The status bit was found with USB captures of the Windows driver and some luck. Tested on CH340G and CH341A. v2: unify general status definitions Signed-off-by: Grigori Goronzy <greg@xxxxxxxxxxxx> --- drivers/usb/serial/ch341.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c index 78adce7..12a430c 100644 --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -39,9 +39,6 @@ /* third irq byte base 0x94 + below */ /* fourth irq byte normally 0xee */ -/* second interrupt byte */ -#define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */ - /* status returned in third interrupt answer byte, inverted in data from irq */ #define CH341_BIT_CTS 0x01 @@ -81,6 +78,10 @@ #define CH341_LCR_CS6 0x01 #define CH341_LCR_CS5 0x00 +/* General status from register 0x07 and second interrupt byte */ +#define CH341_STATUS_TXBUSY 0x01 +#define CH341_STATUS_MULTI 0x04 + static const struct usb_device_id id_table[] = { { USB_DEVICE(0x4348, 0x5523) }, { USB_DEVICE(0x1a86, 0x7523) }, @@ -94,6 +95,7 @@ struct ch341_private { unsigned baud_rate; /* set baud rate */ u8 line_control; /* set line control value RTS/DTR */ u8 line_status; /* active status of modem control inputs */ + u8 uart_status; /* generic UART status bits */ }; static void ch341_set_termios(struct tty_struct *tty, @@ -184,7 +186,8 @@ static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv) if (r == 2) { r = 0; spin_lock_irqsave(&priv->lock, flags); - priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT; + priv->line_status = (~buffer[0]) & CH341_BITS_MODEM_STAT; + priv->uart_status = buffer[1]; spin_unlock_irqrestore(&priv->lock, flags); } else { r = -EPROTO; @@ -195,6 +198,18 @@ out: return r; } +static bool ch341_tx_empty(struct usb_serial_port *port) +{ + int r; + struct ch341_private *priv = usb_get_serial_port_data(port); + + r = ch341_get_status(port->serial->dev, priv); + if (r < 0) + return true; + + return !(priv->uart_status & CH341_STATUS_TXBUSY); +} + /* -------------------------------------------------------------------------- */ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv) @@ -493,7 +508,7 @@ static void ch341_update_line_status(struct usb_serial_port *port, priv->line_status = status; spin_unlock_irqrestore(&priv->lock, flags); - if (data[1] & CH341_MULT_STAT) + if (data[1] & CH341_STATUS_MULTI) dev_dbg(&port->dev, "Multiple status change\n"); if (!delta) @@ -599,6 +614,7 @@ static struct usb_serial_driver ch341_device = { .carrier_raised = ch341_carrier_raised, .close = ch341_close, .set_termios = ch341_set_termios, + .tx_empty = ch341_tx_empty, .break_ctl = ch341_break_ctl, .tiocmget = ch341_tiocmget, .tiocmset = ch341_tiocmset, -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html