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UPSTREAM: USB: gadget: core: create sysfs link between udc and gadget

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udc device and gadget device are tightly coupled, yet there's no good
way to corelate the two. Add a sysfs link in udc that points to the
corresponding gadget device.
An example use case: userspace configures a f_midi configfs driver and
bind the udc device, then it tries to locate the corresponding midi
device, which is a child device of the gadget device. The gadget device
that's associated to the udc device has to be identified in order to
index the midi device. Having a sysfs link would make things much
easier.

Signed-off-by: Roy Luo <royluo@google.com>
Link: https://lore.kernel.org/r/20240307030922.3573161-1-royluo@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 333778731
Change-Id: I9e3f782543eba5e026a65031aaae754daafb69ab
(cherry picked from commit 0ef40f399aa2be8c04aee9b7430705612c104ce5)
Signed-off-by: Roy Luo <royluo@google.com>
This commit is contained in:
Roy Luo 2024-03-07 03:09:22 +00:00
parent 92704e00b5
commit 74c507aab1
1 changed files with 9 additions and 0 deletions
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9
drivers/usb/gadget/udc/core.c
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@ -1392,8 +1392,16 @@ int usb_add_gadget(struct usb_gadget *gadget)
if (ret)
goto err_free_id;
ret = sysfs_create_link(&udc->dev.kobj,
&gadget->dev.kobj, "gadget");
if (ret)
goto err_del_gadget;
return 0;
err_del_gadget:
device_del(&gadget->dev);
err_free_id:
ida_free(&gadget_id_numbers, gadget->id_number);
@ -1502,6 +1510,7 @@ void usb_del_gadget(struct usb_gadget *gadget)
mutex_unlock(&udc_lock);
kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
sysfs_remove_link(&udc->dev.kobj, "gadget");
flush_work(&gadget->work);
device_del(&gadget->dev);
ida_free(&gadget_id_numbers, gadget->id_number);