[PATCH] usb: dwc2: handle OTG HNP SetFeature requests

[tze . yee . ng]

From: Adrian Ng Ho Yin <adrian.ho.yin.ng@xxxxxxxxxx>

Without handling for b_hnp_enable, a_hnp_support, and a_alt_hnp_support,
HNP cannot be enabled when two OTG controllers are connected.

Handle SetFeature for these OTG selectors, gated on otg_caps.hnp_support.
The OTG specification only defines SetFeature for them, so reject
ClearFeature with -EINVAL instead of silently accepting it. Use dev_dbg
for status updates to avoid noisy logs.

Advertise the core's HNP/SRP capability during gadget init by restoring
GUSBCFG_HNPCAP/SRPCAP from otg_caps, mirroring dwc2_gusbcfg_init() on the
host side, instead of clearing them unconditionally.

Clear the HNP flags and GOTGCTL_DEVHNPEN on disconnect/reset so OTG state
does not leak across sessions.

Signed-off-by: Adrian Ng Ho Yin <adrian.ho.yin.ng@xxxxxxxxxx>
Signed-off-by: Tze Yee Ng <tze.yee.ng@xxxxxxxxxx>
---
 drivers/usb/dwc2/gadget.c | 51 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 49 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index c8b02c27d27d..4d905989c09f 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -1780,6 +1780,7 @@ static int dwc2_hsotg_process_req_feature(struct dwc2_hsotg *hsotg,
 	struct dwc2_hsotg_ep *ep;
 	int ret;
 	bool halted;
+	u32 otgctl;
 	u32 recip;
 	u32 wValue;
 	u32 wIndex;
@@ -1809,6 +1810,36 @@ static int dwc2_hsotg_process_req_feature(struct dwc2_hsotg *hsotg,
 
 			hsotg->test_mode = wIndex >> 8;
 			break;
+		case USB_DEVICE_B_HNP_ENABLE:
+			if (!hsotg->params.otg_caps.hnp_support)
+				return -ENOENT;
+			if (!set)
+				return -EINVAL;
+
+			otgctl = dwc2_readl(hsotg, GOTGCTL);
+			otgctl |= GOTGCTL_DEVHNPEN;
+			dwc2_writel(hsotg, otgctl, GOTGCTL);
+			hsotg->gadget.b_hnp_enable = 1;
+			dev_dbg(hsotg->dev, "HNP enabled\n");
+			break;
+		case USB_DEVICE_A_HNP_SUPPORT:
+			if (!hsotg->params.otg_caps.hnp_support)
+				return -ENOENT;
+			if (!set)
+				return -EINVAL;
+
+			hsotg->gadget.a_hnp_support = 1;
+			dev_dbg(hsotg->dev, "a_hnp_support set\n");
+			break;
+		case USB_DEVICE_A_ALT_HNP_SUPPORT:
+			if (!hsotg->params.otg_caps.hnp_support)
+				return -ENOENT;
+			if (!set)
+				return -EINVAL;
+
+			hsotg->gadget.a_alt_hnp_support = 1;
+			dev_dbg(hsotg->dev, "a_alt_hnp_support set\n");
+			break;
 		default:
 			return -ENOENT;
 		}
@@ -3322,6 +3353,13 @@ void dwc2_hsotg_disconnect(struct dwc2_hsotg *hsotg)
 	hsotg->connected = 0;
 	hsotg->test_mode = 0;
 
+	if (hsotg->params.otg_caps.hnp_support) {
+		hsotg->gadget.b_hnp_enable = 0;
+		hsotg->gadget.a_hnp_support = 0;
+		hsotg->gadget.a_alt_hnp_support = 0;
+		dwc2_clear_bit(hsotg, GOTGCTL, GOTGCTL_DEVHNPEN);
+	}
+
 	/* all endpoints should be shutdown */
 	for (ep = 0; ep < hsotg->num_of_eps; ep++) {
 		if (hsotg->eps_in[ep])
@@ -3416,9 +3454,18 @@ void dwc2_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,
 	usbcfg &= ~GUSBCFG_TOUTCAL_MASK;
 	usbcfg |= GUSBCFG_TOUTCAL(7);
 
-	/* remove the HNP/SRP and set the PHY */
+	/*
+	 * Configure HNP/SRP capability from params (same idea as
+	 * dwc2_gusbcfg_init() for host). Unconditionally clearing these
+	 * bits leaves an HNP-capable OTG gadget unable to negotiate.
+	 */
 	usbcfg &= ~(GUSBCFG_SRPCAP | GUSBCFG_HNPCAP);
-        dwc2_writel(hsotg, usbcfg, GUSBCFG);
+	if (hsotg->params.otg_caps.hnp_support &&
+	    hsotg->params.otg_caps.srp_support)
+		usbcfg |= GUSBCFG_HNPCAP;
+	if (hsotg->params.otg_caps.srp_support)
+		usbcfg |= GUSBCFG_SRPCAP;
+	dwc2_writel(hsotg, usbcfg, GUSBCFG);
 
 	dwc2_phy_init(hsotg, true);
 
-- 
2.43.7