[PATCH] usb: dwc2: add support for host mode external vbus supply

[Amelie Delaunay]

This patch adds a way to enable an external vbus supply in host mode,
when dwc2 drvvbus signal is not used.

This patch is very similar to the one done in U-Boot dwc2 driver [1]. It
also adds dynamic vbus supply management depending on the role and state
of the core.

[1] https://lists.denx.de/pipermail/u-boot/2017-March/283434.html

Signed-off-by: Amelie Delaunay <amelie.delaunay@xxxxxx>
---
 drivers/usb/dwc2/core.h |  2 ++
 drivers/usb/dwc2/hcd.c  | 26 ++++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index cd77af3..8ebc85c 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -786,6 +786,7 @@ struct dwc2_hregs_backup {
  * @plat:               The platform specific configuration data. This can be
  *                      removed once all SoCs support usb transceiver.
  * @supplies:           Definition of USB power supplies
+ * @vbus_supply:        Regulator supplying vbus.
  * @phyif:              PHY interface width
  * @lock:		Spinlock that protects all the driver data structures
  * @priv:		Stores a pointer to the struct usb_hcd
@@ -922,6 +923,7 @@ struct dwc2_hsotg {
 	struct usb_phy *uphy;
 	struct dwc2_hsotg_plat *plat;
 	struct regulator_bulk_data supplies[DWC2_NUM_SUPPLIES];
+	struct regulator *vbus_supply;
 	u32 phyif;
 
 	spinlock_t lock;
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index a5d72fc..2cf2fd0 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -365,6 +365,23 @@ static void dwc2_gusbcfg_init(struct dwc2_hsotg *hsotg)
 	dwc2_writel(usbcfg, hsotg->regs + GUSBCFG);
 }
 
+static int dwc2_vbus_supply_init(struct dwc2_hsotg *hsotg)
+{
+	hsotg->vbus_supply = devm_regulator_get_optional(hsotg->dev, "vbus");
+	if (IS_ERR(hsotg->vbus_supply))
+		return 0;
+
+	return regulator_enable(hsotg->vbus_supply);
+}
+
+static int dwc2_vbus_supply_exit(struct dwc2_hsotg *hsotg)
+{
+	if (hsotg->vbus_supply)
+		return regulator_disable(hsotg->vbus_supply);
+
+	return 0;
+}
+
 /**
  * dwc2_enable_host_interrupts() - Enables the Host mode interrupts
  *
@@ -3257,6 +3274,7 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
 
 	/* B-Device connector (Device Mode) */
 	if (gotgctl & GOTGCTL_CONID_B) {
+		dwc2_vbus_supply_exit(hsotg);
 		/* Wait for switch to device mode */
 		dev_dbg(hsotg->dev, "connId B\n");
 		if (hsotg->bus_suspended) {
@@ -4363,6 +4381,9 @@ static int _dwc2_hcd_start(struct usb_hcd *hcd)
 	}
 
 	spin_unlock_irqrestore(&hsotg->lock, flags);
+
+	dwc2_vbus_supply_init(hsotg);
+
 	return 0;
 }
 
@@ -4390,6 +4411,8 @@ static void _dwc2_hcd_stop(struct usb_hcd *hcd)
 	clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
 	spin_unlock_irqrestore(&hsotg->lock, flags);
 
+	dwc2_vbus_supply_exit(hsotg);
+
 	usleep_range(1000, 3000);
 }
 
@@ -4426,6 +4449,7 @@ static int _dwc2_hcd_suspend(struct usb_hcd *hcd)
 		hprt0 |= HPRT0_SUSP;
 		hprt0 &= ~HPRT0_PWR;
 		dwc2_writel(hprt0, hsotg->regs + HPRT0);
+		dwc2_vbus_supply_exit(hsotg);
 	}
 
 	/* Enter hibernation */
@@ -4506,6 +4530,8 @@ static int _dwc2_hcd_resume(struct usb_hcd *hcd)
 		spin_unlock_irqrestore(&hsotg->lock, flags);
 		dwc2_port_resume(hsotg);
 	} else {
+		dwc2_vbus_supply_init(hsotg);
+
 		/* Wait for controller to correctly update D+/D- level */
 		usleep_range(3000, 5000);
 
-- 
2.7.4