USB function's configfs config group is created in a generic way in
usb/gadget/configfs.c:function_make(), which in turn delegates actual
allocation and setup of the USB function instance to a particular
implementation, e.g. in f_acm.c. The said implementation does its job
in a parameter-less function e.g. acm_alloc_instance(), which results
in creating an unnamed config group, whose name is set later in
function_make(). function_make() creates the name by parsing a string
of the form:
<function name>.<instance name>
which comes from userspace as a parameter to mkdir invocation.
Up to now only <function name> has been used, while <instance name>
has been ignored. This patch adds a set_inst_name() operation to
struct usb_function_instance which allows passing the <instance name>
from function_make() so that it is not ignored. It is entirely up to the
implementor of set_inst_name() what to do with the <instance name>.
In a typical case, the struct usb_function_instance is embedded in a
larger struct which is retrieved in set_inst_name() with container_of(),
and the larger struct contains a field to store the <instance name>.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
---
drivers/usb/gadget/configfs.c | 7 +++++++
include/linux/usb/composite.h | 2 ++
2 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 2588511..d6c8ab4 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -564,6 +564,13 @@ static struct config_group *function_make(
usb_put_function_instance(fi);
return ERR_PTR(ret);
}
+ if (fi->set_inst_name) {
+ ret = fi->set_inst_name(fi, instance_name);
+ if (ret) {
+ usb_put_function_instance(fi);
+ return ERR_PTR(ret);
+ }
+ }
gi = container_of(group, struct gadget_info, functions_group);
diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index 5e61589..dba63f5 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -468,6 +468,8 @@ struct usb_function_instance {
struct config_group group;
struct list_head cfs_list;
struct usb_function_driver *fd;
+ int (*set_inst_name)(struct usb_function_instance *inst,
+ const char *name);
void (*free_func_inst)(struct usb_function_instance *inst);
};
--
1.7.0.4
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