USB: musb: AM35x: Workaround for fifo read issue

AM35x supports only 32bit read operations so we need to have
workaround for 8bit and 16bit read operations.

Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/musb/am35x.c

@@ -492,3 +492,33 @@ void musb_platform_restore_context(struct musb *musb,
 	phy_on();
 }
 #endif
+
+/* AM35x supports only 32bit read operation */
+void musb_read_fifo(struct musb_hw_ep *hw_ep, u16 len, u8 *dst)
+{
+	void __iomem *fifo = hw_ep->fifo;
+	u32		val;
+	int		i;
+
+	/* Read for 32bit-aligned destination address */
+	if (likely((0x03 & (unsigned long) dst) == 0) && len >= 4) {
+		readsl(fifo, dst, len >> 2);
+		dst += len & ~0x03;
+		len &= 0x03;
+	}
+	/*
+	 * Now read the remaining 1 to 3 byte or complete length if
+	 * unaligned address.
+	 */
+	if (len > 4) {
+		for (i = 0; i < (len >> 2); i++) {
+			*(u32 *) dst = musb_readl(fifo, 0);
+			dst += 4;
+		}
+		len &= 0x03;
+	}
+	if (len > 0) {
+		val = musb_readl(fifo, 0);
+		memcpy(dst, &val, len);
+	}
+}