tty: usb_serial_mos7720: Fix get_lsr_info

I made a correction for get_lsr_info, now it returns some meaningful
information. I tested it with two simultaneous simplex modem channels.

it is attached

Signed-off-by: Kees Schoenmakers <k.schoenmakers@sigmae.nl>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 15 insertions, 4 deletions

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 759cdd5ae74d..4342a8a0eac9 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -378,10 +378,14 @@ static int mos7720_open(struct tty_struct *tty,
          /* Initialize MCS7720 -- Write Init values to corresponding Registers
           *
           * Register Index
+          * 0 : THR/RHR
           * 1 : IER
           * 2 : FCR
           * 3 : LCR
           * 4 : MCR
+          * 5 : LSR
+          * 6 : MSR
+          * 7 : SPR
           *
           * 0x08 : SP1/2 Control Reg
           */
@@ -1250,15 +1254,22 @@ static void mos7720_set_termios(struct tty_struct *tty,
 static int get_lsr_info(struct tty_struct *tty,
                 struct moschip_port *mos7720_port, unsigned int __user *value)
 {
-        int count;
+        struct usb_serial_port *port = tty->driver_data;
         unsigned int result = 0;
+        unsigned char data = 0;
+        int port_number = port->number - port->serial->minor;
+        int count;
 
         count = mos7720_chars_in_buffer(tty);
         if (count == 0) {
-                dbg("%s -- Empty", __func__);
-                result = TIOCSER_TEMT;
+                send_mos_cmd(port->serial, MOS_READ, port_number,
+                                                        UART_LSR, &data);
+                if ((data & (UART_LSR_TEMT | UART_LSR_THRE))
+                                        == (UART_LSR_TEMT | UART_LSR_THRE)) {
+                        dbg("%s -- Empty", __func__);
+                        result = TIOCSER_TEMT;
+                }
         }
-
         if (copy_to_user(value, &result, sizeof(int)))
                 return -EFAULT;
         return 0;