Re: [PATCH 7/8] hwmon: (lm90) read the channel's label from device-tree

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 20/05/2022 11:32, Slawomir Stepien wrote:
> From: Slawomir Stepien <slawomir.stepien@nokia.com>
> 
> Try to read the channel's label from device-tree. Having label in
> device-tree node is not mandatory.
> 
> Signed-off-by: Slawomir Stepien <slawomir.stepien@nokia.com>
> ---
>  drivers/hwmon/lm90.c | 70 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 70 insertions(+)
> 
> diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
> index 67d48707a8d6..e81cc21e525f 100644
> --- a/drivers/hwmon/lm90.c
> +++ b/drivers/hwmon/lm90.c
> @@ -525,6 +525,7 @@ struct lm90_data {
>  	struct i2c_client *client;
>  	struct device *hwmon_dev;
>  	u32 channel_config[MAX_CHANNELS + 1];
> +	const char *channel_label[MAX_CHANNELS];
>  	struct hwmon_channel_info temp_info;
>  	const struct hwmon_channel_info *info[MAX_CHANNELS];
>  	struct hwmon_chip_info chip;
> @@ -1393,6 +1394,7 @@ static umode_t lm90_temp_is_visible(const void *data, u32 attr, int channel)
>  	case hwmon_temp_emergency_alarm:
>  	case hwmon_temp_emergency_hyst:
>  	case hwmon_temp_fault:
> +	case hwmon_temp_label:
>  		return 0444;
>  	case hwmon_temp_min:
>  	case hwmon_temp_max:
> @@ -1486,6 +1488,16 @@ static int lm90_read(struct device *dev, enum hwmon_sensor_types type,
>  	}
>  }
>  
> +static int lm90_read_string(struct device *dev, enum hwmon_sensor_types type,
> +			    u32 attr, int channel, const char **str)
> +{
> +	struct lm90_data *data = dev_get_drvdata(dev);
> +
> +	*str = data->channel_label[channel];
> +
> +	return 0;
> +}
> +
>  static int lm90_write(struct device *dev, enum hwmon_sensor_types type,
>  		      u32 attr, int channel, long val)
>  {
> @@ -1904,10 +1916,64 @@ static void lm90_regulator_disable(void *regulator)
>  	regulator_disable(regulator);
>  }
>  
> +static int lm90_probe_channel_from_dt(struct i2c_client *client,
> +				      struct device_node *child,
> +				      struct lm90_data *data)
> +{
> +	u32 id;
> +	int err;
> +	struct device *dev = &client->dev;
> +
> +	err = of_property_read_u32(child, "reg", &id);
> +	if (err) {
> +		dev_err(dev, "missing reg property of %pOFn\n", child);
> +		return err;
> +	}
> +
> +	if (id >= MAX_CHANNELS) {
> +		dev_err(dev, "invalid reg %d in %pOFn\n", id, child);
> +		return -EINVAL;
> +	}
> +
> +	err = of_property_read_string(child, "label", &data->channel_label[id]);
> +	if (err == -ENODATA || err == -EILSEQ) {
> +		dev_err(dev, "invalid label in %pOFn\n", child);

You did not make it a required property, so why failing?

> +		return err;
> +	}
> +
> +	if (data->channel_label[id])
> +		data->channel_config[id] |= HWMON_T_LABEL;
> +
> +	return 0;
> +}
> +
> +static int lm90_parse_dt_channel_info(struct i2c_client *client,
> +				      struct lm90_data *data)
> +{
> +	int err;
> +	struct device_node *child;
> +	struct device *dev = &client->dev;
> +	const struct device_node *np = dev->of_node;
> +
> +	for_each_child_of_node(np, child) {
> +		if (strcmp(child->name, "channel"))
> +			continue;
> +
> +		err = lm90_probe_channel_from_dt(client, child, data);
> +		if (err) {
> +			of_node_put(child);
> +			return err;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  

No need for double blank lines.

>  static const struct hwmon_ops lm90_ops = {
>  	.is_visible = lm90_is_visible,
>  	.read = lm90_read,
> +	.read_string = lm90_read_string,
>  	.write = lm90_write,
>  };
>  
> @@ -2027,6 +2093,10 @@ static int lm90_probe(struct i2c_client *client)
>  					return err;
>  			}
>  		}
> +
> +		err = lm90_parse_dt_channel_info(client, data);
> +		if (err)
> +			return err;
>  	}
>  
>  	/* Initialize the LM90 chip */


Best regards,
Krzysztof