From: Thomas Weißschuh <linux@weissschuh.net>

Currently each user of firmware_attributes_class has to manually set up
kobjects, devices, etc.

Provide this infrastructure out-of-the-box through the newly introduced
fwat_device_register().

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Co-developed-by: Kurt Borja <kuurtb@gmail.com>
Signed-off-by: Kurt Borja <kuurtb@gmail.com>
---
 drivers/platform/x86/firmware_attributes_class.c | 125 +++++++++++++++++++++++
 drivers/platform/x86/firmware_attributes_class.h |  28 +++++
 2 files changed, 153 insertions(+)

diff --git a/drivers/platform/x86/firmware_attributes_class.c b/drivers/platform/x86/firmware_attributes_class.c
index 736e96c186d9dc6d945517f090e9af903e93bbf4..29c303c20d47a7dccf59cf54fa1a7e91e582f894 100644
--- a/drivers/platform/x86/firmware_attributes_class.c
+++ b/drivers/platform/x86/firmware_attributes_class.c
@@ -2,7 +2,14 @@
 
 /* Firmware attributes class helper module */
 
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/device/class.h>
+#include <linux/kdev_t.h>
+#include <linux/kobject.h>
 #include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
 #include "firmware_attributes_class.h"
 
 const struct class firmware_attributes_class = {
@@ -10,6 +17,122 @@ const struct class firmware_attributes_class = {
 };
 EXPORT_SYMBOL_GPL(firmware_attributes_class);
 
+static void fwat_device_release(struct device *dev)
+{
+	struct fwat_device *fadev = to_fwat_device(dev);
+
+	kfree(fadev);
+}
+
+/**
+ * fwat_device_register - Create and register a firmware-attributes class
+ *			  device
+ * @parent: Parent device
+ * @name: Name of the class device
+ * @data: Drvdata of the class device
+ * @groups: Extra groups for the class device (Optional)
+ *
+ * Return: pointer to the new fwat_device on success, ERR_PTR on failure
+ */
+struct fwat_device *
+fwat_device_register(struct device *parent, const char *name, void *drvdata,
+		     const struct attribute_group **groups)
+{
+	struct fwat_device *fadev;
+	int ret;
+
+	if (!parent || !name)
+		return ERR_PTR(-EINVAL);
+
+	fadev = kzalloc(sizeof(*fadev), GFP_KERNEL);
+	if (!fadev)
+		return ERR_PTR(-ENOMEM);
+
+	fadev->groups = groups;
+	fadev->dev.class = &firmware_attributes_class;
+	fadev->dev.parent = parent;
+	fadev->dev.release = fwat_device_release;
+	dev_set_drvdata(&fadev->dev, drvdata);
+	ret = dev_set_name(&fadev->dev, "%s", name);
+	if (ret) {
+		kfree(fadev);
+		return ERR_PTR(ret);
+	}
+	ret = device_register(&fadev->dev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	fadev->attrs_kset = kset_create_and_add("attributes", NULL, &fadev->dev.kobj);
+	if (!fadev->attrs_kset) {
+		ret = -ENOMEM;
+		goto out_device_unregister;
+	}
+
+	ret = sysfs_create_groups(&fadev->attrs_kset->kobj, groups);
+	if (ret)
+		goto out_kset_unregister;
+
+	return fadev;
+
+out_kset_unregister:
+	kset_unregister(fadev->attrs_kset);
+
+out_device_unregister:
+	device_unregister(&fadev->dev);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(fwat_device_register);
+
+void fwat_device_unregister(struct fwat_device *fadev)
+{
+	if (!fadev)
+		return;
+
+	sysfs_remove_groups(&fadev->attrs_kset->kobj, fadev->groups);
+	kset_unregister(fadev->attrs_kset);
+	device_unregister(&fadev->dev);
+}
+EXPORT_SYMBOL_GPL(fwat_device_unregister);
+
+static void devm_fwat_device_release(void *data)
+{
+	struct fwat_device *fadev = data;
+
+	fwat_device_unregister(fadev);
+}
+
+/**
+ * devm_fwat_device_register - Create and register a firmware-attributes class
+ *			       device
+ * @parent: Parent device
+ * @name: Name of the class device
+ * @data: Drvdata of the class device
+ * @groups: Extra groups for the class device (Optional)
+ *
+ * Device managed version of fwat_device_register().
+ *
+ * Return: pointer to the new fwat_device on success, ERR_PTR on failure
+ */
+struct fwat_device *
+devm_fwat_device_register(struct device *parent, const char *name, void *data,
+			  const struct attribute_group **groups)
+{
+	struct fwat_device *fadev;
+	int ret;
+
+	fadev = fwat_device_register(parent, name, data, groups);
+	if (IS_ERR(fadev))
+		return fadev;
+
+	ret = devm_add_action_or_reset(parent, devm_fwat_device_release, fadev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return fadev;
+}
+EXPORT_SYMBOL_GPL(devm_fwat_device_register);
+
 static __init int fw_attributes_class_init(void)
 {
 	return class_register(&firmware_attributes_class);
@@ -23,5 +146,7 @@ static __exit void fw_attributes_class_exit(void)
 module_exit(fw_attributes_class_exit);
 
