PM / devfreq: Allow devfreq driver to add custom sysfs ABIs

Extend the devfreq_dev_profile to allow drivers optionally create
device-specific sysfs ABIs together with other common devfreq ABIs under
the devfreq device path.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Huisong Li <lihuisong@huawei.com>
Signed-off-by: Jie Zhan <zhanjie9@hisilicon.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Link: https://patchwork.kernel.org/project/linux-pm/patch/20250623143401.4095045-2-zhanjie9@hisilicon.com/

Author: jiezhan0214

drivers/devfreq/devfreq.c

@@ -831,6 +831,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
 	mutex_lock(&devfreq->lock);
 	devfreq->dev.parent = dev;
 	devfreq->dev.class = devfreq_class;
+	devfreq->dev.groups = profile->dev_groups;
 	devfreq->dev.release = devfreq_dev_release;
 	INIT_LIST_HEAD(&devfreq->node);
 	devfreq->profile = profile;

include/linux/devfreq.h

@@ -103,6 +103,8 @@ struct devfreq_dev_status {
  *
  * @is_cooling_device: A self-explanatory boolean giving the device a
  *                     cooling effect property.
+ * @dev_groups:		Optional device-specific sysfs attribute groups that to
+ *			be attached to the devfreq device.
  */
 struct devfreq_dev_profile {
 	unsigned long initial_freq;
@@ -119,6 +121,8 @@ struct devfreq_dev_profile {
 	unsigned int max_state;
 
 	bool is_cooling_device;
+
+	const struct attribute_group **dev_groups;
 };
 
 /**