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

[Slawomir Stepien <sst@poczta.fm>]

On maj 20, 2022 12:15, Krzysztof Kozlowski wrote:
> 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?

But if you have it in device-tree, then at least inform the user that there is some problem with it.

> > +		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.

Will fix in v2.

> >  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

-- 
Slawomir Stepien