[RFC PATCH] usb: dwc3: gadget: add support for OTG in gadget framework

[Manish Narani]

This patch adds support for OTG in DWC3 gadget framework. This
also adds support for HNP polling by host while in OTG mode.

Modifications in couple of functions to make it in sync with
OTG driver while keeping its original functionality intact.

Signed-off-by: Manish Narani <mnarani@xxxxxxxxxx>
---
 drivers/usb/dwc3/ep0.c    | 49 +++++++++++++++++++++++---
 drivers/usb/dwc3/gadget.c | 87 +++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 116 insertions(+), 20 deletions(-)

diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 4878d18..aa78c1b 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -334,6 +334,8 @@ static int dwc3_ep0_handle_status(struct dwc3 *dwc,
 				usb_status |= 1 << USB_DEV_STAT_U2_ENABLED;
 		}
 
+		usb_status |= dwc->remote_wakeup << USB_DEVICE_REMOTE_WAKEUP;
+
 		break;
 
 	case USB_RECIP_INTERFACE:
@@ -448,11 +450,45 @@ static int dwc3_ep0_handle_device(struct dwc3 *dwc,
 
 	switch (wValue) {
 	case USB_DEVICE_REMOTE_WAKEUP:
+		if (set)
+			dwc->remote_wakeup = 1;
+		else
+			dwc->remote_wakeup = 0;
 		break;
-	/*
-	 * 9.4.1 says only only for SS, in AddressState only for
-	 * default control pipe
-	 */
+	case USB_DEVICE_B_HNP_ENABLE:
+		dev_dbg(dwc->dev,
+			"SET_FEATURE: USB_DEVICE_B_HNP_ENABLE\n");
+		if (set && dwc->gadget.is_otg) {
+			if (dwc->gadget.host_request_flag) {
+				struct usb_phy *phy =
+					usb_get_phy(USB_PHY_TYPE_USB3);
+
+				dwc->gadget.b_hnp_enable = 0;
+				dwc->gadget.host_request_flag = 0;
+				otg_start_hnp(phy->otg);
+				usb_put_phy(phy);
+			} else {
+				dwc->gadget.b_hnp_enable = 1;
+			}
+		} else
+			return -EINVAL;
+		break;
+
+	case USB_DEVICE_A_HNP_SUPPORT:
+		/* RH port supports HNP */
+		dev_dbg(dwc->dev,
+			"SET_FEATURE: USB_DEVICE_A_HNP_SUPPORT\n");
+		break;
+
+	case USB_DEVICE_A_ALT_HNP_SUPPORT:
+		/* other RH port does */
+		dev_dbg(dwc->dev,
+			"SET_FEATURE: USB_DEVICE_A_ALT_HNP_SUPPORT\n");
+		break;
+		/*
+		 * 9.4.1 says only only for SS, in AddressState only for
+		 * default control pipe
+		 */
 	case USB_DEVICE_U1_ENABLE:
 		ret = dwc3_ep0_handle_u1(dwc, state, set);
 		break;
@@ -759,7 +795,10 @@ static int dwc3_ep0_std_request(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 
 	switch (ctrl->bRequest) {
 	case USB_REQ_GET_STATUS:
-		ret = dwc3_ep0_handle_status(dwc, ctrl);
+		if (le16_to_cpu(ctrl->wIndex) == OTG_STS_SELECTOR)
+			ret = dwc3_ep0_delegate_req(dwc, ctrl);
+		else
+			ret = dwc3_ep0_handle_status(dwc, ctrl);
 		break;
 	case USB_REQ_CLEAR_FEATURE:
 		ret = dwc3_ep0_handle_feature(dwc, ctrl, 0);
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 6785595..3b0b771 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -34,6 +34,7 @@
 #include "core.h"
 #include "gadget.h"
 #include "io.h"
+#include "otg.h"
 
 /**
  * dwc3_gadget_set_test_mode - Enables USB2 Test Modes
@@ -1792,25 +1793,51 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 	int			ret = 0;
 	int			irq;
 