 MODULE_AUTHOR("Mark Pearson <markpearson@lenovo.com>");
+MODULE_AUTHOR("Thomas Weißschuh <linux@weissschuh.net>");
+MODULE_AUTHOR("Kurt Borja <kuurtb@gmail.com>");
 MODULE_DESCRIPTION("Firmware attributes class helper module");
 MODULE_LICENSE("GPL");
diff --git a/drivers/platform/x86/firmware_attributes_class.h b/drivers/platform/x86/firmware_attributes_class.h
index d27abe54fcf9812a2f0868eec5426bbc8e7eb21c..4ae700eec1e586e1f9ed96bd6e3843342381816d 100644
--- a/drivers/platform/x86/firmware_attributes_class.h
+++ b/drivers/platform/x86/firmware_attributes_class.h
@@ -5,8 +5,36 @@
 #ifndef FW_ATTR_CLASS_H
 #define FW_ATTR_CLASS_H
 
+#include <linux/container_of.h>
+#include <linux/device.h>
 #include <linux/device/class.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
 
 extern const struct class firmware_attributes_class;
 
+/**
+ * struct fwat_device - The firmware-attributes device
+ * @dev: The class device.
+ * @attrs_kobj: The "attributes" root kobject.
+ * @groups: Sysfs groups attached to the @attrs_kobj.
+ */
+struct fwat_device {
+	struct device dev;
+	struct kset *attrs_kset;
+	const struct attribute_group **groups;
+};
+
+#define to_fwat_device(_d)	container_of_const(_d, struct fwat_device, dev)
+
+struct fwat_device * __must_check
+fwat_device_register(struct device *parent, const char *name, void *data,
+		     const struct attribute_group **groups);
+
+void fwat_device_unregister(struct fwat_device *fwadev);
+
+struct fwat_device * __must_check
+devm_fwat_device_register(struct device *parent, const char *name, void *data,
+			  const struct attribute_group **groups);
+
 #endif /* FW_ATTR_CLASS_H */

-- 
2.50.0

Hi Kurt,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 73f0f2b52c5ea67b3140b23f58d8079d158839c8]

url:    https://github.com/intel-lab-lkp/linux/commits/Kurt-Borja/platform-x86-firmware_attributes_class-Add-device-initialization-methods/20250630-160549
base:   73f0f2b52c5ea67b3140b23f58d8079d158839c8
patch link:    https://lore.kernel.org/r/20250630-fw-attrs-api-v4-1-1a04952b255f%40gmail.com
patch subject: [PATCH v4 1/6] platform/x86: firmware_attributes_class: Add device initialization methods
config: x86_64-randconfig-073-20250701 (https://download.01.org/0day-ci/archive/20250701/202507010553.vgtA0xlb-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14+deb12u1) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250701/202507010553.vgtA0xlb-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202507010553.vgtA0xlb-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> Warning: drivers/platform/x86/firmware_attributes_class.c:39 function parameter 'drvdata' not described in 'fwat_device_register'
>> Warning: drivers/platform/x86/firmware_attributes_class.c:39 Excess function parameter 'data' description in 'fwat_device_register'

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki