[RFC 04/19] dwc3: gadget: add VBUS session handling

[Robert Baldyga]

This patch adds .vbus_session callback to usb_gadget_ops. VBUS session
handling is necessary for OTG mode. VBUS control is performed during
OTG finite-state machine state switching.

Signed-off-by: Robert Baldyga <r.baldyga@xxxxxxxxxxx>
---
 drivers/usb/dwc3/core.h   |  1 +
 drivers/usb/dwc3/gadget.c | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index fdab715..e00d46e 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -828,6 +828,7 @@ struct dwc3 {
 
 	unsigned		tx_de_emphasis_quirk:1;
 	unsigned		tx_de_emphasis:2;
+	unsigned		vbus_session:1;
 };
 
 /* -------------------------------------------------------------------------- */
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 8946c32..80e43a6 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1475,12 +1475,39 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
 	return 0;
 }
 
+static int dwc3_gadget_vbus_session(struct usb_gadget *g, int is_active)
+{
+	struct dwc3 *dwc = gadget_to_dwc(g);
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&dwc->lock, flags);
+
+	/* Mark that the vbus was powered */
+	dwc->vbus_session = !!is_active;
+
+	/*
+	 * Check if upper level usb_gadget_driver was already registered with
+	 * this udc controller driver (if dwc3_gadget_start was called)
+	 */
+	if (dwc->gadget_driver)
+		ret = dwc3_gadget_run_stop(dwc, dwc->vbus_session, false);
+
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	return ret;
+}
+
 static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 {
 	struct dwc3		*dwc = gadget_to_dwc(g);
 	unsigned long		flags;
 	int			ret;
 
+	/* Need to wait for vbus_session(on) from otg driver */
+	if (dwc->dotg && !dwc->vbus_session)
+		return 0;
+
 	is_on = !!is_on;
 
 	spin_lock_irqsave(&dwc->lock, flags);
@@ -1657,6 +1684,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,
 	.set_selfpowered	= dwc3_gadget_set_selfpowered,
+	.vbus_session		= dwc3_gadget_vbus_session,
 	.pullup			= dwc3_gadget_pullup,
 	.udc_start		= dwc3_gadget_start,
 	.udc_stop		= dwc3_gadget_stop,
-- 
1.9.1

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