usb: dwc3: gadget: allocate bounce buffer for unaligned xfers

Allocate a coherent buffer of 1024 bytes (size of a single superspeed
bulk packet) to serve as bounce buffer for an extra TRB needed to align
transfers to wMaxPacketSize.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/core.h

@@ -40,6 +40,7 @@
 /* Global constants */
 #define DWC3_PULL_UP_TIMEOUT	500	/* ms */
 #define DWC3_ZLP_BUF_SIZE	1024	/* size of a superspeed bulk */
+#define DWC3_BOUNCE_SIZE	1024	/* size of a superspeed bulk */
 #define DWC3_EP0_BOUNCE_SIZE	512
 #define DWC3_ENDPOINTS_NUM	32
 #define DWC3_XHCI_RESOURCES_NUM	2
@@ -857,12 +858,14 @@ struct dwc3_scratchpad_array {
 struct dwc3 {
 	struct usb_ctrlrequest	*ctrl_req;
 	struct dwc3_trb		*ep0_trb;
+	void			*bounce;
 	void			*ep0_bounce;
 	void			*zlp_buf;
 	void			*scratchbuf;
 	u8			*setup_buf;
 	dma_addr_t		ctrl_req_addr;
 	dma_addr_t		ep0_trb_addr;
+	dma_addr_t		bounce_addr;
 	dma_addr_t		ep0_bounce_addr;
 	dma_addr_t		scratch_addr;
 	struct dwc3_request	ep0_usb_req;

drivers/usb/dwc3/gadget.c

@@ -3021,6 +3021,13 @@ int dwc3_gadget_init(struct dwc3 *dwc)
 		goto err4;
 	}
 
+	dwc->bounce = dma_alloc_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE,
+			&dwc->bounce_addr, GFP_KERNEL);
+	if (!dwc->bounce) {
+		ret = -ENOMEM;
+		goto err5;
+	}
+
 	init_completion(&dwc->ep0_in_setup);
 
 	dwc->gadget.ops			= &dwc3_gadget_ops;
@@ -3064,15 +3071,18 @@ int dwc3_gadget_init(struct dwc3 *dwc)
 
 	ret = dwc3_gadget_init_endpoints(dwc);
 	if (ret)
-		goto err5;
+		goto err6;
 
 	ret = usb_add_gadget_udc(dwc->dev, &dwc->gadget);
 	if (ret) {
 		dev_err(dwc->dev, "failed to register udc\n");
-		goto err5;
+		goto err6;
 	}
 
 	return 0;
+err6:
+	dma_free_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE, dwc->bounce,
+			dwc->bounce_addr);
 
 err5:
 	kfree(dwc->zlp_buf);
@@ -3105,6 +3115,8 @@ void dwc3_gadget_exit(struct dwc3 *dwc)
 
 	dwc3_gadget_free_endpoints(dwc);
 
+	dma_free_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE, dwc->bounce,
+			dwc->bounce_addr);
 	dma_free_coherent(dwc->sysdev, DWC3_EP0_BOUNCE_SIZE,
 			dwc->ep0_bounce, dwc->ep0_bounce_addr);