linux-kernel - [PATCH v3 2/4] usb: hub: add infrastructure to pass onboard

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Message-Id: <20250821-v6-16-topic-usb-onboard-dev-v3-2-6d2b38a5d818@pengutronix.de>
Date: Thu, 21 Aug 2025 18:31:56 +0200
From: Marco Felsch <m.felsch@...gutronix.de>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Fabio Estevam <festevam@...il.com>, 
 Matthias Kaehlcke <mka@...omium.org>, Liam Girdwood <lgirdwood@...il.com>, 
 Mark Brown <broonie@...nel.org>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, kernel@...gutronix.de, 
 Marco Felsch <m.felsch@...gutronix.de>
Subject: [PATCH v3 2/4] usb: hub: add infrastructure to pass onboard_dev
 port features

On board devices may require special handling for en-/disable port
features due to PCB design decisions e.g. enable/disable the VBUS power
on the port via a host controlled regulator or GPIO.

This commit adds the necessary infrastructure to prepare the common code
base for such use-cases.

Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
---
 drivers/usb/core/hub.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++--
 drivers/usb/core/hub.h |  2 ++
 include/linux/usb.h    |  3 +++
 3 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 256fe8c86828d51c33442345acdb7f3fe80a98ce..50ae500e2ad3711996609fc84806803449a5bf16 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -457,9 +457,19 @@ static int clear_hub_feature(struct usb_device *hdev, int feature)
  */
 int usb_clear_port_feature(struct usb_device *hdev, int port1, int feature)
 {
-	return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
+	struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
+	int ret;
+
+	ret = usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
 		USB_REQ_CLEAR_FEATURE, USB_RT_PORT, feature, port1,
 		NULL, 0, 1000);
+	if (ret)
+		return ret;
+
+	if (hub->onboard_hub_clear_port_feature)
+		ret = hub->onboard_hub_clear_port_feature(hdev, feature, port1);
+
+	return ret;
 }
 
 /*
@@ -467,9 +477,19 @@ int usb_clear_port_feature(struct usb_device *hdev, int port1, int feature)
  */
 static int set_port_feature(struct usb_device *hdev, int port1, int feature)
 {
-	return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
+	struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
+	int ret;
+
+	ret = usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
 		USB_REQ_SET_FEATURE, USB_RT_PORT, feature, port1,
 		NULL, 0, 1000);
+	if (ret)
+		return ret;
+
+	if (hub->onboard_hub_set_port_feature)
+		ret = hub->onboard_hub_set_port_feature(hdev, feature, port1);
+
+	return ret;
 }
 
 static char *to_led_name(int selector)
@@ -6544,6 +6564,37 @@ void usb_hub_adjust_deviceremovable(struct usb_device *hdev,
 	}
 }
 
+/**
+ * usb_hub_register_port_feature_hooks - Register port set/get feature hooks
+ * @hdev: USB device belonging to the usb hub
+ * @set_port_feature: set_feature hook which gets called by the hub core
+ * @clear_port_feature: clear_feature hook which gets called by the hub core
+ *
+ * Register set/get_port_feature hooks for a onboard_dev hub.
+ */
+void usb_hub_register_port_feature_hooks(struct usb_device *hdev,
+		int (*set_port_feature)(struct usb_device *, int, int),
+		int (*clear_port_feature)(struct usb_device *, int, int))
+{
+	struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
+
+	if (WARN_ON_ONCE(is_root_hub(hdev) || !hub))
+		return;
+
+	if (set_port_feature)
+		hub->onboard_hub_set_port_feature = set_port_feature;
+	if (clear_port_feature)
+		hub->onboard_hub_clear_port_feature = clear_port_feature;
+
+	/*
+	 * Keep it simple for now. Just check the power state and re-sync it
+	 * after adding the hooks since the onboard-dev may do some additional
+	 * logic e.g. controlling regulators.
+	 */
+	hub_power_on(hub, false);
+}
+EXPORT_SYMBOL_GPL(usb_hub_register_port_feature_hooks);
+
 #ifdef CONFIG_ACPI
 /**
  * usb_get_hub_port_acpi_handle - Get the usb port's acpi handle
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 297adf2c6078809ca582104f228e5222c464f999..31800b5922ba896dc7cac5f9e3ed1a77e7c5a801 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -76,6 +76,8 @@ struct usb_hub {
 	struct timer_list	irq_urb_retry;
 	struct usb_port		**ports;
 	struct list_head        onboard_devs;
+	int (*onboard_hub_set_port_feature)(struct usb_device *udev, int feature, int port1);
+	int (*onboard_hub_clear_port_feature)(struct usb_device *udev, int feature, int port1);
 };
 
 /**
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 92c752f5446ff37ef09b9296f7711e1a622680ea..1415a826953ac5488619073e2f659188f7988d6e 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -928,6 +928,9 @@ int usb_hub_claim_port(struct usb_device *hdev, unsigned port1,
 		struct usb_dev_state *owner);
 int usb_hub_release_port(struct usb_device *hdev, unsigned port1,
 		struct usb_dev_state *owner);
+void usb_hub_register_port_feature_hooks(struct usb_device *hdev,
+		int (*set_port_feature)(struct usb_device *, int, int),
+		int (*clear_port_feature)(struct usb_device *, int, int));
 
 /**
  * usb_make_path - returns stable device path in the usb tree

-- 
2.39.5