usb: gadget: add quirk_ep_out_aligned_size field to struct usb_gadget

Due to USB controllers may have different restrictions, usb gadget layer
needs to provide a generic way to inform gadget functions to complain
with non-standard requirements.

This patch adds 'quirk_ep_out_aligned_size' field to struct usb_gadget
to inform when controller's epout requires buffer size to be aligned to
MaxPacketSize. A helper is also provided to align buffer size when
necessary.

Cc: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

include/linux/usb/gadget.h

@@ -502,6 +502,8 @@ struct usb_gadget_ops {
  *	only supports HNP on a different root port.
  * @b_hnp_enable: OTG device feature flag, indicating that the A-Host
  *	enabled HNP support.
+ * @quirk_ep_out_aligned_size: epout requires buffer size to be aligned to
+ *	MaxPacketSize.
  *
  * Gadgets have a mostly-portable "gadget driver" implementing device
  * functions, handling all usb configurations and interfaces.  Gadget
@@ -541,6 +543,7 @@ struct usb_gadget {
 	unsigned			b_hnp_enable:1;
 	unsigned			a_hnp_support:1;
 	unsigned			a_alt_hnp_support:1;
+	unsigned			quirk_ep_out_aligned_size:1;
 };
 #define work_to_gadget(w)	(container_of((w), struct usb_gadget, work))
 
@@ -558,6 +561,23 @@ static inline struct usb_gadget *dev_to_usb_gadget(struct device *dev)
 	list_for_each_entry(tmp, &(gadget)->ep_list, ep_list)
 
 
+/**
+ * usb_ep_align_maybe - returns @len aligned to ep's maxpacketsize if gadget
+ *	requires quirk_ep_out_aligned_size, otherwise reguens len.
+ * @g: controller to check for quirk
+ * @ep: the endpoint whose maxpacketsize is used to align @len
+ * @len: buffer size's length to align to @ep's maxpacketsize
+ *
+ * This helper is used in case it's required for any reason to check and maybe
+ * align buffer's size to an ep's maxpacketsize.
+ */
+static inline size_t
+usb_ep_align_maybe(struct usb_gadget *g, struct usb_ep *ep, size_t len)
+{
+	return !g->quirk_ep_out_aligned_size ? len :
+			round_up(len, (size_t)ep->desc->wMaxPacketSize);
+}
+
 /**
  * gadget_is_dualspeed - return true iff the hardware handles high speed
  * @g: controller that might support both high and full speeds