[PATCH 2/5] hwmon: Expose attribute validation and string helpers

[Jihong Min]

Expose the core's string classification and sysfs template validation
through the kernel hwmon API. Let drivers query these properties without
maintaining separate attribute tables.

Reuse the helpers when creating attributes.

Assisted-by: Codex:gpt-6-astra
Signed-off-by: Jihong Min <hurryman2212@xxxxxxxxx>
---
 drivers/hwmon/hwmon.c | 30 +++++++++++++++++++++++++-----
 include/linux/hwmon.h |  3 +++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 10d2df3efdfa..bed16cfd4f1c 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -502,7 +502,14 @@ static ssize_t hwmon_attr_store(struct device *dev,
 	return count;
 }
 
-static bool is_string_attr(enum hwmon_sensor_types type, u32 attr)
+/**
+ * hwmon_is_string_attr - test whether an attribute returns a string
+ * @type: sensor type
+ * @attr: attribute identifier
+ *
+ * Return: true for string attributes, false otherwise.
+ */
+bool hwmon_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) ||
@@ -513,6 +520,7 @@ static bool is_string_attr(enum hwmon_sensor_types type, u32 attr)
 	       (type == hwmon_humidity && attr == hwmon_humidity_label) ||
 	       (type == hwmon_fan && attr == hwmon_fan_label);
 }
+EXPORT_SYMBOL_GPL(hwmon_is_string_attr);
 
 static const struct attribute *hwmon_genattr(const void *drvdata,
 					     enum hwmon_sensor_types type,
@@ -526,7 +534,7 @@ static const struct attribute *hwmon_genattr(const void *drvdata,
 	struct attribute *a;
 	umode_t mode;
 	const char *name;
-	bool is_string = is_string_attr(type, attr);
+	bool is_string = hwmon_is_string_attr(type, attr);
 
 	mode = hwmon_is_visible(ops, drvdata, type, attr, index);
 	if (!mode)
@@ -776,6 +784,20 @@ static const int __templates_size[] = {
 	[hwmon_intrusion] = ARRAY_SIZE(hwmon_intrusion_attr_templates),
 };
 
+/**
+ * hwmon_is_valid_attr - test whether an attribute has a sysfs template
+ * @type: sensor type
+ * @attr: attribute identifier
+ *
+ * Return: true for supported sysfs attributes, false otherwise.
+ */
+bool hwmon_is_valid_attr(enum hwmon_sensor_types type, u32 attr)
+{
+	return (unsigned int)type < ARRAY_SIZE(__templates) &&
+	       attr < __templates_size[type] && __templates[type][attr];
+}
+EXPORT_SYMBOL_GPL(hwmon_is_valid_attr);
+
 int hwmon_notify_event(struct device *dev, enum hwmon_sensor_types type,
 		       u32 attr, int channel)
 {
@@ -843,14 +865,12 @@ static int hwmon_genattrs(const void *drvdata,
 			  const struct hwmon_channel_info *info)
 {
 	const char * const *templates;
-	int template_size;
 	int i, aindex = 0;
 
 	if (info->type >= ARRAY_SIZE(__templates))
 		return -EINVAL;
 
 	templates = __templates[info->type];
-	template_size = __templates_size[info->type];
 
 	for (i = 0; info->config[i]; i++) {
 		u32 attr_mask = info->config[i];
@@ -861,7 +881,7 @@ static int hwmon_genattrs(const void *drvdata,
 
 			attr = __ffs(attr_mask);
 			attr_mask &= ~BIT(attr);
-			if (attr >= template_size || !templates[attr])
+			if (!hwmon_is_valid_attr(info->type, attr))
 				continue;	/* attribute is invisible */
 			a = hwmon_genattr(drvdata, info->type, attr, i,
 					  templates[attr], ops);
diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
index d48e0aa82bc5..b026aa317630 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -138,6 +138,9 @@ devm_hwmon_device_register_with_info(struct device *dev,
 
 void hwmon_device_unregister(struct device *dev);
 
+bool hwmon_is_valid_attr(enum hwmon_sensor_types type, u32 attr);
+bool hwmon_is_string_attr(enum hwmon_sensor_types type, u32 attr);
+
 int hwmon_notify_event(struct device *dev, enum hwmon_sensor_types type,
 		       u32 attr, int channel);