From:   Elson Roy Serrao <quic_eserrao@quicinc.com>
To:     gregkh@linuxfoundation.org, Thinh.Nguyen@synopsys.com,
        balbi@kernel.org
Cc:     linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        quic_wcheng@quicinc.com, quic_jackp@quicinc.com,
        Elson Roy Serrao <quic_eserrao@quicinc.com>
Subject: [PATCH v3 2/5] usb: dwc3: Add remote wakeup handling
Date:   Mon,  6 Feb 2023 11:13:23 -0800
Message-Id: <1675710806-9735-3-git-send-email-quic_eserrao@quicinc.com>
In-Reply-To: <1675710806-9735-1-git-send-email-quic_eserrao@quicinc.com>
References: <1675710806-9735-1-git-send-email-quic_eserrao@quicinc.com>
Precedence: bulk

An usb device can initate a remote wakeup and bring the link out of
suspend as dictated by the DEVICE_REMOTE_WAKEUP feature selector.
Add support to handle this packet and set the remote wakeup capability.

Some hosts may take longer time to initiate the resume signaling after
device triggers a remote wakeup. So add async support to the wakeup API
by enabling link status change events.

Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
---
 drivers/usb/dwc3/core.h   |  2 ++
 drivers/usb/dwc3/ep0.c    |  4 +++
 drivers/usb/dwc3/gadget.c | 73 ++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 72 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 8f9959b..ff6e6f6 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1110,6 +1110,7 @@ struct dwc3_scratchpad_array {
  *	3	- Reserved
  * @dis_metastability_quirk: set to disable metastability quirk.
  * @dis_split_quirk: set to disable split boundary.
+ * @rw_configured: set if the device is configured for remote wakeup.
  * @imod_interval: set the interrupt moderation interval in 250ns
  *			increments or 0 to disable.
  * @max_cfg_eps: current max number of IN eps used across all USB configs.
@@ -1326,6 +1327,7 @@ struct dwc3 {
 
 	unsigned		dis_split_quirk:1;
 	unsigned		async_callbacks:1;
+	unsigned		rw_configured:1;
 
 	u16			imod_interval;
 
diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 61de693..cd7c0cb 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -356,6 +356,9 @@ static int dwc3_ep0_handle_status(struct dwc3 *dwc,
 				usb_status |= 1 << USB_DEV_STAT_U1_ENABLED;
 			if (reg & DWC3_DCTL_INITU2ENA)
 				usb_status |= 1 << USB_DEV_STAT_U2_ENABLED;
+		} else {
+			usb_status |= dwc->gadget->rw_armed <<
+					USB_DEVICE_REMOTE_WAKEUP;
 		}
 
 		break;
@@ -476,6 +479,7 @@ static int dwc3_ep0_handle_device(struct dwc3 *dwc,
 
 	switch (wValue) {
 	case USB_DEVICE_REMOTE_WAKEUP:
+		dwc->gadget->rw_armed = set;
 		break;
 	/*
 	 * 9.4.1 says only for SS, in AddressState only for
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 89dcfac..d0b9917 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -258,7 +258,7 @@ int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
 	return ret;
 }
 
-static int __dwc3_gadget_wakeup(struct dwc3 *dwc);
+static int __dwc3_gadget_wakeup(struct dwc3 *dwc, bool async);
 
 /**
  * dwc3_send_gadget_ep_cmd - issue an endpoint command
@@ -325,7 +325,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 
 			fallthrough;
 		case DWC3_LINK_STATE_U3:
-			ret = __dwc3_gadget_wakeup(dwc);
+			ret = __dwc3_gadget_wakeup(dwc, false);
 			dev_WARN_ONCE(dwc->dev, ret, "wakeup failed --> %d\n",
 					ret);
 			break;
@@ -2269,6 +2269,19 @@ static const struct usb_ep_ops dwc3_gadget_ep_ops = {
 
 /* -------------------------------------------------------------------------- */
 
+static void dwc3_gadget_enable_linksts_evts(struct dwc3 *dwc, bool set)
+{
+	u32 reg;
+
+	reg = dwc3_readl(dwc->regs, DWC3_DEVTEN);
+	if (set)
+		reg |= DWC3_DEVTEN_ULSTCNGEN;
+	else
+		reg &= ~DWC3_DEVTEN_ULSTCNGEN;
+
+	dwc3_writel(dwc->regs, DWC3_DEVTEN, reg);
+}
+
 static int dwc3_gadget_get_frame(struct usb_gadget *g)
 {
 	struct dwc3		*dwc = gadget_to_dwc(g);
@@ -2276,7 +2289,7 @@ static int dwc3_gadget_get_frame(struct usb_gadget *g)
 	return __dwc3_gadget_get_frame(dwc);
 }
 
-static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
+static int __dwc3_gadget_wakeup(struct dwc3 *dwc, bool async)
 {
 	int			retries;
 
@@ -2296,9 +2309,14 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
 	link_state = DWC3_DSTS_USBLNKST(reg);
 
 	switch (link_state) {
+	case DWC3_LINK_STATE_U3:	/* in HS, means SUSPEND */
+		if (!dwc->rw_configured) {
+			dev_err(dwc->dev,
+				"device not configured for remote wakeup\n");
+			return -EINVAL;
+		}
 	case DWC3_LINK_STATE_RESET:
 	case DWC3_LINK_STATE_RX_DET:	/* in HS, means Early Suspend */
-	case DWC3_LINK_STATE_U3:	/* in HS, means SUSPEND */
 	case DWC3_LINK_STATE_U2:	/* in HS, means Sleep (L1) */
 	case DWC3_LINK_STATE_U1:
 	case DWC3_LINK_STATE_RESUME:
@@ -2307,9 +2325,13 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
 		return -EINVAL;
 	}
 
