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[34.32.254.25]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b4865f74002sm1506331366b.42.2025.10.07.14.39.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Oct 2025 14:39:35 -0700 (PDT) From: "=?UTF-8?q?=C5=81ukasz=20Bartosik?=" X-Google-Original-From: =?UTF-8?q?=C5=81ukasz=20Bartosik?= To: Mathias Nyman , Greg Kroah-Hartman Cc: linux-usb@vger.kernel.org, =?UTF-8?q?=C5=81ukasz=20Bartosik?= Subject: [PATCH v2 2/4] xhci: dbc: allow to set serial number through sysfs Date: Tue, 7 Oct 2025 21:39:00 +0000 Message-ID: <20251007213902.2231670-3-ukaszb@google.com> X-Mailer: git-send-email 2.51.0.710.ga91ca5db03-goog In-Reply-To: <20251007213902.2231670-1-ukaszb@google.com> References: <20251007213902.2231670-1-ukaszb@google.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Łukasz Bartosik Add code which allows to set serial number of a DbC device through sysfs. Signed-off-by: Łukasz Bartosik --- .../testing/sysfs-bus-pci-drivers-xhci_hcd | 13 +++++++ drivers/usb/host/xhci-dbgcap.c | 36 +++++++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd index fc82aa4e54b0..071688dbd969 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd +++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd @@ -85,3 +85,16 @@ Description: up to 5000. The default value is 64 ms. This polling interval is used while DbC is enabled but has no active data transfers. + +What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_iSerial +Date: October 2025 +Contact: Łukasz Bartosik +Description: + The dbc_iSerial attribute allows to change the iSerial field + presented in the USB device descriptor by xhci debug device. + Value can only be changed while debug capability (DbC) is in + disabled state to prevent USB device descriptor change while + connected to a USB host. + The default value is "0001". + The field length can be from 1 to 63 characters. + diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c index c2fecaffd6f3..7ad83548ba4d 100644 --- a/drivers/usb/host/xhci-dbgcap.c +++ b/drivers/usb/host/xhci-dbgcap.c @@ -1200,6 +1200,40 @@ static ssize_t dbc_bcdDevice_store(struct device *dev, return size; } +static ssize_t dbc_iSerial_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev)); + struct xhci_dbc *dbc = xhci->dbc; + + return sysfs_emit(buf, "%s\n", dbc->str.serial); +} + +static ssize_t dbc_iSerial_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t size) +{ + struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev)); + struct xhci_dbc *dbc = xhci->dbc; + size_t len; + + if (dbc->state != DS_DISABLED) + return -EBUSY; + + len = strcspn(buf, "\n"); + if (!len) + return -EINVAL; + + if (len > USB_MAX_STRING_LEN/2) + return -E2BIG; + + memcpy(dbc->str.serial, buf, len); + dbc->str.serial[len] = '\0'; + + return size; +} + static ssize_t dbc_bInterfaceProtocol_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -1287,6 +1321,7 @@ static DEVICE_ATTR_RW(dbc); static DEVICE_ATTR_RW(dbc_idVendor); static DEVICE_ATTR_RW(dbc_idProduct); static DEVICE_ATTR_RW(dbc_bcdDevice); +static DEVICE_ATTR_RW(dbc_iSerial); static DEVICE_ATTR_RW(dbc_bInterfaceProtocol); static DEVICE_ATTR_RW(dbc_poll_interval_ms); @@ -1295,6 +1330,7 @@ static struct attribute *dbc_dev_attrs[] = { &dev_attr_dbc_idVendor.attr, &dev_attr_dbc_idProduct.attr, &dev_attr_dbc_bcdDevice.attr, + &dev_attr_dbc_iSerial.attr, &dev_attr_dbc_bInterfaceProtocol.attr, &dev_attr_dbc_poll_interval_ms.attr, NULL -- 2.51.0.710.ga91ca5db03-goog