > +Description: > + Set the bias value for the resistance which is used for > + calculation of in_concentration_input as follows: > + > + x = (in_resistance_raw - in_resistance_calibbias) * 0.65 > + > + in_concentration_input = 500 / (1 + e^x) > + > + Default value: 30000 > diff --git a/MAINTAINERS b/MAINTAINERS > index 19135a9d778e..60f5e57ef385 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -16707,6 +16707,12 @@ F: drivers/iio/chemical/scd30_core.c > F: drivers/iio/chemical/scd30_i2c.c > F: drivers/iio/chemical/scd30_serial.c > > +SENSIRION SGP40 GAS SENSOR DRIVER > +M: Andreas Klinger <ak@it-klinger.de> > +S: Maintained > +F: Documentation/ABI/testing/sysfs-bus-iio-chemical-sgp40 > +F: drivers/iio/chemical/sgp40.c > + > SENSIRION SPS30 AIR POLLUTION SENSOR DRIVER > M: Tomasz Duszynski <tduszyns@gmail.com> > S: Maintained > diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig > index a4920646e9be..c03667e62732 100644 > --- a/drivers/iio/chemical/Kconfig > +++ b/drivers/iio/chemical/Kconfig > @@ -131,6 +131,17 @@ config SENSIRION_SGP30 > To compile this driver as module, choose M here: the > module will be called sgp30. > > +config SENSIRION_SGP40 > + tristate "Sensirion SGP40 gas sensor" > + depends on I2C > + select CRC8 > + help > + Say Y here to build I2C interface to support Sensirion SGP40 gas > + sensor > + > + To compile this driver as module, choose M here: the > + module will be called sgp40. > + > config SPS30 > tristate > select IIO_BUFFER > diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile > index 4898690cc155..d07af581f234 100644 > --- a/drivers/iio/chemical/Makefile > +++ b/drivers/iio/chemical/Makefile > @@ -16,6 +16,7 @@ obj-$(CONFIG_SCD30_CORE) += scd30_core.o > obj-$(CONFIG_SCD30_I2C) += scd30_i2c.o > obj-$(CONFIG_SCD30_SERIAL) += scd30_serial.o > obj-$(CONFIG_SENSIRION_SGP30) += sgp30.o > +obj-$(CONFIG_SENSIRION_SGP40) += sgp40.o > obj-$(CONFIG_SPS30) += sps30.o > obj-$(CONFIG_SPS30_I2C) += sps30_i2c.o > obj-$(CONFIG_SPS30_SERIAL) += sps30_serial.o > diff --git a/drivers/iio/chemical/sgp40.c b/drivers/iio/chemical/sgp40.c > new file mode 100644 > index 000000000000..fdbe75b56873 > --- /dev/null > +++ b/drivers/iio/chemical/sgp40.c > @@ -0,0 +1,372 @@ > +// SPDX-License-Identifier: GPL-2.0+ > +/* > + * sgp40.c - Support for Sensirion SGP40 Gas Sensor > + * > + * Copyright (C) 2021 Andreas Klinger <ak@it-klinger.de> > + * > + * I2C slave address: 0x59 > + * > + * Datasheet can be found here: > + * https://www.sensirion.com/file/datasheet_sgp40 > + * > + * There are two functionalities supported: > + * > + * 1) read raw logarithmic resistance value from sensor > + * --> useful to pass it to the algorithm of the sensor vendor for > + * measuring deteriorations and improvements of air quality. > + * > + * 2) calculate an estimated absolute voc index (0 - 500 index points) for > + * measuring the air quality. > + * For this purpose the value of the resistance for which the voc index > + * will be 250 can be set up using calibbias. > + * > + * Compensation values of relative humidity and temperature can be set up > + * by writing to the out values of temp and humidityrelative. > + */ > + > +#include <linux/module.h> > +#include <linux/iio/iio.h> > +#include <linux/iio/sysfs.h> Not