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usb: gadget: add a forward pointer from usb_function to its "instance"

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We can have multiple usb_functions which origin is the same "instance".
Within one USB configuration there should be only one function of an
instance. This back pointer helps configfs to recoginze to which
instance a given usb_function belongs.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
This commit is contained in:
Sebastian Andrzej Siewior 2012-12-23 21:10:15 +01:00 committed by Felipe Balbi
parent 59835ad727
commit 0062f6e56f
2 changed files with 117 additions and 0 deletions
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116
drivers/usb/gadget/functions.c Normal file
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@ -0,0 +1,116 @@
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/usb/composite.h>
static LIST_HEAD(func_list);
static DEFINE_MUTEX(func_lock);
static struct usb_function_instance *try_get_usb_function_instance(const char *name)
{
struct usb_function_driver *fd;
struct usb_function_instance *fi;
fi = ERR_PTR(-ENOENT);
mutex_lock(&func_lock);
list_for_each_entry(fd, &func_list, list) {
if (strcmp(name, fd->name))
continue;
if (!try_module_get(fd->mod)) {
fi = ERR_PTR(-EBUSY);
break;
}
fi = fd->alloc_inst();
if (IS_ERR(fi))
module_put(fd->mod);
else
fi->fd = fd;
break;
}
mutex_unlock(&func_lock);
return fi;
}
struct usb_function_instance *usb_get_function_instance(const char *name)
{
struct usb_function_instance *fi;
int ret;
fi = try_get_usb_function_instance(name);
if (!IS_ERR(fi))
return fi;
ret = PTR_ERR(fi);
if (ret != -ENOENT)
return fi;
ret = request_module("usbfunc:%s", name);
if (ret < 0)
return ERR_PTR(ret);
return try_get_usb_function_instance(name);
}
EXPORT_SYMBOL_GPL(usb_get_function_instance);
struct usb_function *usb_get_function(struct usb_function_instance *fi)
{
struct usb_function *f;
f = fi->fd->alloc_func(fi);
if (IS_ERR(f))
return f;
f->fi = fi;
return f;
}
EXPORT_SYMBOL_GPL(usb_get_function);
void usb_put_function_instance(struct usb_function_instance *fi)
{
struct module *mod;
if (!fi)
return;
mod = fi->fd->mod;
fi->free_func_inst(fi);
module_put(mod);
}
EXPORT_SYMBOL_GPL(usb_put_function_instance);
void usb_put_function(struct usb_function *f)
{
if (!f)
return;
f->free_func(f);
}
EXPORT_SYMBOL_GPL(usb_put_function);
int usb_function_register(struct usb_function_driver *newf)
{
struct usb_function_driver *fd;
int ret;
ret = -EEXIST;
mutex_lock(&func_lock);
list_for_each_entry(fd, &func_list, list) {
if (!strcmp(fd->name, newf->name))
goto out;
}
ret = 0;
list_add_tail(&newf->list, &func_list);
out:
mutex_unlock(&func_lock);
return ret;
}
EXPORT_SYMBOL_GPL(usb_function_register);
void usb_function_unregister(struct usb_function_driver *fd)
{
mutex_lock(&func_lock);
list_del(&fd->list);
mutex_unlock(&func_lock);
}
EXPORT_SYMBOL_GPL(usb_function_unregister);

1
include/linux/usb/composite.h
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@ -161,6 +161,7 @@ struct usb_function {
/* internals */
struct list_head list;
DECLARE_BITMAP(endpoints, 32);
const struct usb_function_instance *fi;
};
int usb_add_function(struct usb_configuration *, struct usb_function *);