hwmon: (core) Add support for string attributes to new API

The new API is so far only suited for data attributes and does not work
well for string attributes, specifically for the 'label' attributes.
Provide a separate callback function for those.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 31 insertions, 2 deletions

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index a74c075..491231f 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -178,6 +178,22 @@ static ssize_t hwmon_attr_show(struct device *dev,
 	return sprintf(buf, "%ld\n", val);
 }
 
+static ssize_t hwmon_attr_show_string(struct device *dev,
+				      struct device_attribute *devattr,
+				      char *buf)
+{
+	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
+	char *s;
+	int ret;
+
+	ret = hattr->ops->read_string(dev, hattr->type, hattr->attr,
+				      hattr->index, &s);
+	if (ret < 0)
+		return ret;
+
+	return sprintf(buf, "%s\n", s);
+}
+
 static ssize_t hwmon_attr_store(struct device *dev,
 				struct device_attribute *devattr,
 				const char *buf, size_t count)
@@ -205,6 +221,17 @@ static int hwmon_attr_base(enum hwmon_sensor_types type)
 	return 1;
 }
 
+static bool is_string_attr(enum hwmon_sensor_types type, u32 attr)
+{
+	return (type == hwmon_temp && attr == hwmon_temp_label) ||
+	       (type == hwmon_in && attr == hwmon_in_label) ||
+	       (type == hwmon_curr && attr == hwmon_curr_label) ||
+	       (type == hwmon_power && attr == hwmon_power_label) ||
+	       (type == hwmon_energy && attr == hwmon_energy_label) ||
+	       (type == hwmon_humidity && attr == hwmon_humidity_label) ||
+	       (type == hwmon_fan && attr == hwmon_fan_label);
+}
+
 static struct attribute *hwmon_genattr(struct device *dev,
 				       const void *drvdata,
 				       enum hwmon_sensor_types type,
@@ -218,6 +245,7 @@ static struct attribute *hwmon_genattr(struct device *dev,
 	struct attribute *a;
 	umode_t mode;
 	char *name;
+	bool is_string = is_string_attr(type, attr);
 
 	/* The attribute is invisible if there is no template string */
 	if (!template)
@@ -227,7 +255,8 @@ static struct attribute *hwmon_genattr(struct device *dev,
 	if (!mode)
 		return ERR_PTR(-ENOENT);
 
-	if ((mode & S_IRUGO) && !ops->read)
+	if ((mode & S_IRUGO) && ((is_string && !ops->read_string) ||
+				 (!is_string && !ops->read)))
 		return ERR_PTR(-EINVAL);
 	if ((mode & S_IWUGO) && !ops->write)
 		return ERR_PTR(-EINVAL);
@@ -252,7 +281,7 @@ static struct attribute *hwmon_genattr(struct device *dev,
 	hattr->ops = ops;
 
 	dattr = &hattr->dev_attr;
-	dattr->show = hwmon_attr_show;
+	dattr->show = is_string ? hwmon_attr_show_string : hwmon_attr_show;
 	dattr->store = hwmon_attr_store;
 
 	a = &dattr->attr;