used. > +#include <linux/delay.h> > +#include <linux/mutex.h> > +#include <linux/i2c.h> > +#include <linux/crc8.h> If no reason to have other orderings, alphabetical preferred. > + > +/* > + * floating point calculation of voc is done as integer > + * where numbers are multiplied by 1 << SGP40_CALC_POWER > + */ > +#define SGP40_CALC_POWER 14 > + > +#define SGP40_CRC8_POLYNOMIAL 0x31 > +#define SGP40_CRC8_INIT 0xff > + > +DECLARE_CRC8_TABLE(sgp40_crc8_table); > + > +struct sgp40_data { > + struct device *dev; > + struct i2c_client *client; > + int rht; > + int temp; > + int res_calibbias; > + struct mutex lock; Locks should always have documentation of what their scope is. > +}; > + > +struct sgp40_tg_measure { > + u8 command[2]; > + __be16 rht_ticks; > + u8 rht_crc; > + __be16 temp_ticks; > + u8 temp_crc; > +} __packed; > + > +struct sgp40_tg_result { > + __be16 res_ticks; > + u8 res_crc; > +} __packed; > + > +static const struct iio_chan_spec sgp40_channels[] = { > + { > + .type = IIO_CONCENTRATION, > + .channel2 = IIO_MOD_VOC, > + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), > + }, > + { > + .type = IIO_RESISTANCE, > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | > + BIT(IIO_CHAN_INFO_CALIBBIAS), > + }, > + { > + .type = IIO_TEMP, > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), > + .output = 1, > + }, > + { > + .type = IIO_HUMIDITYRELATIVE, > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), > + .output = 1, > + }, > +}; > + > +/* > + * taylor approximation of e^x: > + * y = 1 + x + x^2 / 2 + x^3 / 6 + x^4 / 24 + ... + x^n / n! > + * > + * Because we are calculating x real value multiplied by 2^power we get > + * an additional 2^power^n to divide for every element. For a reasonable > + * precision this would overflow after a few iterations. Therefore we > + * divide the x^n part whenever its about to overflow (xmax). > + */ > + > +static u32 sgp40_exp(int exp, u32 power, u32 rounds) > +{ > + u32 x, y, xp; > + u32 factorial, divider, xmax; > + int sign = 1; > + int i; > + > + if (exp == 0) > + return 1 << power; > + else if (exp < 0) { > + sign = -1; > + exp *= -1; > + } > + > + xmax = 0x7FFFFFFF / exp; > + x = exp; > + xp = 1; > + factorial = 1; > + y = 1 << power; > + divider = 0; > + > + for (i = 1; i <= rounds; i++) { > + xp *= x; > + factorial *= i; > + y += (xp >> divider) / factorial; > + divider += power; > + /* divide when next multiplication would overflow */ > + if (xp >= xmax) { > + xp >>= power; > + divider -= power; > + } > + } > + > + if (sign == -1) > + return (1 << (power * 2)) / y; > + else > + return y; > +} > + > +static int sgp40_calc_voc(struct sgp40_data *data, u16 resistance_raw, int *voc) > +{ > + int x; > + u32 exp = 0; > + > + /* we calculate as a multiple of 16384 (2^14) */ > + mutex_lock(&data->lock); > + x = ((int)resistance_raw - data->res_calibbias) * 106; > + mutex_unlock(&data->lock); > + > + /* voc = 500 / (1 + e^x) */ > + exp = sgp40_exp(x, SGP40_CALC_POWER, 18); > + *voc = 500 * ((1 << (SGP40_CALC_POWER * 2)) / ((1<<SGP40_CALC_POWER) + exp)); > + > + dev_dbg(data->dev, "raw: %d res_calibbias: %d x: %d exp: %d voc: %d\n", > + resistance_raw, data->res_calibbias, x, exp, *voc); > + > + return 0; > +} > + > +static int sgp40_measure_resistance_raw(struct sgp40_data *data, u16 *resistance_raw) > +{ > + int ret; > + struct i2c_client *client = data->client; > + u32 ticks; > + u16 ticks16; > + u8 crc; > + struct sgp40_tg_measure tg = {.command = {0x26, 0x0F}}; > + struct sgp40_tg_result tgres; > + > + mutex_lock(&data->lock); > + > + ticks = (data->rht / 10) * 65535 / 10000; > + ticks16 = (u16)clamp(ticks, 0u, 65535u); /* clamp between 0 .. 