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Message-ID: <20241009054429.3970438-5-guanyulin@google.com>
Date: Wed, 9 Oct 2024 05:42:58 +0000
From: Guan-Yu Lin <guanyulin@...gle.com>
To: Thinh.Nguyen@...opsys.com, gregkh@...uxfoundation.org,
mathias.nyman@...el.com, stern@...land.harvard.edu, elder@...nel.org,
oneukum@...e.com, yajun.deng@...ux.dev, dianders@...omium.org,
kekrby@...il.com, perex@...ex.cz, tiwai@...e.com, tj@...nel.org,
stanley_chang@...ltek.com, andreyknvl@...il.com,
christophe.jaillet@...adoo.fr, quic_jjohnson@...cinc.com,
ricardo@...liere.net, grundler@...omium.org, niko.mauno@...sala.com
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-sound@...r.kernel.org, badhri@...gle.com, albertccwang@...gle.com,
quic_wcheng@...cinc.com, pumahsu@...gle.com,
Guan-Yu Lin <guanyulin@...gle.com>
Subject: [PATCH v4 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/host/xhci-sideband.c | 74 +++++++++++++++++++++++++++++++
include/linux/usb/hcd.h | 4 ++
include/linux/usb/xhci-sideband.h | 5 +++
3 files changed, 83 insertions(+)
diff --git a/drivers/usb/host/xhci-sideband.c b/drivers/usb/host/xhci-sideband.c
index d04cf0af57ae..29501e5d020f 100644
--- a/drivers/usb/host/xhci-sideband.c
+++ b/drivers/usb/host/xhci-sideband.c
@@ -334,6 +334,80 @@ xhci_sideband_interrupter_id(struct xhci_sideband *sb)
}
EXPORT_SYMBOL_GPL(xhci_sideband_interrupter_id);
+/**
+ * xhci_sideband_get - notify 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. Notify 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_hcd *hcd;
+ struct usb_device *udev;
+
+ if (!sb || !sb->xhci)
+ return -ENODEV;
+
+ hcd = xhci_to_hcd(sb->xhci);
+ atomic_inc(&hcd->sb_usage_count);
+
+ udev = sb->vdev->udev;
+ usb_sideband_get(udev);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xhci_sideband_get);
+
+/**
+ * xhci_sideband_put - notify related drivers there's a sideband deactivated
+ * @sb: sideband instance for this usb device
+ *
+ * The inverse operation of xhci_sideband_get, which notifies 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_hcd *hcd;
+ struct usb_device *udev;
+
+ if (!sb || !sb->xhci)
+ return -ENODEV;
+
+ hcd = xhci_to_hcd(sb->xhci);
+ atomic_dec(&hcd->sb_usage_count);
+
+ udev = sb->vdev->udev;
+ usb_sideband_put(udev);
+
+ 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 !!atomic_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..8b8106b9a31e 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -84,6 +84,10 @@ struct usb_hcd {
struct urb *status_urb; /* the current status urb */
#ifdef CONFIG_PM
struct work_struct wakeup_work; /* for remote wakeup */
+#ifdef CONFIG_USB_XHCI_SIDEBAND
+ /* Number of active sideband accessing the host controller. */
+ atomic_t sb_usage_count;
+#endif
#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.rc0.187.ge670bccf7e-goog
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