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

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>

diff --git a/drivers/usb/gadget/functions.c b/drivers/usb/gadget/functions.c
new file mode 100644 (file)
index 0000000..b13f839
--- /dev/null
+++ b/drivers/usb/gadget/functions.c
@@ -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);

diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index 8c7a629..771de7a 100644 (file)
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -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 *);