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Message-ID: <907d0022-0512-4a60-9d57-26b48c986df0@kernel.org>
Date: Fri, 9 May 2025 10:59:42 -0500
From: Mario Limonciello <superm1@...nel.org>
To: Kurt Borja <kuurtb@...il.com>, Hans de Goede <hdegoede@...hat.com>,
Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
Thomas Weißschuh <linux@...ssschuh.net>,
Joshua Grisham <josh@...huagrisham.com>,
Mark Pearson <mpearson-lenovo@...ebb.ca>, Armin Wolf <W_Armin@....de>
Cc: Antheas Kapenekakis <lkml@...heas.dev>,
"Derek J. Clark" <derekjohn.clark@...il.com>,
Prasanth Ksr <prasanth.ksr@...l.com>, Jorge Lopez <jorge.lopez2@...com>,
platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
Dell.Client.Kernel@...l.com
Subject: Re: [PATCH RFC 1/5] platform/x86: firmware_attributes_class: Add
device initialization methods
On 5/9/2025 2:48 AM, Kurt Borja wrote:
> From: Thomas Weißschuh <linux@...ssschuh.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().
>
> Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
> Co-developed-by: Kurt Borja <kuurtb@...il.com>
> Signed-off-by: Kurt Borja <kuurtb@...il.com>
Reviewed-by: Mario Limonciello <mario.limonciello@....com>
> ---
> drivers/platform/x86/firmware_attributes_class.c | 165 +++++++++++++++++++++++
> drivers/platform/x86/firmware_attributes_class.h | 44 ++++++
> 2 files changed, 209 insertions(+)
>
> diff --git a/drivers/platform/x86/firmware_attributes_class.c b/drivers/platform/x86/firmware_attributes_class.c
> index 736e96c186d9dc6d945517f090e9af903e93bbf4..58ab1495ba3bd449cfe17de2827a57a0c5937788 100644
> --- a/drivers/platform/x86/firmware_attributes_class.c
> +++ b/drivers/platform/x86/firmware_attributes_class.c
> @@ -2,7 +2,12 @@
>
> /* Firmware attributes class helper module */
>
> +#include <linux/device.h>
> +#include <linux/device/class.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 +15,164 @@ const struct class firmware_attributes_class = {
> };
> EXPORT_SYMBOL_GPL(firmware_attributes_class);
>
> +static ssize_t fwat_attrs_kobj_show(struct kobject *kobj, struct attribute *attr,
> + char *buf)
> +{
> + const struct fwat_attribute *fattr = to_fwat_attribute(attr);
> + struct fwat_device *fadev = to_fwat_device(kobj);
> +
> + if (!fattr->show)
> + return -ENOENT;
> +
> + return fattr->show(fadev->dev, fattr, buf);
> +}
> +
> +static ssize_t fwat_attrs_kobj_store(struct kobject *kobj, struct attribute *attr,
> + const char *buf, size_t count)
> +{
> + const struct fwat_attribute *fattr = to_fwat_attribute(attr);
> + struct fwat_device *fadev = to_fwat_device(kobj);
> +
> + if (!fattr->store)
> + return -ENOENT;
> +
> + return fattr->store(fadev->dev, fattr, buf, count);
> +}
> +
> +static const struct sysfs_ops fwat_attrs_kobj_ops = {
> + .show = fwat_attrs_kobj_show,
> + .store = fwat_attrs_kobj_store,
> +};
> +
> +static void fwat_attrs_kobj_release(struct kobject *kobj)
> +{
> + struct fwat_device *fadev = to_fwat_device(kobj);
> +
> + kfree(fadev);
> +}
> +
> +static const struct kobj_type fwat_attrs_ktype = {
> + .sysfs_ops = &fwat_attrs_kobj_ops,
> + .release = fwat_attrs_kobj_release,
> +};
> +
> +/**
> + * 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: Sysfs groups for the custom `fwat_attrs_ktype` kobj_type
> + *
> + * NOTE: @groups are attached to the .attrs_kobj of the new fwat_device which
> + * has a custom ktype, which makes use of `struct fwat_attribute` to embed
> + * attributes.
