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Message-ID: <20241106083501.408074-5-guanyulin@google.com>
Date: Wed, 6 Nov 2024 08:32:58 +0000
From: Guan-Yu Lin <guanyulin@...gle.com>
To: gregkh@...uxfoundation.org, Thinh.Nguyen@...opsys.com,
mathias.nyman@...el.com, stern@...land.harvard.edu, sumit.garg@...aro.org,
dianders@...omium.org, kekrby@...il.com, oneukum@...e.com,
yajun.deng@...ux.dev, niko.mauno@...sala.com, christophe.jaillet@...adoo.fr,
tj@...nel.org, stanley_chang@...ltek.com, andreyknvl@...il.com,
quic_jjohnson@...cinc.com, ricardo@...liere.net
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
Guan-Yu Lin <guanyulin@...gle.com>
Subject: [PATCH v6 4/5] xhci: sideband: add api to trace sideband usage
The existing sideband driver only registers sidebands without tracking
their active usage. To address this, new apis are introduced to:
- mark sideband usage: record the sideband usage information in the USB
host controller driver and USB device driver.
- query sideband status: provide a means for other drivers to fetch
sideband activity information on a USB host controller.
Signed-off-by: Guan-Yu Lin <guanyulin@...gle.com>
---
drivers/usb/core/hcd.c | 4 ++
drivers/usb/host/xhci-sideband.c | 92 +++++++++++++++++++++++++++++++
include/linux/usb/hcd.h | 6 ++
include/linux/usb/xhci-sideband.h | 5 ++
4 files changed, 107 insertions(+)
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 1ff7d901fede..6aca6c69bf74 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -2595,6 +2595,10 @@ struct usb_hcd *__usb_create_hcd(const struct hc_driver *driver,
INIT_WORK(&hcd->wakeup_work, hcd_resume_work);
#endif
+#ifdef CONFIG_USB_XHCI_SIDEBAND
+ refcount_set(&hcd->sb_usage_count, 0);
+#endif
+
INIT_WORK(&hcd->died_work, hcd_died_work);
hcd->driver = driver;
diff --git a/drivers/usb/host/xhci-sideband.c b/drivers/usb/host/xhci-sideband.c
index d04cf0af57ae..bd0fc1564052 100644
--- a/drivers/usb/host/xhci-sideband.c
+++ b/drivers/usb/host/xhci-sideband.c
@@ -334,6 +334,98 @@ xhci_sideband_interrupter_id(struct xhci_sideband *sb)
}
EXPORT_SYMBOL_GPL(xhci_sideband_interrupter_id);
+/**
+ * xhci_sideband_get - inform related drivers there's a new active sideband
+ * @sb: sideband instance for this usb device
+ *
+ * An active sideband indicates that another entity is currently using the host
+ * controller. Inform the host controller and related usb devices by increasing
+ * their sb_usage_count. This allows the corresponding drivers to dynamically
+ * adjust power management actions based on current sideband activity.
+ *
+ * Returns 0 on success, negative error otherwise
+ */
+int xhci_sideband_get(struct xhci_sideband *sb)
+{
+ struct usb_device *udev;
+ struct usb_hcd *hcd;
+ int ret;
+
+ if (!sb || !sb->xhci)
+ return -ENODEV;
+
+ hcd = xhci_to_hcd(sb->xhci);
+ refcount_inc(&hcd->sb_usage_count);
+
+ udev = sb->vdev->udev;
+
+ device_lock(&udev->dev);
+ ret = usb_sideband_get(udev);
+ device_unlock(&udev->dev);
+
+ if (ret) {
+ refcount_dec(&hcd->sb_usage_count);
+ return ret;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xhci_sideband_get);
+
+/**
+ * xhci_sideband_put - inform related drivers there's a sideband deactivated
+ * @sb: sideband instance for this usb device
+ *
+ * The inverse operation of xhci_sideband_get, which informs the host
+ * controller and related usb devices by decreasing their sb_usage_count. This
+ * allows the corresponding drivers to dynamically adjust power management
+ * actions based on current sideband activity.
+ *
+ * Returns 0 on success, negative error otherwise
+ */
+int xhci_sideband_put(struct xhci_sideband *sb)
+{
+ struct usb_device *udev;
+ struct usb_hcd *hcd;
+ int ret;
+
+ if (!sb || !sb->xhci)
+ return -ENODEV;
+
+ hcd = xhci_to_hcd(sb->xhci);
+ refcount_dec(&hcd->sb_usage_count);
+
+ udev = sb->vdev->udev;
+
+ device_lock(&udev->dev);
+ ret = usb_sideband_put(udev);
+ device_unlock(&udev->dev);
+
+ if (ret) {
+ refcount_inc(&hcd->sb_usage_count);
+ return ret;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xhci_sideband_put);
+
+/**
+ * xhci_sideband_check - check sideband activities on the host controller
+ * @hcd: the host controller driver associated with the target host controller
+ *
+ * Allow other drivers, such as usb controller driver, to check if there are
+ * any sideband activity on the host controller right now. This information
+ * could be used for power management or other forms or resource management.
+ *
+ * Returns true on any active sideband existence, false otherwise
+ */
+bool xhci_sideband_check(struct usb_hcd *hcd)
+{
+ return !!refcount_read(&hcd->sb_usage_count);
+}
+EXPORT_SYMBOL_GPL(xhci_sideband_check);
+
/**
* xhci_sideband_register - register a sideband for a usb device
* @udev: usb device to be accessed via sideband
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index ac95e7c89df5..9867c178d188 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -85,6 +85,12 @@ struct usb_hcd {
#ifdef CONFIG_PM
struct work_struct wakeup_work; /* for remote wakeup */
#endif
+
+#ifdef CONFIG_USB_XHCI_SIDEBAND
+ /* Number of active sideband accessing the host controller. */
+ refcount_t sb_usage_count;
+#endif
+
struct work_struct died_work; /* for when the device dies */
/*
diff --git a/include/linux/usb/xhci-sideband.h b/include/linux/usb/xhci-sideband.h
index f0223c5535e0..4850fc826e00 100644
--- a/include/linux/usb/xhci-sideband.h
+++ b/include/linux/usb/xhci-sideband.h
@@ -12,6 +12,7 @@
#include <linux/scatterlist.h>
#include <linux/usb.h>
+#include <linux/usb/hcd.h>
#define EP_CTX_PER_DEV 31 /* FIXME defined twice, from xhci.h */
@@ -57,6 +58,10 @@ xhci_sideband_get_endpoint_buffer(struct xhci_sideband *sb,
struct sg_table *
xhci_sideband_get_event_buffer(struct xhci_sideband *sb);
+int xhci_sideband_get(struct xhci_sideband *sb);
+int xhci_sideband_put(struct xhci_sideband *sb);
+bool xhci_sideband_check(struct usb_hcd *hcd);
+
int
xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
bool ip_autoclear, u32 imod_interval, int intr_num);
--
2.47.0.199.ga7371fff76-goog
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