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Tue, 08 Oct 2024 22:45:46 -0700 (PDT) Date: Wed, 9 Oct 2024 05:42:58 +0000 In-Reply-To: <20241009054429.3970438-1-guanyulin@google.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241009054429.3970438-1-guanyulin@google.com> X-Mailer: git-send-email 2.47.0.rc1.288.g06298d1525-goog Message-ID: <20241009054429.3970438-5-guanyulin@google.com> Subject: [PATCH v4 4/5] xhci: sideband: add api to trace sideband usage From: Guan-Yu Lin To: Thinh.Nguyen@synopsys.com, gregkh@linuxfoundation.org, mathias.nyman@intel.com, stern@rowland.harvard.edu, elder@kernel.org, oneukum@suse.com, yajun.deng@linux.dev, dianders@chromium.org, kekrby@gmail.com, perex@perex.cz, tiwai@suse.com, tj@kernel.org, stanley_chang@realtek.com, andreyknvl@gmail.com, christophe.jaillet@wanadoo.fr, quic_jjohnson@quicinc.com, ricardo@marliere.net, grundler@chromium.org, niko.mauno@vaisala.com Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sound@vger.kernel.org, badhri@google.com, albertccwang@google.com, quic_wcheng@quicinc.com, pumahsu@google.com, Guan-Yu Lin 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 --- 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 #include +#include #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);