Re: [RFC] subclasses in sysfs to solve world peace

From: Dmitry Torokhov
Date: Fri Sep 16 2005 - 02:22:37 EST

> >
> > No, like your first picture, except 'interfaces/mice' will be a directory,
> > not a symlink, since it does not have class_device parent. I should have
> > said "Otherwise it gets added into _its_ class directory".
>

Ok, this is _very_ raw and I am creating double symlinks somehow, but still
it shows it can be done:

[dtor@core ~]$ tree /sys/class/input/
/sys/class/input/
|-- devices
| |-- input0
| | |-- capabilities
| | | |-- abs
| | | |-- ev
| | | |-- ff
| | | |-- key
| | | |-- led
| | | |-- msc
| | | |-- rel
| | | |-- snd
| | | `-- sw
| | |-- device -> ../../../../devices/platform/i8042/serio1
| | |-- event0
| | | |-- dev
| | | `-- device -> ../../../../../class/input/devices/input0
| | |-- event0
| | | |-- dev
| | | `-- device -> ../../../../../class/input/devices/input0
| | |-- id
| | | |-- bustype
| | | |-- product
| | | |-- vendor
| | | `-- version
| | |-- name
| | |-- phys
| | `-- uniq
| |-- input1
| | |-- capabilities
| | | |-- abs
| | | |-- ev
| | | |-- ff
| | | |-- key
| | | |-- led
| | | |-- msc
| | | |-- rel
| | | |-- snd
| | | `-- sw
| | |-- device -> ../../../../devices/platform/i8042/serio0
| | |-- event1
| | | |-- dev
| | | `-- device -> ../../../../../class/input/devices/input1
| | |-- event1
| | | |-- dev
| | | `-- device -> ../../../../../class/input/devices/input1
| | |-- id
| | | |-- bustype
| | | |-- product
| | | |-- vendor
| | | `-- version
| | |-- mouse0
| | | |-- dev
| | | `-- device -> ../../../../../class/input/devices/input1
| | |-- mouse0
| | | |-- dev
| | | `-- device -> ../../../../../class/input/devices/input1
| | |-- name
| | |-- phys
| | |-- ts0
| | | |-- dev
| | | `-- device -> ../../../../../class/input/devices/input1
| | |-- ts0
| | | |-- dev
| | | `-- device -> ../../../../../class/input/devices/input1
| | `-- uniq
| `-- input2
| |-- capabilities
| | |-- abs
| | |-- ev
| | |-- ff
| | |-- key
| | |-- led
| | |-- msc
| | |-- rel
| | |-- snd
| | `-- sw
| |-- device -> ../../../../devices/platform/i8042/serio0/serio2
| |-- event2
| | |-- dev
| | `-- device -> ../../../../../class/input/devices/input2
| |-- event2
| | |-- dev
| | `-- device -> ../../../../../class/input/devices/input2
| |-- id
| | |-- bustype
| | |-- product
| | |-- vendor
| | `-- version
| |-- mouse1
| | |-- dev
| | `-- device -> ../../../../../class/input/devices/input2
| |-- mouse1
| | |-- dev
| | `-- device -> ../../../../../class/input/devices/input2
| |-- name
| |-- phys
| |-- ts1
| | |-- dev
| | `-- device -> ../../../../../class/input/devices/input2
| |-- ts1
| | |-- dev
| | `-- device -> ../../../../../class/input/devices/input2
| `-- uniq
`-- interfaces
|-- event0 -> ../../../class/input/devices/input0/event0
|-- event1 -> ../../../class/input/devices/input1/event1
|-- event2 -> ../../../class/input/devices/input2/event2
|-- mice
| `-- dev
|-- mouse0 -> ../../../class/input/devices/input1/mouse0
|-- mouse1 -> ../../../class/input/devices/input2/mouse1
|-- ts0 -> ../../../class/input/devices/input1/ts0
`-- ts1 -> ../../../class/input/devices/input2/ts1

--
Dmitry

Subject: XXX
Signed-off-by: Dmitry Torokhov <dtor@xxxxxxx>
---

drivers/base/class.c | 81 +++++++++++++++++++++++++++++++++++--------------
drivers/input/input.c | 6 +++
include/linux/device.h | 5 ++-
3 files changed, 67 insertions(+), 25 deletions(-)

Index: work/drivers/base/class.c
===================================================================
--- work.orig/drivers/base/class.c
+++ work/drivers/base/class.c
@@ -485,7 +485,7 @@ static char *make_class_name(struct clas

int class_device_add(struct class_device *class_dev)
{
- struct class * parent = NULL;
+ struct class * class = NULL;
struct class_interface * class_intf;
char *class_name = NULL;
int error;
@@ -499,15 +499,18 @@ int class_device_add(struct class_device
goto register_done;
}

- parent = class_get(class_dev->class);
+ class = class_get(class_dev->class);

pr_debug("CLASS: registering class device: ID = '%s'\n",
class_dev->class_id);

