Thanks, I'll check it out.
On Tue, Apr 4, 2023 at 11:32 AM Thomas Weißschuh <thomas@xxxxxxxx> wrote:
>
> On 2023-04-03 15:18:31-0500, Jorge Lopez wrote:
> > Hi Thomas,
> >
> >
> > >
> > > Currently the driver stores all its state in driver-global static data.
> > > The kobjects are stored without any state.
> > > Inside the kobject attribute operations is some fiddly logic that tries
> > > to figure out the corresponding state with a fiddly mechansims.
> > >
> > > The more correct way would be to attach the corresponding state
> > > directly to the kobject.
> > >
> > > Let me know if you want to give this a shot and I'll give an example.
> >
> > Yes. I would like to give it a shot. I can take a look at the code
> > and determine when we can implement it.
> > No promises.
>
> /* data for each kernel object */
> struct bios_property {
> /* This is *not* a pointer, it will be used by the core sysfs
> * code framework to manage this "object" */
> struct kobject kobj;
> int instance_id; /* instance ID to pass to WMI functions */
> /* common members to all properties */
> u8 display_name[MAX_BUFF];
> u8 path[MAX_BUFF];
> /* all the other common stuff */
>
> const struct *property_ops ops;
> union {
> struct string_property_data {
> u8 current_value[MAX_BUFF];
> u8 new_value[MAX_BUFF];
> u32 min_length;
> u32 max_length;
> } string_data;
> /* same for other data types... */
> };
> };
>
> struct property_ops {
> ssize_t (*show_current_value)(struct bios_property *, char *);
> ssize_t (*store_current_value)(struct bios_property *, const char *, size_t);
> };
>
> static ssize_t string_property_show_current_value(struct bios_property *prop, char *buf)
> {
> /* or read from WMI. Does it need to be cached? */
> return sysfs_emit(buf, prop->string_data.current_value);
> }
>
> ssize_t string_property_store_current_value(struct bios_property *prop, const char *buf, size_t count)
> {
> int ret;
>
> if (strlen(buf) > prop->string_data.max_length)
> return -ERANGE;
>
> ret = do_string_specifc_wmi_stuff(buf, count);
> if (ret)
> return ret;
>
> strcpy(prop->current_value, buf);
> return count;
> }
>
> /* different show/store functionality per property type */
> static const struct property_ops string_property_ops = {
> .store_current_value = string_property_show_current_value,
> .show_current_value = string_property_show_current_value,
> };
>
> struct bioscfg_attribute {
> struct attribute attr;
> ssize_t (*show)(struct bioscfg_prop *prop, char *buf);
> ssize_t (*store)(struct bioscfg_prop *prop, const char *buf, size_t count);
> };
>
> /* this is one implementation for *all* property types */
> static ssize_t display_name_show(struct bioscfg_prop *prop, char *buf)
> {
> return sysfs_emit(buf, prop->display_name);
> }
> static struct bioscfg_attribute display_name = __ATTR_RO(display_name);
>
> /* and all the other ones */
>
> /* this dispatches into the type-specific property handlers */
> static ssize_t current_value_show(struct bioscfg_prop *prop, char *buf)
> {
> return prop->ops->show_current_value(prop, buf);
> }
> static struct bioscfg_attribute current_value = __ATTR(current_value);
>
> static struct attribute *attrs[] = {
> &display_name.attr,
> /* other attrs here */
> NULL
> };
>
> /* reflect read-only mode in sysfs */
> static umode_t bioscfg_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n)
> {
> struct bios_property *prop = container_of(kobj, struct bios_property, kobj);
>
> if (attr == ¤t_value.attr && prop->read_only)
> return attr->mode ^ 0222; /* clear writable bits */
> return attr->mode;
> }
>
> static const struct attribute_group attr_group = {
> .attrs = attrs,
> .is_visible = bioscfg_attr_is_visible,
> };
>
> /* the following two functions dispatch from your the core kobj pointer
> * to your custom callbacks operating on nice bioscfg_attribute
> */
> static ssize_t bioscfg_attr_show(struct kobject *kobj, struct attribute *attr,
> char *buf)
> {
> struct bioscfg_attribute *kattr;
> ssize_t ret = -EIO;
>
> kattr = container_of(attr, struct bioscfg_attribute, attr);
> if (kattr->show)
> ret = kattr->show(kobj, kattr, buf);
> return ret;
> }
>
> static ssize_t bioscfg_attr_store(struct kobject *kobj, struct attribute *attr,
> const char *buf, size_t count)
> {
> struct bioscfg_attribute *kattr;
> ssize_t ret = -EIO;
>
> kattr = container_of(attr, struct bioscfg_attribute, attr);
> if (kattr->store)
> ret = kattr->store(kobj, kattr, buf, count);
> return ret;
> }
>
> static const struct sysfs_ops bioscfg_kobj_sysfs_ops = {
> .show = bioscfg_attr_show,
> .store = bioscfg_attr_store,
> };
>
> /* to hook this into the generic kobject machinery */
> static const struct kobj_type bioscfg_kobj_type = {
> .release = free_struct_bios_property,
> .sysfs_ops = &bios_property_sysfs_ops,
> .default_groups = attr_groups,
> };
>
> static int probe(void)
> {
> struct bios_property *prop;
>
> for (each property discovered via WMI) {
> prop = kzalloc(sizeof(*prop));
> prop->readonly = is_read_only(property);
> /* other common properties */
> if (is_string_property(property)) {
> prop->ops = string_property_ops;
> prop->string_data.current_value = "";
> /* other type-specific properties */
> } else {
> ; /* and so on for other types */
> }
>
> kobject_init(&prop->kobj, &bioscfg_kobj_type);
> kobject_add(&prop->kobj, parent, name);
> }
>
> /* Now all properties and their memory are managed by the kernel */
> }
>
> Instead of having one kobj_type for all properties it would also be
> possible to create a new one for each. But I don't think it's worth it.
