hwmon: iio: Add labels from IIO channels

Add labels from IIO channels to our channels. This allows userspace to
display more meaningful names instead of "in0" or "temp5".

Although lm-sensors gracefully handles errors when reading channel
labels, the ABI says the label attribute

> Should only be created if the driver has hints about what this voltage
> channel is being used for, and user-space doesn't.

Therefore, we test to see if the channel has a label before
creating the attribute.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Link: https://patch.msgid.link/20240624174601.1527244-3-sean.anderson@linux.dev
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/hwmon/iio_hwmon.c b/drivers/hwmon/iio_hwmon.c
index 4c8a808..5722cb9 100644 (file)
--- a/drivers/hwmon/iio_hwmon.c
+++ b/drivers/hwmon/iio_hwmon.c
@@ -33,6 +33,17 @@ struct iio_hwmon_state {
        struct attribute **attrs;
 };
 
+static ssize_t iio_hwmon_read_label(struct device *dev,
+                                 struct device_attribute *attr,
+                                 char *buf)
+{
+       struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
+       struct iio_hwmon_state *state = dev_get_drvdata(dev);
+       struct iio_channel *chan = &state->channels[sattr->index];
+
+       return iio_read_channel_label(chan, buf);
+}
+
 /*
  * Assumes that IIO and hwmon operate in the same base units.
  * This is supposed to be true, but needs verification for
@@ -68,12 +79,13 @@ static int iio_hwmon_probe(struct platform_device *pdev)
        struct device *dev = &pdev->dev;
        struct iio_hwmon_state *st;
        struct sensor_device_attribute *a;
-       int ret, i;
+       int ret, i, attr = 0;
        int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1, power_i = 1;
        enum iio_chan_type type;
        struct iio_channel *channels;
        struct device *hwmon_dev;
        char *sname;
+       void *buf;
 
        channels = devm_iio_channel_get_all(dev);
        if (IS_ERR(channels)) {
@@ -85,17 +97,18 @@ static int iio_hwmon_probe(struct platform_device *pdev)
        }
 
        st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
-       if (st == NULL)
+       buf = (void *)devm_get_free_pages(dev, GFP_KERNEL, 0);
+       if (!st || !buf)
                return -ENOMEM;
 
        st->channels = channels;
 
-       /* count how many attributes we have */
+       /* count how many channels we have */
        while (st->channels[st->num_channels].indio_dev)
                st->num_channels++;
 
        st->attrs = devm_kcalloc(dev,
-                                st->num_channels + 1, sizeof(*st->attrs),
+                                2 * st->num_channels + 1, sizeof(*st->attrs),
                                 GFP_KERNEL);
        if (st->attrs == NULL)
                return -ENOMEM;
@@ -147,9 +160,31 @@ static int iio_hwmon_probe(struct platform_device *pdev)
                a->dev_attr.show = iio_hwmon_read_val;
                a->dev_attr.attr.mode = 0444;
                a->index = i;
-               st->attrs[i] = &a->dev_attr.attr;
+               st->attrs[attr++] = &a->dev_attr.attr;
+
+               /* Let's see if we have a label... */
+               if (iio_read_channel_label(&st->channels[i], buf) < 0)
+                       continue;
+
+               a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
+               if (a == NULL)
+                       return -ENOMEM;
+
+               sysfs_attr_init(&a->dev_attr.attr);
+               a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
+                                                      "%s%d_label",
+                                                      prefix, n);
+               if (!a->dev_attr.attr.name)
+                       return -ENOMEM;
+
+               a->dev_attr.show = iio_hwmon_read_label;
+               a->dev_attr.attr.mode = 0444;
+               a->index = i;
+               st->attrs[attr++] = &a->dev_attr.attr;
        }
 
+       devm_free_pages(dev, (unsigned long)buf);
+
        st->attr_group.attrs = st->attrs;
        st->groups[0] = &st->attr_group;