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>

doc/device-tree-bindings/usb/marvell.xhci-usb.txt

@@ -0,0 +1,28 @@
+Marvell SOC USB controllers
+
+This controller is integrated in Armada 3700/8K.
+It uses the same properties as a generic XHCI host controller
+
+Required properties :
+ - compatible: should be one or more of:
+   - "marvell,armada3700-xhci", "generic-xhci" for Armada 37xx SoCs
+   - "marvell,armada-8k-xhci", "generic-xhci" for Armada A8K SoCs
+ - reg: should contain address and length of the standard XHCI
+   register set for the device.
+ - interrupts: one XHCI interrupt should be described here.
+
+Optional properties:
+ - clocks: phandle to system controller clock driving this unit
+ - vbus-supply : If present, specifies the fixed regulator to be turned on
+   for providing power to the USB VBUS rail.
+
+Example:
+	cpm_usb3_0: usb3@500000 {
+		compatible = "marvell,armada-8k-xhci",
+			     "generic-xhci";
+		reg = <0x500000 0x4000>;
+		interrupts = <GIC_SPI 62 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&cpm_syscon0 1 22>;
+		vbus-supply = <&reg_usb3h0_vbus>;
+		status = "disabled";
+	};

drivers/usb/host/Kconfig

@@ -25,6 +25,7 @@ config USB_XHCI_MVEBU
 	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

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 @@ static int xhci_usb_probe(struct udevice *dev)
 	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();