usb: gadget: f_fs: add ioctl returning ep descriptor

This patch introduces ioctl named FUNCTIONFS_ENDPOINT_DESC, which
returns endpoint descriptor to userspace. It works only if function
is active.

Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/function/f_fs.c

@@ -1026,6 +1026,29 @@ static long ffs_epfile_ioctl(struct file *file, unsigned code,
 		case FUNCTIONFS_ENDPOINT_REVMAP:
 			ret = epfile->ep->num;
 			break;
+		case FUNCTIONFS_ENDPOINT_DESC:
+		{
+			int desc_idx;
+			struct usb_endpoint_descriptor *desc;
+
+			switch (epfile->ffs->gadget->speed) {
+			case USB_SPEED_SUPER:
+				desc_idx = 2;
+				break;
+			case USB_SPEED_HIGH:
+				desc_idx = 1;
+				break;
+			default:
+				desc_idx = 0;
+			}
+			desc = epfile->ep->descs[desc_idx];
+
+			spin_unlock_irq(&epfile->ffs->eps_lock);
+			ret = copy_to_user((void *)value, desc, sizeof(*desc));
+			if (ret)
+				ret = -EFAULT;
+			return ret;
+		}
 		default:
 			ret = -ENOTTY;
 		}

include/uapi/linux/usb/functionfs.h

@@ -275,6 +275,12 @@ struct usb_functionfs_event {
  */
 #define	FUNCTIONFS_ENDPOINT_REVMAP	_IO('g', 129)
 
+/*
+ * Returns endpoint descriptor. If function is not active returns -ENODEV.
+ */
+#define	FUNCTIONFS_ENDPOINT_DESC	_IOR('g', 130, \
+					     struct usb_endpoint_descriptor)
+
 
 
 #endif /* _UAPI__LINUX_FUNCTIONFS_H__ */