linux-kernel - [PATCH v13 5/6] usb: gadget: Handle function suspend feature selector

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Message-Id: <1679694482-16430-6-git-send-email-quic_eserrao@quicinc.com>
Date:   Fri, 24 Mar 2023 14:48:01 -0700
From:   Elson Roy Serrao <quic_eserrao@...cinc.com>
To:     gregkh@...uxfoundation.org, Thinh.Nguyen@...opsys.com
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        quic_wcheng@...cinc.com, quic_jackp@...cinc.com,
        Elson Roy Serrao <quic_eserrao@...cinc.com>
Subject: [PATCH v13 5/6] usb: gadget: Handle function suspend feature selector

When host sends function suspend feature selector to the device,
inspect the received packet and trigger function suspend or
function resume accordingly. Inspect the remote wakeup bit and
arm the function for remote wakeup if it is wakeup capable. Also
host queries the function wakeup capability  through a get status
request before sending function resume. Handle such requests in
composite layer.

Signed-off-by: Elson Roy Serrao <quic_eserrao@...cinc.com>
---
 drivers/usb/gadget/composite.c | 65 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 60 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 2111732..d1d7f89 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -941,6 +941,9 @@ static void reset_config(struct usb_composite_dev *cdev)
 		if (f->disable)
 			f->disable(f);
 
+		/* Section 9.1.1.6, disable remote wakeup when device is reset */
+		f->func_wakeup_armed = false;
+
 		bitmap_zero(f->endpoints, 32);
 	}
 	cdev->config = NULL;
@@ -2006,9 +2009,20 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 		f = cdev->config->interface[intf];
 		if (!f)
 			break;
-		status = f->get_status ? f->get_status(f) : 0;
-		if (status < 0)
-			break;
+
+		if (f->get_status) {
+			status = f->get_status(f);
+			if (status < 0)
+				break;
+		} else {
+			/* Set D0 and D1 bits based on func wakeup capability */
+			if (f->config->bmAttributes & USB_CONFIG_ATT_WAKEUP) {
+				status |= USB_INTRF_STAT_FUNC_RW_CAP;
+				if (f->func_wakeup_armed)
+					status |= USB_INTRF_STAT_FUNC_RW;
+			}
+		}
+
 		put_unaligned_le16(status & 0x0000ffff, req->buf);
 		break;
 	/*
@@ -2030,8 +2044,44 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 			if (!f)
 				break;
 			value = 0;
-			if (f->func_suspend)
+			if (f->func_suspend) {
 				value = f->func_suspend(f, w_index >> 8);
+			/* SetFeature(FUNCTION_SUSPEND) */
+			} else if (ctrl->bRequest == USB_REQ_SET_FEATURE) {
+				if (!(f->config->bmAttributes &
+				      USB_CONFIG_ATT_WAKEUP) &&
+				     (w_index & USB_INTRF_FUNC_SUSPEND_RW))
+					break;
+
+				f->func_wakeup_armed = !!(w_index &
+							  USB_INTRF_FUNC_SUSPEND_RW);
+
+				if (w_index & USB_INTRF_FUNC_SUSPEND_LP) {
+					if (f->suspend && !f->func_suspended) {
+						f->suspend(f);
+						f->func_suspended = true;
+					}
+				/*
+				 * Handle cases where host sends function resume
+				 * through SetFeature(FUNCTION_SUSPEND) but low power
+				 * bit reset
+				 */
+				} else {
+					if (f->resume && f->func_suspended) {
+						f->resume(f);
+						f->func_suspended = false;
+					}
+				}
+			/* ClearFeature(FUNCTION_SUSPEND) */
+			} else if (ctrl->bRequest == USB_REQ_CLEAR_FEATURE) {
+				f->func_wakeup_armed = false;
+
+				if (f->resume && f->func_suspended) {
+					f->resume(f);
+					f->func_suspended = false;
+				}
+			}
+
 			if (value < 0) {
 				ERROR(cdev,
 				      "func_suspend() returned error %d\n",
@@ -2574,7 +2624,12 @@ void composite_resume(struct usb_gadget *gadget)
 		cdev->driver->resume(cdev);
 	if (cdev->config) {
 		list_for_each_entry(f, &cdev->config->functions, list) {
-			if (f->resume)
+			/*
+			 * Check for func_suspended flag to see if the function is
+			 * in USB3 FUNCTION_SUSPEND state. In this case resume is
+			 * done via FUNCTION_SUSPEND feature selector.
+			 */
+			if (f->resume && !f->func_suspended)
 				f->resume(f);
 		}
 
-- 
2.7.4