x86: dfi-bt700: Add xHCI USB support

Change from EHCI to xHCI on the DFI BayTrail SoM.

The xHCI USB hub is connected to an GPIO on the DFI BayTrail SoM. For
correct operation, it needs to get reset upon power-up. Otherwise it
may happen that the hub is not detected after a software reboot. This
patch also configures this GPIO in the dts for correct operation.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/board/dfi/dfi-bt700/dfi-bt700.c b/board/dfi/dfi-bt700/dfi-bt700.c
index 8645bdc..3dd2036 100644
--- a/board/dfi/dfi-bt700/dfi-bt700.c
+++ b/board/dfi/dfi-bt700/dfi-bt700.c
@@ -28,3 +28,30 @@
 
 	return 0;
 }
+
+int board_late_init(void)
+{
+	struct gpio_desc desc;
+	int ret;
+
+	ret = dm_gpio_lookup_name("F10", &desc);
+	if (ret)
+		debug("gpio ret=%d\n", ret);
+	ret = dm_gpio_request(&desc, "xhci_hub_reset");
+	if (ret)
+		debug("gpio_request ret=%d\n", ret);
+	ret = dm_gpio_set_dir_flags(&desc, GPIOD_IS_OUT);
+	if (ret)
+		debug("gpio dir ret=%d\n", ret);
+
+	/* Pull xHCI hub reset to low (active low) */
+	dm_gpio_set_value(&desc, 0);
+
+	/* Wait at least 5 ms, so lets choose 10 to be safe */
+	mdelay(10);
+
+	/* Pull xHCI hub reset to high (active low) */
+	dm_gpio_set_value(&desc, 1);
+
+	return 0;
+}