On Fri, 18 Sep 2020 12:33:56 +0300
Cristian Pop <cristian.pop@xxxxxxxxxx> wrote:
> This is a demo usage of new "label" attribute for channel.
While I can see this is a demo in someways, I assume we also have
a valid usecase for doing this beyond as a demo!
So perhaps rephrase that intro.
>
> Signed-off-by: Cristian Pop <cristian.pop@xxxxxxxxxx>
> ---
> Changes in V5:
> Create a separate patch file for this commit
> drivers/iio/adc/ad7768-1.c | 49 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 49 insertions(+)
>
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index 0d132708c429..5ca9f9febb5a 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -161,6 +161,7 @@ struct ad7768_state {
> struct completion completion;
> struct iio_trigger *trig;
> struct gpio_desc *gpio_sync_in;
> + const char **labels;
> /*
> * DMA (thus cache coherency maintenance) requires the
> * transfer buffers to live in their own cache lines.
> @@ -407,6 +408,14 @@ static int ad7768_write_raw(struct iio_dev *indio_dev,
> }
> }
>
> +static int ad7768_read_label(struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan, char *label)
> +{
> + struct ad7768_state *st = iio_priv(indio_dev);
> +
> + return sprintf(label, "%s\n", st->labels[chan->channel]);
> +}
> +
> static struct attribute *ad7768_attributes[] = {
> &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
> NULL
> @@ -420,6 +429,7 @@ static const struct iio_info ad7768_info = {
> .attrs = &ad7768_group,
> .read_raw = &ad7768_read_raw,
> .write_raw = &ad7768_write_raw,
> + .read_label = ad7768_read_label,
> .debugfs_reg_access = &ad7768_reg_access,
> };
>
> @@ -538,6 +548,41 @@ static void ad7768_clk_disable(void *data)
> clk_disable_unprepare(st->mclk);
> }
>
> +static int ad7768_set_channel_label(struct iio_dev *indio_dev,
> + int num_channels)
> +{
> + struct ad7768_state *st = iio_priv(indio_dev);
> + struct device *device = indio_dev->dev.parent;
> + struct fwnode_handle *fwnode;
> + struct fwnode_handle *child;
> + const char *label;
> + int crt_ch = 0;
> +
> + st->labels = devm_kcalloc(indio_dev->dev.parent,
> + num_channels,
> + sizeof(**st->labels),
I think that ends up being the size of a single character which isn't
the intent. I assume aim is a suitable sized array of pointers to
strings which we will fill in later?
If so we can probably just use a static sized array as the maximum
number of channels is well constrained. In this particular driver
that is 1 I think!
> + GFP_KERNEL);
> +
> + if (!st->labels)
> + return -ENOMEM;
> +
> + fwnode = dev_fwnode(device);
> + fwnode_for_each_child_node(fwnode, child) {
> + if (fwnode_property_read_u32(child, "reg", &crt_ch))
> + continue;
> +
> + if (crt_ch >= num_channels)
> + continue;
> +
> + if (fwnode_property_read_string(child, "label", &label))
> + continue;
> +
> + st->labels[crt_ch] = label;
> + }
> +
> + return 0;
> +}
> +
> static int ad7768_probe(struct spi_device *spi)
> {
> struct ad7768_state *st;
> @@ -611,6 +656,10 @@ static int ad7768_probe(struct spi_device *spi)
>
> init_completion(&st->completion);
>
> + ret = ad7768_set_channel_label(indio_dev, ARRAY_SIZE(ad7768_channels));
> + if (ret)
> + return ret;
> +
> ret = devm_request_irq(&spi->dev, spi->irq,
> &ad7768_interrupt,
> IRQF_TRIGGER_RISING | IRQF_ONESHOT,
