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path: root/drivers/iio/chemical/ccs811.c
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2024-12-28iio: chemical: Use aligned_s64 instead of open coding alignment.Jonathan Cameron
Use this new type to both slightly simplify the code and avoid confusing static analysis tools. Mostly this series is about consistency to avoid this code pattern getting copied into more drivers. Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://patch.msgid.link/20241215182912.481706-13-jic23@kernel.org Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2024-05-27iio: Drop explicit initialization of struct i2c_device_id::driver_data to 0Uwe Kleine-König
These drivers don't use the driver_data member of struct i2c_device_id, so don't explicitly initialize this member. This prepares putting driver_data in an anonymous union which requires either no initialization or named designators. But it's also a nice cleanup on its own. While add it, also remove commas after the sentinel entries. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/20240508072928.2135858-2-u.kleine-koenig@pengutronix.de Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2023-05-21iio: Switch i2c drivers back to use .probe()Uwe Kleine-König
After commit b8a1a4cd5a98 ("i2c: Provide a temporary .probe_new() call-back type"), all drivers being converted to .probe_new() and then 03c835f498b5 ("i2c: Switch .probe() to not take an id parameter") convert back to (the new) .probe() to be able to eventually drop .probe_new() from struct i2c_driver. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/20230515205048.19561-1-u.kleine-koenig@pengutronix.de Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2022-11-23iio: chemical: ccs811: Convert to i2c's .probe_new()Uwe Kleine-König
.probe_new() doesn't get the i2c_device_id * parameter, so determine that explicitly in the probe function. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20221118224540.619276-78-uwe@kleine-koenig.org Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2022-08-16i2c: Make remove callback return voidUwe Kleine-König
The value returned by an i2c driver's remove function is mostly ignored. (Only an error message is printed if the value is non-zero that the error is ignored.) So change the prototype of the remove function to return no value. This way driver authors are not tempted to assume that passing an error to the upper layer is a good idea. All drivers are adapted accordingly. There is no intended change of behaviour, all callbacks were prepared to return 0 before. Reviewed-by: Peter Senna Tschudin <peter.senna@gmail.com> Reviewed-by: Jeremy Kerr <jk@codeconstruct.com.au> Reviewed-by: Benjamin Mugnier <benjamin.mugnier@foss.st.com> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Reviewed-by: Crt Mori <cmo@melexis.com> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Marek Behún <kabel@kernel.org> # for leds-turris-omnia Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Petr Machata <petrm@nvidia.com> # for mlxsw Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com> # for surface3_power Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> # for bmc150-accel-i2c + kxcjk-1013 Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> # for media/* + staging/media/* Acked-by: Miguel Ojeda <ojeda@kernel.org> # for auxdisplay/ht16k33 + auxdisplay/lcd2s Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # for versaclock5 Reviewed-by: Ajay Gupta <ajayg@nvidia.com> # for ucsi_ccg Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> # for iio Acked-by: Peter Rosin <peda@axentia.se> # for i2c-mux-*, max9860 Acked-by: Adrien Grassein <adrien.grassein@gmail.com> # for lontium-lt8912b Reviewed-by: Jean Delvare <jdelvare@suse.de> # for hwmon, i2c-core and i2c/muxes Acked-by: Corey Minyard <cminyard@mvista.com> # for IPMI Reviewed-by: Vladimir Oltean <olteanv@gmail.com> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com> # for drivers/power Acked-by: Krzysztof Hałasa <khalasa@piap.pl> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Wolfram Sang <wsa@kernel.org>
2022-07-14Merge tag 'iio-for-5.20a' of ↵Greg Kroah-Hartman