100 %rH */ > + tg.rht_ticks = cpu_to_be16(ticks16); > + tg.rht_crc = crc8(sgp40_crc8_table, (u8 *)&tg.rht_ticks, 2, SGP40_CRC8_INIT); > + > + ticks = ((data->temp + 45000) / 10 ) * 65535 / 17500; > + ticks16 = (u16)clamp(ticks, 0u, 65535u); /* clamp between -45 .. +130 °C */ > + tg.temp_ticks = cpu_to_be16(ticks16); > + tg.temp_crc = crc8(sgp40_crc8_table, (u8 *)&tg.temp_ticks, 2, SGP40_CRC8_INIT); > + > + mutex_unlock(&data->lock); > + > + ret = i2c_master_send(client, (const char *)&tg, sizeof(tg)); > + if (ret != sizeof(tg)) { > + dev_warn(data->dev, "i2c_master_send ret: %d sizeof: %d\n", ret, sizeof(tg)); > + return -EIO; > + } > + msleep(30); > + > + ret = i2c_master_recv(client, (u8 *)&tgres, sizeof(tgres)); > + if (ret < 0) > + return ret; > + if (ret != sizeof(tgres)) { > + dev_warn(data->dev, "i2c_master_recv ret: %d sizeof: %d\n", ret, sizeof(tgres)); > + return -EIO; > + } > + > + crc = crc8(sgp40_crc8_table, (u8 *)&tgres.res_ticks, 2, SGP40_CRC8_INIT); > + if (crc != tgres.res_crc) { > + dev_err(data->dev, "CRC error while measure-raw\n"); > + return -EIO; > + } > + > + *resistance_raw = be16_to_cpu(tgres.res_ticks); > + > + return 0; > +} > + > +static int sgp40_read_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, int *val, > + int *val2, long mask) > +{ > + struct sgp40_data *data = iio_priv(indio_dev); > + int ret, voc; > + u16 resistance_raw; > + > + switch (mask) { > + case IIO_CHAN_INFO_RAW: > + switch (chan->type) { > + case IIO_RESISTANCE: > + ret = sgp40_measure_resistance_raw(data, &resistance_raw); > + if (ret) > + return ret; > + *val = resistance_raw; > + return IIO_VAL_INT; > + case IIO_TEMP: > + mutex_lock(&data->lock); > + *val = data->temp; > + mutex_unlock(&data->lock); > + return IIO_VAL_INT; > + case IIO_HUMIDITYRELATIVE: > + mutex_lock(&data->lock); > + *val = data->rht; > + mutex_unlock(&data->lock); > + return IIO_VAL_INT; > + default: > + return -EINVAL; > + } > + case IIO_CHAN_INFO_PROCESSED: > + ret = sgp40_measure_resistance_raw(data, &resistance_raw); > + if (ret) > + return ret; Nitpick: I find it more readable to have a blank link after cases like this where you have a function, followed by an error check block. > + ret = sgp40_calc_voc(data, resistance_raw, &voc); > + if (ret) > + return ret; > + *val = voc / (1 << SGP40_CALC_POWER); > + /* > + * calculation should fit into integer, where: > + * voc <= (500 * 2^SGP40_CALC_POWER) = 8192000 > + * (with SGP40_CALC_POWER = 14) > + */ > + *val2 = ((voc % (1 << SGP40_CALC_POWER)) * 244) / (1 << (SGP40_CALC_POWER - 12)); > + dev_dbg(data->dev, "voc: %d val: %d.