[PATCH v1 2/4] xhci: dbc: allow to set serial number through sysfs

["Łukasz Bartosik" <ukaszb@chromium.org>]

From: Łukasz Bartosik <ukaszb@chromium.org>

Add code which allows to set serial number of a DbC
device through sysfs.

Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
---
 drivers/usb/host/xhci-dbgcap.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
index c2fecaffd6f3..5cc201afe8f4 100644
--- a/drivers/usb/host/xhci-dbgcap.c
+++ b/drivers/usb/host/xhci-dbgcap.c
@@ -1200,6 +1200,36 @@ 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;
+
+	if (dbc->state != DS_DISABLED)
+		return -EBUSY;
+
+	if (size > USB_MAX_STRING_LEN/2+1)
+		return -E2BIG;
+
+	memcpy(dbc->str.serial, buf, size);
+	/* remove newline and terminate the string */
+	dbc->str.serial[size-1] = '\0';
+
+	return size;
+}
+
 static ssize_t dbc_bInterfaceProtocol_show(struct device *dev,
 				 struct device_attribute *attr,
 				 char *buf)
@@ -1287,6 +1317,7 @@ 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 +1326,7 @@ 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
-- 
2.51.0.536.g15c5d4f767-goog