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Date:   Wed, 14 Dec 2022 16:14:55 +0800
In-Reply-To: <20221214081456.714859-1-pumahsu@google.com>
Message-Id: <20221214081456.714859-2-pumahsu@google.com>
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Subject: [PATCH v2 1/2] usb: core: add hooks for usb suspend and resume
From:   Puma Hsu <pumahsu@google.com>
To:     gregkh@linuxfoundation.org, mka@chromium.org, dianders@chromium.org
Cc:     albertccwang@google.com, raychi@google.com, howardyen@google.com,
        leejj@google.com, hch@infradead.org, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org, Puma Hsu <pumahsu@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Add the hooks that designer can design and bypass the original
suspend/resume. When the handled is set, skip the original
suspend/resume process.

In mobile, a co-processor can be used for USB audio. When the co-processor
is working for USB audio, the co-processor is the user/owner of the USB
driver, and the ACPU is able to sleep in such condition to improve power
consumption. In original process, the ACPU will suspend/resume until the
USB suspend/resume. We add the hooks, so we can control USB suspend/resume
without affecting the ACPU.

Signed-off-by: Puma Hsu <pumahsu@google.com>

---
Changes in v2:
- Remove the wrong input in the Makefile
- Change description in commit message

---
 drivers/usb/core/driver.c | 36 ++++++++++++++++++++++++++++++++++++
 drivers/usb/core/usb.h    |  5 +++++
 2 files changed, 41 insertions(+)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 7e7e119c253f..3d2cfb6c2277 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -35,6 +35,25 @@
 #include "usb.h"
 
 
+static struct usb_device_vendor_ops *usb_dev_vendor_ops;
+
+int usb_dev_register_vendor_ops(struct usb_device_vendor_ops *vendor_ops)
+{
+	if (vendor_ops == NULL)
+		return -EINVAL;
+
+	usb_dev_vendor_ops = vendor_ops;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_dev_register_vendor_ops);
+
+struct usb_device_vendor_ops *usb_vendor_get_ops(void)
+{
+	return usb_dev_vendor_ops;
+}
+EXPORT_SYMBOL_GPL(usb_vendor_get_ops);
+
+
 /*
  * Adds a new dynamic USBdevice ID to this driver,
  * and cause the driver to probe for all devices again.
@@ -1400,11 +1419,19 @@ static int usb_suspend_both(struct usb_device *udev, pm_message_t msg)
 	int			status = 0;
 	int			i = 0, n = 0;
 	struct usb_interface	*intf;
+	bool			handled;
+	struct usb_device_vendor_ops *ops = usb_vendor_get_ops();
 
 	if (udev->state == USB_STATE_NOTATTACHED ||
 			udev->state == USB_STATE_SUSPENDED)
 		goto done;
 
+	if (ops && ops->usb_dev_suspend) {
+		handled = ops->usb_dev_suspend(udev, msg);
+		if (handled)
+			goto done;
+	}
+
 	/* Suspend all the interfaces and then udev itself */
 	if (udev->actconfig) {
 		n = udev->actconfig->desc.bNumInterfaces;
@@ -1501,11 +1528,20 @@ static int usb_resume_both(struct usb_device *udev, pm_message_t msg)
 	int			status = 0;
 	int			i;
 	struct usb_interface	*intf;
+	bool			handled;
+	struct usb_device_vendor_ops *ops = usb_vendor_get_ops();
 
 	if (udev->state == USB_STATE_NOTATTACHED) {
 		status = -ENODEV;
 		goto done;
 	}
+
+	if (ops && ops->usb_dev_resume) {
+		handled = ops->usb_dev_resume(udev, msg);
+		if (handled)
+			goto done;
+	}
+
 	udev->can_submit = 1;
 
 	/* Resume the device */
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h
index 82538daac8b8..9ccb8683071d 100644
--- a/drivers/usb/core/usb.h
+++ b/drivers/usb/core/usb.h
@@ -220,3 +220,8 @@ extern acpi_handle usb_get_hub_port_acpi_handle(struct usb_device *hdev,
 static inline int usb_acpi_register(void) { return 0; };
 static inline void usb_acpi_unregister(void) { };
 #endif
+
+struct usb_device_vendor_ops {
+	bool (*usb_dev_suspend)(struct usb_device *udev, pm_message_t msg);
+	bool (*usb_dev_resume)(struct usb_device *udev, pm_message_t msg);
+};
-- 
2.39.0.rc1.256.g54fd8350bd-goog