1 files changed, 34 insertions, 5 deletions

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 4281f2bfe0e1..3778685c7b99 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -355,6 +355,9 @@ static struct usb_serial_driver * const serial_drivers[] = {
 #define CP210X_PARTNUM_CP2104	0x04
 #define CP210X_PARTNUM_CP2105	0x05
 #define CP210X_PARTNUM_CP2108	0x08
+#define CP210X_PARTNUM_CP2102N_QFN28	0x20
+#define CP210X_PARTNUM_CP2102N_QFN24	0x21
+#define CP210X_PARTNUM_CP2102N_QFN20	0x22
 #define CP210X_PARTNUM_UNKNOWN	0xFF
 
 /* CP210X_GET_COMM_STATUS returns these 0x13 bytes */
@@ -454,6 +457,15 @@ struct cp210x_gpio_write {
 	u8	state;
 } __packed;
 
+static bool cp210x_is_cp2102n(struct usb_serial *serial)
+{
+	struct cp210x_serial_private *priv = usb_get_serial_data(serial);
+
+	return	(priv->partnum == CP210X_PARTNUM_CP2102N_QFN28) ||
+		(priv->partnum == CP210X_PARTNUM_CP2102N_QFN24) ||
+		(priv->partnum == CP210X_PARTNUM_CP2102N_QFN20);
+}
+
 /*
  * Helper to get interface number when we only have struct usb_serial.
  */
@@ -1053,20 +1065,32 @@ static speed_t cp210x_get_an205_rate(speed_t baud)
 static void cp210x_change_speed(struct tty_struct *tty,
 		struct usb_serial_port *port, struct ktermios *old_termios)
 {
-	struct cp210x_serial_private *priv = usb_get_serial_data(port->serial);
+	struct usb_serial *serial = port->serial;
+	struct cp210x_serial_private *priv = usb_get_serial_data(serial);
 	u32 baud;
 
 	baud = tty->termios.c_ospeed;
 
-	/* This maps the requested rate to a rate valid on cp2102 or cp2103,
-	 * or to an arbitrary rate in [1M, max_speed]
+	/*
+	 * This maps the requested rate to the actual rate on cp2102n, a valid
+	 * rate on cp2102 or cp2103, or to an arbitrary rate in
+	 * [1M, max_speed].
 	 *
 	 * NOTE: B0 is not implemented.
 	 */
-	if (baud < 1000000)
+	if (cp210x_is_cp2102n(serial)) {
+		int clk_div;
+		int prescaler;
+
+		baud = clamp(baud, 300u, priv->max_speed);
+		prescaler = (baud <= 365) ? 4 : 1;
+		clk_div = DIV_ROUND_CLOSEST(48000000, 2 * prescaler * baud);
+		baud = 48000000 / (2 * prescaler * clk_div);
+	} else if (baud < 1000000) {
 		baud = cp210x_get_an205_rate(baud);
-	else if (baud > priv->max_speed)
+	} else if (baud > priv->max_speed) {
 		baud = priv->max_speed;
+	}
 
 	dev_dbg(&port->dev, "%s - setting baud rate to %u\n", __func__, baud);
 	if (cp210x_write_u32_reg(port, CP210X_SET_BAUDRATE, baud)) {
@@ -1520,6 +1544,11 @@ static void cp210x_init_max_speed(struct usb_serial *serial)
 		else
 			max = 921600;	/* SCI */
 		break;
+	case CP210X_PARTNUM_CP2102N_QFN28:
+	case CP210X_PARTNUM_CP2102N_QFN24:
+	case CP210X_PARTNUM_CP2102N_QFN20:
+		max = 3000000;
+		break;
 	default:
 		max = 2000000;
 		break;