usb: udc: net2280: convert to readl_poll_timeout_atomic()

Use readl_poll_timeout_atomic() to simplify code

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Felipe Balbi <balbi@kernel.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1600668815-12135-10-git-send-email-chunfeng.yun@mediatek.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/net2280.c

@@ -52,6 +52,7 @@
 #include <linux/usb/gadget.h>
 #include <linux/prefetch.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 
 #include <asm/byteorder.h>
 #include <asm/irq.h>
@@ -360,18 +361,16 @@ net2280_enable(struct usb_ep *_ep, const struct usb_endpoint_descriptor *desc)
 static int handshake(u32 __iomem *ptr, u32 mask, u32 done, int usec)
 {
 	u32	result;
+	int	ret;
 
-	do {
-		result = readl(ptr);
-		if (result == ~(u32)0)		/* "device unplugged" */
+	ret = readl_poll_timeout_atomic(ptr, result,
+					((result & mask) == done ||
+					 result == U32_MAX),
+					1, usec);
+	if (result == U32_MAX)		/* device unplugged */
 		return -ENODEV;
-		result &= mask;
-		if (result == done)
-			return 0;
-		udelay(1);
-		usec--;
-	} while (usec > 0);
-	return -ETIMEDOUT;
+
+	return ret;
 }
 
 static const struct usb_ep_ops net2280_ep_ops;