1 files changed, 49 insertions, 9 deletions

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index bb3f9aa4a909..55122ac84518 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -145,6 +145,8 @@ MODULE_DEVICE_TABLE(usb, id_table);
 #define UART_OVERRUN_ERROR		0x40
 #define UART_CTS			0x80
 
+#define PL2303_FLOWCTRL_MASK		0xf0
+
 static void pl2303_set_break(struct usb_serial_port *port, bool enable);
 
 enum pl2303_type {
@@ -156,6 +158,7 @@ enum pl2303_type {
 struct pl2303_type_data {
 	speed_t max_baud_rate;
 	unsigned long quirks;
+	unsigned int no_autoxonxoff:1;
 };
 
 struct pl2303_serial_private {
@@ -173,11 +176,12 @@ struct pl2303_private {
 
 static const struct pl2303_type_data pl2303_type_data[TYPE_COUNT] = {
 	[TYPE_01] = {
-		.max_baud_rate =	1228800,
-		.quirks =		PL2303_QUIRK_LEGACY,
+		.max_baud_rate		= 1228800,
+		.quirks			= PL2303_QUIRK_LEGACY,
+		.no_autoxonxoff		= true,
 	},
 	[TYPE_HX] = {
-		.max_baud_rate =	12000000,
+		.max_baud_rate		= 12000000,
 	},
 };
 
@@ -223,6 +227,29 @@ static int pl2303_vendor_write(struct usb_serial *serial, u16 value, u16 index)
 	return 0;
 }
 
+static int pl2303_update_reg(struct usb_serial *serial, u8 reg, u8 mask, u8 val)
+{
+	int ret = 0;
+	u8 *buf;
+
+	buf = kmalloc(1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = pl2303_vendor_read(serial, reg | 0x80, buf);
+	if (ret)
+		goto out_free;
+
+	*buf &= ~mask;
+	*buf |= val & mask;
+
+	ret = pl2303_vendor_write(serial, reg, *buf);
+out_free:
+	kfree(buf);
+
+	return ret;
+}
+
 static int pl2303_probe(struct usb_serial *serial,
 					const struct usb_device_id *id)
 {
@@ -552,6 +579,20 @@ static bool pl2303_termios_change(const struct ktermios *a, const struct ktermio
 	return tty_termios_hw_change(a, b) || ixon_change;
 }
 
+static bool pl2303_enable_xonxoff(struct tty_struct *tty, const struct pl2303_type_data *type)
+{
+	if (!I_IXON(tty) || I_IXANY(tty))
+		return false;
+
+	if (START_CHAR(tty) != 0x11 || STOP_CHAR(tty) != 0x13)
+		return false;
+
+	if (type->no_autoxonxoff)
+		return false;
+
+	return true;
+}
+
 static void pl2303_set_termios(struct tty_struct *tty,
 		struct usb_serial_port *port, struct ktermios *old_termios)
 {
@@ -678,14 +719,13 @@ static void pl2303_set_termios(struct tty_struct *tty,
 
 	if (C_CRTSCTS(tty)) {
 		if (spriv->quirks & PL2303_QUIRK_LEGACY)
-			pl2303_vendor_write(serial, 0x0, 0x41);
+			pl2303_update_reg(serial, 0, PL2303_FLOWCTRL_MASK, 0x40);
 		else
-			pl2303_vendor_write(serial, 0x0, 0x61);
-	} else if (I_IXON(tty) && !I_IXANY(tty) && START_CHAR(tty) == 0x11 &&
-			STOP_CHAR(tty) == 0x13) {
-		pl2303_vendor_write(serial, 0x0, 0xc0);
+			pl2303_update_reg(serial, 0, PL2303_FLOWCTRL_MASK, 0x60);
+	} else if (pl2303_enable_xonxoff(tty, spriv->type)) {
+		pl2303_update_reg(serial, 0, PL2303_FLOWCTRL_MASK, 0xc0);
 	} else {
-		pl2303_vendor_write(serial, 0x0, 0x0);
+		pl2303_update_reg(serial, 0, PL2303_FLOWCTRL_MASK, 0);
 	}
 
 	kfree(buf);