[PATCH -next] USB: serial: pl2303: implement reset_resume member

[Hongyu Xie]

From: Hongyu Xie <xiehongyu1@xxxxxxxxxx>

pl2303.c doesn't have reset_resume for hibernation.
So needs_binding will be set to 1 duiring hibernation.
usb_forced_unbind_intf will be called, and the port minor
will be released (x in ttyUSBx).
It works fine if you have only one USB-to-serial device.
Assume you have 2 USB-to-serial device, nameing A and B.
A gets a smaller minor(ttyUSB0), B gets a bigger one.
And start to hibernate. When your PC is in hibernation,
unplug device A. Then wake up your PC by pressing the
power button. After waking up the whole system, device
B gets ttyUSB0. This will casuse a problem if you were
using those to ports(like opened two minicom process)
before hibernation.
So member reset_resume is needed in usb_serial_driver
pl2303_device.
Codes in pl2303_reset_resume are borrowed from pl2303_open.

As a matter of fact, all driver under drivers/usb/serial
has the same problem except ch341.c.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Hongyu Xie <xiehongyu1@xxxxxxxxxx>
Reported-by: sheng.huang <sheng.huang@xxxxxxxxxxxx>
---
 drivers/usb/serial/pl2303.c | 48 +++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 88b284d61681..7cc05123b88c 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -1218,6 +1218,53 @@ static void pl2303_process_read_urb(struct urb *urb)
 	tty_flip_buffer_push(&port->port);
 }
 
+static int pl2303_configure(struct usb_serial *serial, struct pl2303_serial_private *priv)
+{
+	struct usb_serial_port *port = serial->port[0];
+
+	if (priv->quirks & PL2303_QUIRK_LEGACY) {
+		usb_clear_halt(serial->dev, port->write_urb->pipe);
+		usb_clear_halt(serial->dev, port->read_urb->pipe);
+	} else {
+		/* reset upstream data pipes */
+		if (priv->type == &pl2303_type_data[TYPE_HXN])
+			pl2303_vendor_write(serial, PL2303_HXN_RESET_REG,
+					PL2303_HXN_RESET_UPSTREAM_PIPE |
+					PL2303_HXN_RESET_DOWNSTREAM_PIPE);
+		else {
+			pl2303_vendor_write(serial, 8, 0);
+			pl2303_vendor_write(serial, 9, 0);
+		}
+	}
+	return 0;
+}
+
+static int pl2303_reset_resume(struct usb_serial *serial)
+{
+	struct usb_serial_port *port = serial->port[0];
+	struct pl2303_serial_private *priv = usb_get_serial_port_data(port);
+	struct tty_struct *tty = tty_port_tty_get(&port->port);
+	int ret;
+
+	/* reconfigure pl2303 serial port after bus-reset */
+	pl2303_configure(serial, priv);
+
+	/* Setup termios */
+	if (tty)
+		pl2303_set_termios(tty, port, NULL);
+
+	if (tty_port_initialized(&port->port)) {
+		ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
+		if (ret) {
+			dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
+				ret);
+			return ret;
+		}
+	}
+
+	return usb_serial_generic_resume(serial);
+}
+
 static struct usb_serial_driver pl2303_device = {
 	.driver = {
 		.owner =	THIS_MODULE,
@@ -1246,6 +1293,7 @@ static struct usb_serial_driver pl2303_device = {
 	.release =		pl2303_release,
 	.port_probe =		pl2303_port_probe,
 	.port_remove =		pl2303_port_remove,
+	.reset_resume =         pl2303_reset_resume,
 };
 
 static struct usb_serial_driver * const serial_drivers[] = {
-- 
2.25.1