On Wed, 22 Sep 2021 12:39:24 +0200
Roan van Dijk <roan@xxxxxxxxxxx> wrote:
> This is a driver for the SCD4x CO2 sensor from Sensirion. The sensor is
> able to measure CO2 concentration, temperature and relative humdity.
> The sensor uses a photoacoustic principle for measuring CO2 concentration.
> An I2C interface is supported by this driver in order to communicate with
> the sensor.
>
> Signed-off-by: Roan van Dijk <roan@xxxxxxxxxxx>
Hi Roan,
Only thing in here of significance is that the format for available attribute
is wrong + it needs adding to the ABI docs.
Given we are going to have a v4, I noted a few other minor things to tidy up.
Thanks,
Jonathan
> +static int scd4x_read(struct scd4x_state *state, enum scd4x_cmd cmd,
> + void *response, int response_sz)
> +{
> + struct i2c_client *client = state->client;
> + char buf[SCD4X_READ_BUF_SIZE];
> + char *rsp = response;
> + int i, ret;
> + char crc;
> +
> + /*
> + * Measurement needs to be stopped before sending commands.
> + * Except for reading measurement and data ready command.
> + */
> + if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS)) {
> + ret = scd4x_send_command(state, CMD_STOP_MEAS);
> + if (ret)
> + return ret;
> +
> + /* execution time for stopping measurement */
> + msleep_interruptible(500);
> + }
> +
> + /*CRC byte for every 2 bytes of data */
/* CRC..
Please check for similar as otherwise we'll get 'cleanup' patches the moment various
scripts hit this new code and it'll waste our time!
> + response_sz += response_sz / 2;
> +
> + put_unaligned_be16(cmd, buf);
> + ret = scd4x_i2c_xfer(state, buf, 2, buf, response_sz);
> + if (ret)
> + return ret;
> +
> + for (i = 0; i < response_sz; i += 3) {
> + crc = crc8(scd4x_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
> + if (crc != buf[i + 2]) {
> + dev_err(&client->dev, "CRC error\n");
> + return -EIO;
> + }
> +
> + *rsp++ = buf[i];
> + *rsp++ = buf[i + 1];
> + }
> +
> + /* start measurement */
> + if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS)) {
> + ret = scd4x_send_command(state, CMD_START_MEAS);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
> +}
> +
...
> +
> +static IIO_DEVICE_ATTR_RW(calibration_auto_enable, 0);
> +static IIO_DEVICE_ATTR_WO(calibration_forced_value, 0);
> +
> +static IIO_CONST_ATTR(calibration_forced_value_available,
> + __stringify(SCD4X_FRC_MIN_PPM 1 SCD4X_FRC_MAX_PPM));
Ah, I wasn't completely clear on this. See the main ABI doc for
_available
Format for this needs to include brackets to indicate it's a range
rather than 3 numbers
"[MIN 1 MAX]"
Having added this it also needs to be in the ABI documentation.
Whilst somewhat trivial, all ABI should be documented there.
> +
> +static struct attribute *scd4x_attrs[] = {
> + &iio_dev_attr_calibration_auto_enable.dev_attr.attr,
> + &iio_dev_attr_calibration_forced_value.dev_attr.attr,
> + &iio_const_attr_calibration_forced_value_available.dev_attr.attr,
> + NULL
> +};
> +
> +static const struct attribute_group scd4x_attr_group = {
> + .attrs = scd4x_attrs,
> +};
> +
> +static const struct iio_info scd4x_info = {
> + .attrs = &scd4x_attr_group,
> + .read_raw = scd4x_read_raw,
> + .write_raw = scd4x_write_raw,
> +};
> +
...
> +
> +static irqreturn_t scd4x_trigger_handler(int irq, void *p)
> +{
> + struct iio_poll_func *pf = p;
> + struct iio_dev *indio_dev = pf->indio_dev;
> + struct scd4x_state *state = iio_priv(indio_dev);
> + struct {
> + uint16_t data[3];
> + int64_t ts __aligned(8);
> + } scan;
> + int ret;
> + uint16_t buf[3];
> +
> + mutex_lock(&state->lock);
> + ret = scd4x_read_poll(state, buf);
> + mutex_unlock(&state->lock);
> + if (ret)
> + goto out;
> +
> + memset(&scan, 0, sizeof(scan));
> + memcpy(scan.data, buf, sizeof(buf));
I missed this before, but why not do the scd4x_read_poll() directly into scan->data after
you've done the memset? That way you avoid the need for a memcpy.
i.e.
memset(&scan, 0, sizeof(scan));
mutex_lock(&state->lock)
ret = scd4x_read_poll(state, scan->data);
mutex_unlock(&state->lock);
if (ret)
...
> +
> + iio_push_to_buffers_with_timestamp(indio_dev, &scan, iio_get_time_ns(indio_dev));
> +out:
> + iio_trigger_notify_done(indio_dev->trig);
> + return IRQ_HANDLED;
> +}
> +
