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;
+}
+
