On Tue, Oct 12, 2021 at 11:27:14AM +0200, Krzysztof Adamski wrote:
> tmp42x is a multichannel temperature sensor with several external
> channels. Since those channels can be used to connect diodes placed
> anywhere in the system, their meaning will vary depending on the
> project. For this case, the hwmon framework has an idea of labels which
> allows us to assign the meaning to each channel.
>
> The similar concept is already implemented in ina3221 - the label for
> each channel can be defined via device tree. See commit a9e9dd9c6de5
> ("hwmon: (ina3221) Read channel input source info from DT")
>
> This patch adds support for similar feature to tmp421.
>
> Signed-off-by: Krzysztof Adamski <krzysztof.adamski@xxxxxxxxx>
> ---
> drivers/hwmon/tmp421.c | 61 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 61 insertions(+)
>
> diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
> index 707310d616a4..ab64d9825ca4 100644
> --- a/drivers/hwmon/tmp421.c
> +++ b/drivers/hwmon/tmp421.c
> @@ -88,6 +88,7 @@ static const struct of_device_id __maybe_unused tmp421_of_match[] = {
> MODULE_DEVICE_TABLE(of, tmp421_of_match);
>
> struct tmp421_channel {
> + const char *label;
> s16 temp;
> };
>
> @@ -187,6 +188,16 @@ static int tmp421_read(struct device *dev, enum hwmon_sensor_types type,
>
> }
>
> +static int tmp421_read_string(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, const char **str)
> +{
> + struct tmp421_data *data = dev_get_drvdata(dev);
> +
> + *str = data->channel[channel].label;
> +
> + return 0;
> +}
> +
> static umode_t tmp421_is_visible(const void *data, enum hwmon_sensor_types type,
> u32 attr, int channel)
> {
> @@ -194,6 +205,8 @@ static umode_t tmp421_is_visible(const void *data, enum hwmon_sensor_types type,
> case hwmon_temp_fault:
> case hwmon_temp_input:
> return 0444;
> + case hwmon_temp_label:
> + return 0444;
> default:
> return 0;
> }
> @@ -286,9 +299,53 @@ static int tmp421_detect(struct i2c_client *client,
> return 0;
> }
>
> +static int tmp421_probe_child_from_dt(struct i2c_client *client,
> + struct device_node *child,
> + struct tmp421_data *data)
> +
> +{
> + struct device *dev = &client->dev;
> + u32 i;
> + int err;
> +
> + err = of_property_read_u32(child, "reg", &i);
> + if (err) {
> + dev_err(dev, "missing reg property of %pOFn\n", child);
> + return err;
> + }
> +
> + if (i >= MAX_CHANNELS) {
I think this needs to compare against data->channels. Otherwise, if
unsupported channels are listed in dt (say, reg==0x2 with tmp421),
we would end up with label attributes for those channels.
> + dev_err(dev, "invalid reg %d of %pOFn\n", i, child);
> + return -EINVAL;
> + }
> +
> + of_property_read_string(child, "label", &data->channel[i].label);
> + if (data->channel[i].label)
> + data->temp_config[i] |= HWMON_T_LABEL;
> +
> + return 0;
> +}
> +
> +static int tmp421_probe_from_dt(struct i2c_client *client, struct tmp421_data *data)
> +{
> + struct device *dev = &client->dev;
> + const struct device_node *np = dev->of_node;
> + struct device_node *child;
> + int err;
> +
> + for_each_child_of_node(np, child) {
> + err = tmp421_probe_child_from_dt(client, child, data);
> + if (err)
> + return err;
> + }
> +
> + return 0;
> +}
> +
> static const struct hwmon_ops tmp421_ops = {
> .is_visible = tmp421_is_visible,
> .read = tmp421_read,
> + .read_string = tmp421_read_string,
> };
>
> static int tmp421_probe(struct i2c_client *client)
> @@ -317,6 +374,10 @@ static int tmp421_probe(struct i2c_client *client)
> for (i = 0; i < data->channels; i++)
> data->temp_config[i] = HWMON_T_INPUT | HWMON_T_FAULT;
>
> + err = tmp421_probe_from_dt(client, data);
> + if (err)
> + return err;
> +
> data->chip.ops = &tmp421_ops;
> data->chip.info = data->info;
>