+	if (async)
+		dwc3_gadget_enable_linksts_evts(dwc, true);
+
 	ret = dwc3_gadget_set_link_state(dwc, DWC3_LINK_STATE_RECOV);
 	if (ret < 0) {
 		dev_err(dwc->dev, "failed to put link in Recovery\n");
+		dwc3_gadget_enable_linksts_evts(dwc, false);
 		return ret;
 	}
 
@@ -2321,6 +2343,13 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
 		dwc3_writel(dwc->regs, DWC3_DCTL, reg);
 	}
 
+	/*
+	 * Since link status change events are enabled we will receive
+	 * an U0 event when wakeup is successful. So bail out.
+	 */
+	if (async)
+		return 0;
+
 	/* poll until Link State changes to ON */
 	retries = 20000;
 
@@ -2347,12 +2376,30 @@ static int dwc3_gadget_wakeup(struct usb_gadget *g)
 	int			ret;
 
 	spin_lock_irqsave(&dwc->lock, flags);
-	ret = __dwc3_gadget_wakeup(dwc);
+	if (!dwc->gadget->rw_armed) {
+		dev_err(dwc->dev, "%s:remote wakeup not enabled\n", __func__);
+		spin_unlock_irqrestore(&dwc->lock, flags);
+		return -EINVAL;
+	}
+	ret = __dwc3_gadget_wakeup(dwc, true);
+
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	return ret;
 }
 
+static int dwc3_gadget_set_remotewakeup(struct usb_gadget *g, int set)
+{
+	struct dwc3		*dwc = gadget_to_dwc(g);
+	unsigned long		flags;
+
+	spin_lock_irqsave(&dwc->lock, flags);
+	dwc->rw_configured = !!set;
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	return 0;
+}
+
 static int dwc3_gadget_set_selfpowered(struct usb_gadget *g,
 		int is_selfpowered)
 {
@@ -2978,6 +3025,7 @@ static void dwc3_gadget_async_callbacks(struct usb_gadget *g, bool enable)
 static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,
+	.set_remotewakeup	= dwc3_gadget_set_remotewakeup,
 	.set_selfpowered	= dwc3_gadget_set_selfpowered,
 	.pullup			= dwc3_gadget_pullup,
 	.udc_start		= dwc3_gadget_start,
@@ -3821,6 +3869,8 @@ static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
 
 	dwc->gadget->speed = USB_SPEED_UNKNOWN;
 	dwc->setup_packet_pending = false;
+	dwc->gadget->rw_armed = false;
+	dwc3_gadget_enable_linksts_evts(dwc, false);
 	usb_gadget_set_state(dwc->gadget, USB_STATE_NOTATTACHED);
 
 	if (dwc->ep0state != EP0_SETUP_PHASE) {
@@ -3914,6 +3964,8 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
 	reg &= ~DWC3_DCTL_TSTCTRL_MASK;
 	dwc3_gadget_dctl_write_safe(dwc, reg);
 	dwc->test_mode = false;
+	dwc->gadget->rw_armed = false;
+	dwc3_gadget_enable_linksts_evts(dwc, false);
 	dwc3_clear_stall_all_ep(dwc);
 
 	/* Reset device address to zero */
@@ -4066,7 +4118,7 @@ static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
 	 */
 }
 
-static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc)
+static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc, unsigned int evtinfo)
 {
 	/*
 	 * TODO take core out of low power mode when that's
@@ -4078,6 +4130,8 @@ static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc)
 		dwc->gadget_driver->resume(dwc->gadget);
 		spin_lock(&dwc->lock);
 	}
+
+	dwc->link_state = evtinfo & DWC3_LINK_STATE_MASK;
 }
 
 static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
@@ -4159,6 +4213,10 @@ static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
 	}
 
 	switch (next) {
+	case DWC3_LINK_STATE_U0:
+		dwc3_gadget_enable_linksts_evts(dwc, false);
+		dwc3_resume_gadget(dwc);
+		break;
 	case DWC3_LINK_STATE_U1:
 		if (dwc->speed == USB_SPEED_SUPER)
 			dwc3_suspend_gadget(dwc);
@@ -4227,7 +4285,7 @@ static void dwc3_gadget_interrupt(struct dwc3 *dwc,
 		dwc3_gadget_conndone_interrupt(dwc);
 		break;
 	case DWC3_DEVICE_EVENT_WAKEUP:
-		dwc3_gadget_wakeup_interrupt(dwc);
+		dwc3_gadget_wakeup_interrupt(dwc, event->event_info);
 		break;
 	case DWC3_DEVICE_EVENT_HIBER_REQ:
 		if (dev_WARN_ONCE(dwc->dev, !dwc->has_hibernation,
@@ -4487,6 +4545,7 @@ int dwc3_gadget_init(struct dwc3 *dwc)
 	dwc->gadget->sg_supported	= true;
 	dwc->gadget->name		= "dwc3-gadget";
 	dwc->gadget->lpm_capable	= !dwc->usb2_gadget_lpm_disable;
+	dwc->gadget->rw_capable		= dwc->gadget->ops->wakeup ? true : false;
 
 	/*
 	 * FIXME We might be setting max_speed to <SUPER, however versions
-- 
2.7.4