%06d\n", voc, *val, *val2); > + return IIO_VAL_INT_PLUS_MICRO; > + case IIO_CHAN_INFO_CALIBBIAS: > + mutex_lock(&data->lock); > + *val = data->res_calibbias; > + mutex_unlock(&data->lock); > + return IIO_VAL_INT; > + default: > + return -EINVAL; > + } > +} > + > +static int sgp40_write_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, int val, > + int val2, long mask) > +{ > + struct sgp40_data *data = iio_priv(indio_dev); > + > + switch (mask) { > + case IIO_CHAN_INFO_RAW: > + switch (chan->type) { > + case IIO_TEMP: > + if ((val < -45000) || (val > 130000)) > + return -EINVAL; > + mutex_lock(&data->lock); > + data->temp = val; > + mutex_unlock(&data->lock); > + return 0; > + case IIO_HUMIDITYRELATIVE: > + if ((val < 0) || (val > 100000)) > + return -EINVAL; > + mutex_lock(&data->lock); > + data->rht = val; > + mutex_unlock(&data->lock); > + return 0; > + default: > + return -EINVAL; > + } > + case IIO_CHAN_INFO_CALIBBIAS: > + if ((val < 20000) || (val > 52768)) > + return -EINVAL; > + mutex_lock(&data->lock); > + data->res_calibbias = val; > + mutex_unlock(&data->lock); > + return 0; > + } > + return -EINVAL; Trivial, but I'd put the return as a default: in the switch to make it explicit that any other case is not valid at that level (rather than down here). > +} > + > +static const struct iio_info sgp40_info = { > + .read_raw = sgp40_read_raw, > + .write_raw = sgp40_write_raw, > +}; > + > +static int sgp40_probe(struct i2c_client *client, > + const struct i2c_device_id *id) > +{ > + struct device *dev = &client->dev; > + struct iio_dev *indio_dev; > + struct sgp40_data *data; > + int ret; > + > + indio_dev = devm_iio_device_alloc(dev, sizeof(*data)); > + if (!indio_dev) > + return -ENOMEM; > + > + data = iio_priv(indio_dev); > + data->client = client; > + data->dev = dev; > + > + crc8_populate_msb(sgp40_crc8_table, SGP40_CRC8_POLYNOMIAL); > + > + mutex_init(&data->lock); > + > + /* set default values */ > + data->rht = 50000; /* 50 % */ > + data->temp = 25000; /* 25 °C */ > + data->res_calibbias = 30000; /* resistance raw value for voc index of 250 */ > + > + indio_dev->info = &sgp40_info; > + indio_dev->name = id->name; > + indio_dev->modes = INDIO_DIRECT_MODE; > + indio_dev->channels = sgp40_channels; > + indio_dev->num_channels = ARRAY_SIZE(sgp40_channels); > + > + ret = devm_iio_device_register(dev, indio_dev); > + if (ret) > + dev_err(dev, "failed to register iio device\n"); > + > + return ret; > +} > + > +static const struct i2c_device_id sgp40_id[] = { > + { "sgp40" }, > + { } > +}; > + > +MODULE_DEVICE_TABLE(i2c, sgp40_id); > + > +static const struct of_device_id sgp40_dt_ids[] = { > + { .compatible = "sensirion,sgp40" }, > + { } > +}; > + > +MODULE_DEVICE_TABLE(of, sgp40_dt_ids); > + > +static struct i2c_driver sgp40_driver = { > + .driver = { > + .name = "sgp40", > + .of_match_table = sgp40_dt_ids, > + }, > + .probe = sgp40_probe, > + .id_table = sgp40_id, > +}; > +module_i2c_driver(sgp40_driver); > + > +MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>"); > +MODULE_DESCRIPTION("Sensirion SGP40 gas sensor"); > +MODULE_LICENSE("GPL v2");