> + *
> + * 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 *data,
> + const struct attribute_group **groups)
> +{
> + struct fwat_device *fadev;
> + struct device *dev;
> + int ret;
> +
> + if (!parent || !name)
> + return ERR_PTR(-EINVAL);
> +
> + fadev = kzalloc(sizeof(*fadev), GFP_KERNEL);
> + if (!fadev)
> + return ERR_PTR(-ENOMEM);
> +
> + dev = device_create(&firmware_attributes_class, parent, MKDEV(0, 0),
> + data, "%s", name);
> + if (IS_ERR(dev)) {
> + kfree(fadev);
> + return ERR_CAST(dev);
> + }
> +
> + ret = kobject_init_and_add(&fadev->attrs_kobj, &fwat_attrs_ktype, &dev->kobj,
> + "attributes");
> + if (ret)
> + goto out_kobj_put;
> +
> + if (groups) {
> + ret = sysfs_create_groups(&fadev->attrs_kobj, groups);
> + if (ret)
> + goto out_kobj_unregister;
> + }
> +
> + fadev->dev = dev;
> + fadev->groups = groups;
> +
> + kobject_uevent(&fadev->attrs_kobj, KOBJ_ADD);
> +
> + return fadev;
> +
> +out_kobj_unregister:
> + kobject_del(&fadev->attrs_kobj);
> +
> +out_kobj_put:
> + kobject_put(&fadev->attrs_kobj);
> + device_unregister(dev);
> +
> + return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(fwat_device_register);
> +
> +void fwat_device_unregister(struct fwat_device *fwadev)
> +{
> + if (fwadev->groups)
> + sysfs_remove_groups(&fwadev->attrs_kobj, fwadev->groups);
> + kobject_del(&fwadev->attrs_kobj);
> + kobject_put(&fwadev->attrs_kobj);
> + device_unregister(fwadev->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: Sysfs groups for the custom `fwat_attrs_ktype` kobj_type
> + *
> + * Device managed version of fwat_device_register().
> + *
> + * NOTE: @groups are attached to the .attrs_kobj of the new fwat_device which
> + * has a custom ktype, which makes use of `struct fwat_attribute` to embed
> + * attributes.
> + *
> + * 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 +186,7 @@ static __exit void fw_attributes_class_exit(void)
> module_exit(fw_attributes_class_exit);
>
> MODULE_AUTHOR("Mark Pearson <markpearson@...ovo.com>");
> +MODULE_AUTHOR("Thomas Weißschuh <linux@...ssschuh.net>");
> +MODULE_AUTHOR("Kurt Borja <kuurtb@...il.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..ad94bf91e5af30a2b8feb9abf224ee6f0d17600a 100644
> --- a/drivers/platform/x86/firmware_attributes_class.h
> +++ b/drivers/platform/x86/firmware_attributes_class.h
> @@ -5,8 +5,52 @@
> #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 kobject attrs_kobj;
> + const struct attribute_group **groups;
> +};
> +
> +#define to_fwat_device(_k) container_of_const(_k, struct fwat_device, attrs_kobj)
> +
> +/**
> + * struct fwat_attribute - The firmware-attributes's custom attribute
> + * @attr: Embedded struct attribute.
> + * @show: Show method called by the "attributes" kobject's ktype.
> + * @store: Store method called by the "attributes" kobject's ktype.
> + */
> +struct fwat_attribute {
> + struct attribute attr;
> + ssize_t (*show)(struct device *dev, const struct fwat_attribute *attr,
> + char *buf);
> + ssize_t (*store)(struct device *dev, const struct fwat_attribute *attr,
> + const char *buf, size_t count);
> +};
> +
> +#define to_fwat_attribute(_a) container_of_const(_a, struct fwat_attribute, attr)
> +
> +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 */
>
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