usb: dwc3: gadget: pass ev_buff as cookie to irq handler

we don't plan on using multiple event buffers, but
if we find a good use case for it, this little trick
will help us avoid a loop in hardirq handler looping
for each and every event buffer.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/gadget.c

@@ -1536,7 +1536,7 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 
 	irq = platform_get_irq(to_platform_device(dwc->dev), 0);
 	ret = request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt,
-			IRQF_SHARED, "dwc3", dwc);
+			IRQF_SHARED, "dwc3", dwc->ev_buf);
 	if (ret) {
 		dev_err(dwc->dev, "failed to request irq #%d --> %d\n",
 				irq, ret);
@@ -1636,7 +1636,7 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 err1:
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
-	free_irq(irq, dwc);
+	free_irq(irq, dwc->ev_buf);
 
 err0:
 	return ret;
@@ -1659,7 +1659,7 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	irq = platform_get_irq(to_platform_device(dwc->dev), 0);
-	free_irq(irq, dwc);
+	free_irq(irq, dwc->ev_buf);
 
 	return 0;
 }
@@ -2602,14 +2602,13 @@ static void dwc3_process_event_entry(struct dwc3 *dwc,
 	}
 }
 
-static irqreturn_t dwc3_process_event_buf(struct dwc3 *dwc)
+static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt)
 {
-	struct dwc3_event_buffer *evt;
+	struct dwc3 *dwc = evt->dwc;
 	irqreturn_t ret = IRQ_NONE;
 	int left;
 	u32 reg;
 
-	evt = dwc->ev_buf;
 	left = evt->count;
 
 	if (!(evt->flags & DWC3_EVENT_PENDING))
@@ -2649,27 +2648,26 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3 *dwc)
 	return ret;
 }
 
-static irqreturn_t dwc3_thread_interrupt(int irq, void *_dwc)
+static irqreturn_t dwc3_thread_interrupt(int irq, void *_evt)
 {
-	struct dwc3 *dwc = _dwc;
+	struct dwc3_event_buffer *evt = _evt;
+	struct dwc3 *dwc = evt->dwc;
 	unsigned long flags;
 	irqreturn_t ret = IRQ_NONE;
 
 	spin_lock_irqsave(&dwc->lock, flags);
-	ret = dwc3_process_event_buf(dwc);
+	ret = dwc3_process_event_buf(evt);
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	return ret;
 }
 
-static irqreturn_t dwc3_check_event_buf(struct dwc3 *dwc)
+static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
 {
-	struct dwc3_event_buffer *evt;
+	struct dwc3 *dwc = evt->dwc;
 	u32 count;
 	u32 reg;
 
-	evt = dwc->ev_buf;
-
 	count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
 	count &= DWC3_GEVNTCOUNT_MASK;
 	if (!count)
@@ -2686,11 +2684,11 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3 *dwc)
 	return IRQ_WAKE_THREAD;
 }
 
-static irqreturn_t dwc3_interrupt(int irq, void *_dwc)
+static irqreturn_t dwc3_interrupt(int irq, void *_evt)
 {
-	struct dwc3			*dwc = _dwc;
+	struct dwc3_event_buffer	*evt = _evt;
 
-	return dwc3_check_event_buf(dwc);
+	return dwc3_check_event_buf(evt);
 }
 
 /**