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-chemical-sgp40 b/Documentation/ABI/testing/sysfs-bus-iio-chemical-sgp40 new file mode 100644 index 000000000000..469a7c00fad4 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-iio-chemical-sgp40 @@ -0,0 +1,31 @@ +What: /sys/bus/iio/devices/iio:deviceX/out_temp_raw +Date: August 2021 +KernelVersion: 5.15 +Contact: Andreas Klinger <ak@it-klinger.de> +Description: + Set the temperature. This value is sent to the sensor for + temperature compensation. + Default value: 25000 (25 °C) + +What: /sys/bus/iio/devices/iio:deviceX/out_humidityrelative_raw +Date: August 2021 +KernelVersion: 5.15 +Contact: Andreas Klinger <ak@it-klinger.de> +Description: + Set the relative humidity. This value is sent to the sensor for + humidity compensation. + Default value: 50000 (50 % relative humidity) + +What: /sys/bus/iio/devices/iio:deviceX/in_resistance_calibbias +Date: August 2021 +KernelVersion: 5.15 +Contact: Andreas Klinger <ak@it-klinger.de> +Description: + Set the bias value for the resistance which is used for + calculation of in_concentration_input as follows: + + x = (in_resistance_raw - in_resistance_calibbias) * 0.65 + + in_concentration_input = 500 / (1 + e^x) + + Default value: 30000 diff --git a/MAINTAINERS b/MAINTAINERS index 19135a9d778e..60f5e57ef385 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -16707,6 +16707,12 @@ F: drivers/iio/chemical/scd30_core.c F: drivers/iio/chemical/scd30_i2c.c F: drivers/iio/chemical/scd30_serial.c +SENSIRION SGP40 GAS SENSOR DRIVER +M: Andreas Klinger <ak@it-klinger.de> +S: Maintained +F: Documentation/ABI/testing/sysfs-bus-iio-chemical-sgp40 +F: drivers/iio/chemical/sgp40.c + SENSIRION SPS30 AIR POLLUTION SENSOR DRIVER M: Tomasz Duszynski <tduszyns@gmail.com> S: Maintained diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig index a4920646e9be..c03667e62732 100644 --- a/drivers/iio/chemical/Kconfig +++ b/drivers/iio/chemical/Kconfig @@ -131,6 +131,17 @@ config SENSIRION_SGP30 To compile this driver as module, choose M here: the module will be called sgp30. +config SENSIRION_SGP40 + tristate "Sensirion SGP40 gas sensor" + depends on I2C + select CRC8 + help + Say Y here to build I2C interface to support Sensirion SGP40 gas + sensor + + To compile this driver as module, choose M here: the + module will be called sgp40. + config SPS30 tristate select IIO_BUFFER diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile index 4898690cc155..d07af581f234 100644 --- a/drivers/iio/chemical/Makefile +++ b/drivers/iio/chemical/Makefile @@ -16,6 +16,7 @@ obj-$(CONFIG_SCD30_CORE) += scd30_core.o obj-$(CONFIG_SCD30_I2C) += scd30_i2c.o obj-$(CONFIG_SCD30_SERIAL) += scd30_serial.o obj-$(CONFIG_SENSIRION_SGP30) += sgp30.o +obj-$(CONFIG_SENSIRION_SGP40) += sgp40.o obj-$(CONFIG_SPS30) += sps30.o obj-$(CONFIG_SPS30_I2C) += sps30_i2c.o obj-$(CONFIG_SPS30_SERIAL) += sps30_serial.o diff --git a/drivers/iio/chemical/sgp40.c b/drivers/iio/chemical/sgp40.c new file mode 100644 index 000000000000..fdbe75b56873 --- /dev/null +++ b/drivers/iio/chemical/sgp40.c @@ -0,0 +1,372 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * sgp40.c - Support for Sensirion SGP40 Gas Sensor + * + * Copyright (C) 2021 Andreas Klinger <ak@it-klinger.de> + * + * I2C slave address: 0x59 + * + * Datasheet can be found here: + * https://www.sensirion.com/file/datasheet_sgp40 + * + * There are two functionalities supported: + * + * 1) read raw logarithmic resistance value from sensor + * --> useful to pass it to the algorithm of the sensor vendor for + * measuring deteriorations and improvements of air quality. + * + * 2) calculate an estimated absolute