/* first, register with generic layer. */
kobject_set_name(&class_dev->kobj, "%s", class_dev->class_id);
- if (parent)
- class_dev->kobj.parent = &parent->subsys.kset.kobj;
+
+ if (is_a_class_device(class_dev->parent))
+ class_dev->kobj.parent = class_dev->parent;
+ else if (class)
+ class_dev->kobj.parent = &class->subsys.kset.kobj;

if ((error = kobject_add(&class_dev->kobj)))
goto register_done;
@@ -524,7 +527,7 @@ int class_device_add(struct class_device

attr->attr.name = "dev";
attr->attr.mode = S_IRUGO;
- attr->attr.owner = parent->owner;
+ attr->attr.owner = class ? class->owner : NULL;
attr->show = show_dev;
attr->store = NULL;
class_device_create_file(class_dev, attr);
@@ -532,31 +535,45 @@ int class_device_add(struct class_device
}

class_device_add_attrs(class_dev);
+
+ /* this will go away */
if (class_dev->dev) {
class_name = make_class_name(class_dev);
- sysfs_create_link(&class_dev->kobj,
- &class_dev->dev->kobj, "device");
+ sysfs_create_link(&class_dev->kobj, &class_dev->dev->kobj,
+ "device");
sysfs_create_link(&class_dev->dev->kobj, &class_dev->kobj,
class_name);
+ kfree(class_name);
+ } else if (class_dev->parent) {
+ class_name = make_class_name(class_dev);
+ sysfs_create_link(&class_dev->kobj, class_dev->parent,
+ "device");
+ sysfs_create_link(class_dev->parent, &class_dev->kobj,
+ is_a_class_device(class_dev->parent) ?
+ class_dev->class_id : class_name);
+ kfree(class_name);
}

+ if (class && is_a_class_device(class_dev->parent))
+ sysfs_create_link(&class->subsys.kset.kobj, &class_dev->kobj,
+ class_dev->class_id);
+
kobject_hotplug(&class_dev->kobj, KOBJ_ADD);

/* notify any interfaces this device is now here */
- if (parent) {
- down(&parent->sem);
- list_add_tail(&class_dev->node, &parent->children);
- list_for_each_entry(class_intf, &parent->interfaces, node)
+ if (class) {
+ down(&class->sem);
+ list_add_tail(&class_dev->node, &class->children);
+ list_for_each_entry(class_intf, &class->interfaces, node)
if (class_intf->add)
class_intf->add(class_dev, class_intf);
- up(&parent->sem);
+ up(&class->sem);
}

register_done:
- if (error && parent)
- class_put(parent);
+ if (error && class)
+ class_put(class);
class_device_put(class_dev);
- kfree(class_name);
return error;
}

@@ -619,34 +636,48 @@ error:

void class_device_del(struct class_device *class_dev)
{
- struct class * parent = class_dev->class;
+ struct class * class = class_dev->class;
struct class_interface * class_intf;
char *class_name = NULL;

- if (parent) {
- down(&parent->sem);
+ if (class) {
+ down(&class->sem);
list_del_init(&class_dev->node);
- list_for_each_entry(class_intf, &parent->interfaces, node)
+ list_for_each_entry(class_intf, &class->interfaces, node)
if (class_intf->remove)
class_intf->remove(class_dev, class_intf);
- up(&parent->sem);
+ up(&class->sem);
+ }
+
+ if (class && is_a_class_device(class_dev->parent))
+ sysfs_remove_link(&class->subsys.kset.kobj, class_dev->class_id);
+
+ if (class_dev->parent) {
+ class_name = make_class_name(class_dev);
+ sysfs_remove_link(&class_dev->kobj, "device");
+ sysfs_remove_link(class_dev->parent,
+ is_a_class_device(class_dev->parent) ?
+ class_dev->class_id : class_name);
+ kfree(class_name);
}

if (class_dev->dev) {
class_name = make_class_name(class_dev);
sysfs_remove_link(&class_dev->kobj, "device");
sysfs_remove_link(&class_dev->dev->kobj, class_name);
+ kfree(class_name);
}
+
if (class_dev->devt_attr)
class_device_remove_file(class_dev, class_dev->devt_attr);
+
class_device_remove_attrs(class_dev);

kobject_hotplug(&class_dev->kobj, KOBJ_REMOVE);
kobject_del(&class_dev->kobj);

- if (parent)
- class_put(parent);
- kfree(class_name);
+ if (class)
+ class_put(class);
}

void class_device_unregister(struct class_device *class_dev)
@@ -715,6 +746,10 @@ void class_device_put(struct class_devic
kobject_put(&class_dev->kobj);
}

+int is_a_class_device(struct kobject *kobj)
+{
+ return kobj && get_ktype(kobj) == &ktype_class_device;
+}

int class_interface_register(struct class_interface *class_intf)
{
Index: work/include/linux/device.h
===================================================================
--- work.orig/include/linux/device.h
+++ work/include/linux/device.h
@@ -199,7 +199,8 @@ struct class_device {
struct class * class; /* required */
dev_t devt; /* dev_t, creates the sysfs "dev" */
struct class_device_attribute *devt_attr;
- struct device * dev; /* not necessary, but nice to have */
+ struct device * dev; /* not necessary, but nice to have (going away) */
+ struct kobject * parent; /* either device or class_device */
void * class_data; /* class-specific data */

char class_id[BUS_ID_SIZE]; /* unique to this class */
@@ -229,6 +230,8 @@ extern int class_device_rename(struct cl
extern struct class_device * class_device_get(struct class_device *);
extern void class_device_put(struct class_device *);

+extern int is_a_class_device(struct kobject *);
+
struct class_device_attribute {
struct attribute attr;
ssize_t (*show)(struct class_device *, char * buf);
Index: work/drivers/input/input.c
===================================================================
--- work.orig/drivers/input/input.c
+++ work/drivers/input/input.c
@@ -948,18 +948,22 @@ int input_create_interface_device(struct

dev->devt = devt;
dev->class = &input_interface_class;
+ if (handle->dev)
+ dev->parent = &handle->dev->cdev.kobj;
strlcpy(dev->class_id, handle->name, BUS_ID_SIZE);

+
error = class_device_register(dev);
if (error)
return error;

+/*
if (handle->dev) {
sysfs_create_link(&dev->kobj, &handle->dev->cdev.kobj, "device");
sysfs_create_link(&handle->dev->cdev.kobj, &dev->kobj,
kobject_name(&dev->kobj));
}
-
+*/
handle->intf_dev = dev;

__module_get(THIS_MODULE);
-
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