diff mbox series

[v2,4/6] USB: serial: add sysfs attribute to suppress ready signalling on open

Message ID 20220531043707.13427374023E@freecalypso.org
State New
Headers show
Series [v2,1/6] tty: add port flag to suppress ready signalling on open | expand

Commit Message

Mychaela N. Falconia May 31, 2022, 4:37 a.m. UTC 
From: Johan Hovold <johan@kernel.org>

Add a nordy sysfs attribute to suppress raising the modem-control lines
on open to signal DTE readiness.

This can be used to prevent undesirable side-effects on open for
applications where the DTR and RTS lines are used for non-standard
purposes such as generating power-on and reset pulses.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Mychaela N. Falconia <falcon@freecalypso.org>
---
 drivers/usb/serial/bus.c | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/usb/serial/bus.c b/drivers/usb/serial/bus.c
index 9e38142acd38..25f8218b2bce 100644
--- a/drivers/usb/serial/bus.c
+++ b/drivers/usb/serial/bus.c
@@ -29,6 +29,37 @@  static int usb_serial_device_match(struct device *dev,
 	return 0;
 }
 
+static ssize_t nordy_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct usb_serial_port *port = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", tty_port_nordy(&port->port));
+}
+
+static ssize_t nordy_store(struct device *dev, struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct usb_serial_port *port = dev_get_drvdata(dev);
+	bool val;
+	int ret;
+
+	ret = kstrtobool(buf, &val);
+	if (ret)
+		return ret;
+
+	tty_port_set_nordy(&port->port, val);
+
+	return count;
+}
+static DEVICE_ATTR_RW(nordy);
+
+static struct attribute *tty_attrs[] = {
+	&dev_attr_nordy.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(tty);
+
 static int usb_serial_device_probe(struct device *dev)
 {
 	struct usb_serial_port *port = to_usb_serial_port(dev);
@@ -50,8 +81,8 @@  static int usb_serial_device_probe(struct device *dev)
 	}
 
 	minor = port->minor;
-	tty_dev = tty_port_register_device(&port->port, usb_serial_tty_driver,
-					   minor, dev);
+	tty_dev = tty_port_register_device_attr(&port->port,
+			usb_serial_tty_driver, minor, dev, port, tty_groups);
 	if (IS_ERR(tty_dev)) {
 		retval = PTR_ERR(tty_dev);
 		goto err_port_remove;