Re: [PATCH v5 0/4] iio: chemical: Add support for Sensirion SCD4x CO2 sensor
From: Roan van Dijk
Date: Thu Oct 14 2021 - 04:25:00 EST
On 13-10-2021 19:38, Jonathan Cameron wrote:
On Sun, 10 Oct 2021 16:59:19 +0100
Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
On Fri, 8 Oct 2021 12:17:02 +0200
Roan van Dijk <roan@xxxxxxxxxxx> wrote:
This series adds support for the Sensirion SCD4x sensor.
The driver supports continuous reads of temperature, relative humdity and CO2
concentration. There is an interval of 5 seconds between readings. During
this interval the drivers checks if the sensor has new data available.
The driver is based on the scd30 driver. However, The scd4x has become too
different to just expand the scd30 driver. I made a new driver instead of
expanding the scd30 driver. I hope I made the right choice by doing so?
Applied to the togreg branch of iio.git with the issues Randy mentioned tidied
up. Pushed out as testing for 0-day to see if it can find anything we missed
And indeed - I missed a bunch of places where explicit __be16 types should have
been used.
I've applied the following fixup, shout if it's wrong.
Thank you Jonathan for applying this fixup. No need to shout :) Your
changes should fix the issue.
However, I have a question about something else. The co2 concentration
is an IIO_CHAN_INFO_RAW, but doesn't have a scale or offset at this
moment. Is an _scale always required for an _raw in the ABI? I could not
find anything in the documentation if there is a rule for this. Someone
mentioned this to me, so I want to check if I did this right.
The sensor returns the actual co2 value upon reading, like 450 ppm. We
can set an offset of this co2 value with the calibration_forced_value
through the ABI, but this offset is handled internally by the sensor. So
there isn't anything with scaling or an offset needed at the driver side.
Was I right by making it of type RAW? If needed we could make it more
like the scd30 driver, keeping it of type RAW but with scale = 1. What
should I do or is it fine as it is?
Sorry for not asking this earlier.
Thanks,
Roan
diff --git a/drivers/iio/chemical/scd4x.c b/drivers/iio/chemical/scd4x.c
index 09b34201c42b..ebebcb117ba2 100644
--- a/drivers/iio/chemical/scd4x.c
+++ b/drivers/iio/chemical/scd4x.c
@@ -263,7 +263,7 @@ static int scd4x_write_and_fetch(struct scd4x_state *state, enum scd4x_cmd cmd,
static int scd4x_read_meas(struct scd4x_state *state, uint16_t *meas)
{
int i, ret;
- uint16_t buf[3];
+ __be16 buf[3];
ret = scd4x_read(state, CMD_READ_MEAS, buf, sizeof(buf));
if (ret)
@@ -282,12 +282,13 @@ static int scd4x_wait_meas_poll(struct scd4x_state *state)
int ret;
do {
+ __be16 bval;
uint16_t val;
- ret = scd4x_read(state, CMD_GET_DATA_READY, &val, sizeof(val));
+ ret = scd4x_read(state, CMD_GET_DATA_READY, &bval, sizeof(bval));
if (ret)
return -EIO;
- val = be16_to_cpu(val);
+ val = be16_to_cpu(bval);
/* new measurement available */
if (val & 0x7FF)
@@ -333,7 +334,7 @@ static int scd4x_read_raw(struct iio_dev *indio_dev,
{
struct scd4x_state *state = iio_priv(indio_dev);
int ret;
- uint16_t tmp;
+ __be16 tmp;
switch (mask) {
case IIO_CHAN_INFO_RAW:
@@ -405,17 +406,18 @@ static ssize_t calibration_auto_enable_show(struct device *dev,
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct scd4x_state *state = iio_priv(indio_dev);
int ret;
- uint16_t val;
+ __be16 bval;
+ u16 val;
mutex_lock(&state->lock);
- ret = scd4x_read(state, CMD_GET_ASC, &val, sizeof(val));
+ ret = scd4x_read(state, CMD_GET_ASC, &bval, sizeof(bval));
mutex_unlock(&state->lock);
if (ret) {
dev_err(dev, "failed to read automatic calibration");
return ret;
}
- val = (be16_to_cpu(val) & SCD4X_READY_MASK) ? 1 : 0;
+ val = (be16_to_cpu(bval) & SCD4X_READY_MASK) ? 1 : 0;
return sprintf(buf, "%d\n", val);
}
Thanks,
Jonathan
Changes since v5:
scd4x.c:
- Fix bug in trigger_handler
Changes since v4:
scd4x.c:
- Minor fixes in documentation
- Reorder trigger_handler so memcpy is not needed anymore
Documentation:
- Change information about the KernelVersion for the
calibration_forced_value_available
Changes since v3:
scd4x.c
- Change read and write_and_fetch function parameter. CRC byte is now
hidden inside the function.
- Fix minor style issues
- Add calibration_forced_value_available attribute to the driver
- Remove including BUFFER_TRIGGERED
- Change calibbias to raw ADC readings rather than converting it to
milli degrees C.
Documentation:
- Change description of driver attributes
- Add calibration_forced_value_available documentation
Changes since v2:
scd4x.c:
- Change boolean operations
- Document scope of lock
- Remove device *dev from struct
- Add goto block for errror handling
- Add function to read value per channel in read_raw
- Fix bug with lock in error paths
- Remove conversion of humidity and temperature values
- Add scale and offset to temperature channel
- Add scale to humidity channel
- Move memset out of locked section
- Remove unused irq functions
- Move device register at end of probe function
Documentation:
- Copy content of sysfs-bus-iio-scd30 to sysfs-bus-iio
- Remove Documentation/ABI/testing/sysfs-bus-iio-scd30
Changes since v1:
dt-bindings:
- Separated compatible string for each sensor type
scd4x.c:
- Changed probe, resume and suspend functions to static
- Added SIMPLE_DEV_PM_OPS function call for power management
operations.
Roan van Dijk (4):
dt-bindings: iio: chemical: sensirion,scd4x: Add yaml description
MAINTAINERS: Add myself as maintainer of the scd4x driver
drivers: iio: chemical: Add support for Sensirion SCD4x CO2 sensor
iio: documentation: Document scd4x calibration use
Documentation/ABI/testing/sysfs-bus-iio | 41 ++
Documentation/ABI/testing/sysfs-bus-iio-scd30 | 34 -
.../iio/chemical/sensirion,scd4x.yaml | 46 ++
MAINTAINERS | 6 +
drivers/iio/chemical/Kconfig | 13 +
drivers/iio/chemical/Makefile | 1 +
drivers/iio/chemical/scd4x.c | 689 ++++++++++++++++++
7 files changed, 796 insertions(+), 34 deletions(-)
delete mode 100644 Documentation/ABI/testing/sysfs-bus-iio-scd30
create mode 100644 Documentation/devicetree/bindings/iio/chemical/sensirion,scd4x.yaml
create mode 100644 drivers/iio/chemical/scd4x.c