mvebu: usb: xhci: Add VBUS regulator supply to the host driver

The USB device should linked to VBUS regulator through "vbus-supply"
DTS property.
This patch adds handling for "vbus-supply" property inside the USB
device entry for turning on the VBUS regulator upon the host adapter probe.

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Neta Zur Hershkovits <neta@marvell.com>
Cc: Igal Liberman <igall@marvell.com>
Cc: Haim Boot <hayim@marvell.com>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index 5129a57..0bf8274 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -25,6 +25,7 @@
 	bool "MVEBU USB 3.0 support"
 	default y
 	depends on ARCH_MVEBU
+	select DM_REGULATOR
 	help
 	  Choose this option to add support for USB 3.0 driver on mvebu
 	  SoCs, which includes Armada8K, Armada3700 and other Armada
diff --git a/drivers/usb/host/xhci-mvebu.c b/drivers/usb/host/xhci-mvebu.c
index 46eb937..d880af1 100644
--- a/drivers/usb/host/xhci-mvebu.c
+++ b/drivers/usb/host/xhci-mvebu.c
@@ -10,6 +10,7 @@
 #include <dm.h>
 #include <fdtdec.h>
 #include <usb.h>
+#include <power/regulator.h>
 #include <asm/gpio.h>
 
 #include "xhci.h"
@@ -44,12 +45,22 @@
 	struct mvebu_xhci_platdata *plat = dev_get_platdata(dev);
 	struct mvebu_xhci *ctx = dev_get_priv(dev);
 	struct xhci_hcor *hcor;
-	int len;
+	int len, ret;
+	struct udevice *regulator;
 
 	ctx->hcd = (struct xhci_hccr *)plat->hcd_base;
 	len = HC_LENGTH(xhci_readl(&ctx->hcd->cr_capbase));
 	hcor = (struct xhci_hcor *)((uintptr_t)ctx->hcd + len);
 
+	ret = device_get_supply_regulator(dev, "vbus-supply", &regulator);
+	if (!ret) {
+		ret = regulator_set_enable(regulator, true);
+		if (ret) {
+			printf("Failed to turn ON the VBUS regulator\n");
+			return ret;
+		}
+	}
+
 	/* Enable USB xHCI (VBUS, reset etc) in board specific code */
 	board_xhci_enable();