https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into char-misc-next Jonathan writes: IIO new device support, features and minor fixes for 5.20 Several on-running cleanup efforts dominate this time, plus the DMA safety alignment issue identified due to improved understanding of the restrictions as a result of Catalin Marinas' efforts in that area. One immutable branch in here due to MFD and SPMI elements needed for the qcom-rradc driver. Device support * bmi088 - Add support for bmi085 (accelerometer part of IMU) - Add support for bmi090l (accelerometer part of IMU) * mcp4922 - Add support for single channel device MCP4921 * rzg2l-adc - Add compatible and minor tweaks to support RZ/G2UL ADC * sca3300 - Add support for scl3300 including refactoring driver to support multiple device types and cleanup noticed whilst working on driver. * spmi-rradc - New driver for Qualcomm SPMI Round Robin ADC including necessary additional utility functions in SPMI core and related MFD driver. * ti-dac55781 - Add compatible for DAC121C081 which is very similar to existing parts. Features * core - Warn on iio_trigger_get() on an unregistered IIO trigger. * bma400 - Triggered buffer support - Activity and step counting - Misc driver improvements such as devm and header ordering * cm32181 - Add PM support. * cros_ec - Sensor location support * sx9324 - Add precharge resistor setting - Add internal compensation resistor setting - Add CS idle/sleep mode. * sx9360 - Add precharge resistor setting * vl53l0x - Handle reset GPIO, regulator and relax handling of irq type. Cleanup and minor fixes: Treewide changes - Cleanup of error handling in remove functions in many drivers. - Update dt-binding maintainers for a number of ADI bindings. - Several sets of conversion of drivers from device tree specific to generic device properties. Includes fixing up various related header and Kconfig issues. - Drop include of of.h from iio.h and fix up drivers that need to include it directly. - More moves of clusters of drivers into appropriate IIO_XXX namespaces. - Tree wide fix of a long running bug around DMA safety requirements. IIO was using __cacheline_aligned to pad iio_priv() structures. This worked for a long time by coincidence, but correct alignment is ARCH_KMALLOC_MINALIGN. As there is activity around this area, introduce an IIO local IIO_DMA_MINALIGN to allow for changing it in one place rather than every driver in future. Note, there have been no reports of this bug in the wild, and it may not happen on any platforms supported by upstream, so no rush to backport these fixes. Other cleanup * core - Switch to ida_alloc()/free() - Drop unused iio_get_time_res() - Octal permissions and DEVICE_ATTR_* macros. - Cleanup bared unsigned usage. * MAINTAINERS - Add include/dt-bindings/iio/ to the main IIO entry. * ad5380 - Comment syntax fix. * ad74413r - Call to for_each_set_bit_from(), with from value as 0 replaced. * ad7768-1 - Drop explicit setting of INDIO_BUFFER_TRIGGERED as now done by the core. * adxl345 - Fix wrong address in dt-binding example. * adxl367 - Drop extra update of FIFO watermark. * at91-sama5d2 - Limit requested watermark to the hwfifo size. * bmg160, bme680 - Typos * cio-dac - Switch to iomap rather than direct use of ioports * kxsd9 - Replace CONFIG_PM guards with new PM macros that let the compiler cleanly remove the unused code and structures when !CONFIG_PM * lsm6dsx - Use new pm_sleep_ptr() and EXPORT_SIMPLE_DEV_PM_OPS(). Then move to Namespace. * meson_saradc - general cleanup. - Avoid attaching resources to iio_dev->dev - Use same struct device for all error messages - Convert to dev_err_probe() and use local struct device *dev to reduce code complexity. - Use devm_clk_get_optional() instead of hand rolling. - Use regmap_read_poll_timeout() instead of hand rolling. * mma7660 - Drop ACPI_PTR() use that is unhelpful. * mpu3050 - Stop exporting symbols not used outside of module - Switch to new DEFINE_RUNTIME_DEV_PM_OPS() macro and move to Namespace. * ping - Typo fix * qcom-spmi-rradc - Typo fix * sc27xx - Convert to generic struct u32_fract * srf08 - Drop a redundant check on !val * st_lsm6dsx - Limit the requested watermark to the hwfifo size. * stm32-adc - Use generic_handle_domain_irq() instead of opencoding. - Fix handling of ADC disable. * stm32-dac - Use str_enabled_disable() instead of open coding. * stx104 - Switch to iomap rather than direct use of ioports * tsc2046 - Drop explicit setting of INDIO_BUFFER_TRIGGERED as now done by the core. * tsl2563 - Replace flush_scheduled_work() with cancel_delayed_work_sync() - Replace cancel_delayed_work() with cancel_delayed_work_sync() * vl53l0x - Make the VDD regulator optional by allowing a dummy regulator. * tag 