hwmon: (lm90) Read the channel's label from device-tree

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>
Link: https://lore.kernel.org/r/20220525073657.573327-7-sst@poczta.fm
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index fd887a7..a18aed5 100644 (file)
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -685,6 +685,7 @@ struct lm90_data {
        struct device *hwmon_dev;
        u32 chip_config[2];
        u32 channel_config[MAX_CHANNELS + 1];
+       const char *channel_label[MAX_CHANNELS];
        struct hwmon_channel_info chip_info;
        struct hwmon_channel_info temp_info;
        const struct hwmon_channel_info *info[3];
@@ -1587,6 +1588,7 @@ 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:
@@ -1706,6 +1708,16 @@ 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)
 {
@@ -2611,10 +2623,63 @@ 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 property value %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 property in %pOFn\n", child);
+               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;
+}
 
 static const struct hwmon_ops lm90_ops = {
        .is_visible = lm90_is_visible,
        .read = lm90_read,
+       .read_string = lm90_read_string,
        .write = lm90_write,
 };
 
@@ -2750,6 +2815,13 @@ static int lm90_probe(struct i2c_client *client)
        /* Set maximum conversion rate */
        data->max_convrate = lm90_params[data->kind].max_convrate;
 
+       /* Parse device-tree channel information */
+       if (client->dev.of_node) {
+               err = lm90_parse_dt_channel_info(client, data);
+               if (err)
+                       return err;
+       }
+
        /* Initialize the LM90 chip */
        err = lm90_init_client(client, data);
        if (err < 0) {