voc index (0 - 500 index points) for + * measuring the air quality. + * For this purpose the value of the resistance for which the voc index + * will be 250 can be set up using calibbias. + * + * Compensation values of relative humidity and temperature can be set up + * by writing to the out values of temp and humidityrelative. + */ + +#include <linux/module.h> +#include <linux/iio/iio.h> +#include <linux/iio/sysfs.h> +#include <linux/delay.h> +#include <linux/mutex.h> +#include <linux/i2c.h> +#include <linux/crc8.h> + +/* + * floating point calculation of voc is done as integer + * where numbers are multiplied by 1 << SGP40_CALC_POWER + */ +#define SGP40_CALC_POWER 14 + +#define SGP40_CRC8_POLYNOMIAL 0x31 +#define SGP40_CRC8_INIT 0xff + +DECLARE_CRC8_TABLE(sgp40_crc8_table); + +struct sgp40_data { + struct device *dev; + struct i2c_client *client; + int rht; + int temp; + int res_calibbias; + struct mutex lock; +}; + +struct sgp40_tg_measure { + u8 command[2]; + __be16 rht_ticks; + u8 rht_crc; + __be16 temp_ticks; + u8 temp_crc; +} __packed; + +struct sgp40_tg_result { + __be16 res_ticks; + u8 res_crc; +} __packed; + +static const struct iio_chan_spec sgp40_channels[] = { + { + .type = IIO_CONCENTRATION, + .channel2 = IIO_MOD_VOC, + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), + }, + { + .type = IIO_RESISTANCE, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_CALIBBIAS), + }, + { + .type = IIO_TEMP, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + .output = 1, + }, + { + .type = IIO_HUMIDITYRELATIVE, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + .output = 1, + }, +}; + +/* + * taylor approximation of e^x: + * y = 1 + x + x^2 / 2 + x^3 / 6 + x^4 / 24 + ... + x^n / n! + * + * Because we are calculating x real value multiplied by 2^power we get + * an additional 2^power^n to divide for every element. For a reasonable + * precision this would overflow after a few iterations. Therefore we + * divide the x^n part whenever its about to overflow (xmax). + */ + +static u32 sgp40_exp(int exp, u32 power, u32 rounds) +{ + u32 x, y, xp; + u32 factorial, divider, xmax; + int sign = 1; + int i; + + if (exp == 0) + return 1 << power; + else if (exp < 0) { + sign = -1; + exp *= -1; + } + + xmax = 0x7FFFFFFF / exp; + x = exp; + xp = 1; + factorial = 1; + y = 1 << power; + divider = 0; + + for (i = 1; i <= rounds; i++) { + xp *= x; + factorial *= i; + y += (xp >> divider) / factorial; + divider += power; + /* divide when next multiplication would overflow */ + if (xp >= xmax) { + xp >>= power; + divider -= power; + } + } + + if (sign == -1) + return (1 << (power * 2)) / y; + else + return y; +} + +static int sgp40_calc_voc(struct sgp40_data *data, u16 resistance_raw, int *voc) +{ + int x; + u32 exp = 0; + + /* we calculate as a multiple of 16384 (2^14) */ + mutex_lock(&data->lock); + x = ((int)resistance_raw - data->res_calibbias) * 106; + mutex_unlock(&data->lock); + + /* voc = 500 / (1 + e^x) */ + exp = sgp40_exp(x, SGP40_CALC_POWER, 18); + *voc = 500 * ((1 << (SGP40_CALC_POWER * 2)) / ((1<<SGP40_CALC_POWER) + exp)); + + dev_dbg(data->dev, "raw: %d res_calibbias: %d x: %d exp: %d voc: %d\n", + resistance_raw, data->res_calibbias, x, exp, *voc); + + return 0; +} + +static int sgp40_measure_resistance_raw(struct sgp40_data *data, u16 *resistance_raw) +{ + int ret; + struct i2c_client *client = data->client; + u32 ticks; + u16 ticks16; + u8 crc; + struct sgp40_tg_measure tg = {.command = {0x26, 0x0F}}; + struct sgp40_tg_result tgres; + + mutex_lock(&data->lock); + + ticks = (data->rht / 10) * 65535 / 10000; + ticks16 = (u16)clamp(ticks, 0u, 65535u); /* clamp between 0 .. 