'iio-for-5.20a' of https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio: (244 commits) iio: adc: xilinx-xadc: Drop duplicate NULL check in xadc_parse_dt() iio: adc: xilinx-xadc: Make use of device properties iio: light: cm32181: Add PM support iio: adc: ad778-1: do not explicity set INDIO_BUFFER_TRIGGERED mode iio: adc: ti-tsc2046: do not explicity set INDIO_BUFFER_TRIGGERED mode iio: adc: stm32-adc: disable adc before calibration iio: adc: stm32-adc: make safe adc disable iio: dac: ad5380: align '*' each line and drop unneeded blank line iio: adc: qcom-spmi-rradc: Fix spelling mistake "coherrency" -> "coherency" iio: Don't use bare "unsigned" dt-bindings: iio: dac: mcp4922: expand for mcp4921 support iio: dac: mcp4922: add support to mcp4921 iio: chemical: sps30: Move symbol exports into IIO_SPS30 namespace iio: pressure: bmp280: Move symbol exports to IIO_BMP280 namespace iio: imu: bmi160: Move exported symbols to IIO_BMI160 namespace iio: adc: stm32-adc: Use generic_handle_domain_irq() proximity: vl53l0x: Make VDD regulator actually optional MAINTAINERS: add include/dt-bindings/iio to IIO SUBSYSTEM AND DRIVERS dt-bindings: iio/accel: Fix adi,adxl345/6 example I2C address iio: gyro: bmg160: Fix typo in comment ...
2022-06-19iio:chemical:ccs811: rearrange iio trigger get and registerDmitry Rokosov
IIO trigger interface function iio_trigger_get() should be called after iio_trigger_register() (or its devm analogue) strictly, because of iio_trigger_get() acquires module refcnt based on the trigger->owner pointer, which is initialized inside iio_trigger_register() to THIS_MODULE. If this call order is wrong, the next iio_trigger_put() (from sysfs callback or "delete module" path) will dereference "default" module refcnt, which is incorrect behaviour. Fixes: f1f065d7ac30 ("iio: chemical: ccs811: Add support for data ready trigger") Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Link: https://lore.kernel.org/r/20220524181150.9240-5-ddrokosov@sberdevices.ru Cc: <Stable@vger.kernel.org> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2022-06-11iio:chemical:ccs811: Improve error reporting for problems during .remove()Uwe Kleine-König
Returning an error value in an i2c remove callback results in a generic error message being emitted by the i2c core, but otherwise it doesn't make a difference. The device goes away anyhow and the devm cleanups are called. So instead of triggering the generic i2c error message, emit a more helpful message if a problem occurs and return 0 to suppress the generic message. This patch is a preparation for making i2c remove callbacks return void. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/20220515155929.338656-5-u.kleine-koenig@pengutronix.de Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2021-05-17iio: core: move @id from struct iio_dev to struct iio_dev_opaqueJonathan Cameron
Continuing from Alexandru Ardelean's introduction of the split between driver modifiable fields and those that should only be set by the core. This could have been done in two steps to make the actual move after introducing iio_device_id() but there seemed limited point to that given how mechanical the majority of the patch is. Includes fixup from Alex for missing mxs-lradc-adc conversion. Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com> Link: https://lore.kernel.org/r/20210426174911.397061-2-jic23@kernel.org
2021-03-25iio: fix devm_iio_trigger_alloc with parent.cocciGwendal Grignou
Use cocci semantic patch: @@ expression trigger, P; @@ trigger = devm_iio_trigger_alloc(P, ...); ... - trigger->dev.parent = P; To remove trigger->dev.parent, since it is set by default. Signed-off-by: Gwendal Grignou <gwendal@chromium.org> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Link: https://lore.kernel.org/r/20210309193620.2176163-3-gwendal@chromium.org Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2020-08-22iio:chemical:ccs811: Fix timestamp alignment and prevent data leak.Jonathan Cameron
One of a class of bugs pointed out by Lars in a recent review. iio_push_to_buffers_with_timestamp assumes the buffer used is aligned to the size of the timestamp (8 bytes). This is not guaranteed in this driver which uses an array of smaller elements on the stack. As Lars also noted this anti pattern can involve a leak of data to userspace and that indeed can happen here. We close both issues by moving to a suitable structure in the iio_priv() data with alignment explicitly requested. This data is allocated with kzalloc so no data can leak appart from previous readings. The explicit alignment of ts is necessary to ensure consistent padding for x86_32 in which the ts would otherwise be 4 byte aligned. Fixes: 283d26917ad6 ("iio: chemical: ccs811: Add triggered buffer support") Reported-by: Lars-Peter Clausen <lars@metafoo.de> Cc: Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: <Stable@vger.kernel.org>
