USB: serial: ftdi_sio: add support for TIOCSERGETLSR

Willem-Jan noticed that the ftdi_sio driver did not support the
TIOCSERGETLSR ioctl, and some userspace programs rely on it.  This patch
adds the support.

Reported-by: Willem-Jan de Hoog <wdehoog@exalondelft.nl>
Tested-by: Willem-Jan de Hoog <wdehoog@exalondelft.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 6a50965e23f..2d338737219 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -75,6 +75,7 @@ struct ftdi_private {
         unsigned long last_dtr_rts;     /* saved modem control outputs */
         wait_queue_head_t delta_msr_wait; /* Used for TIOCMIWAIT */
         char prev_status, diff_status;        /* Used for TIOCMIWAIT */
+        char transmit_empty;    /* If transmitter is empty or not */
         struct usb_serial_port *port;
         __u16 interface;        /* FT2232C, FT2232H or FT4232H port interface
                                    (0 for FT232/245) */
@@ -1322,6 +1323,23 @@ check_and_exit:
         return 0;
 }
 
+static int get_lsr_info(struct usb_serial_port *port,
+                        struct serial_struct __user *retinfo)
+{
+        struct ftdi_private *priv = usb_get_serial_port_data(port);
+        unsigned int result = 0;
+
+        if (!retinfo)
+                return -EFAULT;
+
+        if (priv->transmit_empty)
+                result = TIOCSER_TEMT;
+
+        if (copy_to_user(retinfo, &result, sizeof(unsigned int)))
+                return -EFAULT;
+        return 0;
+}
+
 
 /* Determine type of FTDI chip based on USB config and descriptor. */
 static void ftdi_determine_type(struct usb_serial_port *port)
@@ -1871,6 +1889,12 @@ static int ftdi_process_packet(struct tty_struct *tty,
                         tty_insert_flip_char(tty, 0, TTY_OVERRUN);
         }
 
+        /* save if the transmitter is empty or not */
+        if (packet[1] & FTDI_RS_TEMT)
+                priv->transmit_empty = 1;
+        else
+                priv->transmit_empty = 0;
+
         len -= 2;
         if (!len)
                 return 0;       /* status only */
@@ -2234,6 +2258,9 @@ static int ftdi_ioctl(struct tty_struct *tty, struct file *file,
                         }
                 }
                 return 0;
+        case TIOCSERGETLSR:
+                return get_lsr_info(port, (struct serial_struct __user *)arg);
+                break;
         default:
                 break;
         }