usb: gadget: udc-core: introduce UDC binding by name

This patch adds udc_attach_driver() which allows to bind an UDC which is
specified by name to a driver. The name of available UDCs can be
obtained from /sys/class/udc. This interface is intended for configfs
interface.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 51 insertions, 21 deletions

diff --git a/drivers/usb/gadget/udc-core.c b/drivers/usb/gadget/udc-core.c
index 4d90a800063c..e7c591621a3b 100644
--- a/drivers/usb/gadget/udc-core.c
+++ b/drivers/usb/gadget/udc-core.c
@@ -311,26 +311,10 @@ EXPORT_SYMBOL_GPL(usb_del_gadget_udc);
 
 /* ------------------------------------------------------------------------- */
 
-int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
+static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *driver)
 {
-        struct usb_udc          *udc = NULL;
-        int                     ret;
-
-        if (!driver || !driver->bind || !driver->setup)
-                return -EINVAL;
+        int ret;
 
-        mutex_lock(&udc_lock);
-        list_for_each_entry(udc, &udc_list, list) {
-                /* For now we take the first one */
-                if (!udc->driver)
-                        goto found;
-        }
-
-        pr_debug("couldn't find an available UDC\n");
-        mutex_unlock(&udc_lock);
-        return -ENODEV;
-
-found:
         dev_dbg(&udc->dev, "registering UDC driver [%s]\n",
                         driver->function);
 
@@ -352,18 +336,64 @@ found:
                 ret = usb_gadget_start(udc->gadget, driver, driver->bind);
                 if (ret)
                         goto err1;
-
         }
 
         kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
-        mutex_unlock(&udc_lock);
         return 0;
-
 err1:
         dev_err(&udc->dev, "failed to start %s: %d\n",
                         udc->driver->function, ret);
         udc->driver = NULL;
         udc->dev.driver = NULL;
+        return ret;
+}
+
+int udc_attach_driver(const char *name, struct usb_gadget_driver *driver)
+{
+        struct usb_udc *udc = NULL;
+        int ret = -ENODEV;
+
+        mutex_lock(&udc_lock);
+        list_for_each_entry(udc, &udc_list, list) {
+                ret = strcmp(name, dev_name(&udc->dev));
+                if (!ret)
+                        break;
+        }
+        if (ret) {
+                ret = -ENODEV;
+                goto out;
+        }
+        if (udc->driver) {
+                ret = -EBUSY;
+                goto out;
+        }
+        ret = udc_bind_to_driver(udc, driver);
+out:
+        mutex_unlock(&udc_lock);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(udc_attach_driver);
+
+int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
+{
+        struct usb_udc          *udc = NULL;
+        int                     ret;
+
+        if (!driver || !driver->bind || !driver->setup)
+                return -EINVAL;
+
+        mutex_lock(&udc_lock);
+        list_for_each_entry(udc, &udc_list, list) {
+                /* For now we take the first one */
+                if (!udc->driver)
+                        goto found;
+        }
+
+        pr_debug("couldn't find an available UDC\n");
+        mutex_unlock(&udc_lock);
+        return -ENODEV;
+found:
+        ret = udc_bind_to_driver(udc, driver);
         mutex_unlock(&udc_lock);
         return ret;
 }