2020-06-14iio: remove explicit IIO device parent assignmentAlexandru Ardelean
This patch applies the semantic patch: @@ expression I, P, SP; @@ I = devm_iio_device_alloc(P, SP); ... - I->dev.parent = P; It updates 302 files and does 307 deletions. This semantic patch also removes some comments like '/* Establish that the iio_dev is a child of the i2c device */' But this is is only done in case where the block is left empty. The patch does not seem to cover all cases. It looks like in some cases a different variable is used in some cases to assign the parent, but it points to the same reference. In other cases, the block covered by ... may be just too big to be covered by the semantic patch. However, this looks pretty good as well, as it does cover a big bulk of the drivers that should remove the parent assignment. Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2020-05-03iio: chemical: Add OF match table for CCS811 VOC sensorManivannan Sadhasivam
Add devicetree OF match table support for CCS811 VOC sensor. Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Manivannan Sadhasivam <mani@kernel.org> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2020-05-03iio: chemical: Add support for external Reset and Wakeup in CCS811Manivannan Sadhasivam
CCS811 VOC sensor exposes nRESET and nWAKE pins which can be connected to GPIO pins of the host controller. These pins can be used to externally release the device from reset and also to wake it up before any I2C transaction. The initial driver support assumed that the nRESET pin is not connected and the nWAKE pin is tied to ground. This commit improves it by adding support for controlling those two pins externally using a host controller. For the case of reset, if the hardware reset is not available, the mechanism to do software reset is also added. As a side effect of doing this, the IIO device allocation needs to be slightly moved to top of probe to make use of priv data early. Signed-off-by: Manivannan Sadhasivam <mani@kernel.org> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2019-06-19treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500Thomas Gleixner
Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Enrico Weigelt <info@metux.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-28Merge 4.16-rc7 into staging-nextGreg Kroah-Hartman
We want the IIO and staging driver fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-02-24iio: chemical: ccs811: Corrected firmware boot/application mode transitionRichard Lai
CCS811 has different I2C register maps in boot and application mode. When CCS811 is in boot mode, register APP_START (0xF4) is used to transit the firmware state from boot to application mode. However, APP_START is not a valid register location when CCS811 is in application mode (refer to "CCS811 Bootloader Register Map" and "CCS811 Application Register Map" in CCS811 datasheet). The driver should not attempt to perform a write to APP_START while CCS811 is in application mode, as this is not a valid or documented register location. When prob function is being called, the driver assumes the CCS811 sensor is in boot mode, and attempts to perform a write to APP_START. Although CCS811 powers-up in boot mode, it may have already been transited to application mode by previous instances, e.g. unload and reload device driver by the system, or explicitly by user. Depending on the system design, CCS811 sensor may be permanently connected to system power source rather than power controlled by GPIO, hence it is possible that the sensor is never power reset, thus the firmware could be in either boot or application mode at any given time when driver prob function is being called. This patch checks the STATUS register before attempting to send a write to APP_START. Only if the firmware is not in application mode and has valid firmware application loaded, then it will continue to start transiting the firmware boot to application mode. Signed-off-by: Richard Lai <richard@richardman.com> Cc: <Stable@vger.kernel.org> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2018-02-24iio: chemical: ccs811: Renamed resistance member in ccs811_reading structRichard Lai