-	irq = dwc->irq_gadget;
-	ret = request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt,
-			IRQF_SHARED, "dwc3", dwc->ev_buf);
-	if (ret) {
-		dev_err(dwc->dev, "failed to request irq #%d --> %d\n",
-				irq, ret);
-		goto err0;
-	}
-
 	spin_lock_irqsave(&dwc->lock, flags);
 	if (dwc->gadget_driver) {
 		dev_err(dwc->dev, "%s is already bound to %s\n",
 				dwc->gadget.name,
 				dwc->gadget_driver->driver.name);
 		ret = -EBUSY;
-		goto err1;
+		goto err0;
 	}
 
-	dwc->gadget_driver	= driver;
+	if (g->is_otg) {
+		static struct usb_gadget_driver *prev_driver;
+		/* There are two instances where OTG functionality is enabled :
+		 * 1. This function will be called from OTG driver to start the
+		 * gadget
+		 * 2. This function will be called by the Linux Class Driver to
+		 * start the gadget
+		 * Below code will keep synchronization between these calls. The
+		 * "driver" argument will be NULL when it is called from the OTG
+		 * driver, so we are maintaning a global variable "prev_driver"
+		 * to assign value of argument "driver" (from class driver) to
+		 * dwc->gadget_driver when it is called from OTG.
+		 */
+		if (driver) {
+			prev_driver	= driver;
+			if (dwc->otg) {
+				struct dwc3_otg		*otg = dwc->otg;
+
+				if ((otg->host_started ||
+						(!otg->peripheral_started)))
+					goto err0;
+			}
+			dwc->gadget_driver	= driver;
+		} else
+			dwc->gadget_driver	= prev_driver;
+	} else
+		dwc->gadget_driver	= driver;
+
+	irq = dwc->irq_gadget;
+	ret = request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt,
+			IRQF_SHARED, "dwc3", dwc->ev_buf);
+	if (ret) {
+		dev_err(dwc->dev, "failed to request irq #%d --> %d\n",
+				irq, ret);
+		goto err0;
+	}
 
 	if (pm_runtime_active(dwc->dev))
 		__dwc3_gadget_start(dwc);
@@ -1819,11 +1846,9 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 
 	return 0;
 
-err1:
-	spin_unlock_irqrestore(&dwc->lock, flags);
-	free_irq(irq, dwc);
-
 err0:
+	dwc->gadget_driver = NULL;
+	spin_unlock_irqrestore(&dwc->lock, flags);
 	return ret;
 }
 
@@ -2977,6 +3002,18 @@ int dwc3_gadget_init(struct dwc3 *dwc)
 
 	dwc->irq_gadget = irq;
 
+	if (dwc->dr_mode == USB_DR_MODE_OTG) {
+		struct usb_phy *phy;
+		/* Switch otg to peripheral mode */
+		phy = usb_get_phy(USB_PHY_TYPE_USB3);
+		if (!IS_ERR(phy)) {
+			if (phy && phy->otg)
+				otg_set_peripheral(phy->otg,
+						(struct usb_gadget *)(long)1);
+			usb_put_phy(phy);
+		}
+	}
+
 	dwc->ctrl_req = dma_alloc_coherent(dwc->sysdev, sizeof(*dwc->ctrl_req),
 			&dwc->ctrl_req_addr, GFP_KERNEL);
 	if (!dwc->ctrl_req) {
@@ -3066,6 +3103,26 @@ int dwc3_gadget_init(struct dwc3 *dwc)
 		goto err5;
 	}
 
+	if (dwc->dr_mode == USB_DR_MODE_OTG) {
+		struct usb_phy *phy;
+
+		phy = usb_get_phy(USB_PHY_TYPE_USB3);
+		if (!IS_ERR(phy)) {
+			if (phy && phy->otg) {
+				ret = otg_set_peripheral(phy->otg,
+						&dwc->gadget);
+				if (ret) {
+					usb_put_phy(phy);
+					phy = NULL;
+					goto err5;
+				}
+			} else {
+				usb_put_phy(phy);
+				phy = NULL;
+			}
+		}
+	}
+
 	return 0;
 
 err5:
-- 
2.1.1