100 %rH */ + tg.rht_ticks = cpu_to_be16(ticks16); + tg.rht_crc = crc8(sgp40_crc8_table, (u8 *)&tg.rht_ticks, 2, SGP40_CRC8_INIT); + + ticks = ((data->temp + 45000) / 10 ) * 65535 / 17500; + ticks16 = (u16)clamp(ticks, 0u, 65535u); /* clamp between -45 .. +130 °C */ + tg.temp_ticks = cpu_to_be16(ticks16); + tg.temp_crc = crc8(sgp40_crc8_table, (u8 *)&tg.temp_ticks, 2, SGP40_CRC8_INIT); + + mutex_unlock(&data->lock); + + ret = i2c_master_send(client, (const char *)&tg, sizeof(tg)); + if (ret != sizeof(tg)) { + dev_warn(data->dev, "i2c_master_send ret: %d sizeof: %d\n", ret, sizeof(tg)); + return -EIO; + } + msleep(30); + + ret = i2c_master_recv(client, (u8 *)&tgres, sizeof(tgres)); + if (ret < 0) + return ret; + if (ret != sizeof(tgres)) { + dev_warn(data->dev, "i2c_master_recv ret: %d sizeof: %d\n", ret, sizeof(tgres)); + return -EIO; + } + + crc = crc8(sgp40_crc8_table, (u8 *)&tgres.res_ticks, 2, SGP40_CRC8_INIT); + if (crc != tgres.res_crc) { + dev_err(data->dev, "CRC error while measure-raw\n"); + return -EIO; + } + + *resistance_raw = be16_to_cpu(tgres.res_ticks); + + return 0; +} + +static int sgp40_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, int *val, + int *val2, long mask) +{ + struct sgp40_data *data = iio_priv(indio_dev); + int ret, voc; + u16 resistance_raw; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + switch (chan->type) { + case IIO_RESISTANCE: + ret = sgp40_measure_resistance_raw(data, &resistance_raw); + if (ret) + return ret; + *val = resistance_raw; + return IIO_VAL_INT; + case IIO_TEMP: + mutex_lock(&data->lock); + *val = data->temp; + mutex_unlock(&data->lock); + return IIO_VAL_INT; + case IIO_HUMIDITYRELATIVE: + mutex_lock(&data->lock); + *val = data->rht; + mutex_unlock(&data->lock); + return IIO_VAL_INT; + default: + return -EINVAL; + } + case IIO_CHAN_INFO_PROCESSED: + ret = sgp40_measure_resistance_raw(data, &resistance_raw); + if (ret) + return ret; + ret = sgp40_calc_voc(data, resistance_raw, &voc); + if (ret) + return ret; + *val = voc / (1 << SGP40_CALC_POWER); + /* + * calculation should fit into integer, where: + * voc <= (500 * 2^SGP40_CALC_POWER) = 8192000 + * (with SGP40_CALC_POWER = 14) + */ + *val2 = ((voc % (1 << SGP40_CALC_POWER)) * 244) / (1 << (SGP40_CALC_POWER - 12)); + dev_dbg(data->dev, "voc: %d val: %d.%06d\n", voc, *val, *val2); + return IIO_VAL_INT_PLUS_MICRO; + case IIO_CHAN_INFO_CALIBBIAS: + mutex_lock(&data->lock); + *val = data->res_calibbias; + mutex_unlock(&data->lock); + return IIO_VAL_INT; + default: + return -EINVAL; + } +} + +static int sgp40_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, int val, + int val2, long mask) +{ + struct sgp40_data *data = iio_priv(indio_dev); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + switch (chan->type) { + case IIO_TEMP: + if ((val < -45000) || (val > 130000)) + return -EINVAL; + mutex_lock(&data->lock); + data->temp = val; + mutex_unlock(&data->lock); + return 0; + case IIO_HUMIDITYRELATIVE: + if ((val < 0) || (val > 100000)) + return -EINVAL; + mutex_lock(&data->lock); + data->rht = val; + mutex_unlock(&data->lock); + return 0; + default: + return -EINVAL; + } + case IIO_CHAN_INFO_CALIBBIAS: + if ((val < 20000) || (val > 52768)) + return -EINVAL; + mutex_lock(&data->lock); + data->res_calibbias = val; + mutex_unlock(&data->lock); + return 0; + } + return -EINVAL; +} + +static const struct iio_info sgp40_info = { + .read_raw = sgp40_read_raw, + .write_raw = sgp40_write_raw, +}; + +static int sgp40_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct device *dev = &client->dev; + struct iio_dev *indio_dev; + struct sgp40_data *data; + int ret; + + indio_dev = devm_iio_device_alloc(dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + data = iio_priv(indio_dev); + data->client = client; + data->dev = dev; + + crc8_populate_msb(sgp40_crc8_table, SGP40_CRC8_POLYNOMIAL); + + mutex_init(&data->lock); + + /* set default values */ + data->rht = 50000; /* 50 % */ + data->temp = 25000; /* 25 °C */ + data->res_calibbias = 30000; /* resistance raw value for voc index of 250 */ + + indio_dev->info = &sgp40_info; + indio_dev->name = id->name; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = sgp40_channels; + indio_dev->num_channels = ARRAY_SIZE(sgp40_channels); + + ret = devm_iio_device_register(dev, indio_dev); + if (ret) + dev_err(dev, "failed to register iio device\n"); + + return ret; +} + +static const struct i2c_device_id sgp40_id[] = { + { "sgp40" }, + { } +}; + +MODULE_DEVICE_TABLE(i2c, sgp40_id); + +static const struct of_device_id sgp40_dt_ids[] = { + { .compatible = "sensirion,sgp40" }, + { } +}; + +MODULE_DEVICE_TABLE(of, sgp40_dt_ids); + +static struct i2c_driver sgp40_driver = { + .driver = { + .name = "sgp40", + .of_match_table = sgp40_dt_ids, + }, + .probe = sgp40_probe, + .id_table = sgp40_id, +}; +module_i2c_driver(sgp40_driver); + +MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>"); +MODULE_DESCRIPTION("Sensirion SGP40 gas sensor"); +MODULE_LICENSE("GPL v2");
sgp40 is a gas sensor used for measuring the air quality. This driver is reading the raw resistance value which can be passed to an userspace algorithm for further calculation. The raw value is also used to calculate an estimated absolute voc index in the range from 0 to 500. For this purpose the raw_mean value of the resistance for which the index value is 250 might be set up as a calibration step. This can be done with in_resistance_calibbias. Compensation of relative humidity and temperature is supported and can be used by writing to output values of out_humidityrelative_raw and out_temp_raw. There is a predecesor sensor type (sgp30) already existing. This driver module was not extended because the new sensor is quite different in its i2c telegrams. Signed-off-by: Andreas Klinger <ak@it-klinger.de> --- .../ABI/testing/sysfs-bus-iio-chemical-sgp40 | 31 ++ MAINTAINERS | 6 + drivers/iio/chemical/Kconfig | 11 + drivers/iio/chemical/Makefile | 1 + drivers/iio/chemical/sgp40.c | 372 ++++++++++++++++++ 5 files changed, 421 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-chemical-sgp40 create mode 100644 drivers/iio/chemical/sgp40.c