The resistance member in ccs811_reading struct is an unsigned 16-bit integer variable used to store RAW_DATA register bytes read from CCS811. It is kind of misleading to name this struct member as resistance. About the RAW_DATA register bytes, the CCS811 datasheet states that: ----- Two byte read only register which contains the latest readings from the sense resistor. The most significant 6 bits of the Byte 0 contain the value of the current through the sensor (0μA to 63μA). The lower 10 bits contain (as computed from the ADC) the readings of the voltage across the sensor with the selected current (1023 = 1.65V)" ----- Hence, the RAW_DATA register byte contains information about electric current and voltage of the CCS811 sensor. Calling this struct member 'resistance' is kind of misleading, although both electric current and voltage are needed to calculate the electrical resistance of the sensor using Ohm's law, V = I x R, in which a new channel type of IIO_RESISTANCE may be added to the driver in the future. Signed-off-by: Richard Lai <richard@richardman.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2018-02-17iio: chemical: ccs811: Typo correction in HW_ID_VALUE constant define namingRichard Lai
This particular constant was named with prefix "CCS881", which should be "CCS811" instead, just like the rest of constant names in the file, as this driver implementation is for AMS CCS811 sensor. "CCS881" could literally be referring to another sensor product unrelated to AMS CCS811 sensor. Signed-off-by: Richard Lai <richard@richardman.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2018-01-08iio: chemical: ccs811: Fix output of IIO_CONCENTRATION channelsNarcisa Ana Maria Vasile
in_concentration_raw should report, according to sysfs-bus-iio documentation, a "Raw (unscaled no offset etc.) percentage reading of a substance." Modify scale to convert from ppm/ppb to percentage: 1 ppm = 0.0001% 1 ppb = 0.0000001% There is no offset needed to convert the ppm/ppb to percentage, so remove offset from IIO_CONCENTRATION (IIO_MOD_CO2) channel. Cc'd stable to reduce chance of userspace breakage in the long run as we fix this wrong bit of ABI usage. Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com> Cc: <Stable@vger.kernel.org> Reviewed-by: Matt Ranostay <matt.ranostay@konsulko.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-09-24iio: chemical: ccs811: Add support for data ready triggerNarcisa Ana Maria Vasile
Add data ready trigger for hardware interrupts that signal new, available measurement samples. Cc: Daniel Baluta <daniel.baluta@gmail.com> Cc: Alison Schofield <amsfield22@gmail.com> Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2017-08-22iio:chemical: drop assign iio_info.driver_module and iio_trigger_ops.ownerJonathan Cameron
The equivalent of both of these are now done via macro magic when the relevant register calls are made. The actual structure elements will shortly go away. Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
2017-08-18iio: chemical: ccs811: Add triggered buffer supportNarcisa Ana Maria Vasile
A software trigger such as hrtimer can be used to capture the data that will be stored in the buffer. Cc: Daniel Baluta <daniel.baluta@gmail.com> Cc: Alison Schofield <amsfield22@gmail.com> Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2017-07-22iio: chemical: ccs811: Add support for AMS CCS811 VOC sensorNarcisa Ana Maria Vasile
Add support for CCS811 VOC sensor. This patch adds support for reading current and voltage across the sensor and TVOC and equivalent CO2 values. Scale and offset values have been computed according to datasheet: - For current: raw value is in microamps => 0.001 scale to convert to milliamps - For voltage: 1.65V = 1023, therefore 1650mV = 1023 => 1650.0/1023 = 1.612903 scale to convert to millivolts - For eCO2: raw value range is from 400ppm to 8192ppm. => (val - 400) * (100 - 0) / (8192 - 400) + 0 = (val - 400) * 0.01283367 => offset: -400, scale = 0.012834 to get a percentage value -For TVOC: raw value range is from 0ppb to 1187ppb. => (val - 0) * 100 / (1187 - 0) + 0 = val * 0.0842459 => scale = 0.084246 for getting a percentage value Cc: Daniel Baluta <daniel.baluta@gmail.com> Cc: Alison Schofield <amsfield22@gmail.com> Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>